Preliminary Rail Design

Report

DraftMarch 2012

This document forms part of the Rowville Rail Feasibility Report and should be read in the context of the broader report. The study team, including SKM, Mott MacDonald, Hassell and Phoenix Facilitation, have prepared this report following appointment by the Victorian State Government.

The Rowville Rail Feasibility Report is a study investigating the feasibility of a heavy rail line from Rowville connecting into the existing train network at Huntingdale Station on the Pakenham/Cranbourne lines. This is Phase 1 of a two part study investigating initial engineering, architectural, environmental and operational considerations. It has also included consultation with the community and stakeholders through various methods.

The overall Rowville Rail Feasibility Report is made up of 8 parts:

Main report Preliminary rail design report Travel demand modelling report Sustainability considerations report Environment and planning investigation report Station layout and urban design report Consultation report Concept timetabling and operations report

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Table of Contents

1. Engineering Summary ................................................................................................... 5

2. Design Brief .................................................................................................................... 6

3. Basis of Design .............................................................................................................. 6

4. Physical constraints and opportunities ...................................................................... 7

5. Alignment Options ....................................................................................................... 10

6. Alignment Option Selection ........................................................................................ 13

7. Civil Structures Required ............................................................................................ 30

7.1 Introduction ...................................................................................................... 30

7.2 Tunnel cross section requirements .................................................................. 34

7.3 Cut-and-cover tunnel ........................................................................................ 36

7.4 Open Cut .......................................................................................................... 38

7.5 Elevated Sections (Viaduct) ............................................................................. 41

7.5.1 Typical Design Elements ............................................................................ 42

7.5.2 Elevated Station Design .............................................................................. 47

7.5.3 Approach Ramps and Tunnel Portals ......................................................... 49

7.5.4 Trackform .................................................................................................... 49

7.5.5 Design issues .............................................................................................. 49

7.5.6 Construction Issues .................................................................................... 53

7.6 Bridges ............................................................................................................. 57

7.6.1 Princes Highway grade separation ............................................................. 57

7.6.2 Monash Freeway grade separation ............................................................ 57

7.6.3 East Link grade separation, Alignment A or A* ........................................... 57

7.6.4 East Link grade separation, Alignment C .................................................... 57

7.7 Sprayed Concrete Lined Tunnel ...................................................................... 58

7.8 TBM Bored tunnel ............................................................................................ 62

7.8.1 General Principles ....................................................................................... 62

7.8.2 Twin tunnels versus single bore .................................................................. 64

7.9 Station design .................................................................................................. 66

7.9.1 Underground Stations ................................................................................. 66

7.9.2 Elevated Stations ........................................................................................ 67

7.10 Fire and Life Safety .......................................................................................... 68

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7.10.1 Fire Engineering Process ............................................................................ 68

7.10.2 Applicable Legislation & Standards ............................................................ 68

7.10.3 Principal Characteristics ............................................................................. 69

7.10.4 Fire Safety Objectives ................................................................................. 70

7.10.5 Fire Hazards & Risks .................................................................................. 70

7.10.6 Concept Requirements -Tunnels ................................................................ 71

7.10.7 Concept Requirements - Stations ............................................................... 72

7.11 Ventilation Concepts ........................................................................................ 74

7.11.1 Tunnel Ventilation System .......................................................................... 74

7.11.2 Station Ventilation ....................................................................................... 74

7.11.3 Public and Back of House Areas ................................................................ 75

7.11.4 Incident Ventilation Operations ................................................................... 75

7.12 Drainage ........................................................................................................... 78

8. Signalling ...................................................................................................................... 79

8.1 Basis of Design ................................................................................................ 79

8.2 Existing infrastructure ....................................................................................... 79

8.3 Implementing new Rowville Rail Link ............................................................... 80

9. Traction Power and Overhead Line Electrification ................................................... 84

9.1 Power ............................................................................................................... 84

9.1.1 Tie Stations ................................................................................................. 84

9.1.2 Substations ................................................................................................. 84

9.1.3 Rowville Line Power Requirements ............................................................ 85

9.2 Electrolysis ....................................................................................................... 86

9.3 Overhead ......................................................................................................... 87

9.3.1 Conductors .................................................................................................. 88

9.3.2 Interface with Dandenong corridor .............................................................. 88

9.3.3 Open route .................................................................................................. 88

9.3.4 Elevated and viaducts ................................................................................. 89

9.3.5 Tunnels and restricted space ...................................................................... 89

9.3.6 Stabling ...................................................................................................... 95

10. Railway Communication ............................................................................................. 96

11. Constructability .......................................................................................................... 99

11.1 Project Timeline ............................................................................................... 99

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11.2 Noise and vibration impacts ............................................................................. 99

11.3 Temporary access Shafts .............................................................................. 100

11.3.1 Cut and Cover Tunnel ............................................................................... 100

11.3.2 Road Header Tunnel ................................................................................. 100

11.3.3 TBM Tunnel .............................................................................................. 100

11.4 Construction Method ...................................................................................... 101

11.4.1 Overall Alignment Considerations ............................................................. 101

11.4.2 Station areas ............................................................................................. 101

11.4.3 Below Ground Alignment .......................................................................... 105

11.4.4 Viaducts .................................................................................................... 112

11.4.5 Railway Infrastructure (Tracks, Power and Signalling) ............................. 113

11.5 Work Sites ...................................................................................................... 113

11.6 Traffic Management ....................................................................................... 115

11.6.1 Huntingdale Station Precinct ..................................................................... 116

11.6.2 North and Wellington Roads ..................................................................... 117

11.6.3 Stud Road and Rowville Station Precinct.................................................. 117

11.6.4 Major Road Crossings .............................................................................. 117

11.7 Maintenance Access Requirements ............................................................... 118

11.8 Protection of Operational Rail Infrastructure .................................................. 118

11.9 Operational Requirements ............................................................................. 120

11.10 Rail, Road and Pedestrian Protection Measures ........................................... 120

12. Railway Operational Safety ....................................................................................... 122

13. Operational Maintenance .......................................................................................... 122

14. Developments from Previous Report ...................................................................... 123

14.1 Knox City Council report Rowville Railway Pre-Feasibility Study 2004 ......... 123

15. Conclusion ................................................................................................................. 125

Appendix A: Civil structures

Appendix B: Signalling Schematic

Appendix C: Overhead Line and Power Schematic

Appendix D: Project Timeline

Appendix E: Tunnelling Advice

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Appendix F: Geotechnical Report

Appendix G: Utilities Information

Appendix H: Alignment Drawings

Appendix I: Flood Levels

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1. Engineering Summary

This report is based on a through suburban electric train service between Melbourne CBD and Rowville. The alignment generally follows Wellington Road, with two options shown for the approach to Rowville. Buried and elevated track would require engineering structures with options for these presented in the report, and a number of alternative vertical alignment options are shown on the alignment drawings.

The issues relating to the construction phase are reviewed, and ideas for managing these are documented.

From Huntingdale station towards Rowville, on leaving Huntingdale the Rowville line is shown located underground under the North Road flyover. Demolition of a small area of existing buildings on the south side of North Road would be required, unless a short length of mined tunnel is used, or a reduced radius curve with corresponding reduced line speed. The report discusses high level engineering options for the redeveloped Huntingdale Station.

Along North Road to Monash Station the central median generally provides suitable corridor width for open cut construction, with bridges to provide road crossings. Cut and cover construction would provide additional amenity value at ground level.

To the east of Monash Station the ground level drops relatively sharply, indicating viaduct construction as appropriate on track alignment grounds. The viaduct would extend to the east of Mulgrave Station. From there the alignment descends below ground level on the east side of the Monash Freeway.

High ground, and the need to remove a peak in the track alignment, require the track to pass below ground level at Waverley Park Station. The tunnel emerges from the ground onto viaduct, on the north side of Wellington Road, adjacent to Jacksons Road, before the Dandenong Valley Parklands.

Two main options exist for the approach to the terminal station across the Dandenong Creek flood plain crossing beneath Stud Road into the Stud Park shopping centre area, or alternatively following Wellington Road below ground, curving northwards at Stud Road. An alternative location for Rowville station on the corner of Wellington and Stud Roads has also been considered.

Buried and elevated structures would be required to account for ground topography and other alignment constraints. At this stage of the design process, it is considered feasible for cut and cover construction methods to be used for a large majority of the route requiring buried track. However, alternatives are considered in this report. Precast concrete viaduct is suggested for the elevated structure.

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Timescales for construction are anticipated to be in the order of four years from start of site works to commissioning, with a significant lead-in period for design, procurement and planning. Temporary lane closures or diversions would most likely be required in order to provide sufficient space for construction operations.

2. Design Brief

The Department of Transport document Feasibility Study for the proposed Rowville Rail Line, Study Brief, 25 March 2011 in conjunction with the SKM document Technical Investigation Plan Rowville Rail Study, 29 June 2011, form the brief for this report.

3. Basis of Design

The following functionality and other requirements have been used in this engineering study: The proposed Rowville Railway line will provide a high quality heavy rail link to Monash

and Knox communities The project will support new services from Huntingdale to Rowville via Monash

University Dual Tracks to be provided from Huntingdale to Rowville May be constructed in stages Stabling and turn-back facilities to be addressed Options for connection to the Dandenong rail corridor at Huntingdale and track

configurations Existing structures to be assessed at high level It is desirable that the line between Huntingdale and Rowville should cater for an

operational speed of at least 130km/h and 80km/h through tunnels Minimum three trains per hour initially, with provision for 6 trains per hour as the

Dandenong Corridor is upgraded Normal standards apply for track geometry including: maximum track gradient 2%

generally and 0.66% at stations for straight track Construction timescale to be addressed Consideration needed for the natural and built environments, and sustainability Maintain, in some form, the existing pedestrian and cycle functionality currently located

in the central reserve between Huntingdale station area and Clayton Road, or state reasons why this is not possible

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4. Physical constraints and opportunities

The alignment lies generally in an existing well developed urban setting with many roads potentially intersected by the track alignment. Therefore, the alignment would be predominantly on viaduct or below ground. The alignment drawings are shown in Appendix H.

Set out in the following table is a summary of the significant physical constraints to the rail alignment along the route.

Significant physical constraints along the track alignment from

West to East

Constraint Implication for alignment

Rail connection to Dandenong rail corridor

Rail connection should provide a grade separated junction, with the Rowville track profile either over or under the existing Dandenong tracks

Suitable location of Huntingdale station post commissioning Rowville line

Rowville tracks connecting into the Dandenong line using an elevated grade separated alignment would require the Rowville platforms to be located approximately 200m north (towards Melbourne) than the existing platforms, this is probably too far for a reasonable interchange with busses. Rowville tracks connecting via a below ground alignment would enable the Rowville platforms to be located below but in the same plan location as the existing station Redevelopment of the station would be required for either option

Future Dandenong Rail Corridor rail lines

The alignment does not preclude, at high level concept stage, possible future tracks which may be provided as part of upgrade works which are currently undefined

North Road Flyover Major highway bridge immediately South of Huntingdale Station

This road bridge constrains the option of an elevated departure from Huntingdale station. New elevated track should lie on north side of North Rd to avoid extreme elevation required to cross the flyover. This would require property acquisitions. The elevated structure span over the North Road northern (eastbound) approach road would be at a skew requiring orthogonal cross spans or a single span of approximately 100m. New track passing to the south of the flyover should be at-grade or below ground level, to avoid clashes with existing infrastructure. The foundations for the flyover structure would require protection and may affect the alignment

Oakleigh Army Barracks The barracks fronting North Road may constrain the ability to construct shallow tunnel they may require demolition and re-construction, or a smaller radius curve to avoid them. The small commercial single storey building at 1340 North Road is similarly a constraint.

High ground on East side of Princes Highway

Creates significant incline for track from Huntingdale Station to Princes Highway that, due to steep topography, precludes use of viaduct along this section and indicates track should be below ground level.

Road median width east of Monash University station area

The below ground railway breaks ground at this area, it is desirable that the portal structure fits within the median width. Local road lane reconfigurations may be required

Undulating ground between Variable height viaduct, or variable depth buried structure, to smooth peaks

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Significant physical constraints along the track alignment from

West to East Blackburn Road and Monash Freeway

and troughs to minimise power requirement

Monash Freeway and Wellington Road flyover

Track level to match Wellington Road as cannot be lowered as would impact major bridge and Monash Freeway Track level above road would not accomplish any useful end

High ground on East side of Monash freeway

To avoid excessive gradients, track must be below ground. The track would be at significant depth below ground to provide gradient on east side meeting standards A station in this area would have platforms below ground

Jacksons Road Important right turn provision exists at this junction, which coincides with the location that the rail line breaks ground

Dandenong Creek flood plain Flood level and freeboard requirement beneath structure would dictate rail elevation

Power Transmission lines Clearance between rail infrastructure and power lines required

EastLink Clearance above EastLink is required, in close proximity to the constraint provided by the power transmission lines

Approach to Stud Park Shopping Centre (Alignment A*)

1) Heritage building 2) Housing and social buildings property acquisitions likely 3) Stud Road track would need to be below ground 4) Topography this means the station would be deep

East Link (Alignment C) Track level at grade, above Wellington Road, or diverted to the north or south, to avoid impact on major bridge and Monash Freeway Track level above road would avoid significant disruption to the existing road intersection (on and off ramps, existing traffic light changes and provision of U-turn for Wellington Road traffic)

Power transmission lines over Wellington Road

Use of cut-and-cover or bored tunnel, because at-grade or viaduct would infringe clearance to power lines

Wellington Road Median east of Eastlink

A number of right turn lanes exist to the east of Eastlink, which coincide with the rail lines below ground/above ground interface point

Rowville Main Drain beneath Wellington Road

Profile of the below ground track needs to be sufficiently deep to avoid affecting surface drainage

North side of Wellington Road from EastLink to Stud Road - little land width available also entrances to industrial area properties

South side of Wellington Road may offer a better corridor for open-cut alongside Wellington Road

Existing buildings on north west corner of Wellington/Stud Road intersection

Both options would require tunnel beneath buildings and therefore possible property acquisitions

Existing housing at Rowville on West Side of Stud Road bounded by Waradgery Drive and Lakeview Avenue

Forms a barrier to open-cut and viaduct construction

Stud Road limited width The east side of Stud Road has a corridor of land that should be wide

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Significant physical constraints along the track alignment from

West to East

enough for open-cut or for diverted road carriage way. If not, viaduct construction would be the most economic solution, but is close to residential properties.

Existing utilities and services Other than the power transmission lines mentioned above there are no major existing utilities or services impacted by the rail alignment that would provide a significant constraint to the track alignment. See Appendix G for details of the major utilities identified.

Biggest physical opportunities along the track alignment from

West to East

Opportunity Implication for alignment

Width of median strip/width of North Road corridor

Open-cut track section can be used along the median in locations where there is no right turn lane reducing median width. It would require suitable barriers to separate the highway traffic and the railway (some at-grade overbridges would be required to maintain road system function from side roads). Cut and cover would be needed at right turn lane locations.

Strip of land on south edge of Wellington Road from EastLink to Stud Road (Wellington Road option)

Allows space for open-cut or viaduct track section for Alignment C into Rowville

Strip of land on east edge of Stud Road from Wellington Road to Stud Park shopping centre

Allows space for track for Alignment B* or C into Rowville

Strip of land between EastLink and Stud Road lying between the industrial area on the north side of Wellington Road and Kingston Links golf course

Allows space for an open-cut /at-grade relatively low cost / lowest cost entry to Rowville on Alignment B but restricted by unfavourable station location at Stamford Inn or Alignment B* with a more favourable station location at Stud Park shopping centre but requiring the demolition of significant quantity of residential properties near Stamford Inn.(this alignment option has not been taken further)

Undeveloped areas either side of Eastlink: Dandenong Valley Parklands South of Caribbean Lake

Allows space for an viaduct/at-grade /open-cut entry to Rowville on Alignment A and A* to a favoured station location at Stud Park shopping centre

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5. Alignment Options

Referring to the alignment plan drawings contained in Appendix H, it is useful to consider the alignment in three sections

West end Huntingdale Station connection

Central section along North Road and Wellington Road

East end at Rowville In the central section the track alignment would be along the road median, or nearly so, with its position refined to reduce the impact on existing roads and services, and to optimise the location of new stations.

West end at Huntingdale Station connection options

A reduced service in the form of a shuttle service only between Rowville and Huntingdale opens up the possibility of a single track connection at Huntingdale. The options are:

a) Re-locate Huntingdale station northward towards Flinders St and provide an elevated track to Rowville curving on viaduct on the north side of North Road to a twin track viaduct along North Road

b) Provide an at-grade track southward under North Road flyover looping and climbing Eastward to a twin track viaduct along North Road

We have not taken this option further because it does not support the operational requirements of the rail link.

During the study process the likely service pattern of a frequent through service between Rowville and Flinders Street has been confirmed. The options are:

A. Piggy-back tracks at Huntingdale station with the Rowville tracks passing below ground southward under North Road flyover looping and climbing eastward to North Road

B. Relocate Huntingdale station northward towards Flinders St using piggy-back tracks with the Rowville tracks curving on viaduct on the north side of North Road to a twin track viaduct along North Road

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Central section along North Road and Wellington Road

Track would be located generally along the central median, either above or below ground depending on route topography and alignment constraints.

Where cut-and-cover tunnel is adopted the alignment may be best along the centre of one of the existing carriageways so that the other carriageway may be kept open during construction.

Where viaduct is adopted the alignment may be best along the centre of the median which minimises modifications and remedial work to the existing road.

East end at Rowville alignment options

The initial options for the approach to Rowville have been identified in Figure 1, described as A, A*, B, B* and C. As the study progressed, these options have been refined and named Golf Course North, Golf Course South and Wellington Road approaches.

Option A/A* (Golf Course North)

Option A entirely avoids existing buildings, and alignment A* provides a direct route to perhaps the most favourable station location for the future developed Rowville although residential property acquisition would be required.

Option B (Golf Course South)

It avoids existing buildings and provides a direct route without property acquisition to a station in the area of the Stamford Inn car-park.

Option B* (Golf Course South)

As B above except the track curves northward across residential housing and the Stamford Inn area to Stud Road and on to a station near the existing shopping centre. Residential property acquisition would be required.

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Option C (Wellington Road)

A similar concept to the heavy rail options in the Knox Report but with a simplified curve at the Wellington Road/Stud Road junction. This avoids residential property acquisition but some commercial property acquisition would be needed

Figure 1: East End at Rowville Alignment Options

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6. Alignment Option Selection

Alignment options and discussion

Rail Connection at Huntingdale An extract of the alignment drawing is below:

Option 1: Tracks on elevated structure and alignment is north of North Road (see

next sheet for layout plan at North Road) Characteristics:

Huntingdale station would be relocated in the up direction (towards Melbourne) to provide space for the curve into North Road. Track would be elevated on viaduct on the north side of North Road, and along North Road

Issues: requires the station to be relocated 200m further away from the

transport interchange requires property acquisition on north side of North Road long span required to clear North Road approach at skew noise and visual impact on local residents due to elevated position existing road intersections would be affected at the transition area

between the elevated track and below ground track Advantages:

likely lower cost than Option 2 which uses buried track

Option 2: Tracks below ground on alignment south of North Road Characteristics:

The Rowville tracks pass below ground southward under the North Road flyover looping and climbing Eastward to North Road

Issues: would need to avoid existing North Road flyover foundations (a

detailed investigation would be needed to quantify the impact) would significantly affect the Army Barracks and also the adjacent

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Alignment options and discussion

small single storey building (this could be avoided by a smaller radius curve with corresponding reduction in design speed to 65km/h

Advantages: Makes use of land area which in the most part is not built up retains the existing location of Huntingdale station which is well

suited for bus interchange Rail Connection at Huntingdale: conclusion

The preferred option is Option 2: tracks below ground on an alignment to the south of North Road. The tunnelling method would depend on availability of the Army barracks site for open excavations for cut and cover construction, which depends on agreements to be addressed as the scheme develops, and on the cost comparison between the different tunnelling types. Alternatively reducing the design speed of the railway to 65km/h at this location would mean the alignment could be adjusted to avoid the buildings. Section 7.1 describes the tunnel types in more detail. It would be worthwhile to investigate further during the next design stage the possibility of a shallow tunnel beneath the barracks without demolition (the Eastern Busway project in Brisbane accomplished a shallow tunnel with 5m cover and 10mm recorded settlement), this would require a detailed assessment of the ground conditions and acceptable settlement limits for the building. The major factor in this recommendation is moving Huntingdale station further away from the bus interchange (a requirement of Option 1) would reduce the interchange functionality, and additionally the elevated alignment would have a significant impact on road intersections along North Road. Station constructability considerations would suggest constructing the new platforms parallel to and off-line from the existing platforms, as described in more detail in Section 11 (Constructability).

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Alignment options and discussion

North Road (Huntingdale to Princes Highway)

An extract of the alignment drawing is below, from west (top) to east (bottom):

The North Road transport corridor has a varying width of 50-60m and comprises six

through traffic lanes, two bus lanes, an 18-20m median with cycle/foot path and relatively narrow verges. In order to limit traffic disruption during the construction stage, the median is the most suitable location for the railway, with the existing cycle/foot path moved to a re-modelled verge area. Option 1: Tracks on elevated structure

Characteristics:

the elevated structure would run along road median Issues:

the largely residential nature of the area would act against this option undulating ground would require the smoothed rail alignment to be

raised to provide clearance above high points on the ground and therefore significant structure height

noise and vibration issues associated with this structure type urban planning issues of a major elevated structure scale and

height in residential area Advantages:

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Alignment options and discussion

would enable a shallow or ground level Monash University station better travel experience for rail passengers (natural light and views) likely to be lower cost than the below ground option

Option 2: Tracks below ground

Characteristics:

the railway would run below ground, most likely within the central median

Issues: costs for buried rail would be higher than elevated shallow tunnel may cause noise and vibration issues at the surface requires the Monash University station to be at significant depth

below ground level groundwater flows may be disrupted by the structure, requiring

diversion drainage services such as sewers crossing Wellington Road would need to be

intercepted and diverted Advantages:

lower urban planning impact than elevated structure

Option 3: Tracks at grade with shallow cuttings and embankments Characteristics:

the railway would be as close to ground level as possible, within the central median

Issues: unacceptable effects on existing road intersections would cause an impermeable barrier along North Road preventing

pedestrians, vehicles and cyclists from crossing noise and vibration issues difficult to achieve without significant retaining walls due to ground

topography Advantages:

lower cost than alternatives

North Road: conclusion The preferred option is Option 2: tracks below ground. The alignment would be along the central median unless planning at detailed design stage indicated advantages of placing the tracks below one or more trafficked lanes, using cut and

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Alignment options and discussion

cover construction. The elevated structure and at-grade track options would generate unacceptably high negative urban planning issues. Option 1: tracks on elevated structure, is not recommended, largely because the undulating ground would require the smoothed rail alignment to be raised to provide clearance above high points on the ground meaning significant structure height. The impact on local residences is considered too high. Additionally traversing the Princes Highway would require a significant engineering structure to span across the intersection without the addition of piers within the intersection area. The construction of tracks below ground could be by a number of methods, described generally as either open cut structure or buried structure. The open cut structure would provide light and natural ventilation, but would require substantial traffic safety barriers which have a tendency to restrict the ability for road users to cross Wellington Road. Road crossing points could be provided by bridges to reduce the barrier effect. A buried structure could be provided by either a cut and cover structure or driven/bored tunnelling methods. Section 7.1 describes the tunnel types in more detail. A major advantage of the cut and cover option is the shallower depth of the rail compared to a bored tunnel, therefore allowing a shallower Monash University station. The most cost effective method of construction would be the open cut and alternatively cut and cover, although the method of providing the buried structure could be reviewed at detailed design stage. However, management of the existing gravity drainage (surface water and sewage), other services, and also the groundwater flow, would need to be addressed. This is considered a manageable issue and would require interceptor and diversion works.

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Alignment options and discussion

Monash University Area An extract of the alignment drawing is below:

This area is on hill, which dictates a below ground station. With the railway approaching from Huntingdale below ground, the track profile to achieve clearance under the Princes Highway means that the station would be up to 18m deep to rail level. Approaching from Huntingdale on an elevated structure is not preferred for the reasons noted in the description for North Road in the previous section. The station construction could be undertaken by cut and cover method in line with the adjacent railway tunnel construction methodology.

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Alignment options and discussion

Monash University Area to the Monash Freeway

An extract of the alignment drawing is below, from west (top) to east (bottom):

The Wellington Road transport corridor is approximately 40m wide in this area and currently comprises six through traffic lanes, a median of approximately 7m width, a narrow verge and service road on the south side, and wide verge on the north side. The north side verge is a suitable opportunity for encroachment to provide for temporary or permanent traffic diversions, with the railway located along the central median. This road would cross Wellington Road, possibly at grade. The two proposals, although not coordinated, can work together if the road connection makes an at-grade intersection with Wellington Road at a location beneath an elevated rail structure. Further work would be required on this during the next design stage. Option 1: Tracks on elevated structure

Characteristics:

the elevated structure would run along the road central median the gently undulating ground would allow the railway to follow the

contours without an excessively high structure the Mulgrave station would be on an elevated structure

Issues: partly residential nature of the area would act against this option noise and vibration issues associated with this structure type urban planning issues of a major elevated structure scale and

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Alignment options and discussion

height in a residential area Advantages:

better travel experience for rail passengers (natural light and views) likely to be lower cost than the below ground option viaduct piers would fit within the existing central median therefore

avoiding the need for widening the road Option 2: Tracks below ground

Characteristics:

the railway would run below ground, most likely below the central median and two lanes of the existing road

Mulgrave station would be below ground and could be located closer to the residential catchment than for Option 1

Issues: requires the Monash University station to be lowered by a further 7-

10m than Option 1 costs for buried rail would be higher than elevated settlement issues at the surface affecting residential properties shallow sections of tunnel (cut and cover) would require services

diversions noise and vibration issues for shallow sections of tunnel

Advantages: lower urban planning impact than Option 1

Option 3: Tracks at grade with shallow cuttings and embankments

Characteristics:

the railway would run as close to ground level as possible, within a widened central median

Issues: effects on existing road intersections requirement for additional land or retaining walls would require services diversions

Advantages: lower cost than alternatives

The preferred option is Option 1: tracks on elevated structure. The relatively smooth

ground profile in this area is suited to allow a matching rail profile. The alignment would be along the central median, the north side verge is relatively close to properties, so is not the preferred location for the railway.

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Alignment options and discussion

Option 2: tracks below ground, is an alternative. This would be at additional capital cost but with reduced impact on the urban environment. The same design options for tracks below ground are available as described for the North Road section above.

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Alignment options and discussion

Monash Freeway to east of Waverley Park Station An extract of the alignment drawing is below, from west (top) to east (bottom):

The rail profile across the Monash Freeway is a continuation of the rail profile to the west, ie between Monash University and the Monash Freeway. The above ground railway shown for the section to the west allows the railway to be established on a structure at the same elevation as Wellington Road, as it crosses the Monash Freeway. It would be located between the two Wellington Road bridge structures. Should the below ground option be chosen for the area to the west (as described in the text above as an alternative option), then the Monash Freeway crossing would also be below ground, with the two rail profile options joining between the Monash Freeway and Waverley station. Waverley station would be below ground due to the steep ground profile immediately to the east of the station location. This ground profile is steeper than the maximum gradient that is achievable for new railway lines.

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Alignment options and discussion

Jacksons Road An extract of the alignment drawing is below:

The Wellington Road transport corridor is approximately 60m wide in this area and

currently comprises six through traffic lanes, a median of approximately 9m width, a narrow verge and service road on the south side, and wide verge on the north side. The north side verge would be suitable for the railway or alternatively for temporary or permanent traffic diversions. There are significant utility services in this verge. This is an important intersection for traffic turning right from Jacksons Road into Wellington Road and vice versa and, as noted in the plan extract above, would need to be closed to right turning traffic if an at-grade railway was located along the central median. There are two options for the alignment in this area: Option 1: tunnel portal and short length of at-grade track in the north side verge

Characteristics:

tracks would cross below the east bound carriageways, with a tunnel portal at chainage 26400m, and a short section of at-grade track leading to elevated structure at chainage 26600m. In order to maintain the Jacksons/Wellington road intersection, the railway would be located on the north side verge

Issues: the largely residential nature of the area may act against this option

because the at-grade section of track and also the elevated structure to the east would be located closer to residences on the north side

utility diversions may be significant Advantages:

would limit the depth of Waverley Station compared to Option 2 better travel experience for rail passengers (natural light and views) likely to be lower cost that the below ground option

An alternative to Option 1 would be to use the central reserve instead of the north side verge, but this would necessitate closure of right turns at this road junction. Stakeholder feedback has indicated that this is not considered acceptable due to the traffic disruption associated with this alternative.

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Alignment options and discussion

Option 2: tracks below ground

Characteristics:

in order to maintain a rail alignment along the centre of Wellington Road and to protect the Jacksons Road intersection, the railway could be buried

It would require a below ground crossing of the Monash Freeway and therefore is linked to the decisions made for the railway profile from the Springvale Road crossing

Could tie-in to the rail profile on elevated structure to the east at approximate chainage 27000m

Issues: Would involve below ground track beyond the immediate area, at

least from Springvale Road to Jacksons Road and beyond - therefore capital costs for buried rail would be higher

would lower Waverley station compared to Option 1, from 15m to 29m below ground to rail level

would close the Gamett Road junction with Wellington Road unless the tunnel was sufficiently deep, which would lower Waverley station by a further 8m approximately

Advantages: Much lower urban planning impact of the railway line

Option 3: elevated structure over Jacksons Road

Characteristics:

the elevated structure to the east would be extended further west, over the Jacksons Road junction, towards Waverley station, therefore providing clearance above the Jacksons Road junction with Wellington Road

Issues: would require a significantly higher elevated structure to the east of

Jacksons Road (adjacent to residential properties) than Option 1 Advantages:

would not affect the road intersection

The preferred option is Option 1: tunnel portal and short length of at-grade track in the north side verge. This has the advantage of balancing the depth of rail to the west at Waverley station and the height of elevated structure to the east. Services diversions associated with the rail alignment along the north side verge may be a considerable cost. The alternative of tracks below ground would lower Waverley Park station. An elevated structure over the junction would create a structure of approximately 17m (ground to rail level) further east as the ground falls away.

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Rowville Approach From approximately chainage 27000m, there are a number of options for the approach to Rowville and for the station location at Rowville. The following sections describe the three main alignment options, which are compared by the sketch in Figure 1 (page 11): (i) Alignment A/A* (Golf Course North) (ii) Alignment B/B* (Golf Course South) (iii) Alignment C (Wellington Road)

Option (i): Golf Course North Option An extract of the alignment drawing is below, from west (top) to east (bottom):

This option uses an elevated structure across the whole of the flood plain, east and

west of Eastlink, to address flood management concerns, and avoids the heritage homestead building to the west of Stud Road. The approach to Rowville would be under Stud Road to a deep station at Stud Park shopping centre.

Characteristics: elevated structure across the flood plain crosses beneath the power transmission lines crosses over Eastlink located close to a heritage listed building

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crosses beneath Stud Road terminates at a deep station beneath the Stud Road shopping

area Issues:

agreements with third parties needed (power transmission company Melbourne Water, Parks Victoria and private landowners)

requires residential property acquisition close to Stud Park requires substantial amendments to current plans for Caribbean

Business Park the station at Stud Park would be approximately 15m deep to

platforms environmental concerns associated with the wetlands and creek

habitats, and loss of open space

Advantages: straightforward rail profile with small number of constraints sidings would be located close to the station

An alternative to the buried structure approach to Stud Park would be to use an elevated structure over Stud Road. This would be up to 15m in height and would require acquisition of properties on the alignment and would significantly affect adjacent properties. The advantage of this option is that the Stud Park station would be within 4-5m of ground level rather than 15m deep.

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Option (ii): Golf Course South Option This option, shown in Figure 1 (page 11), has not been taken forward and detailed alignment drawings have not been progressed. This option is based on an elevated structure from chainage 27000 (where it leaves

Wellington Road) to a point just east of Eastlink. From then it drops into a buried structure until the termination point at Stud Park station. A significant number of properties would be affected by tunnelling in the vicinity of the Wellington road and Stud Road intersection. The constraint of the 500kV power lines as they currently exist would require the power lines to be raised. With the power lines raised, the elevated structure would continue further east over the Rowville Main Drain (due to gradient constraints the railway would probably not be able to dip underneath the drain) and into a tunnel portal in the vicinity of the housing near the Wellington Road/Stud Road intersection. This option has not been taken forward due to the effect on the residential properties and the need to raise the power lines.

Characteristics: elevated structure across the flood plain crosses over Eastlink crosses under power transmission lines buried structure east of Eastlink terminates at a deep station beneath the Stud Road shopping

area Issues:

considerable property acquisitions may be necessary along the route

flood levels make the rail profile difficult and would require the power transmission cables to be raised

flood risk to the tunnel (depending on chosen location of the tunnel portal)

agreements with third parties needed Advantages:

the station at Stud Park would be less deep than for the Golf Course North option

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Option (iii): Wellington Road Option An extract of the alignment drawing is below, from west (top) to east (bottom) and showing alternative locations for Rowville station:

This option follows Wellington and Stud roads. Moving eastwards, the rail crosses from

the north side verge, to the centre median of Wellington Road. It continues on elevated structure over the Wellington Road intersection with Eastlink, with an option to divert south past the intersection to limit structure height, and from then runs in a buried structure along Wellington Road and along Stud Road. Stud Road has an 8m median with an 18m reserve on the east side. There is also an option of crossing to the south verge and terminating at the corner of Wellington Road and Stud Road at ground level.

Characteristics: elevated structure over the Wellington Road/Eastlink intersection tunnel portal located approximately mid way between Eastlink and Stud

Road, tunnel from there to Stud Park shopping centre either runs along the Wellington Road median or south of Wellington

Road Issues:

the alignment across Eastlink creates undulating rail profile would affect right turns along Wellington Road existing median is narrow where the track would transition from above to

below ground would require substantial lane adjustments The alignment needs to dip under the Rowville Main Drain at chainage

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29700m May require acquisition of the Stamford Inn property

Advantages: fewest property acquisitions required the station at Stud Park would be less deep than for the Golf Course

North option An alternative station location near the intersection of Wellington Road and Stud Road is possible based on an engineering assessment.

Approach to Rowville options: Both Option (i): Golf Course North Option, and Option (iii): Wellington Road Option, are feasible. Option (ii): Golf Course South Option, is not preferred due to the issues noted above.

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7. Civil Structures Required

7.1 Introduction

The permissible maximum gradient of the track and the undulating ground levels would require various structural forms along the route. A further controlling requirement is that the route is to be grade separated at all intersections with track passing either under or over road infrastructure. This section describes the form of civil engineering construction along the track alignment.

The following is a step through the alignment to outline the basic structural needs. The structural types are discussed in detail in further sections of the report. The basic types are:

Open cut Cut and Cover Viaduct Sprayed Concrete Lined (SCL) Tunnel (Sequential Excavation Method) Bored Tunnel by Tunnel Boring Machine (TBM)

The alignment under discussion is shown on the drawings listed in Appendix H and adopts A* (see Figure 1) for the routing into Rowville. Subsequent sections of this report discuss the above structural types in more depth.

Huntingdale

The new underground platforms for Huntingdale station would be constructed in cut and cover in the area presently occupied by car parking and commercial property to the east of the existing Huntingdale station, or alternatively in a piggyback formation beneath the existing platforms.

The down line would depart from the mainline in a decline structure passing into cut and cover and thence into the station box.

The up line would emerge from the station box in SCL tunnel in order to pass under the main lines and then pass into open cut to ascend to join the main up line.

This approach would allow the least disruption to the mainline as only the tie-ins would require rail occupation.

If the platforms can be located to the east of the existing station, the effect on the existing station would be small. It may be decided to refurbish the station to blend in with the new section however it is unlikely that this would disrupt the mainline any more than a conventional station refurbishment.

At the south end of the station the alignment would be required to negotiate the foundations of the North Road overbridge, North Road itself, Huntingdale Road and the Oakleigh Army

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Barracks. While cut and cover involving building demolition is an option, an SCL tunnel serviced from the station box would avoid these interfaces and depending on building foundation depth allow the barracks to remain.

The SCL tunnel would join cut and cover construction under the median of North Road at chainage 19100 having passed under the intersection leaving that intersection intact. The length of SCL tunnel from the Huntingdale Station box would be 750m.

North Road

The wide median in North Road allows structural form to be cut and cover. Safe maintenance of the cycle path presently routed long the median would be required. This might be achieved by temporarily combining with the side footways.

There are five crossing points through the median to service local roads. Although these could possibly be reduced in number those remaining would dictate the level of the railway.

The options are for the railway to be in cut and cover thus enabling the median to be restored as currently laid out or to have deep open cut with overbridges at the median crossing points. Open cut may have advantages in reducing the ventilation requirements but has the disadvantages of removing the median amenity and requiring safety measures in the form of crash barriers and high mesh fencing to avoid errant vehicles or their loads from reaching the railway. Right turns would be affected by an open cut structure and therefore cut and cover may need to be used at certain locations

Princes Highway Area

The intersection of Princes Highway with North Road (Wellington Road to the east) is a major and complex junction. It can be negotiated either in staged cut and cover construction or by SCL tunnel.

The location of Monash Station may have a bearing on the selection of construction type. If Monash station is located within the car parking zone of the university precinct then the alignment would have to pass from the median to the north side of Wellington Road and would therefore impact the east bound carriageway of Wellington Road. This station location would therefore favour the use of SCL tunnel not only to negotiate the Princes Highway junction but also cross the carriageway all without interruption to traffic. SCL tunnel might also better facilitate the separation of the tracks to allow an island platform at Monash.

Monash Station

Monash station as shown on the alignment plans would be constructed by cut and cover either under Wellington Road or biased towards the university precinct. Acceptable horizontal alignment and the location of buildings fronting Wellington Road at either end of the university parking area would dictate the station location.

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During construction the lost parking could be re-provided using temporary or permanent multistorey car parks.

Monash Station to Blackburn Road

From the east end of Monash Station the structural form would change from cut and cover or SCL tunnel if the latter is thought preferable to return to the Wellington Road median and close up the distance between the tracks if island platform configuration is used at Monash. The alignment would then emerge in a portal structure and after a short length at grade onto viaduct structure to pass over Blackburn Road.

Blackburn Road to Monash Freeway

The alignment would continue on twin track viaduct. An elevated Mulgrave Station would be constructed adjacent to Springvale Road. On the way to chainage 24850 the structure would lower to at grade either side of the Monash Freeway and pass over the freeway in the space provided between the existing Wellington Road overbridges. Construction would be similar viaduct throughout with no change in concept for crossing the freeway.

Monash Freeway to Jacksons Road

Here the scenario is similar to Monash station in that the Waverley Park Station would be constructed in cut and cover either under Wellington Road or biased to one side of it. Cut and cover or SCL tunnel would be used either side of the station before emerging into open cut. The construction of the station would involve fewer traffic plans and disruption to traffic if its foot print was removed from beneath the intersection of Wellington Road and Jells Road. Again SCL tunnel would have benefit in diverging the tracks if island platforms were used without disturbing additional widths of road corridor. Emerging from the sloping ground, the viaduct would need to be located in the north side verge, as described in section 6, to allow right turning vehicles at the Jacksons Road intersection. Any portal structure in the central median would need to take due regard of the lower elevation of the Wellington Road eastbound carriageway.

Jacksons Road to East Side of Flood Plain

Elevated structure would continue throughout this section to negotiate EastLink descending to at grade, embankment or elevated structure to ensure levels are sufficiently above the 100 year return flood level. At chainage 28600 overhead power lines cross the alignment causing a pinch point between the clearance to the powerlines and the required clearance to the traffic envelope on EastLink. The standard form of viaduct is unlikely to be suitable and a bridge of the through truss type might be required.

Rowville

The tracks would be below ground under Stud Road, this would require the demolition of property (private dwellings) above the alignment. The section under Stud Road could be carried out in cut and cover or SCL tunnel may be considered to avoid disruption to Stud

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Road and the entrance to the shopping area. To descend earlier to maintain the properties would force the level of Rowville station to be overly deep with capital and operational cost penalties and the inconvenience to users of an unnecessarily deep station.

Bored Tunnel Alternative

All the sections noted above as cut and cover or SCL tunnel could be replaced with TBM bored tunnel.

Details of this method are explained in Section 7.8. It is unlikely that there would be any advantage in using TBM bored tunnel for the short section into Rowville station.

Having purchased the TBM for the project the alignment can be considered for additional lengths of tunnel especially if the sections of viaduct are considered to have to high environmental cost, such as the elevated section between Blackburn and Springvale Roads. Four of the five stations are already underground, this option would mean all five are. A tentative alignment is indicated by the red line on drawings SB19323-D-TC-002, 003, 004 and 005. The stations would all be of cut and cover construction. The revised alignment has used the 2% maximum vertical gradient of the original.

To assist this alternative alignment the Mulgrave Station adjacent Springvale Road would be located east of Springvale Road. Monash station would need to move as far west as possible towards Princes Highway to reduce its depth. Cut and cover or SCL would remain at Rowville due its short length and separation.

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7.2 Tunnel cross section requirements

Train Structural envelope, cant space The train structure gauge envelope is defined by the VRIOGS publication VRIOGS 0001-2005 Structural Gauge Envelopes Minimum clearances for Infrastructure adjacent to the Railway

It appears that the likely tunnel sections would be on relatively straight track but it should be noted that any horizontal curvature would cause end and centre throws of the rolling stock which would have to be taken into account when developing the structural envelope from the kinematic. Cant of the track and whether the point of rotation is off the tunnel centreline would also have an influence on the tunnel cross section.

It is important that there is sufficient air space around the train for efficient ventilation. In a circular tunnel this is usually easily achieved.

The type of Overhead Line Equipment (OHLE) would dictate the overall height of the structural envelope. There are various types which would need to be assessed together with a decision whether to cater for an allowance for changing to high voltage (see section n9 for further details).

Emergency Walkway The minimum width of walkway would depend on the standard to be adopted. The US standard NFPA 130 requires a shaped space of minimum width 610mm at walking surface and at 2035mm height and 760mm at 1420 above the walking height. NFPA and Australian DDA regulations allow assistance in emergencies i.e. lifting off the train of wheel chair bound people. The level of the walkway should be such that it can be accessed from both the train and track level with the priority on ease of access from the train.

Service routing Services that would take up space within the tunnel cross section include.

1) Invert drainage 2) Pumping main from low point sumps 3) Fire main and associated valves 4) High Voltage cable ducting 5) Long line cabling for low voltage, signalling equipment and communications

equipment 6) OHLE

Track slab and derailment containment The difficulty of access to restore the train to the track and the destruction of railway equipment if the train departs significantly from its structural envelope has lead to the usual

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requirement of incorporating derailment containment in the form of a raised concrete plinth between the rails.

While most of the alignment is under existing highways the issue of noise and vibration may not require significant attention. However with recent developments of anti vibration devices, such as Pandrol Vipa pads, reducing vibration effects can be achieved in minimal space. There may be areas such as where the alignment passes close to hospitals, laboratories, teaching establishments or even residential areas where noise and vibration reduction may be considered necessary. It should be noted that the Melbourne Loop has a more bulky 1980s version of an anti-vibration design.

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7.3 Cut-and-cover tunnel

The potential length of twin track cut and cover construction is approximately 3.7km.

Cut and cover construction has the benefit of using standard piling equipment that is readily available as similar techniques are used throughout Melbourne in basement construction. The design can easily be adapted to cope with variations in ground conditions above and below the watertable.

A typical cross section is shown in Figure 2. Piles are formed for ground support and in addition a central pile to assist roof support. The central pile can also allow the roof to be constructed in two halves to minimise space take up during construction and hence the impact on traffic.

Top down construction is envisaged whereby subsequent to piling the ground is excavated to soffit level, the roof constructed and the surface features reinstated. By keeping the level of the top of roof 1.5m below ground level there should be sufficient space for utilities to pass over. Special provision may be necessary for water utilities depending on invert levels. Provision can also be built into the roof to take the root ball of trees to be reinstated for reasons of amenity provided there is sufficient depth.

The walls can take the form of secant piles, contiguous piles or King post piles with arched shotcrete lagging depending on the ground support and resistance to water ingress.

The piling is taken below the base slab to ensure stability from lateral loading prior to completion of the base slab and also to provide resistance to hydraulic uplift in areas of high water table.

The method has the advantage that it can allow construction to start on as many fronts as necessary provided sufficient areas are available for handling the excavated material.

Alternatively long lengths of cut and cover can be constructed and excavation carried out from a single point by tunnelling methods under the protection of the roof and piled walls. This method is sometimes referred to as Door Frame tunnelling.

A disadvantage of cut and cover is that long lengths of tunnel can form a barrier to natural groundwater flow especially if deep secant piling is used through permeably strata. This can cause settlement on the water depleted side and ground swelling on the side of water build up.

Although it is anticipated that most of the construction of cut and cover would be in the roadway median it is likely to require adjacent lanes and disrupt road intersections. It will be important to include the cost of traffic management into cost estimates.

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Figure 2: Cut and Cover Tunnel

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7.4 Open Cut

As the railway alignment passes from tunnel to at grade or viaduct there would be sections of open cut. The estimated length of open cut gives a total of approximately 1.5km. Generally these would take the form of similar walls to the cut and cover braced by a base slab.

Provision for a detraining and maintenance walkway on the outside of each track has been made.

If ground conditions allow support of the excavation using soil nailing techniques may be a possible solution. Near vertical and perhaps even vertical walls may be achievable with this technique, as shown schematically in Figure 4.

Soil nailing is an economical technique for stabilizing slopes and for constructing retaining walls from the top down. This ground reinforcement process uses steel tendons which are drilled and grouted into the soil to create a composite mass similar to a gravity wall with the tendons securing the potential slip zones to the stable areas beyond. A shotcrete facing is usually applied, though options such as precast panels incorporating architectural features can be used for the permanent wall facings. Figure 3 shows an example of a deep excavation supported by soil nailing, and Figure 5 shows the main features of a soil nail.

Figure 3: Example of Soil Nailing

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Figure 4: Open Cut

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Figure 5: Typical Soil Nail (From Ischebeck Titan Brochure)

Open cut railway next to road traffic would require special protection to prevent errant vehicles or their loads falling onto the railway. This is likely to require a substantial concrete safety barrier surmounted by a steel mesh security fence. For piled construction the safety barrier can be formed monolithic with the pile capping beam. For soil nailed walls the vehicle barrier has no pile to found on and hence it would need to be founded on competent ground at the excavation edge and tied back by ground anchors. An alternative to anchoring would be to attach the barrier to an RC slab under the traffic lane but this has the disadvantage of extending the width of construction.

The length of tunnelled railway would have repercussions for ventilation design and further design phases may reveal lengths of open cut to be an advantage over fully enclosed cut and cover. Where this occurs it is envisaged that the structure would be very similar to cut and cover with the roof replaced by a structural system of struts and walings to support the tops of the piles.

The negative side of such lengths of open cut is the loss of amenity of the road median and the visual intrusion of the traffic barriers and security fencing.

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7.5 Elevated Sections (Viaduct)

This section describes and discusses the possible options for the 2 elevated sections of the Rowville Rail Link. Viaduct construction is required for an approximate total of 5.8km.

Figure 6: Typical Viaduct

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7.5.1 Typical Design Elements

The typical design for an elevated railway involves a viaduct supported on piers. The viaduct would span over intersections and provide a fully grade separated route for the railway. It is a significant feature within the landscape and therefore careful architectural and urban design is required to positively mitigate the visual intrusion.

Superstructure Construction Recent Australian construction experience is that similar mainly highway viaducts are concrete box girders typically constructed from precast sections. In-situ concrete construction is not considered feasible due to the constrained nature of the alignment and the large amount of falsework required to support the weight of the wet concrete.

Steel superstructures are not recommended due to the capital cost of steel, the potential for increase noise and the high level of ongoing maintenance required. Additionally authorities are becoming less accepting of steel superstructures except in special circumstances due to the limited life of protective coatings. A steel superstructure would require repainting 2 to 3 times during its design life.

There are three possible superstructure forms appropriate for the viaduct with the design of the section driven by the chosen construction method. These are described as follows.

1 - Segmental Box Girder Construction A typical precast unit is 2.5 to 3m long. These are manufactured in a local site under controlled conditions so as to achieve a high quality finish and fit. The sections are then transported to site either by road or along the finished viaduct. The units are then glued into position and pre stressing cables are then used to stress the sections together to improve structural performance. The sections may vary in depth so as to achieve longer spans. Significant spans can be achieved with greater depths through the use of balanced cantilever construction. See Figure 7 and Figure 8.

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Figure 7: Typical Precast box girder segment

The precast segments would be prestressed together using high-tensile prestressing tendons. The tendons can either be internal or external. Internal tendons are inserted through ducts cast into the concrete and may be bonded (by grouting the ducts). This method is structurally more efficient and therefore would offer savings in material quantities. External prestressing is when the tendons are located outside of the concrete cross section, and within the hollow interior of the deck. This method provides easier access for installation and inspection. Normal practice would be to allow the designers to make the decision depending on the performance requirements, which may lead to a combination of both methods being adopted. A significant design parameter would be the preferred choice and availability of contractors plant.

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Figure 8: Segmental construction

Segmental Precast units may also be used in balanced cantilever bridge construction thereby achieving spans greater than 60m and so is suitable for use when crossing an intersection requiring good visibility at a junction, or over the EastLink (High Voltage lines permitting).

2 - Full Span Precast Box Girders For spans up to 40m an entire span may be prefabricated off site before being transported into position. This methodology has the advantage of minimizing the required work at height and is particularly suitable for construction through an urban area as the disruption due to the construction of the deck is minimized. Traffic along Wellington road could be maintained and the only requirement would be for a safety zone.

It is also possible to get very fast rates of construction, providing a huge benefit to the construction program. This method does require significant investment in a heavy duty launching gantry as shown in Figure 9.

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Figure 9: Full span erection on the Taiwan High speed rail

3 - Conventional girder deck bridge using super-tee girders 1800 deep super-tees can achieve spans for up to 30 metres for railway loadings. A likely deck arrangement would feature 4 super-tee girders per span supporting an in-situ concrete deck. No special construction plant is required with the girders erected using a conventional crane. Super-tees are the most common form of bridge superstructure in Australia and have been used on a large number of bridge projects.

The economies of scale associated with a project of this size dictate that a box girder structure, which is substantially more visually appealing superstructure, is likely to be similar in price to a super-tee superstructure. The use of super-tee girders would severely limit the scope for good seamless architecture. Additionally the span lengths would be limited to approximately 30 metres, requiring additional piers compared to a box girder. Super-tees are therefore not recommended for the main deck construction for this project.

Careful consideration of the articulation of the viaduct is required, in particular the location of the bridge expansion joints in relation to the rail expansion joints (if any). Determination of the articulation is somewhat dependent on the method of construction as each construction method lends itself to certain methods of articulation.

Sub-structure construction The purpose of the sub-structure is to support the viaduct deck. Piers are required to be robust against impact from errant vehicles yet slender to improve the aesthetics and reduce the cost. It is more effective to use single columns rather than two or more columns requiring a head stock structure. This form of construction naturally provides a good architectural

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opportunity. For each superstructure module (a module comprises a number of spans between expansion joints), torsional effects (particularly due to horizontal curvature), would need one twin bearing at each movement joint. The piers can be constructed either in-situ using formwork or can be constructed from precast segments stressed together. The form would be dependent on the construction contractors preference.

The foundations for the piers are typically piled using bored or CFA piles. The use of large diameter mono-piles for the foundations (subject to ground sub grade stiffness being adequate against lateral loading) would significantly increase the construction speed by reducing the number of piling operations and removing the need for a separately constructed pile cap. However this would require the use of specialized plant that may need to be sourced from overseas. See Figure 10.

Figure 10: Elegant piers founded on monopiles on the Palm Jumeirah monorail

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7.5.2 Elevated Station Design

The positioning of the station in relation to the local environment is a significant opportunity for high quality urban design. It is to be expected that the majority of passengers would seek to arrive at the station by foot and therefore the local environment should reflect the need for pedestrians to access the station from both sides of Wellington Road. The station precinct should also encourage onward travel by other sustainable means such as cycling.

A key operational aspect of the station that needs to be addressed in the structural design is the location of the ticket barrier and concourse. To minimize operational costs a single concourse is preferred, as well as providing increased security and safety.

There are two basic options for the layout of the station design:

Twin Platform design A twin platform design would allow the station to be constructed independently from the main viaduct construction. This would lead to efficiency in the construction as standardized precast deck units could be used continuously through the station.

A twin platform design requires a separate route for platform interchange. This may either be done at ground level, unlikely due to the presence of the road or via a dedicated structure either over or under the tracks.

The overbridge structure would require additional lifts and stairs to allow for access over the track as well as increasing the visual impact of the station. An alternative is for the passenger interchange to occur beneath the tracks - this space could also act as the main station concourse. The passenger interchange structure could also act as an open access grade separated crossing for pedestrians. See Figure 11.

Figure 11: Bangkok Skytrain station showing elevated pedestrian access routes under the tracks

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Island Platform Design

An island platform design is preferred from an operations and station design aspect. This allows for a single access point of entry to the platform and very easy cross platform interchange. Although the station footprint is reduced there is a need to split the tracks and therefore continuous construction of the deck is not possible. This would increase the cost of the viaducts as a non-standard deck section would be required. See Figure 12.

Figure 12: An island platform on the Singapore Mass transit system

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7.5.3 Approach Ramps and Tunnel Portals

There is a significant interface with the ground at each end of the viaduct and particularly where the route goes into a cut and cover section where a tunnel portal structure would be required. Each ramp offers a substantial challenge for urban and technical engineering design. The normal maximum operating gradient of 2% means that an embankment of over 100m in length would be required before achieving sufficient headroom for pedestrians. The embankment footprint is dictated by the type of material available and the form of construction. The embankments could be formed through recycling the spoil removed from the tunnels. Depending on structural properties of the spoil, the spoil may need to be treated or reinforced to reduce the footprint to an acceptable amount as against the footprint formed by its natural slope angle. The facing of the embankment would be a very important design feature; naturally graded embankments are often turfed though careful selection of species would be required to prevent desiccation. Alternative facings may be combined with geotechnical reinforcement to provide a combined sustainable and structural solution. Within an urban context a reinforced soil wall or steep embankment may be preferable, particularly where there are space constraints.

7.5.4 Trackform

The key issue that would need to be resolved over the full route is the choice of track form. Slab track is typically the preferred option due to its reduced whole life costs though careful design of resilient elements are required to ensure that the track form meets the required noise and vibration criteria. Ballasted track is the traditional form of permanent way and is cheaper initially but requires additional maintenance throughout its life to maintain performance. If there is surrounding structure to stabilize the track, as is the case on viaduct or in tunnel it is generally used to locate slab track and benefit from its longevity.

The design should eliminate or reduce the number of rail movement joints as these are high maintenance. A rail movement joint would be needed for structure expansion lengths of over 100m.

7.5.5 Design issues

The key benefits of an elevated viaduct are as follows:

An elevated viaduct is typically 30% of the cost of a tunnel. Elevating the railway does not sever adjacent communities Speed and ease of construction Safer construction Minimal impact on existing utilities (sewer, water, fibre optic) Good design would lead to the railway becoming a positive feature to the urban

landscape There is no disruption to the local ground water environment so no risk of settlement

impacts of adjacent buildings founded on soft ground due to tunnelling or changes in the water regime

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No requirements for additional specialised underground safety or communication systems as the existing systems can be used

The design would have to address the following key issues in order to achieve the benefits

Particular design effort is required to avoid detrimental visual impact There is a potential for increased noise impacts Construction activities may be extensive Maintenance activities need to be considered in the design Emergency responses requires careful planning Noise and Vibration These design issues are discussed in more detail below.

Adjacent communities The very nature of the elevated route enables existing links across the Wellington Road to be maintained in most cases. At each end of the viaduct, there would be an embankment and a cutting before the route continues underground. These features would act as a barrier and would need careful consideration in the design.

The substructures would need careful positioning to fit within the urban environment. There is potential for creating an unwelcoming, insecure and constrained area directly underneath the viaduct and therefore these areas need high quality urban design in mitigation.

Visual intrusion The design needs to account for the high level visual intrusion of the viaduct. There is significant opportunity for good architecture and urban design to mitigate against the visual intrusion and provide positive elements particularly around stations. Some key principles can be adopted to provide a consistent visual identity along the route and may include; support provided by single piers equally spaced and a continuous sections used throughout.

Traffic interface As the alignment of the elevated sections follows the median of Wellington road for the most part the only interface with traffic would be at junctions. Intersections should be accommodated within a single span though it may be necessary to increase the span locally or amend the intersection design to incorporate a pier. In such cases the piers should be positively protected for impact from errant vehicles. It is not expected that the controlling load case would be vehicle impact protection though local streetscape measures may be required to promote safety such as kerbs or protective barriers

The standard 5.4m headroom would be required across junctions though it is good design if this headroom is maintained along the entire length, and so not constrain any future intersections.

Noise and Vibration The passage of trains over the new railway viaduct would generate noise and vibration. Audible noise would occur at frequencies higher than those related to vibration, which are

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mostly inaudible. The magnitude of both noise and vibration would be predicted during the design phase and compared to acceptable performance limits. A key consideration is that the alignment is in an already noisy urban environment and therefore a key design task is to establish the present ambient noise levels.

The measures which are available to mitigate excessive noise and vibration, are different. The types of special attenuation features would most-likely vary depending on the location; it is possible that some of the features discussed below would not be required generally, or at all.

Mitigation of Noise The following measures each contribute towards the reduction of noise emissions from a railway viaduct. These measures focus on reducing high-frequency (audible) vibrations:

Sound Emitted as a Result of Wheel-to-Rail Contact

Ensure the condition of the rolling stock (particularly the roundness of the wheels), and the condition of the track rail, and track bed, are maintained to a high quality.

Use continuously-welded rail track. Use solid (and heavy) concrete noise barriers. These barriers may be incorporated into

the deck cross section, and are commonly used around the world for elevated railway viaducts, for the purposes of minimising rail noise, and also achieving an aesthetically-pleasing structure. Local up stands, positioned close to the rail provide the best noise mitigation as well as providing containment against derailment. They are not visually obtrusive as do not rise above car floor height.

Structure borne noise

Use spans of heavy material; use concrete spans instead of steel spans. Ensure non-structural viaduct components (e.g. services pipes, access walkways, sight

screens, etc), are resistant to loosening. Maximise the opportunities to dampen vibration within these components.

The relative merits of direct-fixation of rail track, versus the use of ballasted track bed, to limit noise and vibration would require an investigation to adopt the most suitable trackform for the rolling stock.

Resilient track fixings can be specified; these contain compressible components which reduce the vertical stiffness of the connection. These devices are useful in reducing structure-borne vibration/noise. There are a number of recognised systems incorporating resilient fixings that have been used on similar projects. It is important for maintenance that the same fixings are used for both the tunnel and bridge sections to maximise maintenance efficiencies

If ballast track is chosen then additional resilient elements such as a thick and continuous layer of elastomeric ballast mat underneath the ballast would be provided.

If rail track is fixed directly to a concrete slab, this slab can be made to float above the bridge structure in order to limit the generation of structure-borne noise and vibration. The

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floating slab is supported either by a thick and continuous elastomeric mat, or via steel helical springs (e.g. GERB GSI-system).

Mitigation of Vibration The following measures can each be expected to redu