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working paper no. 5

Westminster Waya public realm manual for the City

Maintenance & Specifi cation Review

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Westminster Street Furniture Manual Review

bennett urban planning / Buro Happold/ iCubeWorking Paper 5: Maintenance & Specification Review

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Foreword

This paper was prepared as part of Westminster Street Furniture ManualReview and provides background information on maintenance andspecification issues, which have informed the production of The WestminsterWay: A Public Realm Manual for Westminster.

This is Working Paper 5 and is part of a suite of working papers as outlinedbelow:

Working Paper 1: Review of 1991 Street Furniture ManualWorking Paper 2: Current Practice ReviewWorking Paper 3: Policy ReviewWorking Paper 4: Urban AnalysisWorking Paper 5: Maintenance & Specification ReviewWorking Paper 6: Access Review

Issue Paper 4a: Clutter Reduction Assessment for WP 4 Urban Design ReviewIssue Paper 4b: Listed Street Furniture WP 4 Urban Design Review

Contents

1 Introduction2 General Principles3 Specification4 Maintenance & Cleansing5 Conclusions and Recommendations

References



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1 Introduction

“More than 90% of our urban fabric will still be with us in 30 yearstime....If we want to make the most of our urban assets, sustain theresults of new investment and promote public confidence we mustmanage our urban environment carefully.”

Urban Task Force Report

In order to manage the urban environment effectively, a philosophy must beadopted of continuous improvement, high standards in design and efficientpublic service. Good design must be at the heart of all that is placed in thestreet and means that street furniture must both work properly and look right,i.e. that it is fit for purpose. The total effect of the Council’s design andintervention should reflect its civic pride and commitment to Civic Renewal.

It is not simply about applying ‘high’ standards, but applying high andappropriate standards. Capital cost implications of products and schemes mustnever be too far from being a determining factor, but whole life costs shouldalso be considered and there should be a recognition that bespoke solutionscan be difficult and expensive to maintain. High standards in specification,design, implementation and aftercare should always be sought, and affect oneanother iteratively. This relationship should again, always be considered whenapplying principles of good design.

The 1991 Street Furniture Manual sought to manage the usage of streetfurniture and was part of the ongoing process to influence the design andquality of street furniture in Westminster. Its main achievement was that itproduced greater co-ordination of products and styles as well as raisingawareness that ongoing maintenance and supply of street furniture must beconsidered when commissioning, purchasing or replacing street furniture.

The appearance of the street is affected by a number of issues and policies thathave a part to play throughout its whole life. It is about fitness for purpose:� choosing the right component for scheme;� ensuring it does the job it is intended to do;� putting it in the right place and in the right way; and� looking after it once it is there

Broadly these fall into four stages throughout the life of a component orstreetscape.

PreliminariesBefore a design has been proposed there must be a clear and unambiguousspecification of materials and components to give a greater chance of theproduct being high quality and long lasting, and the specification principlesshould be applied consistently throughout Westminster.

DesignDesign should be an integral part of the procurement process. However qualitycan often be compromised because of: lack of clear design ethos, conflicting



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design solutions, inappropriate signage, neglect of the local character, costconstraints.

ImplementationSchemes that are designed, maintained and implemented well have a betteropportunity to fulfil their expected life than poor schemes.

AftercareAftercare should be fully assessed in the design process, with a new monitoringand maintenance regime instigated promptly following completion ofconstruction. Thought should be given to how the street will be cared for inthe future, which may influence the choice of materials and street furniture.Too often schemes that deliver the right environment on completion fail tomaintain their appearance in the long term because of poor maintenance,incorrect cleansing regime, (possibly because of poor specification), and a lackof enforcement of the existing policies under the New Roads and Street WorksAct (1991).

The objective of this paper is to review how specification and aftercare ofstreet furniture components affects the street furniture manual. It does notcontain a detailed critique of current operational and management practices inWestminster concerning specification, maintenance and cleansing.

Report StructureThis report is split into four further sections that follow this introduction.

Section 2 covers the general principles of specification and maintenanceissues

Section 3 discusses specification issues in more detailSection 4 discusses maintenance and cleansing issues in more detailSection 5 provides conclusions and recommendations for The Westminster

Way



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2 General Principles

As discussed above, the most important factor when considering componentsand schemes is fitness for purpose. It covers a raft of issues but is about usingthe appropriate material in the appropriate place and in the right context.

Fitness for PurposeProducts must be well designed and able to perform the function for whichthey are designed. Although this appears obvious, there are three main reasonswhy street furniture may not do this:� it was the wrong product in the first place;� it was poorly implemented or maintained; or� standards have changed rendering the originally correct product

inappropriate for present use

Whilst the final point is somewhat unavoidable, the first two are not. A newitem of street furniture would not be appropriate if, for example, it was notsocially inclusive, i.e. has protruding or overhanging parts, is a trip hazard etc.or it is easily vandalized, new paving would not be fit if it were slippery whenwet, and all products would be unfit if they were difficult to clean and requiredbespoke cleaning solutions.

The quality of a product is the result of its design, construction andmaintenance. Products must be aesthetically pleasing or at least appropriate butmust also be functional and adaptable such that they can easily be cleaned,maintained and replaced.

An example of an item that could be considered unfit for purpose is a stainlesssteel lighting column. Whilst they can look initially visually stunning, theirappearance fades because of the abuse they receive. They cannot be coated toprevent fly-posting without detracting from their appearance, removal ofstickers causes scratching and deterioration in their surface appearance andcondition. It could therefore be considered that stainless steel columns shouldnot be used except in private developments where they can be maintained atthe developers cost.

ContextThe development of the City of Westminster has created a complex andhistoric townscape which contains over eleven thousand listed buildings in 53Conservation Areas covering some 75% of the City. The wrong choice ofmaterial or product can detract greatly from the urban landscape. Ensuring theright product means avoiding a blanket application of products throughoutWestminster and understanding the context in which materials are used.

One example is that the blanket application of yorkstone paving inConservation Areas would not be appropriate because Conservation Areas arenot all the same and in some mixed use areas other materials – such as pre-castconcrete flags could be used. The emphasis should be placed on the quality ofthe implementation and maintenance, not just the material.

Another example relates to the Millennium Street Furniture Range. It is a rangethat has been identified after a long selection process, and is a striking



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contemporary multi-functional furniture range which includes street lightingcolumns posts and bollards. The hope was to use the range widely and for it tobecome synonymous with Westminster, however, many officers haveexpressed reservations over its potential use because it would look out ofcontext in so many locations and hence its use is limited.

Clutter ReductionThe streets already seem to be at bursting point and new street furniture(whether first time products or newly added furniture) must not add to theclutter. Street furniture should be designed and used creatively to minimise itsimpact and that of the surrounding components.



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3 Specification

This section is split into three parts:

a) Paving Materialsb) Street Furniturec) Whole Life Costing

a) Paving Materials

IntroductionA pavement is any surfaced route that carries traffic – on foot or vehicular –and includes footpaths, roads, driveways, motorways and airport runways.Monolithic pavements are constructed from materials that bind together toform a single mass, such as tarmac or concrete, whereas elemental pavementsare constructed from individual components, such as flags, setts, block pavers.

The most commonly encountered layers are: sub-grades; capping layer; sub-bases; base courses; wearing courses; bedding layers; and paving layers. Thissection primarily deals with the paving layer although it touches on thestructural layers where they have a bearing on the design and type of pavinglayer.

In general, the paving layer should be firm, even, level and slip-resistant evenwhen wet. Well maintained large element paving is preferable to small elementpaving as it provide fewer joints where trip hazards occur. At the footway edgelarge element paving should be protected in some way; either through the useof street furniture, a strengthened sub-base or through reinforcement. Granitesetts and block paving should be avoided on pedestrian routes, except wherethere is a historic precedent, however in locations where they are used, largeelement paving should still be provided as an alternative.

There is a variety of paving materials, which can and are in use in Westminster,which fall into two categories, natural and artificial materials. Natural materialsinclude granite, yorkstone and limestone, whilst artificial materials includeconcrete, tarmac and clay brick paving. Each material has its own specificationand different maintenance standards and their relative advantages for their useand specification in Westminster are discussed below.

Natural Stone Setts

IntroductionSetts more so than most paving, can look beautiful when laid properly andterrible when laid badly. They come in a range of colours depending on therock type and can be expensive, although they are generally lower maintenanceand will last for a number of years – some of the setts currently covering thestreets of London have seen over 200 years of continual use.



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ApplicationSetts appear in a number of locations in London and Westminster and are seenby many as characteristic of and an essential ingredient to most of therevamping of historic areas. New setts are produced to regular dimensions in awide variety of finishes and are laid in the same manner as modern concreteblock paving. Reclaimed stones can also be used but they can be difficult to laymostly because of their randomness. As with other small element paving unitsthey offer opportunities for designers and are popular for the creation of large-scale patterns (such as the European Fan Pattern).

TypeThere are two main types of rock used for the production of setts; sedimentaryand igneous. Sedimentary rocks, such as sandstone or siltstone, are relativelyeasy to cut and shape. Igneous setts, such as basalts and granites, are muchharder. Sedimentary setts have become popular and are being used byTransport for London as an edge treatment for many of their routes. Theycome from the same rock as the larger natural stone flags and may be furtherprocessed enabling the development of modular sett paving.

Igneous rock types such as granites and basalts are popular as cubes. Igneousrock is denser than sedimentary rock and its crystalline nature makes it muchharder to cut with hand tools than most of the sedimentary types. Hence itmust be cut with a diamond blade saw (although it is then finished with ahammer to give it a more natural hewn appearance).

They are usually finished as fine picked (fairly smooth, good non-slip surface),fair picked (moderately smooth) and rough punched (with high spots chiselledoff).

PatternAlthough it is possible to lay setts and cubes in almost any configuration ordesign, the three most popular patterns are: coursed; random; and Europeanfan pattern. Coursed is the most popular pattern and much of the 18th and19th century sett work laid in the streets and squares of towns and cities is laidto this pattern. It is a traditional cobbled street pattern, with the coursesrunning at 90° to the direction of traffic and it often features a longitudinalchannel at each edge. It is simple to lay although it is important that thevertical joints are staggered, whether the setts are new and butt-jointed orreclaimed and mortar/pitch jointed. Different sett widths help to create a morerandom and natural appearance to the work.

A random pattern is basically a jumble of stones positioned wherever they willfit. This method of laying was typically used only on low status work, such asindustrial yards, stables, haul roads and other places where the presence of ahard surface was far more important than appearance, and/or where thebudget was tight. Often areas paved in a random pattern used poorer qualitysetts or rejects and odd sizes from a prestige job nearby or even reclaimedmaterials that were considered worn.

The European fan pattern is the most complicated to set out and only reallyworks with cubes or setts of smaller plan dimensions.



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ConstructionThe construction of pavements with setts and cubes is problematic becauseunlike concrete block paving or tarmac paving, there is no standardspecification to follow. This has resulted in many areas being constructedrecently that have failed because of degradation of the jointing, use ofunsuitable bedding or sub-base materials or bad planning and over-expectationof some designs.

Although setts have a long history as a paving material, it is only recently thatpavements constructed according to traditional methods have experienced thesort of loadings that are imposed by modern vehicles and their relatively highspeeds. What may have been a proven construction methodology for a horse-drawn carriage travelling at 10 kms per hour is not proven or necessarilycapable of carrying thousands of vehicles per day, travelling at 40 kms per hourweighing 20 tonnes or more. With the rise in interest in traditional pavingmethods and materials, TRL is examining the use of natural stone setts forcarriageway use but have to-date no performance records or design standards.

In general though, presently there are two methods for construction, rigid andflexible. Rigid construction refers to the fact that there is no movement in thepaving whilst flexible construction refers to the fact that small amounts ofmovement within the pavement are tolerated, with setts laid on a non-settingbedding material and joints sealed with a non-setting medium. Flexibleconstruction can bear greater loads because of its ability to bend under stressand performs better with straight cut sawn setts.

With either form of construction, various types of jointing can be used: mortarjointing for rigid sett pavements; pitch jointing for rigid or flexible settpavements; and loose jointing for flexible sett pavements.

The jointing of a sett pavement can have a dramatic effect on the finishedappearance of the work and change its character (although the chosen jointingshould never detract from the sett work by being more visually demanding). Itis common to use a high-strength mortar pointing for rigid pavements andsand or grit sealing for flexible. The mortar pointing method is difficult asaccidental spillages of mortar stain setts, any jointing cracks caused by minormovement cannot reseal unaided, and the mortar itself can be degraded overtime by general wear and tear. As with other forms of paving, messy mortarpointing can ruin the finished appearance of a pavement and a poor qualityfinish can make an expensive sett pavement look cheap.

The mortar should be carefully packed into the joints and smoothed below thelevel of the top of the setts. It is common for jointing material to settle overthe first few months and so it is essential that the pavement is inspected every3 months or so and has the joints topped up as and when required. In areasexperiencing heavy surface water flows or on pavements subjected to streetcleaning equipment, it must be used with a joint stabilising product or even apaving sealant to bond together the sand-aggregate and give it more of achance to resist the scouring action.

Pros and Cons� The 'domed' type reclaimed setts can be awkward to walk on for

mobility impaired, those with shopping, luggage or pushchairs;



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� Even relatively flat-topped setts can be difficult to traverse if thejointing is recessed, but the newer sawn setts have wonderfully smoothand level faces, and being laid butt-jointed as is concrete block paving,they present no hazard whatsoever, regardless of the footwear one iswearing;

� Properly constructed sett paving is more or less completelyimpermeable and therefore must be adequately drained to gullies orother suitable drainage points;

� Once complete, it should require no maintenance other than theoccasional sweep with a broom to remove accumulated dust etc;

� Time consuming and labour intensive, therefore relatively expensive;� Jointing requires monitoring to ensure quality of finish;� When laid well, or when laid to a fan pattern, they can add to the overall

look of a scheme;

Westminster ContextSetts appear in a number of locations in Westminster however their use shouldbe limited to areas of historic precedent and schemes approved through SIRG.If used the picked finishes should be used for pedestrian areas and the roughpunched finish for deterrent areas, rumble strips and low-speed traffic areas.Setts should be laid in coursed pattern and random and other patterns shouldnot be used in Westminster unless given specific approval by an officer reviewpanel such as SIRG. Mortar jointing should be used.

Natural Stone Slabs

IntroductionSome of the most visually attractive paving work is done in natural stone andyorkstone flags are common in many parts of historic and cherishedWestminster. It is a product with a structure, texture and colour determined bygeological and natural processes and as such is strong, hard wearing andprovides a natural randomness which benefits the overall appearance of thepublic realm. As with natural stone setts, it is a lower maintenance material andwith care will last many decades.

Although generally available from the UK, it can prove cheaper to import thestone from overseas, however, care must be taken when deciding from whereto quarry the stone in terms of the long term maintenance impact of thedecision. Imported stone must also be certain to pass UK standard testing forpavement flags for water absorption, slip resistance and compressive strength.

ApplicationNatural flags are the traditional choice for historic settings within urban areas.They can be used for vehicular and non-vehicular routes. 50 – 75mm thickunits are best suited for non vehicular usage, such as footways, while the 70 –100mm thick units should be reserved for paving that is likely to experiencesome low speed vehicular traffic such as overrun areas or crossovers.

TypeThe stone paving most commonly used in the London is yorkstone but thereare other stone products available: slate, limestone, granite, basalts, whinstoneand many more. New paving comes in choices of thickness and can be cut to



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suit most specifications such as diamond sawn, combed, riven, picked andflame-textured. It is important to recognise that natural stone products canchange over the years – whilst some finishes will retain their character formany years others will disappear after a few years of heavy pedestrian traffic.

Although stone paving is considerably more expensive than the concretealternatives, it does have a cachet that no other form of paving can offer. It hasa long life-span and a high re-sale value should it ever need to be replaced.

PatternNatural stone flags are available in almost any plan size and it is this variety ofsizes that allows custom patterns and random layouts to be laid. Randompatterns can create a more traditional feel reflecting historic precedent. Bychoosing flag sizes carefully, it is possible to create simple, attractive patterns.However, the two main courses laid are transverse courses (running across thedirection of travel) or longitudinal courses (running in the direction of travel).Footpaths look more effective when laid in transverse course and it is generallyonly larger areas that a random pattern can be applied.

There is also a tradition of prestigious paving projects where highly specialisedand often unique patterns require the stone to be specifically cut to nonrectangular shapes. This custom perhaps reached its peak during the Victorianand Edwardian eras when street masonry was an indicator of civic pride andprosperity.

Curves and arcs invariably involve a great deal of cutting to achieve thenecessary turn in direction. The two most common cutting patterns used toflag a radius are the fan and ring pattern. Each has its merits with the fanpattern reflecting the dominance of the transverse course whilst the ringpattern reflects the dominance of the longitudinal course.

ConstructionLarge element flags should be laid on a full bed of mortar either pre-mixedpaving mortar or mixed on site with a cement-coarse sand mortar. Onpavements that may have to endure vehicular traffic, the flags should be laiddirectly onto a 100mm thick bed of mass concrete.

Generally speaking larger units should be laid with full mortar joints. Whereflags have been laid on a mortar or concrete bed they generally have mortarjoints; flags laid on sand can be butt-jointed and can have sand joints or bemortar pointed. Sand or butt-jointing works best with chamfered or roundedflags as there is less chance of spalling.

Pros and Cons� Expensive capital costs compared to concrete paving� Well-laid stone paving is both time consuming and labour intensive;� Good quality stone flags, well laid and in the right setting are very natural

and organic looking;� No risk of colour fade as there is with coloured concrete products;� Can last an eternity, some products have been laid for decades and have

withstood the test of time,



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Westminster ContextNatural stone flags should be the primary flag chosen for Westminster in areaswhere there is a historic precedent for its use or it is appropriate in the contextof an urban analysis. It should not be applied dogmatically in all conservationareas where it can look out of place. This is despite the potential costeffectiveness of natural stone flags (see the section: whole life costing below),some modern and mixed use area streetscapes would not be improved by itsinclusion and may even detract from its context by creating the wrong type ofsetting. In such areas, large element concrete paving can look equally effectivewhen laid and maintained properly.

Natural stone flags should be laid in transverse courses with the fan pattern forradii, and could be in random or fixed lengths depending on context – largerareas should be assessed separately by an officer review panel such as SIRG.Flags should be laid on a full bed of mortar with a 100mm thick bed of massconcrete where vehicular loadings are anticipated.

Although natural stone can prove cheaper when imported from overseas, caremust be taken when deciding from where to quarry the stone in terms of thelong term maintenance impact of the decision and UK sourced stone shouldbe used where quarries can provide long term replacements.

Pre-cast concrete flags

IntroductionThe standard concrete flag is grey and utilitarian, comes in large element orsmall element sizes and is popular throughout the country. Although it canappear utilitarian it is also a common British standard paving material in mixeduse and some modern settings. In its small element form it has overtakenlarger element paving as the material of choice in many areas because of itsability to better withstand vehicular loading with an equivalent sub-base –although some larger flags can now be bought with reinforcement allowingthem to be used at the footway edge.

ApplicationConcrete flag paving has a long tradition of use on footways. It provides a hardsurface which is long lasting and easy to maintain. The texture of flag pavingprovides a slip resistant surface which is safe and comfortable to walk on.Small element flag paving is designed to accept occasional overrun by vehicles.It is suitable for many types of public pavement including: pedestrianfootways; forecourts and entrances to public buildings; footways wherevehicular overrun is unavoidable and paved areas in public gardens.

TypeAlong with the common, grey, 'pimple' face seen on most concrete flags, thereis a range of alternative finishes and colours available. These include polishedsurface, coarse textured and exposed aggregate. Some products combinecolour and finish so it is possible to specify a coarse textured flag in a buffcolour or an exposed aggregate in a red matrix colour. There is also a choice ofaggregate types with various coloured granites being a popular specification,but there are also flags with blue or green glass nodules as the exposedaggregate.



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Some units, especially the small element, are manufactured with optionalchamfered edges more commonly seen on block paving. This reduces theincidence of spalling especially on pavements subjected to vehicle overrun, butcan be an impediment to mobility impaired pedestrians.

There are three common sizes of larger element units commonly available 900x 600mm (D), 750 x 600mm (C) and 600 x 600mm (B) in 50, 63 and 70mmthicknesses. There are a number of small element sizes, namely: E, F and Gtypes (450 x 450mm, 400 x 400mm and 300 x 300mm respectively).

PatternThe wide range of flag sizes and the ability to combine two or more sizescreates a large number of patterns and bonds. The two most common flagpaving patterns for the footway, however are stack bond and broken bond.Stack bond paving provides continuous lines of same size flags in both thelongitudinal and transvere directions. Broken bond provides a commontranverse bond with a staggerred or alternate finish and is the more traditionalpaving pattern. In Westminster it is common practise to inlcude both patterns,with a three course stacked bond of small element paving at the footway edgeand a broken bond alternate stagger for the clear path of the footway.

Good detailing and selection of the correct flag can reduce the need for cuttingand improve the appearance of the finished pavement. The larger elementpaving means that cutting is inevitable at boundaries or where ironwork andstreet furniture intrude into the paved area. The pattern at curves and arcsshould be the same as for natural stone products with either fan or ring patternused depending on applicability.

ConstructionConcrete flag paving should be laid on a sand or mortar laying course,depending on the type of flag, over a sub-base and be of a thickness to suit theunderlying ground conditions and traffic loading. Installation should be inaccordance with BS 7533: Part 4. The choice of bedding material varies withlarger flags often laid on a full bed of mortar either pre-mixed paving mortar ora mixed-on-site 1:3 cement-coarse sand mortar. On pavements that may haveto endure vehicular traffic, the flags should be laid directly onto a 100mm thickbed of mass concrete.

Pros and Cons� Concrete flags are reasonably priced compared to natural stone

alternatives;� Small element paving has proved successful to withstand vehicle

overrun;� However, thicker or reinforced flags can be considered as alternative to

small element paving;� Easy to obtain as the large elements are stocked by most Builder's

Merchants;� Simple and utilitarian;� Small element paving can cause trip hazards because of the amount of

jointing;



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Westminster ContextLarge element pre-cast concrete paving can look equally effective when laidand maintained properly and should be used in conservation areas and mixeduse settings throughout Westminster where natural stone flags are consideredinappropriate. Small element paving is a recent addition to the Britishstreetscape and is used in Westminster as a practical application to betterwithstand pavement damage caused by overrunning vehicles.

This practice should not be continued as there are alternatives and smallelement paving should not be used unless given the specific approval by anofficer review panel such as SIRG. Edge of footway treatment should bethicker large element paving with an appropriate sub-base to withstandvehicular loading, however, the recent innovation using reinforced concreteflags should be monitored with a view to its wider application.

Block and brick paving

IntroductionConcrete blocks and clay brick paving haveappeared in many areas of Westminster either as themain highway and footway material or supportingsmall element paving as indicated right. They havebeen a major growth area in paving over the last 10– 15 years and their mass production has drivendown the cost. Although it performs well underheavy loading, its greater number of units per square metre means it canbecome a trip hazard for mobility impaired pedestrians.

ApplicationThey are used in all locations for footways, highways and pedestrianised streetsand are also used commonly in Westminster as infill for small element pavedstreets, overrun areas (in particular on corners where loadings are greatest andgradients are problematic) and edging or demarcation for a variety of surfacetreatments.

TypeTheir popularity also stems from their variability – there is an enormous varietyof shapes, sizes, colours, and textures now available. The typical rectangularblocks tend to have one presentable face, although some blocks are reversible,which makes easy work of replacing stained paving.

There two basic types of block paving; the moulded concrete block and thekiln-fired clay brick. Both are available in a similar range of size, and coloursbut the colour concrete of blocks is achieved by the use of concrete dyes andeven the best dyes are prone to some fading in natural daylight, whilst thecolour of clay bricks is natural and so these bricks are not subject to fading.Clay bricks are more expensive than concrete blocks but are generallyconsidered for their aesthetic appeal.

PatternThere are familiar patterns used, such as herringbone, stretcher bond andbasket weave, however, the small size of the blocks/ bricks over such large



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areas mean that the patterns are endless and left to the creativity of thelandscape designer.

ConstructionThe construction of a block or brick paved street depends on a variety offactors regarding such as loading. There are two laying methods commonlyused – flexible paving, indicating that the blocks or bricks are laid on a sandbed and the joints filled with a fine silica sand and rigid paving, usually, claybricks laid on a concrete or mortar bed with mortar joints. The design processis given in British Standard BS 7533:1992 'Guide for Structural Design ofPavements Constructed with Clay or Concrete Block Pavers'.

Pros and Cons� Vast range of prices, from quite cheap to quite expensive� Easy to obtain and replace� Can withstand heavy loading� Less comfortable for mobility impaired

Westminster ContextWhilst they fulfil a particular function, their use in Westminster is a product oftheir engineering qualities and a pragmatic approach taken to the urbanlandscape rather than historic precedent or context. Their use in Westminstershould be limited to areas where specific agreement has been gained from anappointed officer review panel such as SIRG.

Tarmac

IntroductionBituminous macadam is laid hot and rolled smooth and is generally used as ahighway surface although it is also commonly used throughout Westminster asa footway surface. It is cheap and easy to lay but is vulnerable to hot weatherdeviations such as blistering and rutting.

ApplicationMost commonly as a highway surface, but because it is cheap, easy to lay, easyto patch and easy to lay level, it has been widely used as a footway surface inparticular in areas where pavements are narrow.

TypeTarmac is all based on the principle of an aggregate coated with a binder,usually bitumen. Asphalts are a mixture of asphaltic cement or mortar (often abitumen with fine aggregates such as sands and grits) and some coarseraggregate, such as gravel or crushed rock.

There are many types of tarmac generally developed for highways, usingdifferent aggregates, different aggregate sizes, different binders and differentbinder colours. There are two main types of 'tarmac' surface: Bitmac which isgenerally used for footpaths, small areas; and patches for roads; and HotRolled Asphalt (HRA) which is machine-laid as a wearing course on roads.



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ConstructionIf the new material is laid over a badly cracked concrete base, old flagstones, orany other unsound base, any joints or cracks will soon be transmitted to thesurface of the new tarmac, and the surfacing will fail.

Pros and Cons� Tarmac can be a cheap, reliable surface over larger areas although small

areas can often prove quite costly as the set-up costs of transporting aroller and other plant account for a larger proportion of the overall cost.

� All bituminous materials will slowly degrade in UV light, which results inthe binder becoming brittle. This is the primary reason why older bitmachas a crumbly appearance and the aggregate tends to be scuffed free ofthe surface quite easily.

� As bitmac is an oil-based product, spillages of light oils, petrol, diesel,paraffin etc. will dissolve the binder, and this dissolution can penetrate toa significant depth if left unchecked. The only remedy is to cut out thecontaminated material and patch-in with new.

Westminster ContextTarmac should not be used as a footway material in Westminster.

Tactile PavingTactile paving units have been developed to perform a specialised function toalert mobility impaired pedestrians of impending danger. They can be suppliedas pre-cast concrete small element paving and smaller engineering concreteblocks and can a variety of colours – usually red, buff or blue (blocks).Although small element paving is the most popular use of tactile surfacing inWestminster and London, concrete blocks have also been used.

In order to balance the needs of the mobility impaired in conservation or‘sensitive’ areas natural stone tiles are also available and used widely inWestminster. There are two popular forms of natural stone tactile paving,either with the blistered surface bored out of the original material or with metalstuds used as the blister material.

Westminster ContextThe use should be limited to the guidance set out in Working Paper 6 – AccessReview, and the choice of concrete or natural stone should reflect the choiceof the general paving material i.e. natural stone flags should be used in areaswhere there is a historic precedent for its use or it is appropriate in the contextof an urban analysis. Metal studs should not be used in Westminster because oftheir potential to cause slipping accidents.

Resin Bonded AggregatesThese are aggregates set in a transparent epoxy resin matrix. It is used in avariety of ways throughout London, although not in Westminster, and there isa good range of coloured aggregates to choose from but it can be expensive.



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Westminster ContextIn Westminster, resin bonded aggregates could be introduced in a limited wayas a detailed finish for tree pits, replacing tree grates, or other special uses asagreed with an appointed officer review panel such as SIRG.



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b) Street Furniture

IntroductionIn this section, street furniture does not refer to paving materials, but to allother forms: street lighting; bollards; benches, litter bins etc.

There is an incredible variety of street furniture ranges to choose from andbespoke furniture can be made to any specification. However, Westminster hasan established range of components that, in the main, have been usedsuccessfully over the years. The problem has come from the management ofthe public realm. Prior to SIRG, the lack of a system led to a proliferation offurniture to the extent that Westminster now suffers from a complicated andcluttered streets.

This section reviews the component range used in Westminster to attempt toidentify elements, which should be used as a standard specification for therevised draft manual. New items and their specifications are also discussedwhere appropriate.

In general, the design of street furniture should, at best, add to the richness ofthe public realm and at worst be unnoticed and should never detract from it.More specifically individual components should not have protruding oroverhanging parts or be easily damaged by vandals and the design emphasisshould be on the detail not the decoration.

Street LightingGood street lighting is more than lighting columns and is beyond the scope ofthis review and a street furniture manual, but it is the responsibility ofWestminster to provide a safe environment for all highway users, where peopleand vehicles can see and be seen.

Westminster has a fine collection of decorative and cherished lamp columnsand lanterns – there are over 300 gas lamps and 15,000 lamp columns, ofwhich half are a decorative traditional design.

There are six types of lamp column/ lantern which are discussed in the streetfurniture manual:

� Mackenzie-Moncur with Rochester type lantern� Small Grey Wornum� Grey Wornum large Parliament Square� Rochester lantern Eddystone column� Single Head Bracket Arm column� Chicago lamp column

All the above with the exception of the single head bracket arm column areused in designated areas and as such there is no ‘default’ lamp column used inWestminster. The Millennium Street Furniture Range is unlikely to fulfil thatrole and the Geo range has some technical question marks over its adaptability.There is an opportunity for a lamp column to fill the current void and it mustbe developed jointly by street lighting engineering officers and urban designofficers to find a component that provides adequate focussed but adaptable



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lighting within an elegantly designed unit. Adaptability is extremely importantas lighting standards have changed over the years and many lanterns andbrackets have been lost as a result of modernisation.

Clearly whichever product is preferred, good street lighting is essential inparticular for partially sighted pedestrians, and in general the use of high-pressure sodium lamps, which give off a ‘white’ light should be encouragedand their placement should be used to highlight potential hazards and avoidcreating shadows.

BarriersBarriers include bollards, guard railings and gates.

BollardsThe fundamental use of bollards is to segregate vehicles from pedestrians,buildings and stonework. In recent years it has become necessary to usebollards as a means of traffic calming and to prevent vehicular access toalleyways or pedestrian environments and as such their design andconstruction must be able to resist the occasional knock from a vehicle.

Bollards come in all sizes, shapes and materials – tall, short, rectangular,square, cylindrical, octagonal, cast iron, aluminium, steel and plastic. There arefive type of bollard used in Westminster and recorded in the manual:

� City bollard (cast iron/ aluminium/ ductile steel)� Cannon bollard (cast iron)� Manchester bollard (cast iron/ aluminium)� Comyn Ching bollard (cast iron)� Light cannon bollard (cast iron/ aluminium/ ductile steel)

The traditional material for a bollard in Westminster is cast iron and thisshould continue to be used as the standard. Cast iron is the ultimate recyclablematerial and most bollards will last 50-100 years. Of the cast iron bollards inuse, the City bollard should be used as the standard Westminster bollard. Itoffers good protection, is of a design that can be used anywhere throughoutWestminster, parking plates and small signs can be fixed to it to reduce clutter.

Cast iron bollards should be installed unpainted to prevent scratching duringinstallation and should be treated with a specially formulated epoxy acrylicpaint every 5-10 years. They should be securely fixed in concrete mix andextended roots should be used where paving and bedding material take upmore than a third of the standard 300mm bollard root length.

Power bollards have a traditional weakness because they require a side hungopening door and a knock by a vehicle can dislodge doors from their hinges.Power supplies should be investigated as recessed wall and floor mounted andnot bollard mounted to avoid such designs.

Guard RailingWherever the proximity of pedestrians to traffic could be hazardous, guardrailsare used to reduce the chance of accidents. Public safety is paramount andcareful positioning of post & rail directs pedestrians away from dangerespecially at roadside, waterside or other high risk areas.



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Standard pedestrian guard rail types used throughout Westminster are ofgalvanised steel construction and conform to the current BS 7818specification. All standard panels are two metres wide and are either full heightor include a view rail and with in-line or offset verticals. The two types usedare:

� Standard guard rail (galvanised mild steel)� Decorative guard rail (fabricated mild steel)

Guard railing should be limited in its use to major roads and those where thereis a proven accident record. The standard guard railing should be used with aview rail.

BinsLitter BinsThe success or otherwise of litter bins often has more to do with externalfactors than the design of the litter bin itself. In Westminster two types of binare commonly used: Westminster bin (octagonal, cast iron); and Lin Pac plasticbin (round, plastic). Both bins are open and have a tough, strong galvanisedsteel liner and as such are easy to fill, empty and clean.

Litter bins require more attention than most other street furniture items in thatthey need emptying on a regular basis. Their placement and design therefore isrelated to the cleansing regime: in busier pedestrian areas, more larger-sizedbins are required than in quieter areas. Furthermore although the design of castiron bin is successful, safety concerns over bombs placed inside cast iron binshas meant they are considered more of a threat than plastic alternatives, hencethe rise in popularity of the round plastic bins.

The octagonal cast iron Westminster bins should continue to be used in areaswhere it currently exists. A design for an octagonal plastic bin should becommissioned to replace the round plastic bins in areas where they havereplaced the traditional octagonal shape. The round plastic bins shouldcontinue to be used in other areas where octagonal bins are not consideredappropriate.

Eurobins & Recycling CentresEurobins are large and unsightly but fulfil an important function to collectbulk waste and adapted to be used as recycling centres for glass, cans, paperand plastic. Their design is poor and because they require wheels to moveadjacent to refuse collection vehicles for emptying, they can be moved unlesslocked.

A better design should be sought in conjunction with a redesign of recyclingcentres, but until such times all Eurobins should be securely fixed with alocking mechanism.

SeatingThe most important design features for seating in Westminster are that seatingmust be convenient and comfortable but not encourage anti-social behaviouror become tripping hazards.



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Of the six benches used in Westminster presently, two (Sphinx seat andEastgate seat) are ornate benches designed for specific areas, two (CoventGarden and Oxford Street) are potential tripping hazards, one (slatted parkbench) is only appropriate for parks and only the Bench seat can be easilymodified to incorporate a central arm rest to prevent sleeping and isrecommended use is in all areas.

Although this seat has wooden slats and requires a higher maintenance than,say, a concrete or metal seat, it is more comfortable for the mobility impairedand can be maintained with a coat of varnish or stain used every year.

SignageStreet NameplatesStreet nameplates must be out of reach of vandals, fixed to buildings wherepossible and freestanding kerbside nameplates should be avoided. Westminsterhas its standard nameplate designed in 1966 with variations produced forTheatreland and Chinatown.

Traffic RegulationThe graphic style and layout of traffic signs are regulated by Department forTransport’s Traffic Signs Regulations and General Directions 2002. Signsshould be affixed to a standard plain steel/ aluminium post (with externallyilluminated sign where illumination is necessary), or other street furniturewhere possible, such as bollards.

Sponsorship RecognitionSponsorship is a valid and necessary method of raising revenues for the City.Sponsors quite naturally want recognition of their generosity and plaques havebeen used often to do this. Plaques should be high quality and discreet, placedon lamp columns for crediting sponsorship of hanging baskets; or designedcommemorative plaques or graphic additions to special features. Metal floormounted commemorative plaques should only be used if adequate slipresistance is provided.

ParkingPay and DisplayPay and display machines have come a long way in the past ten years andcurrent designs from companies such as Zeag, Metric and SchlumbergerSemacombine functionality, sustainability and aesthetics. The current stock of P&Dmachines should be assessed with a view to determine their suitability forWestminster.

Cycle ParkingSheffield Cycle Stands are the preferred method of cycle parking as stated bySustrans and the Cyclists' Touring Club. These designs do not require aseparate post for a parking plate sign, which can be incorporated as part of thedesign of the stands.

Soft LandscapingHanging BasketsThe justification for hanging baskets or otherwise is not a matter for thisreview, however, where they are considered appropriate, they should be sitedwith care because of aftercare maintenance issues. Without regular feeding andwatering, flowers in hanging baskets die and baskets placed in isolation or in



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groups of two or three can be forgotten. Baskets must be grouped in a fivesand sixes to provide raise their profile.

Baskets should only be used in pairs on lamp columns to avoid undue stressand to create a better appearance for the street. They should also be used onlyin streets which have sufficient width to cater for a 1m diameter hangingbasket. Baskets and brackets should be fixed using a semi-circular steel bracketdesigned specifically for Westminster. All lamp columns used to attach suchbrackets should be tested structurally to ensure they are capable of carrying theadditional load.

Tree Guards and GrillesA standard tree guard has been identified and is an off the shelf product. Theyshould be used only when protecting young trees in areas where there has beena recognisable problem with vandalism of young trees. Tree grilles should notbe used and a clear resin bound aggregate should be used in its place.

Other Street FurnitureThere are a number of authorities who have the right to place street furnitureon streets over which Westminster can only exert pressure and not enforce adesign. These include bus shelters, bus ticketing machines, control boxes andphone boxes and their design can only be addressed in generic terms, namely:

� their proliferation should be limited to avoid adding more congestion toalready congested pavements;

� inappropriate designs should not be set adjacent to or blocking views ofattractive or historic buildings;

� disturbance to pavements during installation works and poor quality ofreinstatement of paving and increase maintenance problems for streetcleaning and create tripping hazards



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c) Whole Life Costing

IntroductionDiscussions with the Transport Research Laboratory indicate that very littleresearch has been undertaken in the field of whole life costing for streetfurniture or paving materials. Unfortunately comparative life expectancy ofmaterials on street can only be judged anecdotally – its is not easy to quantifyand determine true whole life costs including: environmental; sustainability;operational; and maintenance impacts and a whole range of other benefits ordisbenefits from quarrying to manufacture to transporting to recycling.

This is the scale of work that has not been undertaken in research orcommercial studies, and to do so for this paper would be beyond the scope ofthis study. Therefore the discussion in this section is based on empirical dataand assumptions to give an understanding of the capital costs spread over adesign life. It anecdotally covers costs of cleaning and repair, but covers inmore analytical detail an indication of costs of some of the product choices inWestminster.

As part of the review, the UK’s major supplier of paving materials wereconsulted for an assessment of whole life costs but again, they had themselvesvery limited research.

The purpose of this section is to highlight that cost effectiveness must not beseen simply in terms of capital expenditure: the cost of a scheme during itswhole life should always be taken into account. However, just like the cheapestcapital expenditure product is not necessarily the best, the same is true for thewhole life cost and it is just as important to consider appropriateness andcontext.

The section below assesses costs over design life for paving materials. A similarcomparative assessment for other street furniture is not possible because of thevariation of choice, but in principle the following costs should always beconsidered when assessing street furniture and paving:� capital cost;� maintenance costs;

o repaintingo changing components such as bulbs, re-pointing;o removing stickers/ graffiti, etc

� cleansing costs;� replacement costs;� costs of securing additional items where required;

Paving MaterialsInformation set out in the original street furniture manual gave an indication ofrelative costs, produced together with the life span of the individual pavingmaterial. By updating the information and organising it in graphical formshows the relative life span cost of the purchase and implementation of thematerial compared to yorkstone paving (1.0) and shows that granite setts canbe more cost effective because of its long life span, whilst the cost of concretepaving is 1.75 greater. These figures assume the same maintenance regime andtherefore cost for all surfaces.



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The comparisons are based on the following table of costs.

£/sqm Design Life (yrs) £/yr FactorYorkstone Flags 130 100 1.30 1.0Natural Stone Setts 110 125 0.88 0.7Tarmac 35 25 1.40 1.1Concrete Flags 45 20 2.25 1.7Clay Pavers 60 15 4.00 3.1Concrete Blocks 60 15 4.00 3.1

Comparative costs over design life of paving materials(relative to yorkstone paving)

Notes:Natural stone setts costs for new materials range between £30 and £120/sqm,depending on thickness, type of stone, finish and quantity. The £110/sqm costedassumption is for the supply of setts and fix: 75mm sawn setts, 50mm grit sandbed, 150mm DTp1 sub-base and sand jointing. Their design life is long and theyhave been in-situ in a number of places for over 200 years. However, they havenot had to endure vehicular loading for such lengths of time and as such it is notpossible to state with confidence their durability. Therefore and assumption hasbeen made based on 100-150 years lifespan.

Natural stone, again varies considerably, but is costed as an 80mm thick slab, withmortar jointing and 100mm DTp1 sub-base. The material has been in use in manylocations throughout the country and lasts over 100 years. It fails in area subject tovehicle overruns and is dependent upon a robust sub-base and appropriatethickness to withstand such loading. Based on this assumption a lifespan of 100years has been assumed.

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

Concrete Blocks

Clay Pavers

Concrete Flags

Tarmac

Natural Stone Setts

Yorkstone Flags



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Pre-cast concrete paving is a standard cost per unit size and the £45/sqm costsshown are for 900 x 600 x 63 (D63) natural grey slabs with excavation toformation level 220mm below paving level, 100mm DTp1 sub-base, 12mm widemortar pointing. Pre-cast concrete flags have been in use since the 1940s and theirfailures can often be attributed to poor finishing, poor or inappropriateconstruction standards or vehicle overrunning. Given a high quality finish andconstruction, concrete still degrades more quickly that natural stone throughnatural wear and tear and the abrasive nature of cleansing machines. Anassumption has been based on a lifespan of 20 years before requiring replacement.

Tarmac surface has been costed based 25mm wearing course, 50mm base courseand 100mm sub-base, at £35/sqm. Tarmac can crack, blister, rut and suffers fromgeneral deformation in hot weather conditions and as such although it will remainstructurally sound it can become unsightly at best and difficult to walk on at worstwithin a few years. The assumption has been though, for a replacement of thematerial after 25 years.

The costs for concrete blocks and clay pavers £60/sqm, are based on200x100x60mm concrete blocks or 200x100x65mm multi-coloured clay pavers,50mm grit sand bed, 150mm DTp1 sub-base and sand jointing, which wouldwithstand vehicular loading. It has been assumed that concrete blocks and claypavers which suffer vehicular loading will last some 15 years or so before theyrequire replacing or relaying at considerable expense.



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4 Maintenance & Cleansing

IntroductionAll street furniture and paving is enhanced by regular and appropriatemaintenance and cleaning. Street furniture should be painted or varnishedregularly; pavements should be swept and cleaned.

Furthermore over and above ensuring that what is there stays in goodcondition, defective and broken furniture and paving should be replaced as amatter of routine. This not only includes repairing and replacing broken pavingslabs, bollards etc. but also enforcing the legal obligation of statutoryundertakers to reinstate street furniture to the same standard as previouslyexperienced. Westminster has an obligation to demand that street works bystatutory companies leave no material change to the environment.

With respect to cleansing, Westminster is at the forefront of cleansingstandards and this year was announced as the UK’s cleanest City – aconsiderable achievement for a City that attracts so much activity.

Street WorksEnforcement of 1991 New Roads and Street Works Act (NRSWA) powers is asignificant problem because of a difference in the interpretation of thelanguage of the legal framework. Statutory companies do not have the samepriorities as local authorities and are beholden to shareholders and not to civicresponsibility. This often results in quality environments being altered by streetworks and not being reinstated properly because of the prohibitive costs ofdoing so and even a stringent Westminster enforcement programme cannotalways deliver the right level of reinstatement – it is too often dependant to anextent on the professionalism and goodwill of statutory contractors.

A recent project undertaken in nearby London borough demonstrates thispoint. An environmental improvement programme on a street specifiedyorkstone slabs laid on concrete sub-base with mortared joints and provided avery high quality finished product. Despite powers limiting statutory works onnew streets, an ‘emergency’ required works on the street within a month ofcompletion. During the works many yorkstone slabs were broken and chippedand the mortar shattered over a wider area. After completion of the works,infill was used as the sub-base, some of the chipped yorkstone slabs werereinstated and tarmac used to replace the broken slabs. Although this is alegitimate temporary reinstatement for a maximum of six months thetemporary surface was in place almost two years later despite repeated effortsfrom the Council to force the utility company to make good the repair. Wheneventually the tarmac was replaced with yorkstone slabs, the chipped slabs,sub-base and mortar have never been made good leaving a once immaculateenvironment, poor and neglected.

This is too typical of reinstatement works by utility companies and thelegislation that allows this practice to continue must be tightened withappropriate penalties in place for offenders. The best method would be for there-instatement works to be undertaken by the council and paid for by theutility companies – although this may be asking too much.

Notwithstanding the problem of the existing system, Westminster’sresponsibility must be to continue to enforce to the letter of the law the



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obligations of statutory companies, and to maintain a high level of in-housemaintenance, repair and cleansing to demonstrate to those companies that it isserious about creating and maintaining a high quality environment.

PavementsThe practical application of maintaining pavements is not simply aboutenforcement against utility companies. Paving becomes loose and therefore atrip hazard for a variety of reasons and needs to be re-bedded, but it is moreimportant to rectify the cause of the movement and simply packing mortarinto a joint and hoping that it will stop the rocking does not solve the problem.Settlement or subsidence of the substrate layers is the most common reasonfor pavement failure and may be a result of:

� incomplete compaction of the substrate layers during construction;� liquefaction of the bedding layer by water ingress;� failure of restraining edges;� loss of jointing material;� application of loads greater than the pavement was designed to carry;� poor re-instatement of sub-base or jointing after street works;

Whatever the cause, it needs to be investigated and rectified before replacingor re-bedding the paving units.

Jointing is a particular weak point for paving and hence the reason why fullymortared joints are recommended for schemes using natural stone orexpecting to carry vehicular loads. Dry sand jointed pavements seal themselvesover a relatively short period of time but can result in a loss of sand. Commoncauses for loss of jointing sand include:

� erosion by exceptional surface water flow;� loss due to vacuum effect of street cleaning equipment;� loss by blast effects of high-powered engines or power-washers;� loss due to pavement movement;

If dry sand joints are used and power washers are required, the loss should becountered by the application of a suitable sealant or bonding agent which bindthe sand grains to each other and to the sides of the paving joints and therebyreduce the risk of emptying.

Most paving will require little further maintenance, but require regular cleaningwith a power washer. Most powered washers are capable of dealing with themajority of pavement cleaning jobs, but will not remove all stains; oil needs tobe removed with a special oil-cleaning compound, cementitious material has tobe removed by mechanical and/ or chemical action and chewing gum is verystubborn and must be cleaned with either a freezing agent or a chemical-hot-wash cleansing regime, both of which could cause further deterioration to thepavement itself and mortar jointing. Acid based cleaners should be avoided asthey work by chemically reacting with the surface of the paving, etching away avery thin surface layer of concrete products and this can prove detrimental tothe paving with repeated use.



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Street FurnitureAll street furniture items can suffer from wilful and accidental damage. Wilfuldamage ranges from covering the component with stickers to kicking, hackingand uprooting of trees. Accidental damage is generally by vehicles crashing intobollards, guard railing street lighting columns, illuminated guide posts etc.

Fly-posting is a particular problem in Westminster and the solution hastraditionally been to cover every smooth surface with an anti-sticker texturedpaint. This has resulted in a deterioration of the quality of street furniture itemsbecause of a practical need to prevent such action.

Particular items such as street lighting columns suffer from additionalproblems such as broken bulbs and carrying hanging baskets and thereforeeach component must be supplied with a full breakdown of how often toclean, paint and inspect in order to carry out the correct maintenanceprocedure. These guidelines will be set up with the revised product referencesheets and will relate to the particular component, with information fromestablished practice or from the manufacturers themselves.



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5 Summary & Conclusions

In summary this is not a definitive list of what should be used in Westminsterand how to use it, but what should be the accepted default standard and whereofficer approvals should be sought when deviating from that standard.

The objective of the principles set out below is to simplify the current paletteof materials in the City and to concentrate on those materials most appropriateand encouraging their effective implementation and maintenance.Street Furniture and materials specification

General

In general, the design of street furniture should, at best add to the richness ofthe public realm and at worst be unnoticed and should never detract from it.More specifically individual components should not have protruding oroverhanging parts or be easily damaged by vandals and the design emphasisshould be on the detail not the decoration.A new item of street furniture would not be appropriate if, for example, it wasnot socially inclusive, i.e. has protruding or overhanging parts, is a trip hazardetc. or it is easily vandalized, new paving would not be fit if it were slipperywhen wet, and all products would be unfit if they were difficult to clean andrequired bespoke cleaning solutions.

Paving Materials

Natural Stone Setts

The use of Setts should be limited to areas of historic precedent and schemesapproved through SIRG. If used the picked finishes should be used forpedestrian areas and the rough punched finish for deterrent areas, rumblestrips and low-speed traffic areas. They should be laid in coursed pattern andrandom and other patterns should not be used in Westminster unless givenspecific approval by an officer review panel such as SIRG. Mortar jointingshould be used.

Natural Stone SlabsNatural stone flags should be the primary flag chosen for Westminster in areaswhere there is a historic precedent for its use or it is appropriate in the contextof an urban analysis. It should not be applied dogmatically in all conservationareas where it can look out of place. This is despite the potential costeffectiveness of natural stone flags (ref to: whole life costing), some modernand mixed use area streetscapes would not be improved by its inclusion andmay even detract from its context by creating the wrong type of setting. Insuch areas, large element concrete paving can look equally effective when laidand maintained properly.

Natural stone flags should be laid in transverse courses with the fan pattern forradii, and could be in random or fixed lengths depending on context – largerareas should be assessed separately by an officer review panel such as SIRG.Flags should be laid on a full bed of mortar with a 100mm thick bed of massconcrete where vehicular loadings are anticipated.

Although natural stone can prove cheaper when imported from overseas, caremust be taken when deciding from where to quarry the stone in terms of the



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long term maintenance impact of the decision and UK sourced stone shouldbe used where quarries can provide long term replacements.

Pre-cast Concrete FlagsLarge element pre-cast concrete paving can look equally effective when laidand maintained properly and should be used in conservation areas and mixeduse settings throughout Westminster where natural stone flags are consideredinappropriate. Small element paving is a recent addition to the Britishstreetscape and is used in Westminster as a practical application to betterwithstand pavement damage caused by overrunning vehicles.

This practice should not be continued as there are alternatives and smallelement paving should not be used unless given the specific approval by anofficer review panel such as SIRG. Edge of footway treatment should bethicker large element paving with an appropriate sub-base to withstandvehicular loading, however, the recent innovation using reinforced concreteflags should be monitored with a view to its wider application.

Block and Brick pavingTheir use in Westminster should be limited to areas where specific agreementhas been gained from an appointed officer review panel such as SIRG.

TarmacTarmac should not be used as a footway material in Westminster.

Tactile PavingThe use should be limited to the guidance set out in Working Paper 6 – AccessReview, and the choice of concrete or natural stone should reflect the choiceof the general paving material i.e. natural stone flags should be used in areaswhere there is a historic precedent for its use or it is appropriate in the contextof an urban analysis. Metal studs should not be used in Westminster because oftheir potential to cause slipping accidents.

Resin Bound AggregatesIn Westminster, resin bonded aggregates could be introduced in a limited wayas a detailed finish for tree pits, replacing tree grates, or other special uses asagreed with an appointed officer review panel such as SIRG.

Street FurnitureStreet LightingClearly whichever product is preferred, good street lighting is essential inparticular for partially sighted pedestrians, and in general the use of high-pressure sodium lamps, which give off a ‘white’ light should be encouragedand their placement should be used to highlight potential hazards and avoidcreating shadows.

BollardsThe traditional material for a bollard in Westminster is cast iron and thisshould continue to be used as the standard. Of the cast iron bollards in use, theCity bollard should be used as the standard Westminster bollard. It offers goodprotection, is of a design that can be used anywhere throughout Westminster,parking plates and small signs can be fixed to it to reduce clutter.



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Guard RailsGuard railing should be limited in its use to major roads and those where thereis a proven accident record. The standard guard railing should be used with aview rail.

Litter BinsThe octagonal cast iron Westminster bins should continue to be used in areaswhere it currently exists. A design for an octagonal plastic bin should becommissioned to replace the round plastic bins in areas where they havereplaced the traditional octagonal shape. The round plastic bins shouldcontinue to be used in other areas where octagonal bins are not consideredappropriate.

Eurobins & Recycling CentresA better design should be sought in conjunction with a redesign of recyclingcentres, but until such times all Eurobins should be securely fixed with alocking mechanism.

SeatingThe most important design features for seating in Westminster are that seatingmust be convenient and comfortable but not encourage anti-social behaviouror become tripping hazards.

Street NameplatesStreet nameplates must be out of reach of vandals, fixed to buildings wherepossible and freestanding kerbside nameplates should be avoided. Westminsterhas its standard nameplate designed in 1966 with variations produced forTheatreland and Chinatown.

Traffic RegulationThe graphic style and layout of traffic signs are regulated by Department forTransport’s Traffic Signs Regulations and General Directions 2002. Signsshould be affixed to a standard plain steel/ aluminium post (with externallyilluminated sign where illumination is necessary), or other street furniturewhere possible, such as bollards.

Sponsorship RecognitionPlaques should be high quality and discreet, placed on lamp columns forcrediting sponsorship of hanging baskets; or designed commemorative plaquesor graphic additions to special features. Metal floor mounted commemorativeplaques should only be used if adequate slip resistance is provided.

Pay and DisplayThe current stock of P&D machines should be assessed with a view todetermine their suitability for Westminster.

Cycle ParkingSheffield Cycle Stands are the preferred method of cycle parking as stated bySustrans and the Cyclists' Touring Club. These designs do not require aseparate post for a parking plate sign, which can be incorporated as part of thedesign of the stands.



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Hanging BasketsHanging baskets should be sited with attention to maintenance issues. Basketsmust be grouped in a fives and sixes to provide raise their profile.They should only be used in pairs on lamp columns to avoid undue stress andcreate a better appearance for the street. They should also only be used instreets which have sufficient width to cater for a 1m diameter hanging basket.Baskets and brackets should be fixed using a semi-circular steel bracketdesigned specifically for Westminster. All lamp columns used to attach suchbrackets should be tested structurally to ensure they are capable of carrying theadditional load.

Tree Guards and GrillesA standard tree guard has been identified and is an off the shelf product. Theyshould be used only when protecting young trees in areas where there has beena recognisable problem with vandalism of young trees. Tree grilles should notbe used and a clear resin bound aggregate should be used in its place.

Other Street FurnitureThere are a number of authorities that have the right to place street furnitureon streets over which Westminster can only exert pressure and not enforce adesign. These include bus shelters, bus ticketing machines, control boxes andphone boxes and their design can only be addressed in generic terms, namely:

� Their proliferation should be limited to avoid adding more congestionto already congested pavements;

� Inappropriate designs should not be set adjacent to or blocking views ofattractive or historic buildings;

� Disturbance to pavements during installation works and poor quality ofreinstatement of paving and increase maintenance problems for streetcleaning and create tripping hazards

Maintenance & Cleansing

Street furniture should be painted or varnished regularly; pavements should beswept and cleaned to ensure that what is there stays in good condition,defective and broken furniture and paving should be replaced as a matter ofroutine. This not only includes repairing and replacing broken paving slabs,bollards etc. but also enforcing the legal obligation of statutory undertakers toreinstate street furniture to the same standard as previously experienced.Westminster has an obligation to demand that street works by statutorycompanies leave no material change to the environment.

Guidelines should be set out within the revised product reference sheetsrelating to particular components, with information and advice included fromestablished practice or from the manufacturers.

i302 wp5 - maintenance specification · element paving should still be provided as an alternative....

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