Geetam TiwariMoUD Chair Professor

Transportation Research and Injury Prevention Program (TRIPP)/Department of Civil Engineering Indian Institute of Technology (IIT)

New Delhi, India

Urban Safety:

Transport Infrastructure

Design Principles

Patna

VRUs &Urban Transport Infrastructure

Bus commuters on signal free junction and bus stop

Patna

VRUs &Urban Transport Infrastructure

Bus commuters on signal free junction and bus stop

Pedestrians at intersection and midblock

0

0.5

1

1.5

2

2.5

3

0 5 10 15 20 25 30 35

Time, minutes

Dis

tan

ce

, k

m

Metro Walking

Bicycling BRT

2-Wheeler/car

car bicycle BRT metro walk3 km trip

Bicycle takes the shortest time

for 3km; BRT is faster than

metro for short trips

0

2

4

6

8

10

12

0 10 20 30 40 50 60

Time, minutes

Dis

tan

ce, km

Metro

BRT

2-Wheeler/car

car

BRT

metro12 km Trip

Metro is faster than BRT for long trips

Delhi average metro trip 12 km

Scenarios and Factors for peds. Crashes while crossing

Type of problem

Name of scenario Description Factors

influencing

incidence of

crashes

Detection Dash obscured by parked vehicle The pedestrian, initially hidden, generally by

an immobile vehicle, undertakes his/her

crossing when the vehicle arrives, often

while running.

Speed

Vehicle parking

Street width

Pedestrian obscured by stopped vehicle The pedestrian takes advantage of

stationary vehicles in one traffic lane to

commence crossing.

Driver’s

experience

Pedestrian’s

skills

Parental

education of

children

Source: Fleury and Brenac (1997)

Anticipation Dash of non-obscured pedestrian The pedestrian begins to cross,

without paying attention to traffic, or

dashes onto the road whereas and

the driver, who did not anticipate the

pedestrian’s action, did not slowdown.

Speed

Streetplanning

Turning “look but fail to see” Vehicle turning left or right from main

street into a side street when a

pedestrian crosses. Most often the

driver fails to see the pedestrian, orsees him/her too late

Organisation

of trafficlights

Driver’sexperience

Straight on “look but fail to see” Vehicle travelling on a large or a fast

road in an urban area. A pedestrian,

often young or elderly, mis-judges

car’s speed or fails to see it, begins to

cross, generally on a zebra crossing,

often against a traffic light. Driver

detects pedestrian too late or thinksthat the pedestrian will stop crossing.

Pedestrianabilities

Driverexperience.

sustainable safe traffic system

a road environment with an infrastructure adapted to the

limitations of the road user;

vehicles equipped with technology to simplify the driving task and

provided with features that protect vulnerable and other road

users; and

road users that are well informed and adequately educated.

SAFE SYSTEM APPROACH

Forgiving

roads/streets

Speed

management

by design

Stopping distances at different travel speeds

Distance covered during

reaction time (1 second)

Braking distance

Sustainable Safety

Social Usability

Universal Accessibility

Captive Users

Equitable Allocation of Road Space

Modal Hierarchy

Design Principles

Universal Accessibility

Street design has to be inclusive and accessible to all

citizens.

Guiding Principles

• Space Allocation for different road users(pedestrians, bicycles, public transport, cars)

– Seperation vs integration

– Crossing /intersections

• Speed management by design

– Traffic calming

Guiding Principles

• Road geometric standards from Buses/VRUs(pedestrians,bicyclists,publictransport users) perspective

• Traffic management policies that enable safe mobility of VRUs

• Road side vendors/ informal sector to be viewed as service providers

Main roads(arterial) are usually 20-25% of the total network (speeds-50-70km/h)

Road Typology

…different roads are to be designed differently

Speed The history of design speed mentioned in the various codes and journal publications over the years (1936-2003) is given in Annexure 1 of the Urban roads – codes of practice . The following three conclusions which clearly shows that there is a need to Re-think about the Design Speed vs. operating speed, especially in urban areas

1. Wider lane widths (3.5m+) do not have co relation with low crash rates.

2. Operating speed and driver’s behavior (speeding) are related and influenced by lane widths. (Wider lane encourage high speed)

3. In urban areas there should not be difference in operating speed and design speed as the geometric features are based on design speed; it can confuse the driver and encourage higher speeds.

The new Standards like ASVV (CROW Manual-1998) and NCHRP Report (2003) recommend the following Source- NCHRP Report (2003).

Traffic control devices•Traffic signs

•Road Markings

•Traffic signals The application of road markings is

classified under the category of

different users. The road space has

been divided for different road users

depending upon their respective

design speeds. The different users

of the road space are:-

Motorized Vehicles (MV)

Buses

Cycles

Pedestrians

REGULATORY

SIGNS

WARNING SIGNS INFORMATORY

SIGNS

Objective Speed &Carriageway Width for two way traffic ad with a high quality public transport network

Objective Speed(km/h) Desired Carriageway width(m) Minimum Carriageway width(m)

50-70 7.7 7.5

50 7.3 7.1

30 6.9 6.7Note- The sizes stated in the table should be realized between the curbs are between the carriageway

markings.

Objective Speed &Carriageway Width for one way traffic and with a high quality public transport network

Objective Speed(km/h) Desired Carriageway width(m) Minimum Carriageway width(m)

50-70 3.6 3.5

50 3.5 3.3

30 3.3 3.1Note- The sizes stated in the table should be realized between the curbs are between the carriageway

markings.

Source-ASVV- Recommendations for traffic provisions in built up areas , Record 15

Speed Terms

Two lanes Multilane Arterial

FreewayLocal Collector Undivided Divided

Anticipated Operating Speed (mph) 30 35-45 45-55 50-60 60-70

Anticipated Posted Speed (mph) 30 30-45 45 45-55 55

Design Speed (mph) 30 35-50 45-50 45-60 60-70

Cross section – Examples

Cross Section (45 m ROW)

Cross Section – Half Subway

CY

CL

E

TR

AC

K

FO

OT

PA

TH

CY

CL

E

TR

AC

K

FO

OT

PA

TH

MV LANEMV LANE BUS LANE SERVICE

ROAD

SERVICE

ROAD

UN

PA

VE

D

UN

PA

VE

D

UN

PA

VE

D

UN

PA

VE

D

Ready To Use tables

ROW

PRIORITY allotment of remaning widths as per

Requirement

Pedestrian Cycle

lane Track

Service

Lane Green

Segregated

Bus Lane Parking

6M - 12M

12M- 18 M

18m- 24 m

24m onwards

32m onwards

45m onwards

Distribution of Road widths as per Priority

Residential Zone

Type of Road ROW(m) Bus lane

lane (width)- One lane

in each direction

Lane width- two

lanes in each

direction

Remaining Lane

widths

foothpath(on

each Side) Green and Parking Cycle Track / lane

Access:

speed- 15

km/hr

6 nil 3 0 Nil mixed

7 nil 3 1 0.5Nil mixed

8 nil 3 2 1Nil mixed

9 nil 3 3 1.5Nil mixed

10 nil 3 4 1.51( on one side) mixed

11 nil 3 5 21( on one side) mixed

12 nil 3 6 22.5( on one side with intermediate parking bays ) mixed

13 nil 3 7 23( on one side with intermediate parking bays ) mixed

14 nil 3 8 2.53( on one side with intermediate parking bays ) mixed

Distibutory:

Speed -30

km/hr

15 nil 3 9 22.5( on both side with intermediate parking bays ) mixed

16 nil 3 10 2.52.5( on both side with intermediate parking bays ) mixed

17 nil 3 11 2.53( on both side with intermediate parking bays ) mixed

18 nil 3 12 22.5( on both side with intermediate parking bays ) 1.5 m painted

19 nil 3 13 2.52.5( on both side with intermediate parking bays ) 1.5 m painted

20 nil 3 14 22.5( on both side with intermediate parking bays ) 2.5 m segregated

21 nil 3 15 2.52.5( on both side with intermediate parking bays ) 2.5 m segregated

22 nil 3 16 2.53( on both side with intermediate parking bays ) 2.5 m segregated

23 nil 3 17 2.53( on both side with intermediate parking bays ) 3 m segregated

24 painted 3 3 12 22( on both side with intermediate parking bays ) 2 m segregated

25 painted 3.1 3.1 12.6 22( on both side with intermediate parking bays ) 2.3 m segregated

26 painted 3.1 3.1 13.6 22.5( on both side with intermediate parking bays ) 2.3 m segregated

27 painted 3.1 3.1 14.6 2.52.5( on both side with intermediate parking bays ) 2.3 m segregated

28 painted 3.1 3.1 15.6 2.32.5( on both side with intermediate parking bays ) 3 m segregated

29 painted 3.1 3.1 16.6 32.3( on both side with intermediate parking bays ) 3 m segregated

30 painted 3.1 3.1 17.6 32.3( on both side with intermediate parking bays ) 3.5 m segregated

Highway passing through the city 50

Highway passing through the city 50

Main Arterial Roads 3 0 m a n d a b o v e R O W

50

Source : SGArchitects, New Delhi

Source : SGArchitects, New Delhi

Collector Roads 1 5 m a n d a b o v e R O W

30

Access Roads 1 5 m a n d a b o v e R O W

15

Source : SGArchitects, New Delhi

Source : SGArchitects, New Delhi

Intersection Design

Intersection control

conflicting and merging traffic.

Three main types –

signalized , unsignalized and

roundabouts.

Grade separated facilities

are not desirable within urban

limits and accessibility due to

their adverse impact on

accidents, pollution etc.

Grade separated facilities

divide urban landscape into

separate zones, making

pedestrians and cyclists

extremely vulnerable.

Arterial Roads Sub Arterial Roads Distributor Roads Access Streets

Arterial

Roads

1. Roundabouts (3,4 arm)

2. Signalized Crossings (3,4

arm)

3. Grade separated crossing

for motor vehicles

4. Grade Separated Crossings

for cyclists, along Arterial

road (in case of 4 arm

only)

1. Roundabouts (3,4 arm)

2. Signalized Crossings (3,4

arm)

3. Grade separated crossing for

motor vehicles

4. Grade Separated Crossings

for cyclists, along Arterial

road (in case of 4 arm only)

1. Roundabouts (3,4

arm)

2. Signalized Crossings

(3,4 arm)

3. Grade Separated

Crossing for cyclists

along Distributor road

(4 arm only)

1. Traffic calmed crossing

(3 arm only – access

street opening on to an

arterial road)

2. Grade Separated

Crossing for cyclists

along access road

Distributor

Roads

1. Roundabouts

2. Signalized Crossings (3,4

arm)

3. Grade Separated Crossing

for cyclists along

Distributor road (4 arm

only)

1. Roundabouts

2. Signalized Crossings (3,4

arm)

3. Grade Separated Crossing for

cyclists along Distributor road

(4 arm only)

1. Roundabouts

2. Signalized crossing

1. Roundabout

2. Unsignalized/ Traffic

Calmed Crossing (3, 4

arm)

Access Streets 1. Traffic calmed crossing (3

arm only – access street

opening on to an arterial

road)

2. Grade Separated Crossing

for cyclists along access

road

1. Traffic calmed crossing (3

arm only – access street

opening on to an arterial road)

2. Grade Separated Crossing for

cyclists along access road

1. Roundabout (3, 4

arm)

2. Unsignalized/ Traffic

Calmed Crossing (3, 4

arm)

1. Unsignalized/ Traffic

Calmed Crossing (3, 4

arm)

2. Mini Roundabouts

Intersection Design Depending upon the category of the roads intersecting , the code includes the design

standards for the following :

•Roundabouts

•Signalizes Junction

•Traffic Calmed and Un signalized Junction

Median and pedestrian crossing

Safe Intersection design Principles( Candappa et al., 2015):

• Principle 1 – key principle – limit travel speeds through intersections to 50 km/h There is general acceptance that 90◦ collisions between two passenger vehicles involving impact speeds greater than 50 km/h are likely to exceed the biomechanical tolerance threshold of humans given current vehicle structures (Bostrom et al., 2008; Fildes et al.,1994; Tingvall and Haworth, 1999)

• Principle 2 – important principle – avoid 90◦ impact angles Fig. 1 presents the reduction in kinetic energy in the lateral direction that can be achieved through the manipulation of impact angle. For example, at 70 km/h, colliding at a 90◦ angle generates kinetic energy of around double the maximum tolerable lateral kinetic energy of 96.5 kJ. Halving this impact angle, similar to impact angles at roundabouts, reduces the lateral kinetic energy to the biomechanical threshold.

• Travel speeds above 50 km/h, 90◦ impact angles are not compatible with Safe System ideals. Impact speeds of up to 70 km/h were considered tolerable if 90◦impact angles could be modified to more favourable angles (Corben et al., 2010). To aim for a Safe System intersection design then, optimising impact angles where possible is considered an “important” principle.

Roundabouts are safer than signalized or unsignalizedintersections

Impact angle, Kinetic energy and travel speed

ROUNDABOUTS REDUCE DEATHS BY50 -80% AND POLLUTION BY ~30%

• Principle 3 – important principle – physically separate vulnerable roadusers or provide travel speeds <30 km/h Vulnerable roadusers, defined here as pedestrians and twowheeler users (Australian Government Standing Committee on Planning Environment and Territory and Municipal Services, 2014; SWOV – Institute for Road Safety

Research, 2012), are particularly affected by the potential levels of kinetic energy at intersections.

• The absence of any vehicle protection leaves vulnerable roadusersopen to the full force of a crash. In fact, the safest means of ensuring Safe System compatibility with respect to vulnerable roadusers is to physically separate them from other roadusers.

• Temporal separation of vulnerable roadusers from vehicles is less effective in meeting Safe System ideals as this still relies on roaduser compliance and avoidance of error.

• For this reason, temporal separation has not been defined within Principle 4 as it still leaves open the possibility of serious injury.

• Principle 4 – supporting principle – limit points of conflict It can be argued that the risk of severe injury is reduced firstly by preventing the collision altogether. In particular, limiting the points of conflict at an intersection limits the possibility of a crash and so can increase overall safety at an intersection.

• Based on available research, a typical cross-intersection presents to the driver 32 conflict points as opposed to a typical roundabout which presents four to eight conflict points, depending on definitions (AustRoads, 2013; Hauer, 1990).

• Specifically, it must be noted that reducing the permitted movement types within the same intersection design automatically reduces the number of conflict points.

• To aim for a Safe System intersection design, reducing the number of conflict points is considered a supporting principle.

Location of Bus Shelter

Integration of Hawker Space

Roundabout

Safe pedestrian crossing

NON arterial roads and small cities

SPEED LUMPS

Lighting for pedestrians and bicycles

NMV lanes & lighting

CODE BOOK

CODE OF PRACTICE FOR URBAN

ROADS

Institute of Urban Transport, Delhi

WWW.IUTINDIA.ORG

www.cylos.in/report

www.iutindia.org/Capacity

Building/Toolkits.aspx

URSA PTA