vulnerable road users hossein naraghi ce 590 special topics safety june 2003 time spent: 8 hrs

Vulnerable Road Users

Hossein Naraghi

CE 590 Special Topics

Safety

June 2003

Time spent: 8 hrs

Pedestrian safety Pedestrians at risk

Research in US indicates • Number of pedestrian injuries per head of

population is highest for for males 5-9 age group

• Occurs mostly near victim’s home• Victim running across the road• Most occur in the afternoon• Most occur away from pedestrian crossing

facility• In many cases the victim did not see the

vehicle at all, or saw that too late

Pedestrian safety (continued)

Elderly are the other vulnerable group of pedestrians• Having a lower pedestrian accident rate than

most age group• Elderly are more likely to suffer serious injury

• In US fatal pedestrian accident rate

• exceeds 20 percent for pedestrians over age of 75 years

• About 8 percent for pedestrians under age 14 years

Pedestrian safety (continued)

In Britain 50 percent of pedestrian deaths involve people aged over 60 years (Carthy et al 1995)•When crossing a road combination of

• Failure of initial judgment• Made by sensory loss with age

• Failure to modify behavior to avoid a developing incident

• Made by physical and intellectual impairment

• Elderly women are more at risk than men taking account for distance walked and roads crossed

Factors contributing to pedestrian accidents

There are some environmental factors which associated with pedestrian accidents 44% of pedestrian involved in an accident didn’t

see the vehicle, 34% of these were saying that they saw the vehicle too late

• Due to obstruction caused by parked or stationary vehicles (not involved in the collision)

8% of pedestrian crashes occur near the bus stop• Pedestrians trying to catch the bus or the pedestrian

walking in front of a bus 20% of pedestrian accident occurred at pedestrian

crossing • Due to pedestrian error or driver non-compliance

Factors contributing to pedestrian accidents (continued)

The speed of the vehicle was the contributing factor in 8% of pedestrian accidents

• Individual vehicles traveling too fast A US study indicates that pedestrian accidents

• Are mostly occur during morning and afternoon peak periods

• Fridays and Saturdays over-represented• Sundays under-represented

• 67% of accidents occur away from an intersection • Child pedestrian accident mostly occur at mid-block locations• Adults 45-65 years pedestrian accidents are equally likely to

occur at mid-block or intersections• Elderly pedestrian accidents at intersections are more

prevalent

Pedestrian safety treatments

Design strategies for pedestrians fall in three categories

Segregation• Spatial separation of pedestrians and vehicular

network Separation

• Allocation of either time (pedestrian signals) or space (sidewalks) within a shared pedestrian-vehicle facility

Integration• Through shared use of facility

Pedestrian safety treatments (continued)

Safety effectiveness of pedestrian treatments Footpaths or sidewalks

• Have significant safety benefits where pedestrian volume is high

• Residential and business districts

Refuge islands• Permit pedestrians to cross traffic one stream

at a time with a safe waiting area at the center of the roadway

• Such devices are appropriate when pedestrian crossing movement are concentrated, but overall numbers do not warrant a pedestrian crossing


Curb extensions• Consists of local widening of the sidewalk into

roadway• Reduces the time required by pedestrians to

cross the traffic stream• Assist in mutual visibility of pedestrian and

motorists• Reduce pedestrian exposure and vehicular

delay Pedestrian barriers

• Applicable in locations with high pedestrian activities


Zegeer and Zegeer (1988) suggest that pedestrian barriers are most beneficial in particular situations Pedestrian overpasses Vehicle speeds are high High volumes of child pedestrians Little separation between roadway and sidewalk

on high speed roads Near schools and other major pedestrian

generators On bridges with both pedestrian and vehicular

traffic


Traffic signals Pedestrian facilities at traffic signals may

• Have no explicit recognition• Pedestrians have to observe the vehicle signals

• Have concurrent phasing• Walk and do not walk display, either in words or

symbols• May activate automatically in every cycle • May require pedestrian to use a push button

• Have exclusive pedestrian phasing• No potential conflict with vehicular movement


Based upon an analysis in US, there was no statistical difference between intersections that had walk/don’t walk control and those which had no pedestrian indication

Zegeer 1993 suggests that pedestrian displays are necessary when

• Vehicle displays are not visible to pedestrians• Timing is complex

• Exclusive turn phases

• At school crossing• Exclusive pedestrian-only phase

• Allow pedestrian movement in any direction


Pedestrian crossings Zebra crossing

• Comprised a striped crossing and flashing signals to alert motorist to the presence of crossing

• The absence of positive control means that this device is not suitable for

• heavy or fast moving traffic (greater than 35 mph)• Pedestrians are constantly using the crossing

• Zegeer notes that zebra crossing are “used sparingly in most part of the US because of the uncertainty regarding their potential safety effect”

Pedestrian crossings (continued)

Pedestrian operated signals• Display a red-green-yellow to approaching

vehicles, identical to that faced at an intersection

• The sequence initiated by pedestrian pressing a button or in some modern facilities, pedestrians are detected automatically

• They are more positive than zebra crossing• Pedestrians do not have to expose themselves to risk

by stepping onto the crossing

• They are suitable for use where signals are linked, heavy or fast moving traffic or heavy pedestrian demands


Pelican crossings A combination of zebra crossing and a

pedestrian operated signal They are used on more heavily trafficked

roads• On roads with speed limit of 40 mph or greater,

where there are heavy pedestrian flows which would cause delay to motorists

They are used where sight distance is limited


Grade separated facilities Pedestrian overpass and underpass are

appropriate• High speed roadway• High traffic flow• Considerable pedestrian delay• High pedestrian accident problem• Restricted access to roadway

A US research indicates that 95% of people will use overpass if there is no loss of travel time


Facilities for disabled Range of provisions that can be provided for people

with disabilities such as elderly• Use of tactile surfaces to alert pedestrians• Use of audible tones at signalized pedestrian crossing• Use of ramps at curbs• Attention to the maintenance of surfaces so a smooth,

obstruction-free path is available at all times• Raised guide strips at pedestrian crossings to provide

assistance to the people with impaired vision• Particular attention to road work and building sites to

ensure adequate pedestrian facility remain in place


Lighting To provide a measure of personal security Enables pedestrians to see hazard or obstacle at

night Appropriate level of lighting should be provided Higher level of lighting intensity are necessary at

• pedestrian crossings• Refuge islands• Outside commercial and retail establishments which trade

at night• Pedestrian underpasses

Checklist Austroads (1995) provided a useful checklist

for safety audit of pedestrian schemes which can usefully applied to an examination of current pedestrian facilities Check the design in three dimension Ensure that scheme takes account of the likely

range of vehicle speed Ensure that islands are large enough to cater for

pedestrians as well as for the necessary street furniture

Ensure pedestrian routes are continuous

Checklist (continued) Avoid mixing different type of pedestrian controls

in close proximity Minimize pedestrian crossing distances Where pedestrians are to be deterred from

crossing, ensure that fencing is adequate Provide refuge on heavily trafficked roads to

enable pedestrians crossing the road in stages Ensure pedestrian underpass are wide, straight

and open Ensure pedestrian lighting is adequate Footpath should be smooth, skid resistance and

kept clear from overhanging foliage

Checklist (continued) Ensure pedestrian walk time are adequate for

elderly pedestrians Provide audio-tactile devices where possible Ensure that ramps are flush with the invert Manage parking to maximize sight distance at

pedestrian crossing Ensure that street furniture does not obstruct the

vision of pedestrians especially children Ensure that crossings can be identified and

negotiated by visually impaired pedestrians Ensure that refuge islands are wide enough to

accommodate a wheelchair Where possible

Bicyclist safety Bicyclists are over-represented in fatal

crashes There were 585 fatalities per 10^8 km of travel for

bicyclists compare to 112 fatalities per 10^8 km for all road users in Britain

Bicyclists along with other vulnerable road users are significantly under-reported in official road crash statistics

Per capita hour of travel, bicyclists are more than 5 times as likely as car occupants to be killed, while motor cyclists are 30 times as likely to be killed

Bicyclist safety (continued) Safety strategies

Wearing helmet Use of brightly colored clothing Use of under-run barriers on trucks Education Legislation such as sanction on

• Speeding• Alcohol use• Bicyclist conspicuity• Compulsory wearing of helmet

Provision of bicycle facilities• Explicit consideration of bicyclist needs at intersections

Bicyclist safety (continued) Bicyclist requirements

There are four basic requirements of bicyclists in relation to the physical facilities they use

• A space to ride with adequate lateral clearance• A smooth surface• The ability to maintain speed• Route connectivity and continuity

Bicycle facilities On-street, mixed traffic bicycling On-street bicycle only lane On-street shared bus-bicycle lane Bicycle use of road shoulders Bicycle path

Intersection treatments

Problems faced by bicyclists at intersections include Narrowing of the traffic lane to create a squeeze

point• Associated with provision of an extra lane through the

intersection for capacity purposes Insufficient room between the line of vehicles and

the curb• Preventing bicyclists from reaching the head of the queue

Bicyclists may have difficulty in moving from the curb lane to the median lane in order to make a left hand turn

Intersection treatments (continued) In making a left turn, bicyclists are commonly on

the outside of the turning traffic, and in potential conflict with opposing left turners

Bicyclists are generally vulnerable at diverge and merge areas for right turners

Signal detectors are not sensitive enough to detect a bicycle unless special detectors are fitted

• This may cause insufficient time for bicycle to clear intersection

Bicyclists perceive roundabouts to be unsafe

Intersection treatments (continued)

Attention to the needs of bicyclists in the design of intersections can improve these problems. Some good practices are as follow Priority controlled intersections

• If wide curbside lanes or bicycle lanes are provided, these should be carried through the intersection

• Where they can not be carried through, the lane should be terminated well in advance of the intersection (about 170 ft)


Signalized intersections• Curbside approach lanes 13-15 ft wide allow

bicyclists to share the lane with motor vehicles

Crossing between roads and bicycle paths• Off-road bicycle path must be accessible with

a reasonable length• Bicyclists frequently intersect with roads

carrying motor vehicles


•The requirements for safe and consistent use of facilities by bicyclists are as follow

• Adequate sight distance • Clear indication of termination of the bicycle

link• A flat approach, or only a slight gradient• A right angle intersection, or as close to right

angle as possible• Effective control of bicycle movements

Attention to detail Some detail attention in design to provide

safe and convenient operating condition include Ensure that drainage grates cannot trap the

wheel of bicycle Need for lighting for night-time use of facility Squeeze points or lane drops must be clearly

visible to an approaching bicyclist The need for smooth surface for bicyclists leads

to the need for regular maintenance Adequate sight distance needs to be maintained

Traffic calming Roundabouts

For single lane roundabouts, an entry lane width of 13-17 ft will provide adequate clearance for bicycles while allowing only single-file vehicle entry

Chicanes Can create a hazard for bicyclists, since the rider

is required to swing out toward the center of the road and share road space with both same and opposing direction

Traffic calming (continued) Humps

From bicyclists view point, humps• Should not located near the bottom of a steep

grade• Should extend across the full width of the road,

so that bicyclists are not squeezed• Should have a smooth surface

Road closure To ensure road connectivity, bicycle

access should usually be maintained after street closure

vulnerable road users hossein naraghi ce 590 special topics safety june 2003 time spent: 8 hrs

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