Transportation Safety Notes

Highway Accidents

  • World Bank Group – Global Road Safety Facility:
    • 77% of road crash fatalities and injuries occur in the economically productive age group (15-64 years).
    • Male to female fatalities ratio is 3:1, with the 15-49 year age group being the most vulnerable.
    • 635 life years are affected due to disability from road crash injuries per 100,000 people.

Major Speed Calming Measures

  • Narrowing:
    • Lane narrowings achieved by extending sidewalks, curb extensions, pedestrian refuges, etc.
  • Vertical Deflections:
    • Speed bumps, humps, cushions, tables, raised pedestrian crossings, variations in ride surface, etc.
  • Horizontal Deflections:
    • Chicanes, pedestrian refuges, chokers, etc. used to make vehicles swerve slightly.
  • Block or Restrict Access:
    • Median diverters, closing streets to create pedestrian zones, cul-de-sacs, etc.
  • National Laws (WHO, 2016):
    • Seatbelt Law:
      • Driver
      • Front
      • Back
    • Motorcycle Helmet Law:
      • Helmet Standards
      • Motorcycle Occupant Age Restriction: Not restricted
    • Legal Minimum Driving Age: 17 years.
    • National Drink Driving Law:
      • Is Law BAC Based?
      • Random Drink Driving Tests
      • % of Road Crash Fatalities Involving Alcohol: Unknown

Transportation Schemes: Crossings

Zebra Crossing

  • Help pedestrians cross the road.
  • White strips painted on the road in the crossing area.
  • Flashing yellow lights on black and white striped poles at both sides.
  • Curbs are dropped at both ends with tactile paving.
  • Advantages:
    • Pedestrians wait for a short period.
    • Cars should stop for pedestrians.
    • Typically half the price of a traffic light (puffin) crossing.
    • Can look attractive.
    • Low maintenance cost.
  • Disadvantages:
    • Risk of collision if drivers fail to stop.
    • Difficult for blind or partially blind people.
    • Humps or narrowing require water drainage works, which could be costly.

Pedestrian Refuge Island

  • Raised section of pavement between traffic lanes moving in opposite directions.
  • Yellow and white plastic bollards with a blue arrow.
  • Curbs are dropped with tactile paving.
  • Advantages:
    • Clear signal for pedestrians.
    • Easier crossing.
    • Quicker crossing as gaps are required in one direction only.
    • Narrows the road, reducing vehicle speed.
  • Disadvantages:
    • No pedestrian priority.
    • Longer wait times compared to zebra or puffin crossings.
    • Requires good judgment of vehicle speeds and gaps.
    • Less easy to use for visually impaired or disabled people.

Puffin Crossings

  • Use traffic lights to stop vehicles for pedestrians.
  • Pedestrians push a button and wait for a green man signal.
  • Beeping sound when the walking green man is shown.
  • Advantages:
    • Clear signal for pedestrians.
    • Clear signal for vehicle users.
    • Crossing times are automatically extended for slower pedestrians.
    • Vehicle users should not stop when nobody is using the crossing.
  • Disadvantages:
    • Most expensive crossing type.
    • Pedestrians must wait for the signal.
    • Pedestrians may walk into the road when the signal changes without checking traffic.
    • Expensive to maintain.

Transportation Schemes: Speeding

Speed Cushions

  • Short, raised, rounded device in the center of a lane.
  • Wider than a car, requiring drivers to slow down and drive over the center.
  • Advantages:
    • Buses don't need to slow down.
    • More effective than horizontal treatments.
    • Emergency vehicles can travel more quickly than over speed humps or tables.
    • Can be avoided by cyclists.
    • Drainage should not be affected.
  • Disadvantages:
    • Cars drive faster over speed cushions than speed humps or tables.
    • Bus companies and emergency services may oppose wider speed cushions.
    • Traffic may transfer onto alternative routes.

Road Narrowing

  • Reduces the width of the road.
  • Curb extensions at a junction entrance with bollards.
  • Advantages:
    • Targets a specific part of the road.
    • Can be used on junctions.
    • Can prevent vehicle parking.
    • Makes it easier for pedestrians to cross.
    • Emergency vehicles should be able to pass without slowing down.
  • Disadvantages:
    • Not as effective as vertical treatments.
    • Managing water drainage could be complex and costly.
    • Cyclists may feel intimidated.

Speed Table

  • Raised section of road with ramps on both sides.
  • Ramps painted with white arrows.
  • Advantages:
    • Most effective traffic calming treatment.
    • Can be used as part of an informal pedestrian crossing.
    • More acceptable than speed humps to buses.
    • Flexible size.
  • Disadvantages:
    • Expensive.
    • Managing water drainage could be complex and costly.
    • Buses, cyclists and emergency vehicles will need to reduce their speed.
    • Traffic may transfer onto alternative routes.

Speed Cameras

  • Photograph vehicles exceeding the speed limit (usually 10% over).
  • Use a radar device to detect speed.
  • Advantages:
    • Effective at keeping vehicles within the speed limit.
    • Can keep speeds low in the wider area.
    • Suited to busy roads.
    • No negative impact on emergency vehicles or buses.
  • Disadvantages:
    • Requires a funding structure and agreement with local police.
    • Criticism from media that they do not increase road safety and are only there to generate money.

Speed Humps

  • Short rounded top, typically 75mm high.
  • Ramps painted with white arrows.
  • Advantages:
    • More effective than speed cushions and horizontal treatments.
  • Disadvantages:
    • Buses, cyclists and emergency vehicles may need to slow down.
    • Bus companies normally oppose speed humps.
    • Traffic may transfer onto alternative routes.

Transportation Scheme: Parking Management

Parking Restrictions

  • Prevent vehicles parking by the side of the road.
  • Double Yellow lines: Do not allow vehicles to wait at any time (loading/unloading and setting down/picking up passengers are permitted).
  • Advantages:
    • Prevent vehicles blocking access.
    • Keep traffic flowing.
  • Disadvantages:
    • Long legal process and consultation required.
    • Losing parking space may be an issue for residents.

Parking Deterrents

  • Bollards:
    • Good deterrent.
    • Different designs available.
    • Can look unsightly.
    • Can become maintenance liability.
    • Risk to partially sighted people
  • Tree Planting:
    • Not effective on their own, as trees must be planted further apart to grow correctly
    • Visually enhances the street
    • Could be issues with soil, roots and drainage
    • Long term maintenance required
    • Can be sponsored by local organisations
  • Planters:
    • Relatively cheap
    • Suitable for rural areas
    • Easily damaged
    • Can become maintenance liability
  • Boulders:
    • Extremely effective
    • Can be considered unsightly
    • Not suitable in residential areas
    • Probably only suitable in industrial areas with existing HGV problems
  • Posts:
    • Can be quickly installed or removed
    • Can be owned by the community, or sponsored by an organisation
    • Adds to street 'greening'
    • Can become a maintenance liability if not looked after
  • Stepped Kerbs:
    • Little/ no maintenance
    • Very effective
    • Sometimes considered unsightly
    • Also useful for preventing forced access to land
  • Low level planting
    • Long term maintenance required
    • Visually enhances the street
    • Only likely to be effective once established
    • Could be issues with soil and drainage
    • Can collect litter and other debris
  • Raising existing kerbs
    • Unlikely to be effective in isolation
    • Could be useful where kerbs are currently very low
    • No maintenance
    • Very little visual impact on the street

Transportation Scheme: "Rat Running"

Close Road to Through Traffic

  • Building a raised curb area across the road with an obstruction.
  • Advantages:
    • Removes all vehicle through traffic.
    • Relatively cheap way to reduce traffic volume.
    • The road obstruction could contribute to the character of the area.
    • Can be designed to allow access for cyclists.
  • Disadvantages:
    • Could cause delay to emergency services.
    • May cause longer journeys for local residents.

One Way Street

  • Allows vehicles to move in one direction down the road.
  • ‘No-entry’ signs are used to prevent vehicles travelling the wrong way.
  • Arrow signs are used to show it is a one way street.
  • Advantages:
    • Can prevent vehicles using the road as a short cut / rat run.
    • Can create more road space for car and cycle parking.
    • Can help traffic to move more freely.
  • Disadvantages:
    • Likely to increase vehicle speeds.
    • Motor vehicles and emergency vehicles may need to travel greater distance to get to their destination.

Accidents

Railway Accidents

  • Examples:
    • Japan, HyogoHyun, JR Hukuyama Line, Derailment due to over speeding, 2005: 107 fatalities.
    • New York Metro, Derailment due to over speed, 2013: 4 fatalities and 60 Injuries.
    • USA, Columbus, Norfolk Derailment/fire due to rail defects, 2012: 1 Injuries and Hazardous materials release.
    • Korail, YeoSoo, Derailment due to over speed, 2016: Driver’s death and Injuries of 8 passengers.
Classification of Rail Accidents by Effects
  • Collisions:
    • Head-on collision
    • Rear collision
    • Collisions with buffer stops
    • Obstructions on the line (road vehicles, landslides, avalanches)
  • Derailments:
    • Plain track
    • Curves
    • Junctions
  • Other:
    • Fires and explosions (including sabotage/terrorism)
    • Falls from trains, collisions with people on tracks
Classification of Rail Accidents by Causes
  • Drivers’ errors:
    • Passing signals at danger
    • Excessive speed
    • Mishandling engine (e.g. boiler explosions)
  • Signalmen’s errors:
    • Allowing two trains into same occupied block section
    • Incorrect operation of signals, points or token equipment
  • Mechanical failure of rolling stock:
    • Poor design
    • Poor maintenance
  • Civil engineering failure:
    • Track (permanent way) faults
    • Bridge and tunnel collapses
  • Acts of other people:
    • Other railway personnel (shunters, porters, etc)
    • Non-railway personnel
    • Accidental
    • Deliberate (vandalism, terrorism, suicide)
  • Contributory factors:
    • Strength of rolling stock
    • Fires resulting from accidents
    • Effectiveness of brakes
    • Poor track or junction layout
    • Inadequate rules

Derailments

  • A derailment occurs when a vehicle (e.g., a train) runs off its rails.
  • Causes:
    • Mechanical failure of a track component (e.g., broken rails, gauge spread due to sleeper failure).
    • Mechanical failure of a component of the running gear of a vehicle (e.g., axlebox failure, wheel breakage).
    • Fault in the geometry of the track or running gear that results in a quasi-static failure in running (e.g., rail climbing due to excessive wear of wheels or rails, earthworks slip).
    • Dynamic effect of the track-vehicle interaction (e.g., extreme hunting, vertical bounce, track shift under a train, excessive speed).
    • Improper operation of points, or improper observance of signals protecting them (signal errors).
    • Secondary event after collision with other trains, road vehicles, or other obstructions (level crossing collisions, obstructions on the line).
    • Train handling (snatches due to sudden traction or braking forces).

Accident Investigation

Railway Buckling

Rail Buckling

  • If the track buckles, the line must be closed and repaired, causing disruption.
  • Repairs can’t be done until the rail temperature drops.
  • Speed restrictions are introduced on at-risk sections.
  • How to Prevent Rails Buckling:
    • For short rails bolted together, small gaps are left for expansion.
    • Most track is made of long stretches of rail that are stretched and welded together.
    • Track stability is checked each winter and weaknesses are strengthened.
    • Avoid work that will disturb the stability of the track during the summer.
    • Paint “at-risk” rails white to absorb less heat.
    • Enhance measures for calculating rail temperatures, including installing probes.
    • Impose speed restrictions at vulnerable locations when high rail temperatures are widespread.