ROAD TRAFFIC SAFETY...
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| SIDEWALKS, CURBS AND TRAFFIC IN USA |
Road traffic safety refers to methods and measures for reducing
the risk of a person using the road network being killed or seriously
injured. The users of a road include pedestrians,
cyclists, motorists, their passengers, and passengers of
on-road public transport, mainly buses and trams.
Best-practice road safety strategies focus upon the prevention of
serious injury and death crashes in spite of human fallibility[1]
(which is contrasted with the old road safety paradigm of simply
reducing crashes assuming road user compliance with traffic
regulations). Safe road design is now about providing a road environment
which ensures vehicle speeds will be within the human tolerances for
serious injury and death wherever conflict points exist.
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| safety traffic signals.. |
- As sustainable solutions for all classes of road have not been identified, particularly lowly trafficked rural and remote roads, a hierarchy of control should be applied, similar to best practice Occupational Safety and Health. At the highest level is sustainable prevention of serious injury and death crashes, with sustainable requiring all key result areas to be considered. At the second level is real time risk reduction, which involves providing users at severe risk with a specific warning to enable them to take mitigating action. The third level is about reducing the crash risk which involves applying the road design standards and guidelines (such as from AASHTO), improving driver behaviour and enforcement.
Background
Road traffic crashes are one of the world’s largest public
health and injury prevention problems. The problem
is all the more acute because the victims are overwhelmingly healthy
prior to their crashes. According to the World Health Organization (WHO),
more than a million people are killed on the world’s roads each year.
A report published by the WHO in 2004 estimated that some 1.2m people
were killed and 50m injured in traffic collisions on the roads around the world each
year
and was the leading cause of death among children 10 – 19 years of age.
The report also noted that the problem was most severe in developing
countries and that simple prevention measures could halve the number of
deaths.
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| pedestrian crossing and line marking of road |
Built-up areas
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| a curb extension at the mid block |
On existing neighborhood roads where many vulnerable road users, such
as pedestrians and bicyclists can be found, traffic calming can be a tool for road safety. Though not
strictly a traffic calming measure, mini-traffic circles implanted in
existing, normal intersections of neighbourhood streets, have been shown
to reduce collisions at intersections dramatically
(see picture).Shared space schemes, which rely on human
instincts and interactions, such as eye
contact, for their effectiveness, and are characterised by the
removal of traditional traffic signals and signs,
and even by the removal of the distinction between carriageway
(roadway) and footway (sidewalk), are also becoming increasingly
popular. Both approaches can be shown to be effective.
For planned neighbourhoods, studies recommend new network
configurations, such as the Fused
Grid or 3-Way Offset. These layout models organize a neighbourhood
area as a zone of no cut-through traffic by means of loops or dead-end
streets. They also ensure that pedestrians and bicycles have a distinct
advantage by introducing exclusive shortcuts by means of path
connections through blocks and parks. Such a principle of organization
is referred to as "Filtered Permeability" implying a preferential
treatment of active modes of transport. These new patterns, which are
recommended for laying out neighbourhoods, are based on analyses of
collision data of large regional districts and over extended time
periods.They
show that four-way intersections combined with cut-through traffic are
the most significant contributors to increased collisions.
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| traffic lights ።። |
Turning across traffic።።።
Turning across traffic (i.e. turning left in right-hand drive
countries, turning right in left-hand drive countries) poses several
risks. The more serious risk is a collision with oncoming traffic. Since
this is nearly a head-on collision injuries are common. It is the most
common cause of fatalities in a built up area. The other risk is
involvement in a rear-end collision while waiting for a gap in oncoming
traffic.
Countermeasures for this type of collision include:
- Addition of left turn lanes
- Providing protected turn phasing at signalized intersections
- Using indirect turn treatments such as the Michigan left
- Converting conventional intersections to roundaboutsIn the absence of these facilities as a driver about to turn:
- Keep your wheels straight, so that in the event of a rear end shunt, you are not pushed into on coming traffic.
- When you think it is clear, look away, to the road that you are entering. There is an optical illusion that, after a time, presents an oncoming vehicle as further away, and travelling slower. Looking away breaks this illusion.
Reference:
^ Parslow,B and Wyvill, G Seeing in 3-D, course 42, SIGGRAPH 2001,
Los Angeles
Turns across traffic have been shown to be problematic for older
drivers.
Designing for pedestrians
and cyclists።።።
Pedestrians and Cyclists are among the most vulnerable road users,
and in some countries constitute over half of all road deaths.
Interventions aimed at improving safety of non-motorised users:
- Sidewalks of suitable width for the expected pedestrian traffic
- pedestrian crossings close to the desire line which allow pedestrians to cross roads safely
- segregated pedestrian routes and cycle lanes away from the main highway
- Overbridges (tend to be unpopular with pedestrians and cyclists due to additional distance and effort)
- Underpasses (these can pose heightened risk from crime is not designed well, can work for cyclists in some cases)
- traffic calming and speed humps
- low speed limits that are rigorous enforced, possibly by speed cameras
- shared space schemes giving ownership of the road space and equal priority to all road users, regardless of mode of use
- pedestrian barriers to prevent pedestrians crossing dangerous locations
Pedestrians' advocates question the equitability of schemes if they
impose extra time and effort on the pedestrian to remain safe from
vehicles, for example overbridges with long slopes or steps up and down,
underpasses with steps and addition possible risk of crime and at-grade
crossings off the desire line. The Make Roads Safe was criticised in 2007 for proposing such
features. Successful pedestrian schemes tend to avoid over-bridges and
underpasses and instead use at-grade crossings (such as pedestrian
crossings) close the intended route. Successful cycling scheme by
contrast avoid frequent stops even if some additional distance is
involved given that the main effort required for cyclists is starting
off.
In Costa Rica 57% of road deaths are pedestrians, however a
partnership between AACR,
Cosevi, MOPT and iRAP has proposed the construction of 190 km of
pedestrian footpaths and 170 pedestrian crossings which could save over
9000 fatal or serious injuries over 20 years.
Major highways
Major highways
including motorways, freeways, Autobahnen and Interstates are designed for safer high-speed
operation and generally have lower levels of injury per vehicle km than
other roads.
Safety features include:
- limited access from properties and local roads.
- Grade separated junctions
- Median dividers between opposite-direction traffic to reduce likelihood of head-on collisions
- Removing roadside obstacles.
- Prohibition of more vulnerable road users and slower vehicles.
- Placements of energy attenuation devices (e.g. guard rails, wide grassy areas, sand barrels).
- Eliminating road toll booths
The ends of some guard rails on high-speed highways in the United
States are protected with impact attenuators, designed to gradually
absorb the kinetic energy of a vehicle and slow it more
gently before it can strike the end of the guard rail head on, which
would be devastating at high speed. Several mechanisms are used to
dissipate the kinetic energy. Fitch Barriers, a system of sand-filled barrels,
uses momentum transfer from the vehicle to the sand. Many other systems
tear or deform steel members to absorb energy and gradually stop the
vehicle.
In some countries major roads have "tone bands" impressed or cut into
the edges of the legal roadway, so that drowsing drivers are awakened
by a loud hum as they release the steering and drift off the edge of the
road. Tone bands are also referred to as "rumble strips", owing to the sound they create.
An alternative method is the use of "Raised Rib" markings, which
consists of a continuous line marking with ribs across the line at
regular intervals. They were first specially authorised for use on
motorways as an edge line marking to separate the edge of the hard
shoulder from the main carriageway. The objective of the marking is to
achieve improved visual delineation of the carriageway edge in wet
conditions at night. It also provides an audible/vibratory warning to
vehicle drivers, should they stray from the carriageway, and run onto
the marking.
Better motorways are banked on curves in order to reduce the need for
tire-traction and increase stability for vehicles with high centers of
gravity.
An example of the importance of roadside clear zones can be found on
the Isle of Man TT motorcycle race course. It is much more
dangerous than Silverstone because of the lack of
runoff. When a rider falls off at Silverstone he slides along slowly
losing energy, so minimal injuries. When he falls of in the Manx he
impacts with trees and walls. Similarly, a clear zone alongside a
freeway or other high speed road can prevent off-road excursions from
becoming fixed-object crashes.
The U.S. has developed a prototype automated roadway,
to reduce driver fatigue and increase the carrying capacity of the
roadway. Roadside units participating in future Wireless
vehicle safety communications networks have been studied.
Motorways are far more expensive and space-consumptive to build than
ordinary roads, so are only used as principal arterial routes. In
developed nations, motorways bear a significant portion of motorized
travel; for example, the United Kingdom's 3533 km of motorways
represented less than 1.5% of the United Kingdom's roadways in 2003, but
carry 23% of road traffic.
The proportion of traffic borne by motorways is a significant safety
factor. For example, even though the United Kingdom had a higher
fatality rates on both motorways and non-motorways than Finland, both
nations shared the same overall fatality rate in 2003. This result was
due to the United Kingdom's higher proportion of motorway travel.
Similarly, the reduction of conflicts with other vehicles on
motorways results in smoother traffic flow, reduced collision rates, and
reduced fuel consumption compared with
stop-and-go traffic on other roadways.
The improved safety and fuel economy of motorways are common
justifications for building more motorways. However, the planned
capacity of motorways is often exceeded in a shorter timeframe than
initially planned, due to the under estimation of the extent of the
suppressed demand for road travel. In developing nations, there is
significant public debate on the desirability of continued investment in
motorways.
Motorways around the world are subject to a broad range of speed
limits. Recent experiments with variable speed limits based on
automatic measurements of traffic density have delivered both
improvements in traffic flow and reduced collision rates, based on
principles of turbulent flow analysis. 
With effect from January 2005 and based primarily on safety grounds,
the UK’s Highways Agency's policy is that all new
motorway schemes are to use high containment concrete step barriers in the central
reserve. All existing motorways will introduce concrete barriers into
the central reserve as part of ongoing upgrades and through replacement
as and when these systems have reached the end of their useful life.
This change of policy applies only to barriers in the central reserve of
high speed roads and not to verge side barriers. Other routes will
continue to use steel barriers.
More people die on the hard shoulder than on the highway itself.
Without other vehicles passing a parked car, following drivers are
unaware that the vehicle is parked, despite hazard lights. Truck drivers
indicate that they are parked by putting their cab seat behind their
truck. In the UK, the AA and police park their vehicles on the hard
shoulder at a slight angle so that following drivers can see down the
side of their vehicle and are therefore aware that they are stopped.
30% of highway crashes that occur in the vicinity of toll collection
booths in the countries that have them, these can be reduced by
switching to electronic toll systems.Information campaigns።።
- Decade of Action by World Health Organization and Fédération Internationale de l'Automobile (2011-2020)
- traffic awareness campaigns such as the "one false move" campaign documented by Hillman et al.
- Speeding. No one thinks big of you. (New South Wales, Australia, 2007)
- Road Safety is no Accident World Health Organization
- Designated driver campaign, (U.S., 1970s-present)
- Click It or Ticket, (U.S., 1993–present)
- Clunk Click Every Trip (UK 1971)
- Green Cross Code (UK 1970–present)
traffic signals።።።
