The Arizona Department of Transportation's crosswalk policy is based on research conducted over a seven-year period by the City of San Diego. The San Diego approach to evaluating crosswalk needs, which resulted from that research, has resulted in that city being consistently ranked as the safest pedestrian city in the nation. The San Diego study showed traffic engineers that nearly six pedestrian accidents were occurring in marked crosswalks for every one mishap in unmarked crosswalks (those unpainted crosswalks that exist by State law at all intersections). When this ratio was adjusted in terms of relative crosswalk usage, there was still an impressive 2 to 1 difference in accidents.
Overall, the question of crosswalks is a difficult one and there are no easy answers. The following discussion surveys some of the factors which enter into traffic engineers' decisions to mark crosswalks and are offered here in the interest of broader public understanding.
HOW SECURE ARE YOU IN A CROSSWALK?
Marked crosswalks are widely classified as safety devices and most jurisdictions give the pedestrian the right-of-way when within them. Interestingly, however, there is strong evidence that these very facts prompt many pedestrians to feel overly secure when using a marked crosswalk - to the degree that they may aggressively place themselves in a hazardous position with respect to vehicles in the mistaken belief that the vehicle can and will stop in all cases, even when it may be impossible to do so. It is not unusual, also, for this type of pedestrian behavior to cause rear-end collisions.
By contrast, a pedestrian using an unmarked crosswalk generally feels less secure, less certain that the vehicle will stop - and exercises more caution in waiting for safe gaps in traffic before crossing. The end result is fewer accidents at unmarked crosswalks.
THE CROSSWALK AS A WARNING DEVICE
One of the commonly accepted functions of the marked crosswalk is that it serves as a warning device to the traveling public.
And yet, studies show that the driver's view of a crosswalk is greatly reduced at the safe stopping sight distance - where he should be able to perceive and react to a pedestrian in a crosswalk - due to the effects of foreshortening and distance diminishment. The view of the crosswalk is further affected by road alignment, irregularities in the pavement and other variables like weather, a dirty windshield, glare, and adverse lighting conditions.
Meanwhile, the pedestrian's view of the same crosswalk is quite impressive and he's prone to assume that, since he can see the crosswalk so well,certainly the driver can see it just as effectively. This resulting overconfidence is seen as another factor in the disproportionate share of accidents in marked crosswalks.
ANOTHER CONTRIBUTOR: EXPOSURE RATIO
Assume that for every pedestrian who crosses a street in a marked crosswalk there are some 70 vehicles that drive over it. This is a ratio of use only - obviously each pedestrian does not encounter 70 vehicles. The pedestrian may have only encountered a few, if any, vehicles. Similarly, few, if any of the 70 drivers may have had to slow down or stop for the pedestrian.
In many locations on our roads and streets, the pedestrian and the driver most often encounter marked crosswalks with no necessity to slow down or stop. The result of this relatively low incidence of actual exposure is that it tends to precondition both the pedestrian and the driver to a presumption of safe passage and they are ill-prepared to react when danger does occur.
Does this mean marked crosswalks should not be installed?
Not necessarily. The marked crosswalk is a useful traffic engineering device for channelizing pedestrians and helping pedestrians find their way across complex and confusing intersections. it will continue to be used until a better means is developed to show the preferred route to pedestrians when crossing the street.
The answer, of course, is the understanding by pedestrians that as much caution needs to be used when using a marked crosswalk as those unmarked - which is the purpose of this brief discussion.
TRADEOFFS: ADVANTAGES vs. DISADVANTAGES
The decision to install or not install a marked crosswalk should not be taken lightly. Rational warrants have been adopted in "Arizona's Crosswalk Policy" for their installation. Care should be taken that crosswalks are not installed where there is a question of their resulting in traffic casualties.
In general, marked crosswalks have the following advantages and disadvantages:
- May help pedestrians orient themselves and find their way across complex intersections.
- May help show pedestrians the shortest route across traffic.
- May help show pedestrians the route with the least exposure to vehicular traffic and traffic conflicts.
- May help position pedestrians where they can be seen best by oncoming traffic.
- May help utilize the presence of luminaires to improve pedestrian nighttime safety.
- May help channelize and limit pedestrian traffic to specific locations.
- May aid in enforcing pedestrian crossing regulations.
- May act, in a limited manner, as a warning device and reminder to drivers that this is a location where pedestrian conflicts can be expected.
- May cause pedestrians to have a false sense of security and to place themselves in a hazardous position with respect to vehicular traffic.
- May cause the pedestrian to think that the driver can and will stop in all cases, even when it is impossible to do so.
- May cause a greater number of rear-end and associated collisions due to pedestrians not waiting for gaps in traffic.
- May cause an increase in fatal and serious injury accidents.
- May cause a disrespect for all pedestrian regulations and traffic controls.
Unjustified and poorly located marked crosswalks may cause an increased expense to the taxpayers for installation and maintenance costs which may not be justified in terms of improved public safety. Indeed, such crosswalks may tend to increase the hazard to pedestrians and drivers alike.
In conclusion, it is appropriate to restate that marked crosswalks will continue to be a useful traffic control device. But, it is important that the general public recognize what marked crosswalks can and cannot do. It is also important that public officials not install them, unless the anticipated benefits clearly outweigh their associated risks.
This document is based on a booklet called "Pedestrian Crosswalks - How Safe Are They?", published by the Arizona Department of Transportation.