Traditional pavement markings used to designate crosswalks are very obvious to approaching and crossing pedestrians. At the same time, these markings can be difficult to detect by a moving motorist, particularly in low-visibility conditions such as darkness or dense fog. The detection of a pedestrian preparing to cross the street can also be difficult for motorists in low-visibility conditions and at locations with obstructions, such as parked vehicles, that block the motorist's view.

  If pedestrians believe motorists can see the crosswalk and can see them preparing to cross, and begin to cross the street on that assumption, the result may be crashes occurring because of inappropriate perceptions. To avoid this type of problem, a fully signalized crosswalk may be installed, complete with pedestrian and traffic signals to allow pedestrians to cross when traffic is stop-controlled by the signal. However, this may be very expensive and in many cases is not warranted.

  An alternative is to increase the motorist awareness of the crosswalk and pedestrians in the vicinity preparing to cross the street. One approach to making motorists aware of crosswalks is through the use of signs. The Manual on Uniform Traffic Control Devices recommends the use of an advance pedestrian crossing sign (W11-2) in advance of locations where pedestrians may cross but not expected by motorists (FHWA, 1988).

  However, static signs may often not be observed by motorists, particularly if they are placed in a visually cluttered environment. In addition these signs do not have the ability to provide real-time information, i.e., not just indicate that a crosswalk is present, but that a pedestrian is also present. An alternative approach, which uses real-time information, is the installation of in-pavement lighting on both sides of the crosswalk.