Introduction of massive rail vehicles onto street rights of way, crossing large numbers of other streets, and passing through residential neighborhoods, business districts and other urban settings poses immediate threats to the safety of vehicles and their occupants on the streets, as well as to automobile traffic, pedestrians and others present in environments through which the rail vehicles pass. Crossing gates, fences and other barriers to entering or crossing at grade rail tracks are essential safety devices required to protect surrounding traffic and personnel in the vicinity of rail transportation systems. All such safety equipment must be rigorously maintained in near perfect working order, while other levels of vigilance are necessary to separate all other activities from the track and vehicle paths of at grade rail systems.
In spite of the extensive installation of safety equipment on tracks, crossings and trains themselves, at grade rail systems pose the most prevalent threats, and are the cause of the greatest numbers of serious accidents, injuries and fatalities of any type of mass transportation system. Safety threats are so pervasive that most at grade rail systems are forced to operate at well below their design speeds, yet continue to be involved in destructive and deadly collisions, even under normal operating conditions. While safety hazards persist, the vehicle and pedestrian activity systems negatively impacted by at grade rail operations are often curtailed or detoured in order to separate them from the track and operations areas of the rail systems. This often leads to permanent relocation or closure of streets, pedestrian crossings and other impacted activity settings.
The historical and continuing accident record of at grade rail, and the failure of extensive efforts to significantly reduce or eliminate this risk pose the greatest limitations to successful implementation of at grade rail services in existing urban settings.