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Turn Restrictions for Roadside Safety in Urban Applications

Keeping the flow of traffic moving smoothly is a core goal of many traffic planners.  Dedicated turn lanes in specific areas provide increased traffic flow and safety.  Sometimes, however, enhancements are needed to protect turning drivers and others from oncoming vehicles.  The more drivers have to think about how to turn, the more likely it is for an accident to result.  Removing the need for decision-making on the part of the driver often improves roadside safety and traffic through-put. 

Lights and Barriers
Traffic planners create dedicated turn lanes for left- and/or right-hand turns from one road to another.  This reduces congestion and ultimately driver frustration and error.  Painting lines on a road to make a lane is sometimes enough; however, traffic lights and barriers are more effective at protecting turning drivers from collisions.  For instance, at busy four-way intersections, left-hand turn lanes that are not dictated by a traffic light are more likely to produce traffic accidents.  When drivers are forced to gauge the speed of oncoming traffic that is not stopping, the capabilities of their vehicle, as well as pedestrian traffic that may be present, it makes a recipe for disaster.  By protecting left-turning drivers with a dedicated left-hand turn traffic light, these incidents can be reduced or eliminated.  Barriers separating turn lanes also help drivers remain safe.  Lanes not protected by barriers allow the potential for drivers to cut into a lane too late and block traffic in lanes designed to travel straight through an intersection.  They also prevent drivers from leaving a left-hand turn lane and entering a traffic stream that may be moving faster than anticipated. Traffic-channeling devices like channelizing curbing and flexible delineators help to provide this turn restriction.

Traffic Safety Signs Tell Drivers What to Do
Accidents result mainly because drivers were doing something that they were not aware would cause an accident.  Actions like turning at a light during a specific time period or when pedestrians are present often result in accidents because drivers were unaware of potential dangers.  Wise use of traffic safety signs can help to reduce these unfortunate events.  For instance, collisions can be reduced by placing a sign at a right-hand turn lane that a) informs drivers that occupants of this lane are required to turn right; b) warns them to beware of pedestrian traffic; and c) allows or disallows a right-hand turn when the light is red. Signs restricting turning traffic when traffic flows are heavier, such as at rush hour, are also very effective.   

As traffic flows, there are often thousands of actions happening at once that need to be managed.  The potential for disaster is magnified at intersections where many drivers are trying to accomplish different goals.  Elements such as traffic lights, barriers, flexible delineators, and clearly-defined traffic sign messages help reduce deadly accidents and improve roadside safety.