Traffic barriers are devices which are used to control traffic. They can be used in a wide variety of situations, from environments where barriers may be needed for safety to events at which temporary traffic redirection is necessary. Numerous firms manufacture a range of traffic barriers, and most departments of transportation and public safety maintain an array of barriers in storage facilities which they can bring out as needed.
A traffic barrier may be designed to be permanent, or temporary. An example of a permanent barrier is a guardrail, which is designed to keep traffic from running off the road. Guardrails are used in situations where it is safer for people to stay on the road, as for example on windy roads along cliffs. Temporary barriers can be moved around and relocated as needed. The road cones used to mark out roadwork sites are a well-known example of a temporary traffic barrier.
Solid traffic barriers include things like concrete, composite, and plastic walls such as those used for barriers along some major roadways to separate traffic going in different directions. It is also possible to use stanchions with movable boards or cables as traffic barriers, along with bollards, vertical posts mounted in the roadway.
One of the big advantages of bollards is that the post can be lifted out of its housing, allowing someone to pass into an area normally rendered inaccessible by bollards. This can be very useful for things like blocking off streets to cars while allowing emergency services to get through if they need to. Bollards can also be designed to block unauthorized traffic while moving or being moved for people who are allowed into a particular area.
Along with traffic barriers, it is generally necessary to use traffic signs. Traffic signs alert drivers to upcoming events in the roadway which may be important to know about, such as a redirection of through traffic, or the merging of an existing lane. Especially when traffic is being rerouted or detoured temporarily, signs are very important, because drivers may be accustomed to following a particular route which they will not be able to access because of the redirection.
For safety reasons, ordinary civilians are usually not allowed to use traffic barriers. The exception to this is in an emergency such as a car accident, where installing flares and road cones in the road to alert drivers to a problem may be advisable. Otherwise, civilians need to contact government safety officials with requests for traffic barriers.