Overview
Traffic control is an outdoors occupation, night or day for long hours in all weathers, and is considered a dangerous occupation due to the high risk of being struck by passing vehicles. Safety equipment is vitally important. Fatigue is a big issue, as tired TC's may forget to watch their traffic, or may inadvertently turn their "Stop bats" to the "Slow" position. Many drivers are annoyed by the disruption to their route, and some are sufficiently antisocial as to aim at traffic controllers. Other drivers simply don't pay enough attention to the road, often from using their mobile (cell-) phones, or because they are tired from a night shift at work. Not a few are exceeding the posted speed limit.
Typically, a worksite will be set up with warning signage well in advance of the actual work area. This may involve (in Australia) "Roadworks Ahead", temporary speed restrictions, "Worker Symbolic" (a stylised workman with a pile of rubble, black sihouette on a retroflective orange background), "Reduce Speed", "Lane Status" boards (indicating that some lanes on a multilane will be closed), "Prepare to Stop" and advisory signs telling what's happening (e.g. Water Over Road, Trucks Entering, and Power Line Works Ahead). If lanes have been closed, large flashing arrows (arrow-boards) on trailers may be utilised to give motorists hundreds of meters warning to move over. Motorists will be advised they are leaving a worksite by speed reinstatement or "End Roadworks" signs.
The worksite will usually involve reserving a part of the road for the work area. How this is done depends on the type of road: on a multi-lane road, one or more lanes will be closed off and traffic merged into the remaining lane(s), using cones and "Chevron" signs and arrow-boards to guide motorists. On a wide road (more than 3 meters per lane in Australia), traffic could be "diverted" around the work area by using cones to define a new road centerline and another line of cones around the work area. Sometimes, it is necessary to close a road and detour traffic.
Often, the road is not wide enough to permit opposing streams of traffic past the work area. Then it is necessary to use "Stop/Slow", where each stream is allowed past the work area in turn. On an intersection, this may involve four or more streams. At signalised intersections, it may be necessary to have the traffic lights disabled.
Sometimes on dual carriageways, it is necessary to divert one carriageway onto the opposing carriageway, forming a "contraflow". This cannot be done "on the fly", as high-speed (100+km/h), high-volume (500 - 1000+ vehicles per hour) traffic is involved, generating a huge risk to workers. In this case advisory signs will be erected weeks or even months in advance, and new lanes defined by bollards anchored firmly to the road-base will be installed, usually at night when traffic is expected to be minimal. Programmable Variable Message Boards may be utilised at strategic locations to inform motorists. Such "contraflow" situations also pose significant risk to pedestrians who may not be alert to traffic coming from the wrong direction.
Read more about this topic: Road Traffic Control