In all situations, if in doubt as to how much space to put between the damaged vehicles and the nearest emergency vehicle, a rule of excess should prevail. If in doubt, stay back for safety's sake. It is far easier and safer to move a vehicle forward than it is to be forced to rapidly back it up or abandon it entirely should an unanticipated, life-threatening situation develop.
Traffic should be kept moving by being detoured or re-routed if possible. Immediate traffic detours that move approaching traffic around and away from the crash scene are recommended. If traffic is detoured and kept far enough away from the crash area, motorists are less likely to slow or stop, causing traffic congestion at the scene. What is to be avoided is the complete stopping of traffic, especially for any extended period. If traffic is stopped completely on a typical high-volume interstate highway and expressway, the traffic jam can extend one mile for each minute that traffic is not moving. After five minutes of total shutdown, the possibility of getting additional emergency service units into or out of the immediate crash scene area becomes extremely difficult and time consuming. A detour around the area minimizes traffic congestion and maximizes scene protection.
Advance Warning Safety Considerations
Making approaching traffic aware of a crash or fire scene ahead can be done by various means. Initially, vehicle emergency warning lights provide notification of the hazard ahead. Operators of emergency vehicles must realize that during night incidents, particularly on two-lane highways, the headlights of their emergency vehicle may totally blind approaching vehicles as they look toward the crash scene. The headlights of any emergency vehicle on the scene that may impair the vision of approaching drivers should be turned off. The driver should use their parking lights only to minimize this problem.
Red-burning highway road flares, a generally accepted means of warning of a traffic impediment, are also inherently dangerous at a crash scene. The burning phosphorus flare can ignite combustible materials or flammable vapors within its flammable range. The residue that spits from a burning flare can cause significant injury to unprotected hands or eyes. Personnel using flares for traffic control should be sure that the flare itself is the only thing present that is going to get burned.
If safe to do so, individual flares can be placed on the approach side of the emergency scene and continued towards approaching traffic at 15-foot intervals. To enhance the visibility of this advance warning during the day or at night, burning flares can be placed close to orange traffic cones. The glow from the burning flare reflects off the cone and illuminates it. As a general rule, the total length of this line of cones and flares should extend from the scene towards approaching traffic a distance equal to twice the posted speed limit in paces. Each pace taken by a responder is estimated at 3 feet in length. For example, where the posted speed is 35 miles per hour, flares and cones are placed every 15 feet for a distance of 70 paces from the crash scene. This is approximately 210 feet.
On a highway where traffic may be expected to be traveling up to 65 mph, the line of flares should extend for at least 300 feet, the length of a football field from goal line to goal line. If the damaged vehicles are located in a limited sight distance situation such as over the crest of a hill or at a curve in the roadway, emergency vehicles, flares and cones should be placed to adequately warn approaching traffic on the other side of the hill or curve. Bad weather can also require that the advance warning to approaching motorists be extended. If in doubt, continue to extend the area of advance warning for approaching traffic.
It must be remembered that flashing lights, flares or traffic cones only warn the fully alert and responsible motorist approaching the scene. Traffic cones and flares only suggest what you want the approaching motorist to do. They will not stop the inattentive or impaired driver from driving right into the scene. Only vehicles, large vehicles at that, can stop an approaching vehicle. At no time should flares, cones, or individuals be blindly relied upon as the sole means of traffic control.