If you are working in the medical field as a paramedic or EMT, emergency transportation options need to be set up rather quickly to get the person or persons you've rescued to a medical facility.
Whether it's an automobile crash or a pedestrian who has been injured, many of these accidents to which paramedics respond will happen on a busy road. While you may occasionally find yourself on a small road with no other traffic, chances are more likely that you'll find yourself trying to do your job (assessing the patient's injuries, stabilizing the patient and then putting the injured individual in an ambulance) in a very congested area. This means that while you're working, all the surrounding traffic has to come to a complete stop and be diverted, so that you can do your job.
Police and Firefighters Often Help
The closure of a road, especially a major highway, is often handled by police officers, who will initially set up flaming torches on the pavement. They may also be driving police cars that are outfitted with safety signals, similar to train crossing gates, that can be elevated from the top of the car. Redirecting traffic, for example, making sure that a three lane highway is reduced to one lane (the furthest lane from where you are working), is crucial. In suburban areas, police officers or firefighters may be summoned to redirect traffic down a side street away from the area where there's been an accident.
Fire trucks are often dispatched to a scene, particularly when dealing with automobile accidents. There is always the chance of a fire in a car accident, but the sheer size of the fire truck makes it the perfect "structure" to put in the middle of a disaster. It can block other vehicles from going down a road, and it also prevents pedestrians and other "rubber-neckers" from looking at a scene that might be grim.
Traffic not only needs to be quickly redirected, but ambulances need to be able to get as close to the injured parties as possible. This way, you, as the first responder, won't have any obstacles in your way, so you can put the injured person in an ambulance and get him or her away from the accident. In the case of multiple life-threatening injuries, an entire highway may need to be shut down, so that a helicopter can land safely to provide emergency transportation to the nearest hospital.
Many accidents also leave behind an enormous amount of debris. This might include glass or metal from a collision, blood on the ground from the injuries sustained or even the remnants of the supplies you, as an EMT, might have used to attend to the injured. Consequently, besides the ambulance taking the injured party away from an accident, there might often be a tow truck present to haul away the vehicle, as well as a sanitation truck to clean up the road.