Drive to Survive: Case Studies Chris Daly
A 30-year-old firefighter was responding in his personal vehicle to a report of a high-water emergency. The firefighter was responding to the fire station on June 16, 2003, to pick up a fire apparatus when he drove over a large pool of water on the roadway.
The firefighter lost control of his personal vehicle, traveled off the road, and struck the signpost of a large billboard. During the course of the crash, the victim firefighter sustained fatal injuries.
Driver Considerations
A crash investigation by the state police revealed that no speed estimate could be made based on the lack of roadway evidence. However, a witness stated that the victim firefighter had passed her on the roadway while she was traveling at approximately 40 miles per hour (mph). This witness later discovered the crash when she continued farther down the road. Based on this witness statement, there is evidence that the victim firefighter was traveling in excess of 40 mph on a wet road.
Fire apparatus operators must understand the dangers of driving in inclement weather. Although there are many issues to consider, this case study will focus on hydroplaning. As a tire rotates on the axle, the tire tread is designed to push water and moisture out of the way so that the rubber tire face can come in contact with the road (photo 1). If the vehicle is traveling too quickly and the tire is spinning too fast, the tire tread will not have enough time to effectively move the water out of the way. As a result, a wedge of water could build up in front of the tire. Eventually, the tire may ride up on this wedge of water and lose contact with the road. This is a hydroplane.
1 The purpose of tire tread is to “push” or channel water out of the way so that the rubber tire face can come in contact with the road surface. (Photos by author.)
Driving a vehicle at a high speed on a wet roadway can lead to a hydroplane situation. The speed at which a tire will hydroplane depends on three major factors: the depth of the tire tread, the air pressure in the tire, and the depth of the water that the vehicle is driving through. A shallower tire tread will not be able to move as much water as a deeper tire tread. An underinflated tire will not be able to push the water out of the way as effectively as a properly inflated tire. And last, deeper water will be able to more easily overwhelm the tire tread.
Fire apparatus operators must understand the importance of slowing down in wet weather to give the tire enough time to properly push the water out of the way. Drivers must also understand the importance of avoiding large standing pools of water and instead try to stay in the tracks of the vehicles tra