Truck Performance Study of the Public Roads Administration 400139
NEARLY all rural roads today are two-lane roads. The great majority will always remain two-lane roads. The presence in the traffic stream on such a road of vehicles moving at speeds substantially less than the average speed of the stream, whether such vehicles be trucks or passenger cars, is a cause of inefficiency, inconvenience, and accident hazard. The problem created is a serious one, and the public is genuinely concerned.
What to do to improve matters; whether to widen the roads, or speed up the vehicles, or both; and what measures, either singly or in combination, will give the greatest relief at the least total cost? are questions that require answers; and it is to these questions that the hill-climbing studies are addressed.
In the case of passenger cars, slow speed is usually a matter of the driver's habits or choice. The cars themselves are usually capable of higher speeds. In the case of trucks and tractor-trailer combinations, slow speed on hills is often a matter of the design or loading of the vehicles. The vehicles are capable of no greater speed under the existing conditions of load and grade. To deal intelligently with the problem created by the presence of such vehicles in the traffic stream, it is obviously necessary to know, within reasonable limits, the speeds of which they are capable under various grade conditions. It was for this purpose that the hill-climbing tests were undertaken.