Page:America's Highways 1776–1976.djvu/348

From Wikisource
Jump to navigation Jump to search
This page has been validated.

Stopping Distance

Braking performance of motor vehicles is another important area which the Public Roads researchers have been studying for over three decades. The braking ability of all types of motor vehicles is an essential factor in the safe and efficient movement of traffic on our highways. The sight distance needed for stopping is one of the important geometric design elements.

In 1941, the Public Roads Administration started a broad program of brake performance studies of motor vehicles in everyday traffic. The Advisory Committee on Motor Vehicle Brake Research was formed to direct and guide the program. This was the beginning of a series of studies conducted at 7- to 10-year intervals, the latest of which was completed in 1974. The objectives of these studies were to: (1) Establish a better understanding of the features of vehicle braking performance; (2) determine what levels of brake performance can reasonably be met by vehicles in service; (3) determine the essential elements of reasonable brake regulations; and (4) determine practical means of enforcing brake regulations.

Military Highway Transport

Most highway research was initiated to provide basic information for the development of street and highway design and traffic operations for civilian traffic. Much of this information has been applicable also to military traffic movements, but military convoys required special study. In the spring of 1940, a study to determine the effect of certain highway conditions on the operation of military convoys was conducted by BPR at the request of the Department of the Army.

Ruote 82 in Connecticut winds its way down hill, but note, that there are two lanes for up-hill traffic, allowing slower traffic such as trucks, to use the outer lane and faster traffic to pass on the inner lane.