an hour, design provided stopping sight distances of 475 to 600 feet were necessary. Sufficient sight distance for overtaking and passing vehicles has a direct bearing on safety of operation. (5) Shoulders should be af ample width to encourage drivers to stay in the traffic lane without fear of getting too close to roadside ditches or obstructions. Also they provide refuge for disabled vehicles. (6) The separation of traffic by center strips is obviously a deterrent to the most serious accident, that of head-on collisions. (7) Highway grade separations as well as railroad grade separations, when traffic volumes are large, eliminate the potential of collision at intersections. (8) Other important items of design include adequate lighting, proper channelization, and skid-resistant surface. Many recent studies show the value of controlled access as a means of eliminating accidents, providing maximum freedom of movement, improving property values, and preserving costly investments. All of these design features are part of the design policy adopted by the American Association of State Highway Officials in cooperation with the United States Bureau of Public Roads. It is a policy based upon a considerable amount of research into the characteristics of traffic movements and driver behavior. Continuing research is needed to insure that in the future the design elements will further contribute to the safety of movement. I have a few charts to illustrate specific results of research studies. conducted by the State highway departments, the United States Bureau of Public Roads, and the National Safety Council. They are typical of accident studies made by these organizations. Chart I-Accident Rates Lower on Better Highways: This chart shows the results of a study conducted by the Connecticut State Highway Department over a 4-year period in which the accident rates on rural State highways meeting good design standards were compared with the rates on all rural State highways. All other factors except the physical character of the road can be presumed to be the same-same drivers, same motor vehicles, same enforcement, and same signs and markings. The chart is of particular interest since it shows the total effect of good standards in reducing accidents, as well as the variation in accident rates due to traffic volumes mentioned earlier. The 7 bars represent the 7 design groups based on traffic volumes and range from under 750 vehicles daily to more than 22,500 daily. The first 4 groups cover 2-lane highways, the fifth covers 2-lane highways in the higher traffic volumes with partial control of access, and the sixth and seventh bars are 4- and 6-lane highways with full control of access. The top of the bar in each case represents the accident rate on all rural State highways and the bottom portion represents the rate on those rural State highways that meet modern design standards. The figure at the bottom of the bar shows the percentage of reduction in accidents on the well-designed highways for each group. You will note that the accident reduction ranges from 18 percent, in the 2-lane highway group from 3,000 to 5,000 vehicles a day, up to 60 percent, on the 4-lane divided highways with full control of access. 61030-55-52 This Connecticut study showed that 7,770 accidents might have been avoided during the 4-year study period if all rural State highways had been improved to accepted design standards. It was estimated further that another 8,200 accidents could have been avoided on urban State highways, or a total of 16,000 accidents, which is 43 percent of all those that did occur. That figure 43 percent-begins to suggest the major part which road improvements can play in the accident prevention program. Chart II-Widening Pavements Reduced Accidents 39 Percent: The effect of a single element of design-pavement width-on accident reduction is very well illustrated by this summary of a study recently completed by the division of highways of the Illinois Department of Public Works and Buildings. Accidents that had no connection with pavement width were not considered in this study. The accidents on a total of 244 miles of narrow 18-foot pavements which had been widened in recent years to 22 feet and 24 feet were analyzed for a period approximately 2 years before and 2 years after the widening. The total of 244 miles included in the study had an accident rate of 230 per 100 million vehicle-miles of travel before widening. After widening the rate dropped to 140-a reduction of 39 percent. Chart III-How Width of Structures Affects Accidents: Numerous studies have shown clearly that the width of bridges in relation to the width of approaches has a considerable bearing on accidents. The analysis of accident data in this respect from 10 States by the Bureau of Public Roads and the National Safety Council is portrayed in this chart. Where structure width was 1 foot or more narrower than the approach width, the accident rate was 100 accidents per 100 million vehicles. Where the structure width was up to 5 feet wider the rate dropped to 58 and where the structure width was 5 or more feet wider the rate dropped to 12. Chart IV Effect of Shoulder Width on Accidents: This chart shows the result of shoulder width on accidents on two-lane highways. It is taken from a study of the 1,169 miles of 2-line highways on the interstate system of California by the division of highways of the California Department of Public Works. The accident occurrence with no shoulders was 342 accidents per 100 million vehicle-miles against 180 accidents where shoulders were 4 to 5 feet wide. Shoulders of 8 feet or more in width showed a further reduction to 165 accidents. Chart V-Accident Rate on Shirley Highway Compared to Parallel Highway: I have spoken previously about the greater efficiency as well as the safety of controlled access highways. This map, prepared from data provided by the Virginia Department of Highways, shows the comparison of all the accidents during 1953 on the Shirley Highway, a 4-lane divided limited access highway just south of Washington, and the parallel U. S. 1, which is a 4-lane undivided highway with no access control. This map is an actual working diagram prepared by the Virginia Department of Highways. You will note that all accidents are shown by diagrams and symbols indicating the location and type. Where one accident involves more than one injury it is indicated by numbers in the symbol. Comparative accident records are shown by the summary. There were 277 accidents on U. S. 1 and 100 on Shirley Highway; there were 71 injury accidents compared to 34; 142 persons were injured on U. S. 1 against 67 on Shirley Highway. There were 10 fatal accidents on U. S. 1 with 3 on Shirley Highway, giving a comparative fatality rate of 20.5 compared to a 6.1 rate. You will note that the property damage on U. S. 1 is calculated at $115,000 as compared with $83,000 on Shirley Highway. There was a more favorable ratio the year before. There were 9 persons killed on U. S. 1 and 2 on Shirley Highway. The death rate was 17.9 on U. S. 1 as compared with 4.4 on Shirley Highway. While the rate on Shirley Highway this year is considerably above the average of other fully controlled access facilities the map is shown to illustrate how the comparative analyses are made. The significant thing on this illustration is that there were 7 less people killed and 75 less injured on a facility which provides much more ease of movement and time saving. Chart VI-Controlled Access Reduces Traffic Deaths: This chart shows that the striking safety record of the Shirley Highway is not an isolated example but is typical of the experience of controlled access facilities throughout the United States. In 8 of the 10 examples shown, the fatality rate per 100-million vehicle-miles for a controlled access highway is compared with the rate for approximately the same period on either parallel or adjacent facilities with no control of access. Comparative rates are not available in the case of the New York Thruway and the Pennsylvania Turnpike shown on the right. In all cases where comparisons are possible, the rates on the controlled access facilities are materially lower. Because the Interstate System includes substantial mileage of the character shown on the last chart, we are able to make some forecast of the effect which its modernization would have upon the accident problem. Using these records as a base, we can estimate that upon completion of the system, some 3,500 lives per year would be saved. As an average, 1 life would be saved annually for each 10 miles of the system. At that rate, during the first 10 years following the improvement of the Interstate System, about 35,000 lives would be saved, which is roughly the equivalent of a year's traffic toll in the Nation. Data are not available for the same kind of comparison on other classes of roads and streets. But there is no longer any room for doubt that modern design features and adequate capacity can contribute importantly to safety on all roads. As our highways are improved, substantial savings can be anticipated in life, limb, and property, along with the increased efficiency and economy of operation over the road as components of our transportation system. I think by showing you 4, 5, or 6 charts I will make the major points in our presentation. First, I want to show you the results of an accident study that was made in the State of Connecticut by the Connecticut State Highway Department. (The chart referred to is as follows:) ACCIDENT RATES ARE LOWER MILES 2 LANES, NO CONTROL PARTIAL SOURCE: CONNECTICUT STATE HIGHWAY DEPARTMENT Mr. FRITTS. This study shows the difference in the accident rates on those highways that meet modern design and those that do not. The traffic factors are the same. We have the same drivers, the same motor vehicles, the same enforcement, and the same signs and markings. The chart is of particular interest since it shows the total effect of good standards in reducing accidents as well as variation in accident rates due to traffic volumes mentioned as we will show later. The 7 bars represent 7 design groups of highways, based on traffic volumes, ranging from 750 in the left over to 22,000 and over on the right. Senator GORE. Do you have these in tabular form so they can be placed in the record? Mr. FRITTS. We do not, but we will be able to furnish the committee with a copy of those charts if you so desire. Senator GORE. That will be fine. As you refer to each one it will be included in the record. Mr. FRITTS. The first 4 bars represent accident rates on 2-lane highways. The fifth covers 2-lane highways in the higher traffic volume groups from 5,000 to 7,700 with partial control access. The sixth and seventh bars represent the higher traffic range. You will not that the chart shows at the top the rate on the entire system, including all the highways, good and bad. The gray portion of it shows the accident rate on those highways that have been built today to modern design standards. You will see that the reduction in the rate of accidents varies from 18 percent on the fourth bar, which is the lowest reduction we have, up to as much as 60 percent when modern 4-lane divided controlled access highways are provided. I would like to call your attention particularly to the 18-percent figure because that shows the effect of large numbers of vehicles on 2-lane highways, 18 and 23 percent, from 3,000 to 7,700 vehicles. It is not possible to make the accident reduction unless additional lanes are provided. This study shows, overall, that 43 percent of all those accidents might have been prevented if the entire highway system were built to appropriate design standards. Here is an individual study made in the State of Illinois. This was just completed. (The chart referred to is as follows:) |