BUILDING SAFETY INTO THE HIGHWAY

Building Safety Into

BY E. V. MILLER Engineer of Plans THE ever increasing demand for highway safety must be met, but it is costing money. Some one must pay! Ten years ago we talked safety and recognized some of the shortcomings in highway design, but we did not feel the real importance of safety enough to sell our ideas to the public. When the public became aroused over the increasing death rate on our highways the engineers apologetically whispered that they had some tricks up their sleeves that might help reduce this mounting toll of lives, but these tricks would cost money. Too often we were roundly criticized by the citizenry for abandoning certain stretches of road that weren't good for over 30 or 35 miles per hour when we knew the public was driving these roads at a speed nearer 50. We knew the roads were dangerous, but certain influential persons were always ready to criticize the manner in which the road dollar was spent until the people as a whole found out that the tricks we spoke about were only good common sense coupled with a little engineering science. Then we, so to speak, got together. We now know pretty well what the public wants, what they expect and what they can pay for. Now, what changes have the people asked for and what have they got? Let's go back about ten years and make a few comparisons: In 1926, all roads were built as cheaply as possible, with material close at hand. Long hauls were not tolerated and side borrow was used for fills when the adjacent cuts did not balance. In fact, material from cuts was oftentimes wasted to relieve the long hauls. No laboratory analysis was made of the roadway materials. We took what was there and if by comparison we decided it was not material suitable as a surface, we added six inches of suitable surfacing material. The road was then open to traffic. Not even a roller was used to compact the surface, your tires were supposed to do that. If guard rail was erected it was the old wire mesh type which served its purpose well on low speed roads. Little thought, if any, was given to sight distance on vertical curves. Horizontal curvature was limited, yes, but 35 miles per hour was the Arizona speed limit and top road speeds were around 50 miles an hour. We did not build for over that speed. Our main roads were generally built 24 feet wide in those days, 18 feet of gravel with three foot shoulders. With proper maintenance these were good roads. Of course,, they were dusty, sometimes rough and corrugated, but no one can say they did not serve the purpose for which they were built and that was to get from here to there in any weather. But speed of cars was increasing each year and the motoring public was not satisfied with just a road between here and there. They wanted something done about the dust; they didn't like to be held up with high water in dips; they asked for more shoulders, wider lanes and curvature for 60 to 70 miles an hour continuous and safe speed. The highway engineer was literally put on the spot. First, we experimented with road oils and thought we had the answer for the dust question at a cost of about $2,000.00 per mile, but we soon found that where a $2,000.00 a a mile oil cake may be satisfactory with some types of materials, generally it was a waste of money unless suitable base material was added and the mineral aggregate in the oil cake was of a certain minimum specification. This, then, meant prospecting for the right kind of materials. There are hundreds of miles of road that have and will cost from $8,000.00 to $15,000.00 per mile for the surfacing only, because of the lack or scarcity of these materials. Most of the first oil cakes were laid 18 feet wide, whereas today practically all are 22 feet wide or an increased cost of 22 per cent for width alone. Then the demand for safer shoulders was met by flattening of both cut and APRIL, 1937 fill slopes. This went hand in hand with the elimination of the old dangerous and unsightly side borrow pit. Material for the fills is now obtained from pits located off the right of way and generally hidden from view. This practice naturally increased the cost of handling road material to the extent of the haul, at least. The flattened slopes increased the amount of material by 250 cubie yards per 100 foot station for a five foot fill. Assuming that the average would be just one-half of this, or 125 cubic yards per station, the increase per mile is 6600 cubic yards, say at 25c per yard in place, of $1,650.00 per mile. This, of course, does not include the roadside improvement features such as slope rounding, planting, etc., which often may be placed in the safety category. Where protection is needed on curves or where fills are over five feet in height, guard rail is used at a cost of about $1.00 per foot of rail.

the Highway

The plate guard rail of today, being more efficient than the old mesh of 10 years ago, also costs more per foot. Sidewalks or walkways are now being constructed on all projects adjacent to built-up communities. The average cost of a 5 foot oiled walkway is about 80c per lineal foot, or $4,224.00 per mile for one side only. This seems like a large expenditure to place on the motorist for the protection of the pedestrian, but we believe it is more than worth the cost if a few lives are saved. A pedestrian has no chance with the fast traffic of today when walking on the roadway. Another additional cost chargeable to safety and incidentally convenience, is the elimination of dips. This cost can not very well be given in dollars per mile for some of our older roads have many dips while others have but a few. Between Gila Bend and Yuma (120 miles) it will take $970,000 to eliminate the 89 remaining dips. Safe travel in rough country necessitates the use of a standard of design that will allow traffic to flow evenly at a given speed. In other words, if a highway through the mountains is to be designed for 45 miles per hour critical speed, there should never be one place where that speed would be excessive. In reconstruction of some of our older mountain roads, to provide safe and faster traffic, we find that to double the speed the cost is three or four times the original investment. In order to provide room for these widened and flattened roadways the right-of-way width must be increased. Looking back 10 years we find the old 66 foot right-of-way still the vogue. We did get 100 feet where the cost was low but never did we dream of 400 feet which we have on miles of open road. Our basic right-of-way width is 100 feet and to obtain this much is quite an expense when the country side has built up around 60 feet or 66 feet. To obtain more naturally costs in proportion to the amount taken. The right-of-way of today is usually fenced to keep stock off the roadway. The cost of this is about $800.00 per mile, plus cattle guards and cattle passes that are needed. A modern highway, from center stripe

An Address Before the Good Roads Association