WHAT RELOCATION OF HIGHWAYS MEANS

BY: PERCY JONES, Jr., Chief Locating Engineer

ARIZONA HIGHWAYS

CIVILIZATION FOLLOWS THE IMPROVED HIGHWAY

Volume VII

DECEMBER, 1931

Number 12

To the layman, traveling detours and observing highway construction generally, it probably appears that there is a disproportionate amount of reconstruction of roads-roads that, not many years ago, he considered very good and which would be quite satisfactory if only the riding surface were improved. Sometimes, traveling the last road finished he may even see the signs of three constructed roads which would date approximately as of the years 1915, 1920 and 1930 each, this not counting the original wagon track which with very few exceрtions, was about the only kind of road we had in Arizona prior to 1915.

The thought may occur to him that the highway engineers are spending a great deal of money correcting their past mistakes or those of their predecessors. There are not many predecessors. Those who are working today in the higher engineering positions are, with allowance made for the increase in business and force of the Highway Department, the same men who worked in lesser positions on the first highways and the last railroads built in the state.

Early Problem

The first problem in Arizona that confronted the highway engineer, that is, when the automobile came into general use, was to build a system of roads that one could travel 365 days in the year and to construct, with a limited amount of money, this system of highways within a limited time. To keep within the amounts budgeted for highways this compelled the engineer to locate roads with numerous curves and with a grade that, in many cases, followed closely the ground line.

Dips were constructed in lieu of bridges and seldom could a location be secured that was ideal for both structures; consequently the location favoring the dip was often adopted, owing to the lesser cost.

The locations made and the highways constructed to the standards of 1920 soon became obsolete. The speed of all classes of traffic has materially increased, together with a large increase in the number ber of cars using the highways, larger busses and trucks were constantly being put into service.

All this tended to make the sharper curves dangerous, the dip also a menace the amount of money available is many times that at the command of the Arizona Highway Department, the engineers feel that the road built to the present standard will not call for revised alignment for many years to come. However, the engineer would indeed be bold who would say that the future will not see a demand for even higher standards.

Cheaper Than Detours

Minor changes, for example, offsetting a location of some road 50 feet or so, may often look to the layman as a waste of money, and that the old road could have been re-graded and widened at much less expense than building an entire new section to one side of the present center line. Most engineers cannot take any decided issue with the layman on this point, as it is only after having the figures before them at the completion of several jobs that it has dawned upon them that they were spending nearly as much on detours as would be the saving in utilizing the old road. Furthermore, believe it or not, engineers are generally human; and criticism received when the public is compelled to travel a bad detour at last penetrates even the thickest hide.

To sum up the factors why existing roads are changed:

Changes Are Progress

Those of us who have worked through the past ten years on highway location and construction have learned much as to the requirements of today as compared with the beginning of the period. We are probably better qualified to predict to safe travel and, in some cases, the cause of intolerable delays during floods.

The reason stated above the necessity of a road that could be traveled 365 days in the year, and the necessity of such a system of highways, was the subordinate to the fact that had a higher type of road been constructed it would have involved the expenditure of millions of dollars which were not available.

The above program having been completed, a higher standard of location and construction was adopted, and while the standard does not equal the location and construction in some of the states where

ARIZONA HIGHWAYS

In the next ten years than we were the past; however, we do not know what will be required ten to twenty years in advance and it is probable we never will have this knowledge. We must bear in mind one thing-when no changes are made progress will have ceased.

With the exception of widening, which may be regarded as betterment rather than reconstruction, I do not believe there will be much reconstruction in the rough mountainous country for a considerable time to come. As a rule, the principal mountain roads are of later date than the valley roads and were built to a more satisfactory standard, and with the exception of widening and surface improvement, alignment is the only improvement to which they are susceptible. Bridges to replace dips do not occur as frequently in the mountains as they do in the valleys; bridges should have been constructed in the first place.

To improve the alignment of a mountain road materially as a rule calls for an entire re-routing an ambitious program considering the benefits to be derived.

The replacing of a gravel surface with an oiled surface may cause the relocation of a valley or desert road, because the improved surface renders the elimination of dips necessary, and by that time the grading is a very small part of the cost of the job. Frequently the construction of a suitable detour amounts to more than the saving in yardage of earth work effected by using the original alignment. Therefore, except when right of way may prevent, there is often an advantage in paralleling the original road with a new one, for no other reason than to simplify the detour problem.

Speed Change Alignments

In the mountains grading is the big cost. Compared with it the cost of the oiled surface is small; therefore the mountain roads are generally oiled without reconstruction.

No great improvement in the ratio of grades on mountain roads has been made or is liable to be made. Our standard for maximum grade is the same as it was fifteen years ago. The tendency is to sacrifice grade for improved alignment. The old make of car could get around a curve but it had trouble on a long hill. Hills do not worst the modern car, particularly if its speed can be maintained. Curves cut speed.

Mountain roads that are being located now, or have been located within the past four or five years, are located to a materially higher standard than those This change was necessitated by the building of Coolidge Dam, forcing an entirely new routing of Highway to Upper Gila Valley.

to which we have been accustomed. A 100 ft. radius was accepted for the minimum for curves on mountain roads for years; 200 to 300 ft. radius were preferred, but the cost of the road would not be materially increased to get them if the 100 ft. radius fit the country. Above a 500 ft. radius any curve was usable if there was any reason for it.

Today we locate upon a 1,000 ft. minimum radius in ordinary rough country. When it becomes very rough and utterly unreasonable to maintain the 1,000 ft. standard curves to a 500 ft. radius will be considered. The 300 ft. radius is acceptable only upon the faces of cliffs, where anything else would be in space or under the mountain. Compared with our ideas of reasonable cuts ten years ago, the 300 ft. curve is under the mountain.

We do not think the alignment of the roads as located now will be changed. It is hard to imagine straighter roads than the later ones, yet ten and even fif-teen years ago we considered our lo-cations good.

A DRY

Temperance Lecturer: "Now, suppose I had a pail of water and a pail of beer on this platform, and then brought on a donkey. Which of the two would he take?"

Loud Voice: "He'd take the water." Temperance Lecturer: "And why would he take the water?"

Voice: "Because he's an ass."