OFFICE OF PUBLIC EOADS AND RURAL ENGINEERING. 333 



of establishing the relation between the cost of maintenance and the 

 amount of traffic carried by the road surface. The intent is to develop 

 a set of index figures which will aid in ascertaining the traffic endur- 

 ance of the various types of surfaces. 



The completion of the experimental road on Mount Vernon Avenue, 

 Alexandria County, Va., in the fall of 1915, and the Russell Road in 

 the same county in the spring of 1916, has added 6.3 miles to the 

 experimental roads under maintenance and observation. The same 

 system of records is in use on the 25 experimental sections of these 

 roads. 



The post road in Fairfax County is now being surfaced as an 

 experimental road and probably will be ready for maintenance early 

 in the present fiscal year. 



Owing to the increased mileage under observation and the growing 

 quantity of work, it has been necessary to assign a superintendent of 

 road construction to the immediate supervision of the repair and 

 maintenance of these roads. 



During the past fiscal year, 46.237 square yards of surface have 

 been retreated, and 6,788 square yards resurfaced in addition to the 

 routine patrol work. 



MAINTENANCE OF COMPLETED POST ROADS. 



Post roads built under the act of August 24, 1912, are being main- 

 tained at the expense of the States or local subdivisions. In Maine 

 and Ohio arrangements have been made for cooperative observation, 

 and this office is advising with the State authorities regarding the 

 maintenance of the post roads. A monthly report in which the total 

 cost of maintenance is distributed under various important headings 

 is supplied by the State highway departments. This office assumes 

 the expense of taking traffic observations. 



In Maryland the post road has been made an experimental road 

 and its maintenance as such is elsewhere described. 



In Virginia the post road in Fairfax County is now being sur- 

 faced as an experimental road and will be taken over for maintenance 

 by this office on its completion. The total mileage of the above roads 

 now under maintenance is 55.2. 



NATIONAL PARK AND FOREST ROADS. 



T. Warren Allen, Chief. 



An approximate total of 127 miles of reconnaissance surveys and 

 350 miles of location surveys have been made during the year. Main- 

 tenance work has been done on approximately 160 miles. Construc- 

 tion work is in progress on about 170 miles, of which approximately 

 70 miles were completed during the fiscal year 1916. 



The road across the Rabbit Ear Pass in the Routt National Forest 

 in Colorado will open large sections of country hitherto inaccessible, 

 and be available for through traffic. This road is very nearly com- 

 pleted. 



The Escalante-Winder Road in the Powell National Forest in 

 Utah, which is in progress of construction, will facilitate communica- 

 tion with a settlement in the valley of the upper Colorado which 

 has heretofore been practically cut off from the rest of the world. 



The building of the Trinity River Road, which is now under con- 

 struction in Trinity County, CaL, will be of great benefit to home- 



