318 AiSrisruAL eepoets of department op ageicultuee. 



EXPERIMENTAL MAINTENANCE OF SELECTED BOADS. 



During the year experimental earth-road maintenance has been 

 conducted on about 8 miles of road in Alexandria County, Va. The 

 data secured has closely checked that secured in the two preceding 

 years and contract with the county for cooperation will not be re- 

 newed. 



The experimental maintenance work has been continued in Mont- 

 gomery County, Md., on the Eockville Pike and Bradley Lane, which 

 are bituminous macadam, surface-treated; and on the Chevy Chase 

 experimental road, which includes sections of bituminous macadam 

 by both the mixed and penetration methods, as well as sections of 

 brick and various kinds of concrete construction. 



Using reports from the traffic censuses conducted by the Division 

 of Road Economics according to the French method in connection 

 with the data obtained under this project, the two sets of data thus 

 provided are being used to develop a system of expressing main- 

 tenance costs on a basis of the ton-miles of traffic. These studies will 

 be continued with the view to expanding the scope of this system so 

 that the traffic limits may be found between which a given road sur- 

 face is more economical in the long run that any other. The total 

 mileage under observation during the fiscal year was 11.02 miles, 

 and construction of other experimental sections during the same 

 period, together with the surface treatment of the Montgomery 

 County post road for experimental purposes, will increase the mile- 

 age next year to 22.7. 



The traffic census in Montgomery County indicates a weight of 

 traffic for 6 months ending June 30, 1915, almost equal to that of the 

 entire traffic during the calendar j^ear 1914. This increase of traffic 

 necessarily has increased the cost of the experimental maintenance 

 and has made the entire reconstruction of the bituminous surface of 

 Bradley Lane necessary. This work was begun during the fiscal 

 year, but has not yet been completed. 



Arrangements are being made to cooperate with four counties in 

 Florida in maintaining the road from Brooksville to St. Petersburg 

 and from Fort Myers to Punta Rassa under similar conditions of co- 

 operation as those prevailing on the Washington-Atlanta Road. 



national park and forest roads. 



T. Waeren Allen, Chief. 



This division has charge of certain road work in national parks, in 

 cooperation with the Department of the Interior, and of road work 

 in the National Forests, in cooperation with the Forest Service of the 

 Department of Agriculture. The work accomplished during the year 

 follows : 



NATIONAL PARK ROADS. 



Arkansas Hot Springs Reservation. — ^An inspection of road conditions was 

 completed. 



Wind Cave National Park. — An inspection of road conditions was made. 



Rainier National Park. — After an inspection of road conditions was made, a 

 consultation was lield witli the superintendent of the park and recommendations 

 made as to the best methods to take in widening the road for automobile use 

 from Longmlre Springs to Paradise Park. 



