364 ANNUAL EEPORTS OF DEPARTMENT OF AGRICULTURE. 



ROAD CONSTRUCTION. 



EXPERIMENTAL ROADS. 



The amount appropriated by Congress for field experiments in 

 road work was $60,000. Continuing the previous policy of the of- 

 fice, all the field experiments made during the fiscal year have been 

 in the vicinity of Washington and have been divided in the same 

 two classes as formerly, namely : 



1. New experimental construction. 



2. Maintenance of experimental roads already constructed. 



NEW CONSTRUCTION. 



The new construction completed includes a bituminous gravel con- 

 crete road surface about 4| miles long between Alexandria and Gum 

 Spring in Fairfax County, Va., and a surface treated gravel road 

 about 2 miles long from Gum Spring to Mount Vernon, in Fairfax 

 County. The purpose of the first experiment was to devise some 

 method of utilizing local gravel in the construction of a high-class 

 bituminous concrete road surface suitable for all sorts of travel. The 

 purpose of the second experiment was to determine the best way of 

 utilizing bituminous materials in the surface treatment of existing 

 gravel roads so as to provide for fairly heavy automobile traffic with- 

 out the rapid deterioration of the surface. The experiment includes 

 three different surface treatments. Both of the experiments in new 

 construction are described in detail in Department Bulletin No 586, 

 issued by this office, in which costs, methods, and results are tabulated. 



At the close of the fiscal year construction was in progress on an 

 experimental topsoil road through the Chapawamsic Swamp in 

 Prince William County, Va., about 4 miles long. 



ROAD MAINTENANCE. 



The remainder of the fund appropriated for road experiments has 

 been devoted to the maintenance of existing experimental roads in 

 Montgomery County, Md., and Alexandria County, Va. The methods 

 employed in maintaining the various experimental sections, the re- 

 sults obtained, and the distribution of costs are all shown in Depart- 

 ment Bulletin No. 586. 



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POST ROADS. 



In the last annual report of the director mention was made of 14 

 post-road projects completed prior to July 1, 1916. During the fiscal 

 year two additional projects have been completed, namely, the Lick- 

 ing and Muskingum Counties (Ohio), post road, 24 miles, and the 

 McDowell County (N. C.) , post road, 13.3 mile slong. With the 397.6 

 miles previously reported, this brings the total mileage of post roads 

 already completed to 434.9 and leaves the project at Dubuque, Iowa, 

 19.2 miles long, as the sole remaining uncompleted post road. This 

 was near completion at the close of the fiscal year. 



