6 BULLETIK^ 407, U. S. DEPARTMENT OF AGEICULTUEE. 



scarified and reshaped with some difiiculty, as the left edge from 

 station 221 + 00 to station 230 + 00 was 3 inches higher than the 

 crown. From station 201 + 00 to station 208 + 89 and from station 

 215 + 28 to station 219 + 00 the old macadam was entirely removed 

 to correct the profile and a new subgrade constructed. Six inches 

 of "l|-inch" crushed granite (passing a 2J-uich screen and retained 

 on a IJ-inch screen) was then placed. It was also necessary to add 

 such stone to weak spots in the base between station 229 + 00 and 

 station 234 + 00. The entire base was rolled with a 10-ton macadam 

 roller. A gap of 639 feet occurs on this section at the viaduct over 

 the Potomac railroad yards. 



Shoulders. — Earth shoulders on Section I were constructed 4 feet 

 wide with a slope of 1 inch to the foot, and they were finally trimmed 

 and rolled upon completion of the work. On Section II 4-foot gravel 

 shoulders of approximately 4 inches of compacted gravel from the 

 Haney pit were constructed on both sides throughout the entire 

 length. On Section III, from station 219 + 00 to station 235 + 50 

 similar gravel shoulders were constructed on both sides, except 

 where a sufficient amount of material developed in the course of 

 reshaping the old macadam with which to form a firm shoulder. 



Cut-off. — Near station 2 + 50 a branch (or cut-off) was built for a 

 distance of 230 feet along the southerly branch of the Washington- 

 Virginia Railroad to allow traffic to pass through the new road and 

 reach the Military Road going to Georgetown without twice crossing 

 the railroad track. The surface of this cut-off was constructed as 

 parts of experiments Nos. 1 and 2. 



BigTit of way. — ^Approximately 10.2 acres of land were acquired by 

 Alexandria County to provide for widening the old road and for the 

 new right of way. All lands so acquired are marked at every point 

 of curvature and tangency along the new right of way by means of 

 concrete monuments. 



Curves. — The reverse curve between stations 34 + 07 and 37 + 75 

 was widened gradually to a total width of 24 feet and suitably banked. 

 The curve between stations 84 + 10 and 88 + 76 was widened grad- 

 ually to a total width of 22 feet, and also suitably banked. The 

 curve between stations 89 + 73 and 93 + 99 was also widened gradu- 

 ally to 22 feet. 



Guard rail. — Wooden guard rails were constructed on Section I 

 as follows : 



From station 19+20 to station 34, left. 



From station 20+26 to station 22+55, right. 



From station 73+80 to station 81+64, right. 



From station 74+24 to station 78+70^ left. 



From station 91+50, 3 panels on the right. 



From station 98+70 to station 108+78, both sides. 



At Hume Spring 4 panels of guard rail were erected. 



