HIGHWAY BEIDGE LOCATION 
equivalent horizontal span. The overflow banks at the site of cross- 
ing No. 2 are also higher with reference to flood-water elevation, so 
that a shorter approach structure is permissible. The yardage of 
concrete for crossing No. 1 is 1405 cubic yards or 2.44 cubic yards per 
EXPOSED SOLID ROCK 
6 APPROACH SPANS AT 35-0"-2IO'-0- 
^ARCH SPAN 147-0— 
TOTAL LENGTH 575-0"- 
CR0SSINGN0.I 
— 7 APPROACH SPANS AT 25-OM r^M SPAN 113-6-1 K APPROACH SPANS AT 25'-tf- 
TOTAL LENGTH. 452-0"— 
CROSSING N0.2 
Fig. 2.— Designs for two crossings of the same stream. Conditions at crossing No. 2 permit a 
design of considerably less cost than at crossing No. 1 
lineal foot, whereas for crossing No. 2, farther downstream, the total 
yardage is only 969 cubic yards or 2.14 cubic yards per lineal foot. 
The total cost of crossing No. 2, is therefore, seen to be about — - — or 
1405 
2 14 
69 per cent of crossing No. 1, and the cost per lineal foot oVjor 88 
per cent of that for crossing No. 1. 
ANGLE OF CROSSING 
The introduction of a skew angle involves several factors operating 
to increase the first cost. (1) Where steel is employed for super- 
structure work the price per pound is generally slightly more, owing 
1 TOE OF SLOPE 
Fig. 3.— Diagram illustrating length of wing wall required 
to prevent erosion at toe of slope 
to the cost of fabrication. The weight may prove to be greater than 
that of a square span of equal length. This will be true if the floor 
beams are placed parallel to the piers, as is sometime done. (2) The 
piers and abutments will be increased in length and the wing walls on 
