PORTLAND CEMENT CONCRETE ROADS. 
17 
is generally made to allow greater clearance between the passing 
vehicles on curves for additional safety. As the clearance allowed 
Edge of Standard Section 
Edge of Widened 
Pavement 
R= Radius of Center of Standard Section of Pavement 
W= Width of Standard Section of Pavement 
cl = Distance from Edge of Pavement to Center of Nearest 
Wheel (taken as i£ ft for Passenger Cars and ||ft. for 
Trucks). 
C= Clearance between Vehicles. 
L= Length of Wheel Base of Vehicles (taken as 12 ft for 
Passenger Car and 17 ft for Truck). 
G= Gauge of Vehicles (taken as 4| Ft for Passenger Car 
and 5 Ft for Truck). 
b s Width, of Vehicles overhanging Wheels (taken as j Ft for 
Passenger Car and l£ Ft. for Truck). 
RVR + ^W-a. 
L'-G. 
R 4 + G=V^I-d? 
3 
Fig. 3. 
R 3 -R r (C+2b). 
R 4 =V^I 
L 2 -G. 
r,+g=VrI-l? 
(r 4 +g) 2 =r|;-l 2 
Total Width Required* 
R-R4+eu + iW 
-Method of computing amount of widening on curvet 
on the tangents is from 3 to 3^ feet, it is believed that a minimum 
of 5 feet should be provided on the curves. 
101130°— 22 2 
