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 Rwement 



VV= Width of Standard Section of Pavement 



a,= Distance from Edge of Pavement to Center of Nearest 



Wheel (taken as i^ ft for Passenger Cars and I|ft for 



Trucks), 

 C= Clearance between Vehicles. 

 L= Length of Wheel Base of Vehicles (taken AS i?. FT for 



Passenger Car and 17 ft for Truck). 

 G= Gauge of Vehicles (taken as 4| Ft for Passenger Car 



AND 5 Pr for Truck). 

 b=W!DTH. OF Vehicles overhanging Wheels (taken as ^ Ft for 



Passenger Car and li Ft for Truck). 



R. 



= R+^w-a;, 



(R, + Gf =R|-L^ 



=VRi"L^-G. 

 -t-G=\/R|-L^ 



R3=R,-(C+2b). 



R,+G=VRf-L? 



(R4+G/=Ri-L' 



Total Width Required- 

 R"R4+cb+^W. 



Fig. 



-Method of computing amount of widening on curves. 



on the tangents is from 3 to 3i feet, it is believed that a minimum 

 of 5 feet should be provided on the curves. 

 101130°— 22 2 



