92 GARDEN PLANNING 



grades, and textural finish suited to conditions. 



The average distance between centres of tires 

 is four feet nine inches. Add to this one foot six 

 inches to allow nine inches outside of each tire, 

 and the result, six feet three inches, is a service- 

 able width for the automobile runway. Six feet 

 six inches is quite commonly used and is a good 

 width under nearly all circumstances, unless 

 curbs be built on the outside, when the overall 

 width will be increased by about eight inches. 

 It is assumed that each runway is eighteen 

 inches wide with a grass plot between. They 

 are sometimes built twelve inches and twenty- 

 four inches, the former being too narrow and the 

 latter unnecessarily wide. 



The ramp should in no case have a width less 

 that the overall width of the runway. It is 

 better, when ramp and runways do not join but 

 are separated by a sidewalk, to have the narrow 

 part or throat of the ramp equal to or bur slight- 

 ly wider than the width of the runways. This 

 will give the effect of continuity of the side lines. 

 The width of the opening along the street curb 

 will vary according to local conditions. From 

 observations and measurements to determine 

 what a driver will do when turning off the street 



