BANKING ON CURVES

Timaru Herald, Volume CXXV, Issue 18382, 28 September 1929, Page 12

BANKING ON CURVES

HIGHWAY STANDARDS. Main highway specifications during the last two years have provided for increased banking on curves, but it appears that the limit has been reached and the Highways Board is not disposed to encourage higher speeds. Some time ago the automobile associations urged the Highways Board to consider providing still more superelevation on corners with a view to security at the higher touring speeds which would be inevitable in a few years. The Highways Board increased the banking after it had functioned for three years, the reason being that speeds were greater and horse drawn traffic had decreased. The board considers that the degree of super-eleva-tion now applied will permit the following speeds with safety and comfort:— Curve Radius Permissable Chains. m.p.h. IS 15 15-3 20-28 3-75 23-37 75-15 33-45 15-40 40-50 Replying to the representations of the North Island Motor Union, the chairman of the Highways Board writes: “It is the duty of road-con-struction and road maintaining authorities to endeavour to give the reasonable service to all classes of traffic. Even if motor-cars alone were to be considered, the suggestion that super-elevation should be such as to allow with safety a speed of at least 30 miles an hour is quite impracticable. “To take a case in point, if on the Rimutaka Hill section, all the curves were super-elevated sufficiently to allow the road to be traversed comfortably at 30 miles an hour, the inclination of ..he road surface at many of the curves would be so /steep that it would be almost impossible to walk on foot across the road. In addition, it would be impossible for horse drawn vehicles to traverse the road, and it would be extremely dangerous, and in many cases impossible, for motor-lor-ries to use the road. “It is necessary to point out that complaints have actually been received alleging that the super-elevation now being provided is excessive for the safety of horse drawn traffic, and also for the safety of heavy motor-lorries. On curves up to three chains radius in side cuttings and block cuttings, the visibility should limit the speed, and indeed the visibility on such curves is so short that the motorist should be discouraged in his own interests from travelling at more than a reasonable rate.”