Page:Historic highways of America (Volume 15).djvu/182

 transportation. The road was in every way properly constructed, and thoroughly rolled with a steam roller; but in spite of every precaution it soon began to ravel, and repeated rolling was only of temporary benefit, for the rock was too hard and tough for the traffic. Subsequently, when the road was resurfaced with limestone, which was much softer than the trap, it became excellent. Since then all roads built on the island have been constructed of native granite bowlders with good results, and at a much lower cost.

If, however, this hard and tough rock, which gave such poor results at Nantucket, were used on a road where the traffic was sufficient to wear off an ample supply of binder, very much better results would be obtained than if a rock lacking both hardness and toughness were used; for, in the latter case, the wear would be so great that ruts would be formed which would prevent rain water draining from the surface. The water thus collecting on the surface would soon make its way to the foundation and destroy the road. The dust in dry weather would also be excessive.