Page:Historic highways of America (Volume 15).djvu/198

 where the heaviest travel would come the roadbed was made eight inches deep. On soils having springs and on embankments over causeways the depth was ten inches with stone foundation, known as telford. Where springs existed, they were cut off by underdrains.

It had been the practice of engineers in their specifications to call for the best trap rock for all the stone construction. As this rock is hard to crush and difficult to be transported some seventy or eighty miles to this part of New Jersey, I found that in order to construct all of the road from this best material it would take more money than the bonds would provide; so I had half of the depth which forms the foundation made of good dry sedimentary rock. Of course, in this there is considerable slate, but the breaking is not nearly so costly as the breaking of syenite or Jersey trap rock, and there was a saving of thirty per cent. As the surface of the road had to take all the wear, I required the best trap rock for this purpose.

Since the construction of these roads in Chester Township, roads are now built