On the dry, sandy soils I put the macadam six inches deep; this depth was applied to about six miles of road. On roads 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 under the state-aid act by county officials and paid for as follows: One-third by the state, ten per cent by the adjoining property holders, and the balance (56-2/3 per cent) by the county. The roads constructed under this act are generally leading roads and those mostly traversed by heavy teams. They are constructed similarly to those in Chester Township, excepting that they are generally twelve feet wide and from ten to twelve inches deep. Many of them have a telford foundation, which is now put down at about the same price as macadam, and meets most of the conditions better than macadam. The less expensive stone is used for foundations, and the best and more costly for surface only. In this way the cost of construction has been greatly reduced.
In regard to the width, a road nine or ten feet wide has been found to be quite as serviceable as one of greater width, unless it is made fourteen feet and over. It is not claimed that a narrow road is just as good as a wide road, but it has been found better to have the cost in length than in width in rural districts. In and near towns, where there is almost constant passing, the road should not be less than from fourteen to twenty feet in width. The difficulty in getting on and off the stone road where teams are passing is not so great as is supposed. To meet this difficulty in the past, on each side of the road the specifications require the contractor to make a shoulder of clay, gravel, or other hard earth; this is never less than three feet and sometimes six to eight feet in width, according to the kinds of soil the road is composed of and the liability of frequent meeting and passing. In rural districts the top-dressing of these shoulders is taken from the side ditches; grass sods are mixed in when found, and in some cases grass seed is sown. As the stone roadbed takes the travel the grass soon begins to grow, receiving considerable fertilizing material from the washing of the road; and when the sod is once formed the waste material from the wear of the road is lodged in the grass sod and the shoulder becomes hard and firm, except when the frost is coming out.