The Future of Road-making in America

by Archer Butler Hulbert

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.

Another mode of building a rural road cheaply and still have room for passing without getting off the stone construction is to make the roadbed proper about ten feet wide, ten or twelve inches deep; then have wings of macadam on each side three feet wide and five or six inches deep. In case ten feet is used the two wings would make the stone construction six feet wide. If the road is made considerably higher in the center than the sides, as it should be, the travel, particularly the loaded teams, will keep in the center, and the wings will only be used in passing and should last as long as the thicker part of the road.

The preparation of the road and making it suitable for the stone bed is one of the most important parts of road construction. This, once done properly, is permanent. Wherever it is possible the hills should be cut and low places filled, so that the maximum grade will not exceed five or six feet rise in one hundred feet; where hills cannot be reduced to this grade without incurring too much expense, the hill, if possible, should be avoided by relaying the road in another place.

Wherever stone roads have been constructed it has been found that those using them for drawing heavy loads will increase the capacity of their wagons so as to carry three or four times the load formerly carried. This can easily be done where the road has a maximum grade of not greater than five or six per cent, as before stated; but when the grade is greater than this the power to be expended on such loads upon such grades will exhaust and wear out the horses; thus a supposed saving in heavy loading may prove to be a loss.

In the preparation of the road it is necessary to have the ditches wide and deep enough to carry all the water to the nearest natural water way. These ditches should at all times be kept clear of weeds and trash, so that the water will not be retained in pools. Bad roads often occur because this important matter is overlooked.

On hills the slope or side grade in construction from center of road to side ditches should be increased so as to exceed that of the longitudinal grade; that is, if the latter is, say, five per cent, the slope to side should be at least six per cent and over.

Where the road in rural districts is on rolling ground and hills do not exceed three or four per cent, it is an unnecessary expense to cut the small ones, but all short rises should be cut and small depressions filled. A rolling road is not objectionable, and besides there is no better roadbed for laying on metal than the hard crust formed by ordinary travel. In putting on the metal, particularly on narrow roads, the roadbed should be "set high;" it will soon get "flat enough." It is better to put the shouldering up to the stone than to dig a trench to put the stone in. If the road after preparation is about level from side to side and the stone or metal construction is to be, say, ten inches deep, the sides of the roadbed to receive the metal should be cut about three inches and placed on the side to help form the shoulder; the rest of the shoulder, when suitable, being taken from the ditches and sides in forming the proper slope. The foundation to receive the metal, if the natural roadbed is not used and the bed is of soft earth, should be rolled until it is hard and compact. It should also conform to the same slope as the road when finished from center to sides. If the bed or foundation is of soft sand rolling will be of little use. In this case care must be taken to keep the bed as uniform as possible while the stone is being placed on the foundation.