period, the States anticipate a decrease of about 28,000 miles in rural mileage and an increase of about 28,000 miles in the urban category. These changes are not particularly significant, in relation to the to mileages.
About 54 percent of the existing rural mileage and 48 percent of the existing urban mileage will require improvement within the 10-year period. Costs of needed improvements average about $11,000 a mile for rural roads and $77,000 a mile for urban streets.
It is not contemplated that every mile of local roads and streets will be surfaced in the 10-year period. Although the time and means available for preparation of the estimates precluded the development of exact detail, it is known that about 400,000 miles of roads exist only as passable trails. These roads of low essentiality warrant little or no improvement for the limited service they render.
The estimate of needed work on local roads and streets during the 10-year period 1955–64 totals $27.2 billion, of which $13.3 billion is for rural roads and $13.9 billion for city streets.
Itemization of costs
An itemization of the estimates of costs for the 10-year period 1955–64 for right-of-way, grading, surfacing, and structures is shown in table 3. shown are the numbers of new and replacement structures needed.
To provide maximum service on the interstate system in terms of capacity, speed, and safety, it is obvious that there should be strict adherence to those standards of design which have proved effective in accomplishing these objectives. The total cost is impressive. The magnitude and proportion of right-of-way and structure costs are particularly large—almost 50 percent more in percentage relation to the total than for any of the other systems.
Such expenditures are required to obtain control of access, long sight distances, easy grades and curves, grade separations and traffic interchanges, frontage roads, and the like. Provision of these features, characteristic of the interstate system, makes improvement of these routes cost as much as one-third more than other Federal-aid primary roads in rural areas, and even more in urban areas. For this added cost, the interstate system roads will have longer service lives and will be capable of carrying twice as much traffic as other roads not incorporating these features, and will carry it more efficiently.
Looming in importance both on a cost basis and a percentage basis is the magnitude of the right-of-way problem in urban areas. The total urban right-of-way costs for the 10-year period are estimated at $8.2 billion, 23 percent of all urban costs and 8 percent of the entire $101 billion estimate. The problems and costs involved in acquiring right-of-way have been among the principal deterrents in urban construction programs. The longer acquisition is deferred, the greater will be the difficulties in obtaining satisfactory rights-of-way.
As might be expected, the costs of both right-of-way and structures, in amount and in percentage of system cost, are greatest for the urban portion of the interstate system. The sree: cost Ferg mile of right-of-way alone in urban areas is more than double the total cost per mile in rural areas, on the interstate system.
