daily traffic of 4,190 vehicles, and on the 300 urban miles an average of 17,350 vehicles daily. The State highway departments estimate that the 34,861 miles proposed for improvement, if they had been improved as proposed in 1948, would have served on the 31,640 miles of rural sections included an average of 3,450 vehicles, and on the urban sections totaling 3,221 miles an average of 15,360 vehicles daily.
On the basis of these traffic volumes, it is estimated that the system, if it had existed in 1948 in the proposed state of improvement, would have served in that year, on its shortened improved length of 37,159 miles, approximately 62,115 million vehicle-miles of travel. Of this total, 42,380 million vehicle-miles would have been served by the 33,638 miles of rural routes, and 19,735 million vehicle-miles would have been served by the 3,521 miles of urban routes.
These estimates indicate that the system, if it had becn improved as proposed in 1948, would have accommodated on its rural sections, constituting approximately 1 percent of the total rural road mileage, more than 21 percent of the total vehicle-mileage on rural roads. On its sections included within the urban areas of cities of 5,000 population or more, constituting approximately 1 percent of the total city street mileage, it would have served more than 10 percent of the total mileage of urban travel.
COST ESTIMATE OF PROPOSED IMPROVEMENTS
The cost of improvements found to be required has been estimated by the State highway departments on the basis of prices prevailing in 1948. The Federal-aid highway price index for 1948, referred to average prices for the years 1925-29 as 100, was 158.2. Compared with 1940 prices, the average for 1948 was nearly 114 percent higher. Costs of the improvements are, therefore, estimated at high prices; in fact, at the highest prices obtaining for any year in the history of the Federal-aid highway program.
If, in the future, as appears probable, there is some decline from the 1948 price level, the cost of the proposed improvements is likely to be less than the estimate; but no attempt has been made to anticipate the probability in this regard.
Total costs
On the basis of 1948 prices, as stated, the estimated cost of all work proposed on the interstate highway system, as thus far designated, is $11,266,400,000. Of this total, $5,973,000,000 is for improvement of rural sections of the system and $5,293,400,000 is for work proposed on urban sections. The cost of urban improvements is 47 percent of the total.
Widening
Of the $11,266,400,000 total cost, $957,800,000 is for the widening of 8,687 miles of the system as it exists at present, an average of $110,300 per mile. For all rural sections to be widened, a total of 8,306 miles, the cost is $729,300,000, averaging $87,800 per mile. For the 381 miles of urban sections to be widened, the cost is $228,500,000, averaging $599,800 per mile.
Reconstruction
The cost of reconstructing 14,283 miles of the system, involving more than widening but no extended relocation, is estimated at
