6 



BULLETIN 136, U. S. DEPARTMENT OF AGRICULTURE. 



radial roads will tend to vary inversely with their number. Plates 

 IV, VI, and IX show the distribution of the main market roads in 

 three counties. 



ECONOMIC VALUE OF THE MARKET ROAD. 



The service rendered by highways radiating from a town may be 

 measured directly by the tonnage which is hauled over them; and 

 their economic importance is indicated by this tonnage and varies 

 directly with it. There are two ways -of computing the tonnage of 

 traffic on a road: (a) By actual count, and (b) by determining traffic 

 areas supplemented with producers' and merchants' estimates of 

 tonnage. 



The actual count of traffic determines the average number of teams 

 hauling produce each day, their loads, and the average distance 

 traveled. From the count on a sufficient number of days a close 

 estimate of the average annual traffic may be had. 



Table 2. — Traffic record of seven unimproved roads. 



Road 

 No. 



Location. 1 



Lauderdale County, 

 Ala. (2) 



Boone and Story Coun- 

 ties, Iowa (16) 



Cumberland and Sa- 

 gadahoc Counties, 

 Me. (8) 



Leflore County, Miss. 

 (3) 



Montgomery County, 

 Md. (1)..' 



Muskingum County, 

 Ohio (2) 



Jackson County, Oreg. 

 (3) -- 



Totals and aver- 

 ages 



Length 

 in miles. 



28.3 

 45.1 



32.1 

 24.1 

 5.4 

 20.9 

 50. 5 



206.4 



Tons per 



day, each 



area. 



Average 

 haul 



(nearest 

 mile). 



Mer- 

 j chants' 

 Equiva- i and pro- 

 lent annual | ducers' 

 ton-miles, estimates 

 ( ton- 

 miles). 



367,894 

 162, 342 



227,451 

 197,386 



14,044 

 111,026 



51,810 



228, 046 

 105,662 



1,131,953 



90, 628 



5, 892 



132,711 



32, 170 



Traffic 



area 



(acres). 



154, 432 

 113,521 



38, 182 

 60, 736 

 12, 531 

 41,952 

 73,881 



495, 235 



Reported 

 costs 

 (cents 



per ton- 

 mile). 



16.0 

 37.2 



23.6 

 36.2 

 26.0 

 28.0 

 36.6 



29.1 



1 Numbers in parentheses indicate the number of traffic areas. 



From a map, supplemented by field observations, the traffic area 

 served by a highway may be determined. This is the area on 

 which originates market produce and for which supplies must be 

 hauled from market. In a wheat country, for example, the average 

 annual wheat acreage tributary to a highway will determine approxi- 

 mately the principal market traffic. Even a rough estimate of the 

 traffic area is valuable for determining the relative importance of 

 highways and indicates the order in which their improvement should 

 be undertaken. It is also an excellent check on traffic count. 

 Traffic data for a number of roads recently investigated by the 



