Engineering and Contracting . d fartherover good roads than they will over poor roads. Thisdifference in the volume of the traffic before a road isimproved and after it is improved is pretty constant overfairly large areas, and when established by a numberof traffic censuses, may be relied on. Therefore, in com-puting the justifiable cost of an improvement, it is cus-tomary to increase the figures derived from the censusby a percentage which represents the increase in trafficthat has been observed to result from the improvementof other roads in the same region. The justifiablecost is then comp
Engineering and Contracting . d fartherover good roads than they will over poor roads. Thisdifference in the volume of the traffic before a road isimproved and after it is improved is pretty constant overfairly large areas, and when established by a numberof traffic censuses, may be relied on. Therefore, in com-puting the justifiable cost of an improvement, it is cus-tomary to increase the figures derived from the censusby a percentage which represents the increase in trafficthat has been observed to result from the improvementof other roads in the same region. The justifiablecost is then computed by substitution in the formula, n — mC = , in which n equals the daily average num- of vehicles of all classes passing over the road, mthe annual maintenance of cost per kilometer in pesos,and C the justifiable cost of construction per kilometer,or perhaps more accurately the calculated value of theroad to the community. No extra allowance is made forautomobiles or other heavy traffic, as all roads built in. Fig. 1—Candelaria Bridge on Candelaria-Tiaong Road, Torjabas Piovince. entirely erroneous impression as to the volume of thetraffic can be secured either by selecting stations so nearto the towns that the traffic is largely local, or by select-ing stations so far from the towns that no local trafficis included. Moreover, both daily and seasonal variationsin traffic density must be allowed for. An engineer whoappreciates the problem will find no difficulty in obtain-ing satisfactory data, but carelessness in regard to theselection of stations or the choice of improper periods fortaking the census will usually render the data securedworse than valueless. Where the construction of a road over an entirely newroute is contemplated the problem is more there are trails near the new route and more orless parallel to it. These must be investigated and theirtraffic studied. It may be that water routes are nowlargely used. The problem then become
Size: 2715px × 920px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, bookpublisherchicago, bookyear19
