128 HIGHWAY CONSTRUCTION 



not quickly repaired, the pavements soon become unsatisfactory and 

 are destroyed. To keep them in good repair, incessant attention is 

 necessary, and is consistent with economy. Yet claims are made that 

 particular pavements cost little or nothing for repairs, simply because 

 repairs in these cases are not made, while any one can see the need of 

 them. 



Cost of Cleaning and Sprinkling. Any pavement, to be con- 

 sidered as properly cared for, must be kept dustless and clean. While 

 circumstances legitimately determine in many cases that streets must 

 be cleaned at daily, weekly, or semi-weekly intervals, the only admis- 

 sible condition for the purpose of analysis of street expenses must be 

 that of like requirements in both or all cases subjected to comparison. 



The cleaning of pavements, as regards both efficiency and cost, 

 depends (1) upon the character of the surface; (2) upon the nature of 

 the materials of which the pavements are composed. Block pave- 

 ments present the greatest difficulty; the joints can never be perfectly 

 cleaned. The order of merit as regards facility of cleansing, is: (1) 

 asphalt, (2) brick, (3) stone, (4) wood, (5) macadam. 



Cost of Service and Use. The annual cost for service is made up 

 by combining several items of cost incidental to the use of the pave- 

 ment for traffic for instance, the limitation of the speed of movement, 

 as in cases where a bad pavement causes slow driving and consequent 

 loss of time; or cases where the condition of a pavement limits the 

 weight of the load which a horse can haul, and so compels the making 

 of more trips or the employment of more horses and vehicles ; or cases 

 where conditions are such as to cause greater wear and tear of vehicles, 

 of equipage, and of horses. If a vehicle is run 1,500 miles in a year, 

 and its maintenance costs $30 a year, then the cost of its maintenance 

 per mile traveled is two cents. If the value of a team's time is, say, 

 $1 for the legitimate time taken in going one mile with a load, and in 

 consequence of bad roads it takes double that time, then the cost to 

 traffic from having to use that one mile of bad roadway is $1 for each 

 load. The same reasoning applies to circumstances where the weight 

 of the load has to be reduced so as to necessitate the making of more 

 than one trip. Again, bad pavements lessen not only the life-service 

 of horses, but also the value of their current service. 



Cost for Consequential Damages. The determination of conse- 

 quential damages arising from the use of defective or unsuitable pave- 



