HIGHWAY CONSTRUCTION 127 



comprised in its cheaper maintenance; the greater facility it offers for 

 traveling, thus reducing the cost of transportation; the lower cost of 

 repairs to vehicles, and less wear of horses, thus increasing their term 

 of serviceability and enhancing the value of their present service; the 

 saving of time; and the ease and comfort afforded to those using the 

 roadway. 



First Cost. The cost of construction is largely controlled by the 

 locality of the place, its proximity to the particular material used, and 

 the character of the foundation. 



The Relative Economies of Pavements whether of the same 

 kind in different condition, or of different kinds in like good condition 

 are sufficiently determined by summing their cost under the following 

 headings of account : 



(1) Annual interest upon first cost. 



(2) Annual expense for maintenance. 



(3) Annual cost for cleaning and sprinkling. 



(4) Annual cost for service and use. 



(5) Annual cost for consequential damages. 



Interest on First Cost. The first cost of a pavement, like any 

 other permanent investment, is measurable for purposes of comparison 

 by the amount of annual interest on the sum expended. Thus, assum- 

 ing the worth of money to be 4%, a pavement costing $4 per square 

 yard entails an annual interest loss or tax of $0.16 per square yard. 



Cost of Maintenance. Under this head must be included all out- 

 lays for repairs and renewals which are made from the time when the 

 pavement is new and at its best to a time subsequent, when, by any 

 treatment, it is again put in equally good condition. The gross sum 

 so derived, divided by the number of years which elapse between the 

 two dates, gives an average annual cost for maintenance. 



Maintenance means the keeping of the pavement in a condition 

 practically as good as when first laid. The cost will vary considerably 

 depending not only upon the material and the manner in which it is 

 constructed, but upon the condition of cleanliness observed, and the 

 quantity and quality of the traffic using the pavement. 



The prevailing opinion that no pavement is a good one unless, 

 when once laid, it will take care of itself, is erroneous; there is no such 

 pavement. All pavements are being constantly worn by traffic and 

 by the action of the atmosphere; and if any defects which appear are 



