HIGHWAY BONDS. 11 



In issuing bonds for building highways the element of investment 

 is of great importance. The allowable variations in grade and align- 

 ment are considerable, as are also the variations in the types of drain- 

 age structures. But there exists always a minimum standard below 

 which it is uneconomical for any community to build on borrowed 

 money. 



It is manifestly poor policy to build an expensive surface or 

 a relatively long-lived surface on defective grades with poor align- 

 ment, or where the drainage features are short-lived and temporary. 

 Construction should be so adjusted to the service needed that its 

 purpose is accomplished without waste. A county with impassable 

 muddy clay roads must obtain, with a bond issue of $100,000, a 

 maximum mileage of improvement. If roads are constructed cost- 

 ing $10,000 per mile, but 10 miles can be built. It is quite proba- 

 ble that the best economic result will be obtained by building 40 

 miles of road at a cost of $2,500 per mile. This money should be 

 spent largely for enduring features, such as grading, drainage, etc. 



The common error, however, in county bond issues is to fix the 

 sum to be voted upon and then to demand an exorbitant mileage 

 for that sum. There is presented in Table 5 and in Appendix C the 

 percentage of the cost of drainage and grading, exclusive of surfacing, 

 and the percentage of cost of the surfacing on a considerable mileage 

 of road from several States. 



Not all the surfacing need be a perishable feature. It is becoming 

 more and more common to construct roads with surfaces built in 

 two courses, the lower of which is regarded as a permanent feature 

 of construction. This is particularly true of those types of road that 

 are built with concrete foundations for bituminous-macadam, brick, or 

 asphalt surfaces. Most hard roads are now seldom allowed to wear 

 into the foundation course of the surfacing. It is probably conserva- 

 tive to regard 40 per cent of the surfacing cost of macadam or more 

 enduring pavements as a cost for permanent features. Well-built 

 macadam roads, from the recorded costs in Table 5, would therefore 

 indicate a cost of 62 per cent of the total cost for permanent features 

 and bituminous-macadam roads about 56 per cent. This method of 

 estimating can not be applied to gravel or any natural soil road. 

 Under most existing systems of maintenance the entire surfacing of 

 such roads steadily deteriorates. It is generally accepted that roads 

 built with surfaces entirely of concrete or with a brick pavement and 

 a concrete foundation are permanent. It is not, however, yet known 

 how long the best concrete surface will wear and it is certain that 

 serious failures of concrete surfaces have resulted from poor construc- 

 tion. The best vitrified brick surfaces may have a life of 30 years 

 or more, but repairs will usually be required and sufficiently exten- 



