PORTLAND CEMENT CONCRETE PAVEMENTS. 23 



From a purely economical standpoint the choice of means for haul- 

 ing the materials would probably be made about as follows : 



First. Where the maximum haul does not exceed 3 miles and the 

 amount of concrete to be laid does not exceed about 5,000 cubic yards, 

 team haul would probably be economical. 



Second. If the amount of concrete to be laid exceeds about 5,000 

 cubic yards, or if the maximum haul exceeds about 3 miles, and the 

 materials are hauled in from the same direction, an industrial rail- 

 way, tractors, or motor trucks may be economically used. 



Third. Where the materials are hauled in from each end of the 

 road, or where it is desired to operate more than one mixer at the 

 same time, the industrial railway is usually more practical and 

 economical. 



Where the sand and coarse aggregate are shipped in by rail, the 

 work of unloading the railroad cars and loading the wagons or cars 

 in which the materials are to be hauled out to the work can usually 

 be most economically done by means of machinery especially adapted 

 to this kind of work. In order to avoid paying demurrage, and to 

 have the materials on hand when they are needed, it is nearly always 

 necessary to handle a considerable part of the materials the second 

 time. Hence it may be desirable to have two sets of unloading and 

 loading machinery in cases where the stock piles and bins are located 

 out on the work instead of at the siding where the materials are 

 delivered. 



The kind of unloading and loading device to employ depends to 

 a very great extent on the quantities of materials to be handled and 

 the other conditions to be met. If the stock piles and bins are ad- 

 jacent to the siding where the materials are delivered, and a consid- 

 erable quantity of work is to be done, a locomotive crane may fre- 

 quently be used to advantage, while, if the stock piles and bins are 

 out on the work, it may be economical to handle the material at the 

 siding with scrapers or similar devices and install an elevating device 

 at the bins where the materials are stored. In other cases the extent 

 of the work may not be sufficient to warrant any machinery whatever 

 for handling the materials, in which event the handling ma}/ be rather 

 expensive. 



CAPITAL REQUIRED. 



The amount of capital required to carry on concrete road construc- 

 tion successfully depends almost wholly on the size of the project and 

 the circumstances under which the work is to be done. Where a con- 

 siderable quantity of work is to be done in the same community it 

 may be possible to keep a very elaborate equipment busy, even though 

 the individual projects are comparatively small. On the other hand, 

 it may be poor economy to provide more than the smallest practicable 



