g8 NEW YORK STATE MUSEUM 



Where the soil foundation is clay, or for any reason difficult to drain, 

 the Telford method is used. In this case a course of flat stones about 

 six inches deep, set on edge and closely wedged together, is placed upon 

 the soil and crushed stone is placed over this four inches thick and rolled 

 solid. In good practice it is customary to roll the earth before the stone 

 is laid upon it and then 10II the stone foundation. The Telford founda- 

 tion forms a bridge which prevents the road from sinking in moist soil and 

 is rendered completely effective by tile drains on each side of the road. 

 After the road is built if must be kept constantly in repair and the neglect 

 of this principle is to a great extent responsible for the poor roads of the 

 United States. 



The Macadam and Telford systems above described are necessary 

 for roads designed fur heavy traffic in all weathers, but roads for 

 pleasuie driving in summer only, do not need the same expensive prepa- 

 ration. 



As an example of the methods adopted for the construction of high 

 class roads I am permitted by the courtesy of the Massachusetts High- 

 way Commission to quote the following extracts from its pamphlet of 

 Instructions to engineers, published in 1896 : 



Gravel. You will use gravel for surfacing the road bed under tel- 

 ford ; also for surfacing the sub-grade where the natural soil is clayey, 

 loamy, or where ordered under other conditions by the chief engineer. 

 The gravel must be practically free from sand and clay. 



Broken stone. State highways are divided as follows with reference 

 to the broken stone (sizes given are in inches) : 



1 All trap rock, 1 bottom 1st course to be 1^ to 2^; top course to 

 be y 2 to 1%; 



2 All trap rock, both courses to be ij£ to 2^ ; 



3 Local stone other than trap, bottom course to be 1^ to 2^ ; top 

 course to be y to 1 y ; 



4 Local stone other than trap, both courses to be y to 2^ ; 



5 Bottom course of local stone other than trap, y to 2^ ; top course 

 of trap rock, y to 1^; 



6 Bottom course of local stone other than trap, y to 2^; top course 

 of trap rock, 1^ to 2^ ; 



7 All trap rock, bottom course to be y to 1^; top course to be iy 

 to 2}., ; 



8 Local stone other than trap, bottom course to be y to 2^ ; top 

 course to be 1^ to 2^. 



When 'local stone other than trap ' is used you must not allow any soft 

 or disintegrated rock to go upon the road; all such rock must be rejected 

 before breaking. If the contractor fails to remove such rock, immedi- 

 ately report the fact in writing to the chief engineer. 



