354 AGRICULTURAL APPROPRL\TIOX BILL, 1924. 



track until sections of it were destroyed. A bulletin is now in process 

 of preparation which will probably be ready this month, giving the 

 results of the tests. 



The State Highway Department of Illinois, also, built an experi- 

 mental stretch of highway and raw truck traffic of controlled weight 

 over it. The results of such tests and studies are leading to very 

 material modifications in designing paved roadways and these 

 modifications I believe will result in better roads, at perhaps a lower 

 cost. It is estimated that new principles of design adopted in Illinois 

 may save Sl.oOO per mile in the cost and yet result in a more satis- 

 factory and stronger road. The Bureau will cooperate with the 

 IlJinois Highway Department in carrying forward this study. 



FOR INVESTIGATIONS OF THE CHEMICAL AND PHYSICAL CHARACTER OF 



ROAD MATERIALS. 



Mr. Anderson. The next is on page 257, '"For investigations of 

 the chemical and physical character of road materials, ior conducting 

 laboratory and field experiments and for studies and invest igatit)ns 

 in road design, independently or in cooperation with the state high- 

 way departments, and other agencies," and so forth. This is your 

 laboratory item. 



Mr. MacDon.vld. That is the laboratory and also research item 

 and we are omitting it from the appropriation requests of the De- 

 partment now because under the Federal highway act. provision is 

 made for carrying laboratory testing and investigational under our 

 administration fund. The allotment of this item comes out of the 

 administrative fund this year. I shall be very glad, if you wish, to 

 go into tlie character of work we are carrying on. 



Mr. Anderson. I think that we would be interested in your 

 statement about what is being done under this. 



Mr. MacDonald. We must recognize the fact at this time that 

 the whole science of modern road building is in the making, and 

 because of this fact we are proceeding on tne theory that the more 

 extended the investigational and research work that the States and 

 the Federal Government carry forward during this period the more 

 efficient will be our use of the materials which are available for road 

 buihfing and the better will be the results which we obtain from the 

 use of those materials. The science of highway building has many 

 phases, all involving technical and detailed studies from which the 

 practical results may seem to be only slowly developing. Not only 

 IS this true of the bringing to life of new principles, but also in estab- 

 lishing procedures to insure the application of knowledge already 

 secured. For example, to control tne (|uality of the matei-ials going 

 into Fi'deral-aid projects (he l)ureau does not attempt to make the 

 tests in a central laboratory, but in cooperation witii the States wo 

 do attempt to insure uniform standards of laboratory tests and 

 practices, then uniform specifications for testing materials and the 

 making of check tests. Tiuit is, tlie bureau keeps in close touch 

 with all of the State laboratories in which the actual tests "of road 

 miileiiiils are made, and by constant cooperation and fre(iuen( 

 ciieck tests lielps to keej) tiie work of tiie State laboratories on a 

 uniform basis. The bureau and the several State laboratories 

 fre()uently make tests of the same material to compare methods and 



