470 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



determine to what degree the motor truck is offering a service 

 correlated to that of the railroads, a study has been under way 

 during the past year in Massachusetts and Khode Island. 



The bureau representatives have gone directl}^ to the principal 

 manufacturers and motor-trucking companies in these States with 

 questions as to the reasons whj^ commodities are shipped by motor 

 truck, the portion of the business that is handled by motor trucks, 

 railroads, and ship lines, respectively, the extent to which correlated 

 service involving two or more agencies has developed, and the rates 

 charged for service. 



The investigation was still in progress at the close of the fiscal 

 year, so that it is not possible at this date to report any conclusions. 

 However, it may be said that the study gives promise of developing 

 interesting information with respect to a recent transportation 

 development involving motor trucks and railroads and ship lines 

 offering combined service. 



THE INFLUENCE OF HIGHWAY IMPROVEMENT ON RURAL LAND 



VALUES. 



The influence of road improvement on land values is an economic 

 question with regard to which there has been a great amount of 

 speculation. Much of the information on which opinion is based is, 

 however, far from scientific and possibly inaccurate. The bureau 

 has engaged within the past year in an effort to obtain, for one set of 

 conditions, at least, an array of information scientifically gathered, 

 which will suggest the real influence of various type of highway im- 

 provement on land values under different conditions as to crops, 

 population, soil characteristics, and other factors affecting the value 

 of rural land. 



The increase in land value obviously has an important bearing on 

 the taxation of land for highway purposes. To determine this effect 

 of road improvement, the bureau's studies include improvements of 

 all types from dirt to concrete, and it is anticipated that a report 

 that will contain valuable basic data will be ready soon. 



PHYSICAL RESEARCHES AND TESTS. 



Researches in the physical field designed to supply scientific data 

 for use in road design have become one of the most important and 

 useful activities of the bureau. The various tests and investigations 

 are followed closely by highway engineers the country over, and an 

 encouraging indorsement of their value is found in the increasing 

 attention they are attracting in foreign countries. 



The investigations which have attracted the greatest amount of at- 

 tention are the tests of the effect of impact on road slabs and the 

 tests of bituminous pavements of various composition to determine 

 their relative stability under traffic. The phenomenon that is being 

 observed in the latter investigation is the formation of the familiar 

 " washboard " wrinkles which appear in the surface of bituminous 

 roads under traffic. 



For the impact experiments a series of 120 special road slabs were 

 constructed during the preceding fiscal year. These are now being 

 tested. Two large, portable impact machines, designed to deliver to 

 the slabs blows such as are delivered to actual road slabs by motor- 

 truck wheels have been put into operation. Up to the present time 



