BULLETIN OF THE 



ii 



No. 220 



Contribution from the Office of Public Roads, Logan Waller Page, Director 

 June 7, 1915. 



ROAD MODELS. 



Prepared by the Office of Public Roads. 



CONTENTS. 



Page. 



Introduction 1 



Roman roads 2 



French roads 3 



Macadam method of construction 5 



Telford method of road building 6 



Location and alignment 7 



Foundation, or subgrade, and shoulders 7 



Earth and sand-clay roads 10 



Gravel roads - • 12 



Page. 



Macadam roads 13 



Cement concrete roads 17 



Bituminous concrete roads — " Topeka speci- 

 fication ' ' 18 



Paved roads other than concrete 18 



Culverts and bridges 20 



Roadside treatment 21 



Road machinery 22 



INTRODUCTION. 



The Office of Public Roads of the United States Department of 

 Agriculture made an exhibit of road models for the first time in 1909 

 at the Alaska- Yukon-Pacific Exposition. The aim was to put on 

 view such striking examples in miniature of model roads that visitors 

 would not only appreciate the beneficent effects of improved roads 

 but would, at the same time, be able to understand the methods of 

 their construction. 



Since the Alaska- Yukon-Pacific Exposition closed, the exhibit of 

 the Office of Public Roads has been displayed at Omaha, Nebr., dur- 

 ing the National Corn Exposition; at Knoxville, Tenn., during the 

 Southern Appalachian Exposition; at Chicago, 111., during the 

 National Land and Irrigation Exposition; at New York City during 

 the Travel and Vacation Exposition and the Domestic Science Expo- 

 sition; at Atlantic City, N. J., during the American Road Congress; 

 at Lethbridge, Alberta, during the International Dry-Land Congress; 

 at Buenos Aires, Argentina, during the International Agricultural 

 Exposition; at Turin, Italy, during the International Exposition; 



Note. — This bulletin contains illustrations and descriptions of the models in miniature of roads, bridges, 

 and culverts and of road machinery exhibited by the Office of Public Roads at expositions and fairs and 

 on railroads. Methods of construction are discussed. 

 87538°— Bull. 220—15 1 



