284 EXPERIMEISTT STATION EECOKD. • [Vol.43 



structural-steel paints, because of the fact that vehicles composed largely of this 

 oil increase the tendency to check. 



A list of paints known to be satisfactory for highway bridges, and standard 

 specifications for highway bridge paints, are appended. 



Highway classification undertaken by Bureau Public Roads {Engin. Neics- 

 Rec, 8^ (1920), No. 13, pp. G35-631).—T\\q program outlined by T. H. Mac- 

 Donald, chief of the Bureau of Public Roads of the U. S. Department of Agri- 

 culture, as being undertaken in cooperation with the War Department, State, 

 highway departments, and local interests for the systematic development of high- 

 ways on the basis of their service functions is briefly outlined. 



Field manual (Boise, Idaho: Dept. Pub. Works, Bur. Hujliicays, 1919, pp. ^6, 

 figs. 8). — This manual contains instructions to employees of the Idaho Bureau 

 of Highways on Federal and State-aid road work. 



Rein forced-concrete roads, J. H. Walkek (Surveyor and ifvnic. and County 

 Engin., 57 (1920), No. l,Jf59, pp. 7, 8). — Experience in England with concrete 

 roads is briefly sununarized with reference to factors affecting design. 



A thickness of 10 in., consisting of an S-in. base and a 2-in. wearing surface, 

 is advocated. Proper reinfoi'cement and the consequent elimination of expan- 

 sion joints is considered most feasible, the reinforcement consisting of a top 

 and bottom layer connected by diagonal tension members. 



Reinforced-concrete road construction, I. F. Shellaed (Surveyor and 

 Munic. and County Engin., 56 (1919), No. 1,458, pp. Jfl5, Jtl6). — Experience in 

 the design and construction of a trial length of reinforced-concrete road is 

 related. The concrete was one course, 6 in. thick, of 1 part cement, l* parts 

 coarse sand, and 3 parts 1 and 2 in. crushed limestone. The reinforcement was 

 placed 2 in. from the bottom. No transverse joints were provided, but there 

 was a longitudhial joint the whole length. The road has carried excessive traffic 

 for three months successfully. 



Concrete road work: Special reference to available aggregates, A. N. 

 Johnson (Concrete [Detroit, Mieh.], 16 (1920), No. 4, pp. i79-i 83). —Consider- 

 able Information on the subject is summarized, including tabular data on the 

 proportioning and quantities of aggregates. 



Stresses in concrete roads. — Determining the correct position of rein- 

 forcement (Surveyor and Munic. and County Engin., 57 (1920), No. 1,464. P- 

 138). — A brief analysis of the stresses in concrete roads on firm and on yielding 

 foundations leads to the conclusion that a layer of reinforcement is desirable 

 near the upper surface of the concrete, and that where lower reinforcement is 

 necessary it is ineffective unless upper reinforcement is also used. It is further 

 concluded that every yard of reinforced concrete road should be considered on 

 its merits. 



Reduction of labor in the computation of vertical curves, B. E. Brevid 

 (Engin. and Contract., 53 (1920), No. 14, p. 413, figs. 2).— A short method foi- 

 the computation of vertical highway curves is given. 



Can Ave afford to delay road improvement? H. J. Fixmer (Engin. and 

 Contract., 53 (1920), No. 14, pp. 4O6-4O8, flgs. 2).— Graphic data are reported 

 showing cost per vehicle and per ton-mile, based on daily traffic for roads of 

 various annual costs and also the saving effected by improved roads. These 

 indicate that in spite of high prices road building is justified. 



Traffic on Iowa highways, T. R. Agg (Iowa Agr. CoL, Off. Pub., 18 (1920), 

 No. 34, pp. 14< Pls- 18, figs. 3). — An investigation is reported which was under- 

 taken to secure data relative to the weight of each class of vehicles using Iowa 

 highways. 



Traffic weighings were made at seven stations selected with regard to pos- 

 sible variation in the weight of vehicles in different parts of the State. The 



