Railway signal systems :  hearing, 75th Congress, 1st session, on H.R. 185, to promote safety of employees and travelers on railroads by requiring common carriers engaged in interstate commerce to install, inspect, test, repair, and maintain block-signal systems, interlocking, highway grade crossing protective devices, automate train-stop, train-control, cab-signal devices, and other appliances, methods, and systems intended to promote safety of railroad operations, Mar. 19, 1937. 

 - [Washington, D.C.],  1937. 
 - iii, 64 p. 
<br/><br/> Document for sale by the Superintendent of Documents, paper.  CRDP Program Historic Shelflist record. 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Railroads--Safety appliances--United States.<br/>Railroads--Safety measures.--United States
<br/><br/><label>Gov. Doc. Class. No.: </label>Y 4.IN 8/4:SI 2/3