When the 4000-series rail cars were first used, they were notable for being made of steel rather than wood and were considered safer, according to the CTA. The cars are able to reach about 45 mph, in contrast to modern trains that reach speeds of 55 mph. The 4000-series rail cars are also smaller than the trains commuters are now used to riding. In addition, the vintage cars don’t use computer chips, have no air conditioning and have incandescent lights, according to the CTA.