Fun fact: Maryland's transit agency recently moved to diesel technology for its next generation of commuter train locomotives. The railroads in this area were first electrified more than a century ago, and most of the last several generations of locomotives were electric. But the overhead catenary is in bad shape, and some lines have stops that haven't been electrified. Maryland apparently believes that, over the 20-30 year service life of these locomotives, the infrastructure is likely to deteriorate further (to 19th century levels), instead of improve, such that diesel is the smarter option.