Metra Western Avenue diesel shop, Chicago. Diesel-electric locomotives shown here include F40PH and F40C models. Commuter rail locomotives like these work in difficult conditions - they have to accelerate quickly from stops, brake heavily for the next station, and do that in all weather extremes 5 or 6 days a week. They need regular maintenance (hence facilities such as Western Avenue), but a fraction of the maintenance steam locomotives needed. Just one of the reasons GM grew to dominate the diesel locomotive business, only to eventually lose its edge and be seriously challenged by General Electric.