One way that China keeps the cost of subways down is by standardizing the train sets. They have three types of trains (A, B, C) that are used in almost all sub

One way that China keeps the cost of subways down is by standardizing the train sets. They have three types of trains (A, B, C) that are used in almost all subway systems across the country. You need a high-capacity train? A. You have a smaller line with fewer passengers? C. Something in-between? B. There are a few variants for cities with special circumstances. Chongqing uses variants that can handle steeper slopes, because the city is incredibly hilly (like San Francisco). By standardizing, prices can be kept down. Cities don't have to come up with custom solutions. Just define your needs and pick the standard variant that matches them. Something similar could be done with buses.