You are right that they need to find more goods to ship on the return trip. The current route actually runs on existing tracks so didn't require a lot of investment.
For cities like Lanzhou, Xining, Urumqi etc it makes sense to develop a land route. The economics are even better than Chongqing since Chongqing actually has access to the Yangtze river.
Re:China's Silk Road Illusions
by seanmcdirmid on Thursday October 26, 2017 @12:49AM
(#15556428)
The tracks aren't as important as the trains in this case; e.g. Crews and fuel as well as not using those on more productive routes. Chongqing as a gateway to the western china is a bit weird since it actually isn't that west :) Chinese geography is a bit wonky like that.
Chongqing has access to large ships: https://en.m.wikipedia.org/wiki/Port_of_Chongqing
The advantage of rail for Chongqing is mainly shipping time, which is important for higher value electronics.
The railroads to Europe are still heavily subsidized, and are coming back to china mostly empty. They'll make more sense when trade becomes more balanced, but that isn't today.