The 72 year old has been travelling on this same train almost since it first opened in 1974. In those days, the "green trains" were still a symbol of the comfort and convenience brought by modern socialist development, and Mr Xu has fond memories of that time.

"Taking this train, we used to go to join the army, go to fairs in the larger cities, and pay New Year visits," he reminisces.

But though the "green train" continues to wind its way along the same 184-kilometer route across Shandong province as it did forty years ago, the world outside the carriage window has changed dramatically.

Sleek electric high-speed trains have rapidly replaced the old diesel services all over China, and Mr Xu's train is the only "green" line still running in Shandong.

The "green train", whose fares start at just one yuan ($ 0.17), is still a favorite mode of transport for most residents that live along the line. [Photo/wechat: taiandzwww]

For Mr Xu, time has also changed many things. "Now, few of my buddies are still alive, and I am lucky to be able to visit them through this same old train," he says.