This is talking about a rail system on the moon.

Lmao I had to check that article, I called it.

Explore concepts for constructing and operating the system with robotics, including grading and foundation preparation, track placement and alignment, joining and finishing, inspection, maintenance and repair.

My guess is they want to land self autonomous robots there to build it for them.

Interestingly enough you bring that up though.....

China is supposedly going to build one.

https://www.scmp.com/news/china/science/article/3255351/nasas-dream-comes-true-china-plans-build-giant-rail-gun-launch-hypersonic-planes-space

That link though to chinas railgun, mentions it as a rail network, interestingly enough.

This facility can propel a heavy object to speeds approaching 1,000km/h (620mph)– close to the speed of sound. In the coming years, the length of the test line will be extended to achieve a maximum operating speed of 5,000km/h.

This is the most ambitious electromagnetic propulsion facility on the planet, poised to support the development of next-generation high-speed railways and gather vital scientific and engineering data for the space electromagnetic launch project.