It would be cool to have a massive fixed railgun that could be used for sub orbital travel and material transport.
This would be a late game addition, but would allow the player to launch themselves or material across the map in moments. Different types of pods for different applications. A ballistic one for sending material (with a receiver, hopefully), a powered one for propulsive landing and exploration, a emergency pod for resupply during exploration, an explosive one for... Well, blowing stuff up.
Trains are effective and efficient, but ballistic orbital travel is a step above!