Class I StarPort:
The Imperium usually creates a Class I StarPort by landing two modular cutters. One carries earth-moving and surfacing equipment and a work crew. It clears a levels space for several small starships to set down, with at least one area large enough for a starship of about 1,000 tons displacement to put down without undue risk. If the Starport Authority has deemed it necessary, the crew will also string metal fencing around the port, defining an extrality line. The other cutter can carry an office module which becomes the port's headquarters building, but this may be optional at some Class I StarPorts. If the office is present, and it is present on Centry, it operates the landing lights and approach beacon, handles the standard paperwork on transient vessels, stores cargo of Imperial concern (mail mostly) and provides a comfortable waiting area for passengers. THERE ARE NO FACILITIES FOR SERVICING OR REFUELING STARSHIPS. If possible, the StarPort will be located near a body of water, from which water (unrefined fuel) can be skimmed by StarShips. Some emergency spare parts and supplies are stocked, but supplies may be depleted for a time after a use or two. [If they are present, you can expect to pay a premium for the spares, too! -- comment added by Leif] If supplies are needed but not present, a crew may have to send a message aboard an outbound ship and wait for the next shipment to arrive. No covered berths or hangars are present, and some Class I StarPorts must temporarily stop operations after a particularly hard rain or storm. Expect no retail stores or food service, either, although the StarPort Manager may share his coffee with you if you're nice to him/her! Directions are available to the nearest habitation, along with advice on local customs/taboos/law levels (ie. what weapons you can carry and which ones will get you locked up)/any other information required to keep a visitor safe, IF THE TRAVELERS BOTHER TO ASK! (Major hint, here.)
This entry is mostly taken straight from the GURPS Traveller book "StarPorts - Gateways to Adventure" by John M. Ford, published by Steve Jackson Games (2000), p. 8.