Transit Tube Access

Transit Tube Access is the entry and exit building for the Transit Tube system. Duplicants who need to use a tube stop briefly at the access point and are then launched into the network. If multiple Duplicants are waiting, they queue up at the building and use it one at a time.

Although the building itself is only two tiles tall, it requires at least two additional tiles of open space above it for the tube segment. Duplicants enter and leave the Transit Tube system from the upper part of the Transit Tube Access, so two access points must be connected top to top if you want Duplicants to travel directly between them. A T junction cannot be created directly above the access point; if one is placed there, the tube connection takes priority and detaches from the building.

Transit Tube Access has an internal battery that stores 40 kJ and consumes 10 kJ per use, so a full charge supports 4 Duplicants before it needs to recharge. Once fully charged, it stops drawing power from the grid until energy is spent. One source notes that, in practice, a charging access point can sometimes support a fifth Duplicant because it may have accumulated enough energy by the time that Duplicant reaches the front of the queue.

The building also has an internal storage of 10 kg of Brackwax. When Smooth Transit is enabled, each use consumes 50 g of Brackwax to increase Duplicant travel speed through the tube network.

A few practical behaviors are worth keeping in mind:

• Duplicants do not treat an unpowered access point as a valid route. They will look for another path instead of waiting for it to recharge.
• The access point does not begin charging until a tube connection has been attached.
• Automation can turn Transit Tube Access on or off, but this does not stop Duplicants from leaving the tube system through it.
• Because the building launches Duplicants from its upper portion, placement and tube alignment are important when designing vertical transport shafts.

Transit Tube Access is therefore best treated as the control point for a tube network: it provides the connection between the colony and the tubes, stores enough energy for several rapid transfers, and can optionally consume Brackwax to speed up traffic.