Saltsjöbanan

The first time you see Saltsjöbanan, you’ll probably think the trains look familiar. And you’re right—vintage subway trains have been rebuilt to accommodate some 15,000 passengers that travel from the communities by the sea to downtown Stockholm.

Even though Saltsjöbanan is a railway, the coaches are former subway trains. Today, some 30 coaches roll along the 23-kilometre long route.

First to implement CTC
The Saltsjöbanan Railway was one of the first to embrace electricity back in 1913. They were also pioneers when it came to another innovation: the use of a CTC (Centralised Traffic Control System) which meant that the entire operations could be remote-controlled from the dispatching office.

The challenge
The true challenge for Cactus was to integrate modern technology with certain portions of the technology introduced back in1938. Cactus and SL (Stockholm Transit) have collaborated to establish communications with interlocking systems and traffic control. Here, modern fibre technology and redundant modems with continuous supervision have been applied.

Unusually smooth solution
Integrating new technology has been a smooth solution. This option ensured an uncommonly speedy and secure switchover. The trick was maintaining the same interface between the remote control station and the interlocking systems. In this case, the interface consisted of an 80-pole contact device. By connecting the new remote control system via the old interface, it was possible to ensure that operations would be in working order. The technology made it easy to test and connect new units. Station after station could be tested at night. Any failures arising could be taken care of straight away. The actual switchover was basically a formality.