It is based on relays and was developed by Norsk Signal Industri for the Norwegian State Railways (NSB) during the early 1960s.
The systems are installed at railway stations and passing loops and consist of single relays built form drawings.
NSB-87 was developed by SattControl, now part of ABB Group, who made the computer and communication systems, based on PLC.
[5] During the 1990s, NSB and its successor the Norwegian National Rail Administration chose to install Siemens ESTW on the Gardermoen Line, and Adtranz-developed NSB-GS at Oslo Central Station.
[12] As of 2010, the administration's plan is to build the Eastern Østfold Line with ERTMS by 2014, and from 2015 convert the remaining parts of the network.