The Association of Train Operating Companies (Atoc) is to add an additional system to its forthcoming £100m National Reservation Service (NRS).

NRS will replace the existing 20-year-old mainframe-based reservation system, providing a modern service to connect train operating companies and travel agents, allowing more efficient and detailed ticket bookings for train journeys.

Passengers will be able to book train tickets much closer to the time they want to travel and will be able to specify criteria such as what sort of seat they would like.

Atoc is now adding the Availability Service, which will sit along side the main reservation system but will only deal with travel queries, freeing up the bandwidth of the main system to concentrate on bookings.

According to NRS programme manager Steve Pickman, an increase in online use has spurred the demand for a separate Availability server.

'We have realised that since the project was first conceived, internet use has expanded significantly,' he told Computing. 'The bulk of these requests are for availability, which are much easier requests than a booking transaction.'

The NRS team has decided to opt for a managed service provider to deliver the Availability Service.

'Instead of expanding the core system, which is based on HP NonStop, we are exploring an alternative route of dealing with Availability on a separate machine,' Pickman said.

Atoc has yet to award a contract, but says it hopes to do so before the end of the year.

NRS is scheduled to go live on Boxing Day, and the Availability Service, which will process around 600 queries per second with a capacity of 5,000 per second, will follow in July next year.

NRS will cost around £100m, with a large chuck of that - some £31m - being spent on the main contract to design, procure and manage the software that will run NRS, awarded to Ernst & Young.

In March, ATOC awarded Global Crossing a contract to provide a managed data network to connect the systems of the country's rail operators, travel agencies, booking companies and call centres to the National Reservation Service.