With 3,196 miles of track, Network Rail’s Southern Region is the UK’s largest private operator of an electrical distribution system.
The three-year Southern Region Power Upgrade (SRPU) programme, begun in 2003, was undertaken to support the introduction of two thousand new, more comfortable, carriages and is believed to be the largest DC project of its type undertaken anywhere in the world. The work was necessary because the sophisticated new trains draw around 23 per cent more power than the old rolling stock from the 750V traction power supply system.
ABB, in consortium with Mowlem Railways, was one of four regional contractors appointed by Network Rail. It was awarded the ‘Kent’ region and carried out around £80 million of project work, including the construction or upgrading of 27 substations and 17 feeders and installing around 70 panels of ABB ZX1.2 gas insulated MV switchgear and 25km of 33kV cable.
Working on one of the world’s busiest rail networks was particularly challenging, and imposed many constraints, as all site deliveries, possessions and outages had to be planned down to the finest detail.
Management of ‘possessions’ – the windows of opportunity when the consortium had access to work on individual sites – was a core element handled by specific team members often requiring twelve months’ notice for access rather than the usual six.
In order to keep on-site work and costs down, substantial use was made of containerised substations, housed in robust, long-lasting stainless steel enclosures, which were fitted out off site.