More about Electrification
A new state of the art signalling system which will allow for more frequent commuter trains on the network is being progressively installed as part of the electrification project. This work will be completed in 2012.
Much of the existing signalling equipment is obsolete and incompatible with electrification, so a new system is needed that is immunised from the high voltage of the overhead system. All points machines and signals lights will be replaced and a sophisticated train control system installed. Track circuits which detect where the trains are on the network will be replaced with a more reliable and cost effective system using axle-counters.
The new technology incorporates enhanced features not used elsewhere in New Zealand, including automative train protection which prevents trains from passing red stop signals by accident. One of the features of the new system is the capacity for bi-directional running which will enable trains to be run in both directions on either track, giving the operator more flexibility on the overall network.
Among the first routes to be resignalled were those important for the Rugby World Cup between Britomart and Morningside. The new signalling allowed post match crowds to be cleared swiftly from Kingsland Station.
The most visual signs of the Auckland network's electrification will be the overhead wires and masts that will power the new electric trains. These began appearing on the network in 2011.
There will be several different types of masts and portals covering 80 km of rail corridor from Papakura to Swanson, including the Onehunga and Manukau branch lines. Work is being carried out in phases starting on the Western Line. The masts will carry the same 25kV power system that is currently used on the North Island Main Trunk and on the railways of Europe.
The system will be powered by substations at Penrose and Southdown. Each will be independent and will on its own be able to provide enough power to run the entire system.
Four other substations will distribute power around the rail network. The power needed to run the trains will be less than 1% of Auckland's current capacity.
Assessing the visual impact of electrification has formed a substantial part of the preparatory work for the project. The masts and overhead wires carrying power to the electric trains will change the appearance of the Auckland rail network. Overall, the areas with the greatest potential for adverse visual effects are stations, high-amenity public landscapes and residential areas with houses built close to the rail corridor. These are the areas where we have paid closer attention to the mast design to minimise the impact.
Several different types of mast need to be used around the network to hold the wires at the correct height and tension to ensure proper contact with the train's pantograph (the part of the train that connects with the power source). Some will be single-track cantilevers like the ones pictured right - a simple mast with a cantilever holding the wires. In other areas a portal - a U-shaped structure spanning the tracks - will need to be used.
On average the masts will be about 50-60m apart but will be closer together on curves to ensure correct tension. We have endeavoured to use as often as possible the single-track cantilever structure, which provides the least obtrusive profile