More about Electrification
A new state of the art signalling system which will allow for more frequent commuter trains on the network is now fully installed as part of the electrification project.
Much of the existing signalling equipment was 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 were replaced and a sophisticated train control system installed. Track circuits which detect where the trains are on the network were 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 are the overhead wires and masts that power the new electric trains. These began appearing on the network in 2011.
There are 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 was carried out in phases starting on the Western Line. The masts carry the same 25kV power system that is currently used on the North Island Main Trunk and on the railways of Europe.
The system is powered by substations at Penrose and Southdown. Each is independent and can, on its own, provide enough power to run the entire system.
Four other substations distribute power around the rail network. The power needed to run the trains is less than 1% of Auckland's current capacity.
Assessing the visual impact of electrification formed a substantial part of the preparatory work for the project. The masts and overhead wires carrying power to the electric trains have changed 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 paid closer attention to the mast design to minimise the impact.
Several different types of mast needed 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 were 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 - needed to be used.
On average the masts are about 50-60m apart but are closer together on curves to ensure correct tension. We endeavoured to use as often as possible the single-track cantilever structure, which provides the least obtrusive profile