The extension of the tram network through the city centre of Birmingham will include the first section of tram in the UK without power from overhead electrical cables.
Midland Metro Alliance director Alejandro Moreno, explained to New Civil Engineer reveals the challenges behind building the £1.3bn package of works.
Funding for the six extensions to the existing metro system was approved in principle by the West Midlands Combined Authority last week.
The existing 25km line runs from Grand Central New Street Station in Birmingham city centre out to Wolverhampton St. George in the north. The six new lines, totalling 32km, will extend and branch off this existing line. They will include links from the city centre to the new High Speed 2 (HS2) stations at Curzon Street and at Birmingham Airport.
Midlands Metro Alliance extensions route map
It is this new city centre section. Trams will run on battery power between stations which are around 500m to 1km apart. The batteries will then be charged when the trams come back into contact with the overhead lines on the outer sections of the line.
“In the city centre, it’s really important to make sure the architectural point of view is protected,” said Moreno. “Removing the overhead lines will make it look much better and integrated.
“To run it on batteries, the tram will arrive at the last metro stop with catenary [overhead lines]. The pantograph [connection between the tram and the overhead lines] will drop and the tram will be able to run without the catenaries.”
To do this, Transport for West Midlands is in the process of retrofitting its existing tram fleet with the new battery technology. It is also the intention, he said, that when additional trams are procured, they will already include the battery technology.
The Alliance is also working to streamline the design and construction process for the 32km extensions and 51 new stations. Moreno said it was working to standardise stations and track sections to make it cheaper, easier, safer and quicker to build. Stations could then be customised with different lighting, colour schemes or vegetation.
“We’re engaging with the supply chain to streamline the process, but we don’t intend to have, say, three suppliers for the same product in a tram stop. We are aiming to have one supplier with a framework agreement.”
Challenges in building the new lines especially those which run through the city centre include a 9% gradient going up to a stop at Pinfold Street and building a section of track crossing an abandoned rail line. In addition, the team must to strengthen and waterproof cellar structures under a road along which the line will pass. It will also have to relocate all underground services because access to buried services under the line will be limited after the tram line is built.
To address the skills gap, the alliance is also working with the local colleges to provide training. Moreno said these skills would still be relevant after the metro was completed.
The scheme is scheduled to be finished by 2026, ready to tie in with the opening of the HS2 stations.