Tuesday, 11 October 2016

A New Mersey Railway tunnel

For 6 weeks there will be no direct civilised form of transport between the Wirral and Liverpool as Merseyrail refurbish the lines in the original Mersey Tunnel, which is 130 years old this year. So things have moved on a bit since it was first built and you would hope that in real terms building a new one would be cheaper.
The original railway was about £500,000 per mile in 1885, about £57 million today. The Queensway Road tunnel of 1934 cost £8 million or about £517 million in 2016, while, the Kingsway tunnel was twin bore and completed in 1972 for £33.5 million which is about  2016 £470 million in 2016.
The Crossrail twin-bore tunnels cost £69 million per km in 2011 about £80 million now. I'm using Stephen Morley's site for calculating the modern value, other sites give different results.

The orange line one possible route connecting the Northern line, heading south, with the Wirral line toward Chester & Ellesmere Port and beyond, it is 3.2 km long, giving a total of £256 million. Given the improvements in tunnelling technology and bearing in mind the extra expense that was put into the approached for Kingsway and that it is double bore of larger diameter and that Queensway has an even larger diameter that does seem like an unreasonable cost. It could be cheaper if a single bore was used, which may be allowable with such a short tunnel, though modern safety regulations could mean it has to be 2. The short blue line would allow the integration of parts of the Birkenhead dock lines.
One reason to build it, other than to improve redundancy, would be to allow extra trains directly to Wrexham, through the original tunnel or if a junction facing Hamilton square was also included then a loop using both tunnels via the Stock Interchange Line could be provided.

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