Tunnelling preferred option for Heathrow rail link

Heathrow Southern Railway executive director Graham Cross has said tunnelling is his preferred option for the new 13km long “missing link” railway line connecting Heathrow Airport to the local network in the South East.

Three routes between the airport and Chertsey are under consideration, with business cases for each being assessed. But Cross’s intervention suggests tunnelling is currently the frontrunner, despite it being the most expensive at £1.6bn.

Speaking at a conference on attracting third party investment into the rail industry, he said the route could be tunnelled along its entire length, avoiding problems associated with the two other options.

An above ground option with the line run next to the M25 had the advantage of avoiding built up areas, Cross said. But this option would face challenges as the line would intersect with utilities and slip roads.

The second and cheapest option would involve the line leaving Heathrow on the same new route as the first option, but then join an existing Network Rail line at Virginia Water. Cross said this was attractive because it would cost £300M less than the tunnelled option and provided access to Reading via Wokingham. But he said it would take more time for trains to get to Heathrow.

“We discovered that once you start to look at tunnelling a bit of it, the incremental costs of tunnelling that bit more isn’t that much higher because most of the cost is sunk in to the tunnel boring machines,” said Cross. “Also going through tunnel avoids environmental issues such as noise impact.

“I think tunnelling is probably the preferable option, but we’re now assessing the business case – whether it’s better to be slightly cheaper and slightly slower or go for the full expense but be quicker.”

Last year, it was announced that Aecom would provide some initial finance for the scheme in its first investment in a design, build, finance and operate project in the UK.

Reproduced by kind permission of New Civil Engineer