Highways England’s giant ‘superspan’ gantry to improve journeys on M6 smart motorway


A giant 131ft-wide (40m) structure will be lifted into place over the M6 motorway in Cheshire this week as part of a major Highways England (HE) project to help improve the journeys of the 118,000 drivers who use the route every day.

The huge 20-tonne gantry will span the width of the motorway, hold 10 large electronic signs, and is the biggest single structure being installed as part of a £274m (US$363m) upgrade of a 20 mile-long (32km) stretch of the M6 to ‘smart motorway’ status.

The HE scheme between junction 16 at Crewe and junction 19 at Knutsford involves converting the hard shoulder to a permanent extra running lane and introducing new variable speed limits to help tackle congestion and keep traffic flowing. A similar smart motorway scheme on a stretch of the M62 in West Yorkshire, which was completed in 2013, has resulted in commuters saving an average 30 minutes each week.

HE’s ‘superspan’ gantries are constructed off-site using a series of symmetrical steel bars, and are becoming a familiar site on motorways across the country. The gantry on the M6 between junctions 18 and 19 will be lifted into place overnight on June 27, with a crane lowering it onto two pillars that have already been installed on either side of the motorway. HE has already installed a new cable ducting system for the power and fiber cables that will supply the structure’s electronic signs, which will then be fitted to the gantry at a later date.

Around 500 people are currently working on the project to upgrade the M6 to a smart motorway through Cheshire. When the scheme is complete, 258 electronic signs will be used to alert drivers to changes in the speed limit, lane closures, and incidents ahead.

A total of 70 CCTV cameras will also be installed to provide 100% coverage of the route and allow HE’s traffic officers and the emergency services to respond quickly to incidents. The agency will also build 18 emergency refuge areas (ERAs) to provide drivers with a safer place to stop if they break down.

“This is a major milestone for the project, and a lot of planning and preparation work has been carried out to make sure the gantry can be lifted into place as quickly and safely as possible,” explained Arun Sahni, project manager at HE.

“The ‘superspan’ gantry is one of a series of structures we’re installing along the smart motorway route to hold over 250 electronic signs that will provide drivers with live information about their journeys, and help to improve journey times by tackling stop-start conditions caused by sudden braking.

“We’d like to thank drivers for their patience while this work takes place. We’re on schedule to complete the smart motorway upgrade by spring next year and are doing everything we can to minimize disruption, including keeping all of the lanes open in both directions during the day.”

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Tom has edited Traffic Technology International (TTi) magazine and its Traffic Technology Today website since May 2014. During his time at the title, he has interviewed some of the top transportation chiefs at public agencies around the world as well as CEOs of leading multinationals and ground-breaking start-ups. Tom's earlier career saw him working on some the UK's leading consumer magazine titles. He has a law degree from the London School of Economics (LSE).