STRUCTURES & INFRASTRUCTURE
THE
BIG PUSH BOB WRIGHT
T
he ongoing £1.2 billion East Coast Main Line (ECML) upgrade is made up of four major projects: the remodelling of the track and supporting infrastructure at King’s Cross to increase capacity, the Stevenage turnback (completed in 2020), power supply upgrades to the whole route and the Werrington grade separation.
RAI L AI RO PER ATIO NS
The existing Werrington Junction layout, just north of Peterborough, constrains efforts to increasing the frequency of East Coast Main Line passenger services, as slow freight trains moving onto the Great Northern Great Eastern route (GNGE) need to cross over the two Fast and one Slow ECML lines. As described in Rail Engineer (see Issue 181, Jan/Feb 2020), Network Rail considered dive-under and flyover options to separate the GNGE services from ECML traffic. But an overbridge was discounted as it would have been a substantial visual intrusion in the flat topography and would also have required diversion of the National Grid’s high-voltage transmission lines. As an alternative to traditional ‘top down and open cut’ options, the chosen innovative solution - which minimised disruption to rail services - was a 750m radius, 155m long portal tunnel constructed alongside the ECML on the new dive-under’s alignment and then jacked into place. Over a nine-day partial closure of much of the ECML between 16-24th January, main contractor Morgan Sindall Infrastructure successfully installed the 11,000t concrete portal, the first time in the UK that a curved structure of this scale has been installed by jacking.
Making sure The programme constraint here was the nine-day partial closure of the three ECML lines, which governed the planning and methodology for this project. Limited services continued using the Up and Down Stamford lines to bypass the works.
Rail Engineer | Issue 189 | Mar-Apr 2021
PHO TO: NET WO RK
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