Preparations to use autonomous plant typify the innovative approach adopted to upgrading a section of the A14 to motorway status.
First the good news. Highways England’s business plan is working well for the A14 upgrade between the M11 near Cambridge effectively to
the A1(M) at Alconbury. Spend on the £1.5bn project – which will lead to the road’s upgrade to motorway status – is running at a tightly controlled £40M a month. Having just reached the halfway stage, construction is on programme and to budget.
Now the even better news. All the above appears to vindicate an adventurous style of project management born of applying forethought and innovation to promote efficiency.
Engineers are using their heads – as well as drones, 3D excavator control systems and even driverless plant – the latter dependent on the results of impending trials.
Before continuing, a quick glance is required at the route’s changing status. Original plans had the existing A14 being upgraded while remaining an all purpose trunk road. They are now out the window.
Reclassification as a motorway will be formally confirmed later this year, subject to a nod from the Secretary of State. Already, Highways England printed material is referring to the A14(M).
We’ve respected traditional earthworks seasonal working but also invested in our haul roads to ensure the availability of these during winter months
“The A14 upgrade has always been to IAN161, the smart motorways’ standard. Alterations needed to create the A14(M) are minimal – it’s almost a matter of just changing green signs to blue,” says the construction director of the project’s integrated delivery team, Julian Lamb. The team comprises Highways England, together with Atkins/CH2M, and Costain/Skanska/Balfour Beatty.
Changing the signage will of course be accompanied by measures to preclude tractors, horses and pedestrians, with the intention of promoting free flowing motorway traffic. They say on site that theirs is the first motorway to be built in England since the Birmingham north relief road – M6 Toll – back at the turn of the century.
“Half a generation ago,” remarks Lamb. Civil engineer Lamb’s current role represents his third stint along the course of the A14. He started on the current project in 2015, along with others charged with injecting “buildability” into what was recognised as a hugely complex project.
Open-mindedness to new ideas and ways of working was encouraged – with Highways England’s Innovation, Technology & Research Strategy just about to be published. Acceptance of beneficial change became a given.
Some of the A14’s upgrade was to be new build, some of it on-line. Much of the road was across flood plain and had to sit above natural ground level. A huge 10M.m3 of earth had to be moved. “It was muck shifting that really drove our thinking,” says Lamb.
Technology has changed much in “half a generation” and this is indicated on site by the adoption of Topcon 3D machine control systems as “positioning tools” for excavators and dozers.
Expressed simply, software determines the current position of each machine and compares the terrain on which it sits to that of the required formation. Data is then displayed inside the excavator or dozer’s cab, which allows the operator easily and efficiently to grade the ground to match the intended design.
The benefits claimed for such intelligent muck shifting are substantial (see box).
According to Topcon, its equipment is installed in around 50 machines belonging to Walters Group, one of two major earthworks contractors working on the 32km long road. Between them, the two companies have shifted an incredible 8M.m3 in just two seasons – those of 2017 and 2018.
We have a media area where those working on the project can catch up with progress across the job, viewing timelapse videos
“We’ve respected traditional earthworks seasonal working but also invested in our haul roads to ensure the availability of these during winter months,” says Lamb. “Some targeted areas have been worked in the winter where this suits.”
This January, trials of machine controls of even greater complexity are scheduled to be carried out on site. They involve the use of autonomous – or driverless – earthmoving machinery about which details are currently very scarce. Highways England is keen to keep the trials under wraps for the time being, until the viability of the equipment has been confirmed.
Everyone is tight lipped. More will be revealed if the trials are successful; and there is the possibility that autonomous plant could be used on some of the A14’s remaining 2M.m3 of muck shift.
Maintaining the theme of innovation, drones are being employed to measure the extent of earthworks and to carry out environmental and ecological surveys – plus other things. Lamb says they are remarkably useful: “Not least for checking up on our bats, for example, with minimal intrusion.”
The project has its own drone pilots on site, all properly licensed to fly. Three types of drone are being used: survey specific ones, media grade for taking progress images and movies plus social grade drones for keeping the likes of Facebook up to date.
“We’re trying to get the message out to everyone, including of course the public. We have a media area where those working on the project can catch up with progress across the job, viewing timelapse videos, for example, of specific events.” It is part of the initiative to help ensure the A14’s integrated delivery team – hailed by Lamb as a major factor in the project’s success so far – retains its constructive cohesiveness.
Lamb goes on to mention work on the project’s 750m long viaduct across the river Ouse and its flood plain, plus the bridge that adjoins this, over the East Coast Main Line (ECML) railway. For these, as with other structures along the route, as much precasting was carried out as possible, for slabs, copings and so on, in a yard adjacent to the nearby A1.
“Precasting was carried out under cover away from the weather. Here as elsewhere we wanted to move construction into a manufacturing environment. This and the decision to precast decks in the first place proved efficient, timely and of course ultimately safer, removing working at height during erection of the bridge deck.”
Each deck is 44m long and weighs 1,065t. They are big.
For some substructure construction, pile caps were eliminated, with 2.4m diameter columns being founded directly on their individual piles.
For the bridge over the ECML, an early decision to alter the road’s vertical alignment proved a particular masterstroke. The cost of raising the bridge’s deck height was more than offset by time savings generated through not having to interfere with the railway’s catenaries or track – which would have occurred if the original alignment had been maintained.
“No full possessions of the railway were needed, which avoided huge potential delays,” Lamb says. “The decision confirmed the substantial benefits which can be obtained by bringing a project’s contractor and designer together to thrash things out at an early stage.”
At the other end of the job, at junction 29 by Bar Hill, clever thinking again saved time, bother and money. The steel beam and concrete decks of two new bridges were built in their entirety including handrails in a prefabrication yard close by the junction; then manoeuvred into place using multi-wheeled SPMTs (self propelled modular transporters).
“Each deck is 44m long and weighs 1,065t. They are big. Had we built them insitu, we would have required maybe 100 lane, carriageway and full road closures. Instead we only needed the one weekend in September during which both decks were successfully installed. Things went amazingly well.”
Machine Control: The Benefits
No level pegs are needed, no batter profiles, no engineers frustrated about their pegs being knocked out, no chain men.
”Earth moving is hugely simplified by use of our machine control systems,” claims Topcon machine control business development manager Andy McCann.
GPS sensors on the plant locate the position of each machine relative to the prescribed earthworks design and then, via an onboard computer, guide the operators to where they need to be.
“Achieving the right position, level and grade first time is par for the course. The efficiencies are substantial. There are savings in money, time and materials. With fewer people around, there are obvious safety benefits.
Accurate earth moving is made simple, highly efficient and safe
“Back office staff can communicate with the operator, monitor where the plant is, check progress and collect data – all remotely. Importantly, design changes can be sent to the driver instantaneously.”
Cost of equipping an excavator/dozer is approximately £25,000.