A project to remodel Junction 19 of the M1 in Leicestershire is the latest proving ground for Cementation Skanska’s Building Information Modelling (BIM) approach to geotechnics.
While the use of Building Information Modelling (BIM) is becoming the norm in architecture and building design, to date, take up has been slow in geotechnical engineering, possibly because it is difficult to see the benefits it can bring.
However, with the UK government driving the use of BIM on all publicly funded projects from 2016, it is an approach that should be, and inevitably will have to be, embraced by the geotechnical fraternity, says Cementation Skanska BIM coordinator Scott White.
“Cementation Skanska decided to introduce BIM three years ago,” he explains. “While clients were not driving us to use it, we felt that BIM had a lot to offer to geotechnical work, particularly in improving efficiency, quality and safety.”
White says the ultimate aim is for BIM to encompass all of Cementation Skanska’s operations, from planning through to delivery, including all aspects of design and construction, finance and subcontractor and supplier management. However, the first step has been to ensure that it is suitable for geotechnical engineering.
As a result, alongside development of models and tools, plus training, BIM has been trialled on Cementation Skanska sites over the past couple of years, the latest of which is the scheme to improve Junction 19 of the M1 in Leicestershire.
Junction 19 is the Catthorpe Interchange, which is also the start of both the M6 and the A14. The interchange was originally built as a forked junction, where the M1 and M6 split, with a local road running beneath.
However, when the A14 was built in 1994, the junction was adapted to include two roundabouts with the local road linking the major routes. About 142,000 vehicles use the junction daily, the interchange is highly congested and has a poor accident record and is a barrier to cyclists, pedestrians and horse riders.
Skanska was awarded the contract in 2005 to replace the interchange with a three level junction, creating direct links between the A14 and the M1 northbound; the M6 and the A14 in both directions; the M6 and the M1 southbound; and the M1 northbound and the M6. The M1 will remain on its current alignment and there will also be three new overbridges for minor roads (so local traffic can avoid the junction) and enhanced routes for pedestrians, cyclists and equestrians.
Work began in January this year and the new junction is expected to be open by autumn 2016. As roads will be open throughout works, construction is being carried out in multiple phases to minimise disruption to traffic and local residents.
Cementation Skanska is installing about 750 rotary bored piles of varying diameter for piers, abutments and wingwalls to the three main road links and the three bridges over the minor roads (see box).
“BIM is an ideal approach to this project, which involves 22 construction phases on a live junction,” explains Cementation Skanska project engineer Kevin Burns. “We use BIM to plan and carry out piling, including sequencing with other contractors, and it also allows us to react quickly to any changes during the works.”
White, who is responsible for BIM coordination at Junction 19, explains that once the BIM model was created, it was used to output elevations, plans and piling schedules. This information is shared with the site team via the cloud, allowing them to download data onto iPads using Wi-Fi and 4G cards in work areas.
“One of the biggest benefits is helping the team to visualise the work programme,” Burns says. “BIM allows us to work out where the rigs will be, plus the optimum positions for cranes and other machinery. This helps reduce plant movements and allows us to identify and resolve any issues before work begins. As a result, we are far more efficient and safer and piling quality is maintained.
“On restricted sites, for example, we can check that a rig can get onto position and ensure there are no clashes on site with other contractors. We can also use this information to create health and safety plans, toolbox talks and use it in daily planning meetings. And of course, we can continually update the models very easily, if and when plans change.”
The piling teams use field management software on their iPads to compile daily reports and complete pile records. This data, along with any other information – including photos, materials deliveries and rig breakdowns for example – is then uploaded to the cloud and the BIM model is updated with as-built information.
“BIM saves a huge amount of time and reduces errors, as the information does not have to be written down during the day into notebooks and then typed up at the end of a shift,” Burns says. “Quality is improved further because the site team is working to the most up-to-date plans, which results in less snagging and remedial work – with obvious time and cost benefits both to ourselves and the client.
“We have created digitised versions of our standard forms,” he adds. “This means the team is working in a familiar environment, helping them to embrace the new approach.”
In fact, feedback from the piling crews has been extremely positive, he says. “We are refining things all the time. Because there are distinct packages of work on this project, with breaks of days and sometimes weeks between phases, we have time to introduce new ideas ready for the next stage.”
This ‘on the ground’ feedback and refinement is invaluable, White confirms. “It’s all part of the learning process and, with time, steps such as conformity checks will be fully integrated into the process.”
At the moment, Cementation Skanska is only using BIM for rotary bored and CFA piles, plus diaphragm walling, but White expects it to be rolled out to other types of foundation in the near future.
White believes that adopting BIM in geotechnical practice is essential. “The UK government will require a minimum BIM Level 2 on centrally-procured public projects by the beginning of 2016. This means that all project team members will need to provide outputs via a 3D BIM environment, managed as a series of self-contained models and using software that allows exchange of data.”
Cementation Skanska is aiming to be Level 2 compliant a year early – by the end of 2014 – he says. “We believe that while BIM Level 2 will initially only be needed on public sector projects, inevitably it will trickle down to the private sector, so we need to be ready. Regardless, we want to work this way, as we believe that BIM can help reduce disruption, delays and disputes and enables better working practices.”
Foundations for the M1 Junction 19 improvement project
Cementation Skanska is using one Bauer BG28 and one BG22 rig on the M1 Junction 19 project, each supported by an 80t crawler crane. It is working on six structures: three for the main road links (Structures 1, 2 and 3) and three bridges over local roads (Structures 8, 9 and 10).
The 750 piles are 750mm, 900mm, 1,500mm and 1,800mm in diameter and are up to 25.5m long, installed through the underlying Lower Lias Clay. They will support abutments, wing walls and piers for bridges and underpasses.
Structure 1, taking the new A14/M6 link road under the M1, will use 1,500mm and 1,800mm diameter piles. Structure 2, carrying northwest bound traffic on the A14 over both the M1 and the new A14/M6 link, before joining the M1 northbound, will be built on 750mm diameter piles.
Structure 3 will carry M6 southbound traffic over the new A14/M6 link and tie into the new Catthorpe Viaduct (which was replaced in 2012). This will also be supported by 750mm diameter piles.
Structure 8 will carry traffic from the southbound M1 over a local road and onto the A14/M6 southbound link. This will be supported by 900mm diameter piles, as will Structure 9, which will carry the new A14/M6 link over a minor road.
Structure 10 will take traffic from the northbound M1 over a local road to join with the M6 westbound. It will sit on 750mm diameter piles.
Cementation Skanska reached the halfway point of piling by July, just before a six week break over the summer. Most of the foundations are due to be finished by February next year.
There will then be a long break, before piling crews return in late 2015 or early 2016 to pile the last of the minor road overbridges.