The team on the nationally significant A556 have used a lot of ingenuity to successfully employ BIM on the 7.5km Greenfield road scheme.

At first glance construction of a new A556 dual carriageway that will link the M56 junction 7 with the M6 at junction 19, seems quite straightforward. But the 7.5km road, which will enable the existing congested A556 to become “Chester Road,” has a number of remarkable characteristics that make it a trailblazer from innovating on the use of BIM to being the first Highways Agency road to go through the Nationally Significant Infrastructure Planning (NSIP) process.

However its start was not very auspicious. Despite being put on the Major Trunk Roads programme in 1987, the project was dropped after a change of government in 1998 and then rejected during a review of options in 2003. However by 2005 it was back on the table and in October 2010 it was announced in the comprehensive spending review. 

Also in 2010 contractor Costain had been brought into the scheme under an early contractor involvement arrangement. By August 2014 when the development consent order was granted by the Planning Inspectorate the contractor was ready to go. 

“We had already worked up a detailed design so that when we got the DCO we could go straight on site,” says David Owens, Costain’s design manager for the project.

The timing for the scheme was important in other ways too with publication of the government’s construction strategy in May 2011 mandating the use of collaborative building information modelling (BIM) on all projects by 2016. With the project set for construction completion in April 2017 Costain working with designer Capita, was pioneering BIM on the greenfield road. 

“The technology for producing a 3D design for buildings are very different to the tools that we have at our disposal for roads, rail, utilities or anything linear,” says Owens.   Proprietary systems were used where available for each of the disciplines on the project. Highway design was modelled using AutoCAD Civil 3D 2013, while structures such as the six bridges on the scheme were modelled in REVIT 2014, and other packages used for the objects such as signs, lighting and drainage. 

“Discreet objects like signs or lighting columns are designed in tools which embed asset data. For other assets such as pavement and road safety barrier we expanded the information we needed to know about them through a link to a database, a technique usually only seen in GIS community,” he says.

The team then created what Owens describes as “middlewear” to allow each of the BIM elements to talk to each other. This meant linking the information from the various packages making connections to the database which could then be used to derive the data required for handover to the client as part of the Construction Operators Building Information Exchange process or COBie. 

“In building projects the Level 2 BIM deliverable information can be obtained from the workflow of REVIT or AECOSIM but we don’t have this for our tools,” says Owens. By collaborating with software developers Owens expects this to change in later versions. “This means we have informed change and overcome a significant hurdle at the same time,” he says. 

“Currently it is difficult to go from my design model to COBie but we have a theory and mechanism for doing it in a slow production sense. Over the next two years it might just be design and hit the button to get what we need.”

Although it has required investment and dedication Owens says the benefits are clear. “The design team were resolving interface issues before we even looked at clash detection because this is a coordination model. I feel that we have a better product as a result.”

For example on the Chapel Lane overpass construction activities were not allowed to disturb a large diameter underground service, with vibrations or loadings not permitted. Using the model the team created the structure with piled foundations and longitudinal and transverse drainage runs and worked with the service owner to develop a solution which in the end saved £1.2M.

Now that the project is under construction the model is being used in its 4D application as a simulation tool. “It might seem like a straightforward road project but we have done some really innovative things here, which will inform BIM on future projects,” he says.