Mace and Glider at 40 Leadenhall Street: from delay to digital exemplar

Mace won the tender to be the principal contractor on TH Real Estate's 40 Leadenhall Street office scheme in the City of London in 2015. Delays relating to the original client, the state of the economy, and a new client, M&G Real Estate, taking ownership of the scheme meant the contractor didn't get to start on site until the day before the covid lockdown started in 2020.

Designed by Make Architects to echo classic North American skyscraper designs, the project features two stepped towers, the northern at 34 storeys and the southern at 14 storeys. Together, the two towers create more than 80,000 sq m of office space and 7,000 sq m of retail and amenity space. Faced with the usual challenges of building on a tight footprint, Mace has leaned heavily on offsite construction, with prefabrication from its MEP business.

The long delay to starting on site presented an unexpected benefit: Mace's use of digital technology had moved on significantly since it had won the tender.

"Some of the technology we're using now, we weren't using at the time," explains Max Kidwai, BIM (digital) construction lead and BIM lead and project information manager at Mace for 40 Leadenhall Street. "Certainly there are workflows and processes that we've now got in place that we didn't have then. There's a lot more structured data, which will help the client when they insure the building, and when they come to sell it, the client will have a more valuable asset."

During the delay period, Mace took the decision that the project should be an exemplar of its use of digital technologies and processes, and secured the client's buy-in.

Kidwai explains: "Initially our requirements weren't very advanced: a coordinated model with some minor bits of model data. But we took the client through the additional technology we wanted to introduce to the project, and we got the green light. We have been taking the client on a journey. As they've started to see the benefits of the digital technology, they've developed more of a digital mindset."

Indeed, adding further to the challenges, the client decided that it wanted the project to be a market-leading smart building once construction was already underway – more of that later.

To fulfil Mace's desire for the project to be a digital exemplar, the contractor required all the trades to work with the federated model.

"Each of the designers and trades is providing three file formats for every model that they give," Kidwai states. "For example, if it's just concrete slabs, they will give us a Navisworks file, an IFC file and a Revit file. We've gone a bit further and ensured that all our trades – block work, drylining, joinery, fire stopping, all the trades – are given those models as well.

"We've been using Navisworks to create the federated model and do clash detection. Then we've used Solibri as well to do rule checking (door swings, fire-stopping distances). We're using BIMCollab to manage and catalogue the clashes or issues that we have with the model. We then have a Microsoft PowerBI dashboard, which we use to spot trends."

This digital ecosystem allows Mace to manage the supply chain and the project stakeholders. "I share the same interactive Power BI dashboards (and a PDF for those not fully comfortable with the digital approach) on a weekly basis with all of the project team and relevant stakeholders," Kidwai explains.

As a result of covid's operational impacts, Mace turned to BIM360 to maintain collaborative working across the project team. "Some of the individual teams didn't have connected servers where they could collaboratively work on a Revit model. With an eye on security, Autodesk BIM360 Docs is a safe common data environment for people to share work-in-progress models," says Kidwai. "And it's worked really well because you can actually live link in with other people's Revit models, so as they make changes, it makes changes in your Revit files."

Bringing the supply chain along on the digital journey was important. "It's been a collaborative approach. We've given training to our supply chain. We've brought them into coordination workshops, which they might not have done before, with the designers. They've had the opportunity to bring their expertise to bear, expertise the designers may not have," Kidwai says.

Mace is using the Disperse platform, which delivers 360-degree photos, to monitor project progress. The walk round to take the photos takes place each Friday. Kidwai has used the output in coordination workshops, checking on whether clashes have been resolved or not. It's being used on an exceptional reporting basis. "We're setting the photography against our programme – it gives us another set of eyes and highlights areas where we expected work to happen but hasn't. That's actually more key than how far something has progressed."

Mace MEP's modules feature QR codes that allow for tagging and tracking via BIM360. Once the building is in operation, its maintenance team will be able to scan those codes and see all the data collected during design and construction.

Reflecting on progress to date, Kidwai highlights the biggest win: "Bringing the client into the digital space. Indeed, not just the client, but the whole team, the trades, bringing them all on a digital journey."