Working for Highways England, AECOM’s team successfully delivered one of the UK’s largest ever ground investigations to support the Lower Thames Crossing (LTC) scheme.

As a key project in the National Infrastructure Plan, the planned 14.3-mile highway crossing will ease the strain on the UK’s busiest motorway, the M25, will increase connectivity across the River Thames, reduce congestion and provide a major boost to the economy in both the region and nationally. It includes dual tunnel bores accommodating three-lane carriageways for 2.6 miles below the river. With each bore measuring 16.4 meters in diameter, it will be the third widest bored tunnel in the world and the largest in Britain.

Acting as Principal Contractor and drawing collaboratively on our supply chain representing the greater part of the industry, AECOM has undertaken phased ground investigations (GI) across Kent and Essex – an area exceeding 7,500 square kilometers. The GI obtained data which is crucial in helping mitigate potential construction problems down the line, gaining consent, increasing certainty around cost and ensuring all the engineering needed to build the tunnel and associated roads is as best planned as possible.

Assured data

Establishing an overarching project management office (PMO) setting the standards for the investigation, our role as Principal Contractor ensured all parties generating data working for us were effectively aligned and coordinated, providing consistency of product. Multiple parties contributed to generating the data and owned their role in this but importantly for our client, AECOM retained single point accountability for the products and implemented tools and systems to assure the data, critical for a project of this scale and complexity.

We established an innovative dedicated central hub for logging, analyzing and storing core samples from the investigations from several thousand locations. This facility was important in ensuring the consistency and quality of geotechnical data both digitally and physically – increasing confidence in the value. Furthermore, by retaining the samples locally and appointing resources dedicated to processing them in one single collaborative location, the speed of generation of data was much improved.

The team has implemented bespoke digital innovations and tools for people, systems, safety and data management, facilitating ease of information collection, reporting and presentation. The data collected on this complex infrastructure project will form the backbone of the scheme’s consenting and design, ultimately influencing the overall scheme to mitigate ground risks and ensure it delivers value for Highways England’s customers.

Health, safety and wellbeing

We recognized the demanding nature of the GI on staff involved, particularly this being heightened in 2020 with the onset of the global pandemic. As one of many actions to ensure the right project culture, we introduced immersive inductions to be attended by all staff, involving staged relevant role-played scenarios and client leadership emphasizing the importance of wellbeing.

Keeping the sites safe and secure was a fundamental part of our role in acting as the single point of accountability of all suppliers on the GI. Collaborating with the wider project team, we implemented industry leading health and safety provisions and common digital tools for all companies involved which have been so successful that they are now taken up and used outside of the project.

In the 2020 Ground Engineering Awards, AECOM won the Health and Safety award with Equipe Training for the implementation of GI Audits and Inspections for this project, an accolade which recognizes our role and LTC’s legacy in helping raise safety performance. Many follow on actions to improve overall safety and work processes relating to GI have been picked up from the work of the project and formally introduced by relevant industry bodies, including documented standards for rotary drilling and several other techniques addressing the absence of documented procedures.

Meeting challenges head on

Over the course of the project, AECOM and the wider team were faced with an array of challenges that had the potential to delay the project. The scale of the project was only one of these but significant in that we were responsible for more than 20km of drilling, employing at peak some 50 drill rigs, and in excess of 10,000 individual tests involving an overall team of more than 1,500 colleagues.

The GI was the first substantial presence on site in the field and it was imperative that wider relationships with stakeholders and landowners was not compromised or detrimental to the wider project. An indication of the success of our interactions in this respect include the fact that through technical solutions we attained licenses for work for investigations in the congested navigation channel and other challenging land areas. We obtained access through negotiation for around 90% of planned locations with landowners commending our approach to work.

We adapted for scope changes with revised route alignment, stoppages when whales made an extremely uncommon appearance in our survey area of the River Thames at the time of our work and dealt with difficult ground conditions due to weather by deploying hovercrafts or track matting to avoid halting progress work progress providing data at the time it was needed. We developed safe approaches to continued working to obtain critical data despite the global pandemic.

We provided an uninterrupted delivery despite the constraints of the coronavirus pandemic and even accommodated filming onsite for The Thames: Britain’s Great River With Tony Robinson featuring one of our engineers.