Civil Engineering


A45 Chowns Mill Roundabout Improvements

Half-Hamburger solution to reduce congestion

Carnell were principal contractor on this high-profile scheme, collaborating with National Highways and several other delivery partners to improve the severely congested roundabout.

The extensive works saw the roundabout redesigned into a ‘half hamburger’ layout at the A45/A6 Chowns Mill junction along with widening the roads approaching the roundabout to create extra capacity for traffic.

The £24m scheme was significant, as it was the largest scheme delivered outside of National Highways ‘Major Projects’ and all eyes were on the partners involved to deliver against imperatives of Safety, Customer & Delivery.

Using Lockdown to Deliver ahead of Programme

The functionality of all filter drains, especially those not constructed to specification, will diminish over time. Silt from surface run-off and fine particles from the carriageway sub-layers fill the voids between the aggregate.

Vegetation / overburden will grow on the surface of the filter drain to further restrict water reaching the carrier pipe.

With an impermeable barrier formed in the filter drain, it will hold water, leading to surface ponding and during times of heavy rainfall, standing water in the running lanes. Road user safety and network resilience will both be compromised as a result.and immediately reinstated to the drain. This provided an estimated reduction of more than 1300 HGV movements on the network and a Carbon saving of over 70 tonnes.

Customer engagement

Carnell were committed to investing time and resources to understand the surrounding communities. They worked collaboratively to solve issues and deliver Social Value initiatives and legacies that were in line with community’s needs.

We achieved excellent results by offering the Community / Customers a wide range of opportunities to receive information and engage with the Team and our “you said, we did “ approach.

National Highways have shortlisted the A45 Chowns Mill scheme in their Annual Awards under the Customer ‘Making a Difference’ Awards 2021.

The Scheme in Numbers

Since work began on the junction in February 2020, the scheme has involved:

  • around 275,000 man hours
  • installing 43 new lighting columns, with energy saving LED lamps
  • laying 6,250m of kerbing – stretching to almost four miles
  • using 60,000 tons of imported stone
  • lifting three superspan gantries, each around 40m long and weighing up to 25 tons, into place