Planning, collaboration and digital tools were key to streamlining delivery, fast-tracking the DCO process and engaging communities in this nationally significant project. Discover how.
The A428 between St Neots and Caxton Gibbet is the only stretch of single carriageway between the M1 near Milton Keynes and Cambridge, two of the UK’s fastest growing cities.
Each day, over 25,000 vehicles use this road – double its intended capacity – causing frequent delays and incidents. With considerable local housing and job growth expected, this number is likely to grow to 32,900 vehicles by 2040.
To address this, National Highways (NH) launched the A428 Black Cat to Caxton Gibbet improvements scheme. The scheme will create a new 10-mile dual carriageway with three major grade-separated junctions between the Black Cat and Caxton Gibbet roundabouts, significantly reducing congestion, improving safety and supporting regional growth.
Our team was appointed to lead the preliminary design development and the complex Development Consent Order (DCO) application process for this transformative project.
Speaking of its success to date, Chris Taylor-Dawson, NH Complex Infrastructure Programme (CIP) Director said: “The A428 team demonstrated an exceptional commitment to leadership and collaboration. AECOM’s role was instrumental in ensuring the DCO’s early acceptance, and the whole team should be very proud.”
Setting strong foundations for success
The A428 Black Cat to Caxton Gibbet improvements scheme was initially part of NH’s Regional Investment Programme (RIP) for the East region. However, after being classified a Tier 1 scheme – which applies to nationally significant projects that typically require investments of over £500 million – it was transferred to NH’s Complex Infrastructure Programme (CIP). It is the largest road project currently being constructed in the UK.
Given the scheme’s complexity, with coordination needed across five local authority areas and numerous stakeholders, a collaborative approach was essential from the outset.
The A428 leadership team, comprising senior representatives from NH and its delivery partners – including AECOM – was established to introduce a new, collaborative way of working on the project.
Driven by this shared purpose with clear ambitions from the start, and with the support of a behavioural facilitator and the IBIP (Improving Behaviours, Improving Performance) team, the group set up a collaborative structure, embedding collaboration from the top down.
This approach was pivotal in setting strong foundations for success on the A428 Black Cat to Caxton Gibbet improvements scheme, which was delivered in collaboration with NH, our supply chain and our contractor partners: Costain, Skanska, HW Martin and Walters.
Our role in securing early DCO approval
The DCO process is notoriously complex and challenging, requiring input from professionals across multiple organisations and disciplines. This is why fostering strong collaborative behaviours from the start was key.
A significant part of our role was to prepare a robust and comprehensive DCO application. This involved approximately 20,000 pages of submissions in 257 documents, as well as drafting more responses for written and oral questions required for the examination.
Thanks to our extensive DCO expertise, we were well placed to lead the team in preparing for and successfully navigating this process. To ensure effective collaboration, we held dedicated workshops on topics such as DCO examination preparation, efficiencies, resilience, lessons learnt and behaviours. We also organised a peer review when the A303 leadership team and A428 legal team ran a ‘dummy’ examination scenario under examination conditions.
By co-locating staff at key stages, we were able to carry out integrated reviews to further speed up the process. As a result, we secured early acceptance of the DCO application – a major achievement for the scheme.
Prioritising health, safety and wellbeing
Given the high-pressured DCO environment, health, safety and wellbeing were a top priority throughout the project.
One way of ensuring this was through the use of surveys and real-time reporting dashboards to manage staff work volume and identify any potential overburdening. This – as well as regular check-ins – was integral to managing workloads and minimising stress. This approach not only ensured individual support but also contributed to the overall programme’s success, helping the team meet deadlines effectively.
The health and safety of road workers and road users was also given highest priority during development of the preliminary design and DCO application documents.
The importance of early contractor engagement
Another key factor for success was involving Tier 1 and 2 contractors from the early stages of design and planning, allowing us to incorporate their expertise in buildability, construction sequencing, earthworks and utilities design, traffic management planning and DCO documents. In addition to improving the scheme design and optimising construction methods, this also enhanced safety, quality and overall project efficiency.
Value engineering workshops further enabled the team to review and challenge the design as it progressed against the scheme objectives. These sessions, involving NH staff, AECOM and our contractor partners, resulted in significant savings and efficiencies.
Boosting stakeholder engagement through digital tools and innovation
For a scheme of this scale and impact, community engagement was essential to building trust and support and gaining public buy-in. To boost participation and deepen public understanding, we partnered with NH to develop and integrate innovative digital tools into the consultation process. Collectively, these increased engagement among people under 45 by 10 per cent.
Examples include:
- Virtual consultation room: the first of its kind for NH, this platform facilitated public consultations, helping to reach previously under-engaged audiences.
- Minecraft model: partnering with the nonprofit organisation BlockBuilders, we designed the scheme in Minecraft – a first for a UK highways project – for the statutory consultation.
- Augmented reality app and traffic animation tools: by visualising the Black Cat Junction during construction, we allowed stakeholders to explore proposed works from multiple perspectives and demonstrated how traffic disruption will be minimised during construction.
- Digital Environmental Statement: this user-friendly web-based platform combined interactive mapping, virtual flythrough videos and before-and-after imagery to bring the project to life and provide quick and easy access to environmental information.
Delivering excellence with tangible results
Having met all key delivery milestones, the A428 Black Cat to Caxton Gibbet improvements scheme demonstrates what’s possible through a truly integrated team adopting collaborative behaviours.
The project, which is due to be completed in 2027, has already received multiple awards, including the 2024 CIHT Collaboration Commended Award for delivering ‘Shared Success’ and NH’s Best Health & Safety Performance award.