National Highways EV Fleet Transition

Project at a Glance

The Challenge

National Highways is in the process of transitioning its fleet of Traffic Officer Vehicles to electric vehicles as part of a broader decarbonisation programme. To support this transition, Kier – operating on behalf of National Highways – appointed Hybrid Electrical Solutions to design and deliver electric vehicle charging infrastructure across six operational depots.

The brief was straightforward in principle: provide dedicated EV charging capacity for Traffic Officer Vehicles at each site. In practice, the challenge was significantly more complex.

Live, Operational Environments

Every site on the programme is a working National Highways depot. Gritter lorries, maintenance vehicles and heavy plant operate continuously through these sites – particularly in winter months – and any electrical works had to be planned around live operations without compromising depot function or safety. Access to electrical infrastructure was constrained, and in several cases service heads could not be fully inspected without isolating the entire depot.

Ageing Electrical Infrastructure

The electrical installations across the six depots varied widely in age, capacity and condition. Several sites had older distribution boards – including Federal Electric DBs that have since been discontinued by the manufacturer – and in some cases the existing installation had no clearly documented spare capacity. Before any charger could be specified, Hybrid first had to establish what the infrastructure could actually support.

Occupied Offices Within Working Depots

At Chieveley, Easton Lane and Coldharbour, the most direct cable routes from the electrical distribution points to the proposed EVCE locations passed through occupied offices and internal corridors. Working during normal hours was not acceptable – both for the noise disruption to staff and the practicality of pulling cables through live workspace environments. Out-of-hours working was required at these sites, adding programme complexity and cost.

Each Site Was Different

No two depots presented the same challenge. Hindhead is not a standard depot at all – it is the Tunnel Service Building for the Hindhead Tunnel, with a private transformer supplying a 2,077-Amp LV switchboard to power tunnel infrastructure including jet fans and lighting. Parkgate already had redundant EVCE infrastructure from a previous installation that needed to be assessed and repurposed. Coldharbour had only five physical parking bays available where six were originally specified. Each site required its own solution.

Our Solution

Hybrid mobilised a structured, evidence-led programme across all six sites. Rather than applying a standard installation template, every depot was assessed individually – beginning with a detailed feasibility study and concluding with a commissioned, client-approved installation.

Phase 1 – Feasibility Studies and Load Monitoring

Hybrid visited each site and installed calibrated load monitoring equipment to the incoming DNO supply (or sub-distribution equipment, where more appropriate). Measurements were captured every three seconds over a seven-day period, generating a granular picture of actual demand across all three phases at each location. The results defined the true spare capacity available to support EV charging without overloading the existing supply.

The load monitoring data confirmed that all six sites had sufficient electrical headroom to proceed, though the picture varied significantly by location:

At Hindhead, the private transformer infrastructure provided over 1,000 Amps of headroom, making this the only site where a load-balancing Equalizer was not required. At Coldharbour – the tightest site at 53 Amps spare – Hybrid recommended five chargers rather than the six originally specified, as the available capacity could not safely support the full scope without risking the existing depot supply.

Phase 2 – Design and Cable Route Survey

With load monitoring complete, Hybrid’s engineers surveyed each site to identify the most practical and cost-effective cable route from the supply point to the proposed charger locations. This involved assessing existing cable management systems, floor ducting, above-ceiling voids, external wall routes and – at some sites – the need for groundworks or civil works to extend ducting infrastructure.

At Easton Lane, the cable route was required to pass above the ceiling through multiple offices and corridor areas. The initial survey confirmed that night installation would be necessary, and this was formally specified in the feasibility report and programme. At Hindhead, existing CMS and floor ducting could largely be utilised, though a small section of civil work was required to extend the floor ducting network to the boundary wall, and fire expansion foam along the cable route needed to be carefully removed and reinstated.

At Parkgate, a redundant cable was already installed between the proposed charging bay location and the Main Intake Cupboard. Hybrid assessed this cable for compliance and recommended repurposing it with modifications – avoiding the cost and disruption of a full new cable run, and reducing overall project expenditure for the client.

Phase 3 – Installation and Commissioning

Hybrid managed the full installation programme across all six depots, coordinating with Kier and National Highways representatives on access arrangements, working hours and site logistics. Out-of-hours teams were deployed at Chieveley, Easton Lane and Coldharbour to complete the intrusive cable installation through occupied areas, with daytime works completing the external and distribution elements.

All sites were equipped with 22kW Easee Charging Stations, specified for Traffic Officer Vehicles exclusively. Easee Equalizer units were installed at five of the six sites to intelligently manage and balance load demand between the EVCE and existing depot requirements, ensuring that charger output automatically reduces during periods of high depot demand and maximises when capacity is available.

Each installation was commissioned and signed off upon completion.

Outcomes

Hybrid Electrical Solutions – EV Charging Capability

Hybrid Electrical Solutions – EV Charging Capability

• Electrical feasibility studies including seven-day load monitoring and spare capacity analysis
• Site surveys across live, operational environments with access constraints
• Design and specification of EV charging infrastructure for fleet and commercial sites
• Easee 22kW charging station and Equalizer installation and commissioning
• Out-of-hours cable installation through occupied office and corridor environments
• Legacy electrical infrastructure assessment and compliant upgrade
• Intelligent load balancing design to protect existing depot electrical capacity
• Coordination with Kier and National Highways on programme sequencing and access
• Full Health & Safety documentation and risk identification