Waltham Cross is a critical hub for the NLR project, supporting major infrastructure upgrades to strengthen electricity transmission into London. These upgrades are a key part of modernising the electricity network to support the Waltham Cross substation to operate at a higher voltage, enhancing network stability and future proofing the infrastructure to accommodate for our growing energy needs.

We are upgrading the Waltham Cross substation in Lee Valley Park to increase its electricity transmission capacity. The works will see transformers and electrical equipment replaced with higher capacity units, enabling the system to operate at increased voltage levels.  

This work involves building an extension to the Waltham Cross substation and constructing a building to house the two new Super Grid Transformers (SGTs) we will be replacing the two existing transformers with.  

We’ll also be upgrading the existing overhead line with higher voltage conductors. In addition, we will replace or remove several overhead line towers within Lee Valley Regional Park to accommodate this upgraded line.  

We are working with the Lee Valley Regional Park Authority to minimise impacts on park users and protect the local environment during construction.  

Please contact us using the details below if you have any questions or would like more information on our work at Waltham Cross.

To find out more about community benefits, please visit our home page. 

Construction activity within Lee Valley Park  

Construction of the haul road, site access and site compound began in spring 2026 and are expected to continue until works are complete.  

As confirmed by the local planning authority, our permitted working hours at Waltham Cross Substation have been extended. To support the timely delivery of the project, construction activities can now take place between 7:30am to 6:30pm, Monday to Friday, and 7:30am to 4:30pm on weekends.  

To facilitate our work, we have set up key operational zones for construction activity within Lee Valley Park. These have been established in the former Cornmill Meadows Car Park, and the Fisher’s Green Car Park. As a result, please note that there are a reduced number of parking spots in both car parks.  

The surrounding areas will see increased levels of construction traffic and contractor presence as we prepare for the main construction works. Preparation works include installing new access roads and welfare facilities and making upgrades to fencing and security systems to ensure site safety.  

Construction traffic

We are working closely with the local authority and have developed comprehensive management plans to manage increased traffic in Lee Valley Regional Park. Our plans are designed to minimise impacts on park visitors and local traffic as much as possible.  

National Grid employees and contractors will access the site in construction vehicles via Holyfield Road and Stubbins Hall Lane. We are also setting up a temporary haul road on the east side of the site, to facilitate safe vehicle movements.  

Five-way traffic lights will be in place to ensure the safe movement of construction vehicles, park visitors and pedestrians. The traffic management is expected to remain in place for at least two years while deliveries are ongoing. During peak activity, there will be a maximum of 30 Heavy Goods Vehicles (HGVs) deliveries per day, although traffic levels will vary depending on the stage of works.

All construction vehicles within the park area will operate within the 10-mph speed limit, with marshalling points established at the top of the access road to control site movements.

Keeping communities informed

We aim to minimise the impact of our project as much as possible and to keep people informed about the work we’re doing at Waltham Cross.  

We have started to hold Community Liaison Group (CLG) meetings with key stakeholders to make sure we’re doing what we can to reduce disruption. Our first meeting was on Tuesday 17 March 2026, and you can view the slide deck we presented by clicking here.  

We note that works are still being scheduled in this area, and the programme and details of our activities are subject to change.  

Register your details with us here to receive information as it becomes available. You can also follow our WhatsApp channel for real-time updates on our activity. Read our Frequently Asked Questions document, including the QR code you can scan to join.