Lower Thames Crossing DCO adds M25 60mph limit

From 5 November 2025, a targeted update to the Lower Thames Crossing’s planning permission is in force. It locks in a 60mph westbound speed limit between junctions 26 and 27 of the M25 from the day the crossing opens, with enforcement kit and funding, to protect Epping Forest’s Special Area of Conservation from extra traffic emissions.

The change arrives via the A122 (Lower Thames Crossing) Development Consent (Amendment) Order 2025, S.I. 2025/1161. It amends the original DCO (S.I. 2025/462, corrected by S.I. 2025/1014). The Secretary of State made the Order on 4 November 2025 after considering consultation responses under the 2011 Change Regulations; it took legal effect the next day. The instrument was signed by Kayla Marks at the Department for Transport.

If you teach or study planning, a Development Consent Order is the single consent created by the Planning Act 2008 for nationally significant projects. A non‑material change is the route for modest adjustments that do not reshape the project. It still requires publicity and targeted consultation under regulations 6 and 7, and a decision by the Secretary of State.

Why Epping Forest is central here: it is a Special Area of Conservation, which means decision‑makers must prevent an Adverse Effect on Integrity. The risk is ‘in‑combination’ air quality impacts from extra traffic-especially nitrogen oxides (NOx and NO2) and ammonia (NH3)-which can add nitrogen to sensitive habitats through deposition.

What exactly has changed: the Order amends paragraph 26(4) of Part 3 of Schedule 2 by updating entry HR013 in the Register of Environmental Actions and Commitments within the Code of Construction Practice. The commitment now requires the technology and infrastructure needed so the enforcement authority can apply a 60mph limit westbound between junctions 26 and 27. Reasonable funding must be provided to the highway and enforcement authority to set the limit and carry out enforcement.

The measures are to be in place from the start of operation. In parallel, monitoring must begin no later than six months after construction starts and continue for at least four years after opening. Monitors will track NOx, NO2 and NH3 against pre‑operation values so changes in nitrogen deposition linked to vehicle emissions can be assessed.

Evidence is meant to build year by year. Annual reporting will bring together the monitoring results, traffic data and regional pollution trends, with Natural England consulted on the review. This keeps the data open to scrutiny and keeps the ecological test clear as the new road moves from construction into use.

There is a get‑out clause-but only if the science supports it. After pre‑opening monitoring and any extra assessment, National Highways may ask in writing for the measures to be stood down. The Secretary of State can agree, but only where Natural England has been consulted and it is clear the protections are no longer needed to avoid an Adverse Effect on Integrity.

Equally, there is a backstop. If monitoring and updated modelling show increases in nitrogen deposition or in NOx or NH3 that would lead to an Adverse Effect on Integrity, the 60mph control and enforcement must be in place. Natural England can agree an alternative approach, but the presumption is that the limit remains to protect the site.

For you as a learner or teacher, this is a practical case study of how environmental safeguards are hard‑wired into a consent. Watch the Code of Construction Practice and the REAC-especially entries like HR013-because that is where commitments sit, how they are funded, and how long they must last.