Emergency services closed a section of the M25 in both directions on Tuesday after a large fire erupted at an industrial estate near St Albans, prompting warnings about the risk of "secondary explosions" and a precautionary evacuation of the motorway.
Motorway shut as smoke and debris threaten carriageway
National Highways confirmed motorists were stopped between junction 22 (St Albans) and junction 21A while firefighters tackled a "significant" blaze close to the motorway. The authority warned drivers that smoke and debris could affect the carriageway and that the closure was a precaution owing to the potential for further explosions.
"Due to the risk of secondary explosions, smoke and debris affecting the carriageway, the motorway has been closed in both directions as a precaution."
Hertfordshire Fire and Rescue Service said crews were responding to an incident in Ventura Park on Old Parkbury Lane, Colney Street, St Albans. Fire service officers advised local residents to keep doors and windows closed and to avoid the area while crews continued their work.
"We are currently responding to an incident in Ventura Park, Old Parkbury Lane, Colney Street, St Albans. If you live locally, we advise to keep doors and windows closed and please avoid the area while emergency crews carry out their work."
Traffic impact and reopening
National Highways later said the M25 had reopened on the advice of firefighters, though substantial delays persisted. At one stage motorists faced waits of around 90 minutes on approaches, with approximately 5 miles of congestion reported. Speed restrictions of 40mph were in place following firefighters' instructions to manage smoke and traffic flow.
Despite lanes re-opening, drivers were warned it could take time for the backlog to clear and that local roads remained closed while emergency activity continued.
Local conditions and safety advice
Local accounts and media reports described a strong smell of "burning timber and plastic" in the area as smoke billowed above the industrial estate. Herts Police confirmed road closures between Radlett Lane and Old Parkbury Lane, and between Smug Oak Lane and the Premier Inn Hotel, urging motorists to avoid these routes.
- Location: Ventura Park, Old Parkbury Lane, Colney Street, St Albans
- M25 closed: Between J22 (St Albans) and J21A (both directions) — later reopened on advice of firefighters
- Traffic impact: Delays of up to 90 minutes and 5 miles of congestion reported; 40mph temporary speed limit
- Local advice: Keep doors and windows closed; avoid the immediate area
Incident timeline
| Event | Details |
|---|---|
| Fire reported | Significant blaze at Ventura Park, Old Parkbury Lane |
| M25 closed | Both directions between J22 and J21A due to risk of secondary explosions |
| Public safety advice | Residents told to keep doors/windows closed; local road closures implemented |
| M25 reopened | Reopened on firefighters' advice; significant congestion and speed restrictions remain |
Community disruption and next steps
The closure of the M25 — London's orbital motorway and a key freight and commuter artery — risked widespread disruption across the region during the afternoon rush. While National Highways and firefighters moved to reopen the carriageway, the effects of the closure remained visible: long tailbacks, local road closures and a palpable smell of burning reported by residents downwind of the site.
Emergency services did not release details of the unit where the fire began or whether any casualties were sustained. Police and fire investigators are likely to remain on scene while they assess the cause and any potential contamination from burning materials.
I spoke to a resident near the estate who asked not to be named. She said: "You could see the smoke for miles — it made the whole house smell. We were told to shut the windows and keep the kids inside." Her account underlines the immediate household disruption even for those not directly impacted by road closures.
Motorists and residents are advised to follow updates from National Highways, Hertfordshire Fire and Rescue Service and Herts Police for traffic and safety information as emergency services continue their response.
