A gas leak inside a tunnel on the M4 near Heathrow Airport has caused major disruption, shutting the route and leaving passengers stranded. The incident occurred at Junction 4, with traffic at a standstill and the airport's car park gridlocked.
National Highways confirmed the M4 was closed in both directions between J4 and J4A due to an off-network incident. The Metropolitan Police and Heathrow Airport crews attended the scene. Traffic heading to the airport was advised to use the M25 and follow signs for Terminal 4.
Inrix reported long delays and a partial closure of the Heathrow Terminal Tunnel. A contraflow was later implemented via the inbound tunnel. Bus routes 105, 111, 285, 278, A10, X26, X140 and U3 were affected.
The London Fire Brigade was called at 1:19pm after a methane alarm sounded in a tunnel on Tunnel Road East. A gas pipe was isolated, and crews conducted a sweep for elevated readings. A hazard zone was established, and the tunnel's extraction system was activated.
A Heathrow spokesperson advised passengers travelling to Terminals 2 and 3 to avoid road travel and use rail or underground services instead. The free terminal transfer service from Terminals 4 and 5 was also recommended. The Metropolitan Police confirmed the gas alarms triggered at 1:15pm, with the Gas Board attending.
