The HSR project would create a direct rail connection from Staines to Heathrow Airport.
The council says it has the potential to boost economic growth, improve sustainable transport, and enhance connectivity for residents.
But support is subject to three conditions.
Trains must stop at Staines, there must be robust evidence that will confirm no harm to Staines Moor nor any increased groundwater flood risk.
Spelthorne’s councillors say terms of the HSR link must be reviewed and agreed before any final commitment is made.
The proposed HSR route would use existing rail infrastructure from Staines to Windsor before tunnelling beneath Staines Moor which is a design intended to minimise disruption and protect the town’s character.
The alternative Southern Light Rail (SLR) proposal was found to pose greater risks to privacy, the landscape, and the environment.
Cllr Chris Bateson, Chair of the Working Group, said, “We have carefully reviewed both proposals, assessing their environmental, social, and economic impacts and believe the Heathrow Southern Rail proposal is an important step towards greener, more efficient travel to Heathrow. A direct link from Staines would ease congestion and support our local economy.”
Cllr Howard Williams, Chair of the Business, Infrastructure and Growth Committee, added, “However, our support depends on firm assurances that Staines Moor will be protected, and flood risks fully addressed – our environment must not pay the price for progress. Spelthorne will continue to engage actively with HSR to ensure that our residents’ and Borough’s interests are front and centre in every stage of development.”
