HS2 will block access to schools and homes and cause traffic chaos if it has to divert a sewer,campaigners fear.

The sewer, in West End Road, Ruislip, stands in the way of the tunnel for the high-speed line that runs from Northolt to close to West Ruislip station.

Works could leave a section of the road out of action for several weeks, according to Ruislip Against HS2 chairman Lottie Jones, who said the work would be ‘hugely disruptive’.

“They will have to dig up certain parts of West End Road, there are no two ways about it,” she said.

“How are parents going to get to Ruislip Gardens School? How are people who live in the estate going to get in and out? How are people going to access RAF Northolt?

“For the past three years we have asked how long it will take to carry out that work, but [HS2] can’t tell us,” she said.

The possible need to divert the sewer means the only way to find out is to dig down into West End Road and investigate.

HS2 spokesman Davis Meechan said: “We are aware of the sewer under West End Road, but until we have carried out a more detailed investigation it is too early to say what work will need to be done.

“If we did have to close the road for a short time, we would be able to keep traffic moving by only closing a single lane and working around peak hours.”

Mrs Jones said: “I don’t think the scale of this has hit people. I don’t think people are aware just how much this will affect them.

“Just because we have the tunnel under Ruislip does not mean it won’t cause massive disruption in the area for the years it will be built.

“People are concerned enough about more traffic with a new Sainsbury’s or the Arla development in South Ruislip.

“Imagine what will happen if you also have roads being used by HS2.”

West End Road is one of the pockets of ‘land potentially required during construction’, which were flagged up by HS2 in its Environmental Impact Statement. It is already extremely busy, being the main route from Ruislip to the A40.

The required area above the sewer runs from Sidmouth Drive, in which Ruislip High School is located, to just past Bedford Road, which is the only access to the Ruislip Gardens estate and Ruislip Gardens Primary School.