A risk of trains colliding with platforms and mud beneath the tracks have been listed among the reasons for ongoing speed restrictions affecting rail services through Northfleet.

Network Rail Kent and Sussex has posted a lengthy explanation on Twitter this morning, outlining the reasons for delays which have been affecting passengers travelling through the area since December.

The rail company explained trains were being delayed on their way to London as a result of a 20mph speed restriction through Northfleet, which was affecting some passengers further into the City.

They added: "This has been in place since early December so we are conscious many of you have noticed these delays for some time and we owe you an explanation.

"The line through Northfleet has suffered from two issues, the first one being what we call 'wet beds'. These are small patches where the drainage is lacking, usually for historic reasons, and the sub-base has liquified and turned to claggy mud.

"We fix them in a variety of different ways including using a big hoover called a RailVac."

While that problem had been fixed at Northfleet, the rail company said restrictions were still in place because the station platforms were on a curve and the movement of trains had shifted the track too close to the platform.

They added: "This happens naturally and in some areas we actually glue the ballast stones that support the track to stop it from happening. That isn’t the case here and both tracks need to be shifted back to their correct alignment before we can lift the 20mph restriction.

"Without the restriction there would be a danger a train could hit the platform, causing far more delay than simply slowing trains. In order to fix the alignment we need to send a “tamper” along.

"Tampers are also needed to line up the track over the fixed wet beds too. They lift up the track and compact the ballast underneath it, also checking the alignment with data pre-loaded in its memory.

"That also requires the line to be closed and unless it’s an emergency, we work with @Se_Railway to find the best time and date to do that. While the speed restriction is causing delays, we have to balance that with the disruption of closing the route."

They said the tamping was unlikely to be done before March, but they were working on getting the work done sooner, adding: "we are also trying to balance the delays vs the disruption and we’re really sorry for the lateness some of you have felt as a result of this.

"Finally, many thanks for your ongoing patience and if this thread interests you and want to come and get involved in rebuilding our railways, we’re always hiring."

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