Services are being disrupted after speed restrictions were imposed due to the heatwave.

Network Rail Scotland confirmed that the restrictions have come in across west central Scotland and Fife as "a precautionary measure".

It added: "We will continue to monitor through the afternoon. "

Services have beensuspended between Bathgate and Edinburgh.

Those between Edinburgh and Glasgow Queen Street via Falkirk High were halved to a half-hourly service departing the capital at 15 & 45 minutes past the hour and from west on the hour & the half hour.

Services between Edinburgh and Dunblane were also halved to an hourly service.

There were also cancellations on the Glasgow to Lanark line, where services were halved to hourly.

ScotRail said that "high track temperatures"  meant speed limits have been imposed.

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ScotRail said "disruption is expected till 7pm".  

It has led to cancellation and delays to services.

ScotRail has also warned that there may be further issues elsewhere.

The operator said: "Temperatures are expected to be very high again today. Network Rail will be working hard to protect the infrastructure, but there may be disruption to the network. "

David Dickson, Network Rail’s infrastructure director for the ScotRail Alliance said: “On very sunny days, rails in direct sunshine can be as much as 20 degrees centigrade above air temperature causing the steel to expand markedly and could, if not carefully monitored and action taken, buckle causing travel disruption.

“Our engineers and specialist extreme weather teams are monitoring track-side temperatures and vulnerable locations and will, if necessary, introduce temporary speed restrictions during the hottest part of the day to keep trains running, albeit more slowly than normal.”

There has been no shortage of anger over the delays and cancellations from travellers about the disruption.

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Wedding and lifestyle photographer David Scott lodged a complaint to ScotRail on social media saying: "The sun's out, cancel the trains. It’s raining, cancel the trains. It’s snowing, cancel the trains. Forecast is for a mild breeze on Saturday, let me know if trains will be cancelled then as well. Four days disruption in a row to Lanark."

Writer and teacher Kat Doyle added: "This ScotRail train is a joke! Delays because the trains can’t handle the weather, broken engine and broken air conditioning.

"People are packing into the coolest carriage for relief. We’re stuck in the middle of nowhere. Iss this the best Scotland can do in summer?"

There was concern for one girl travelling to Edinburgh who collapsed in the heat.

There was concern for one girl travelling to Edinburgh who collapsed in the heat.

The latest issues comes a day after trains were cancelled at Glasgow Central due to "multiple points failures".

ScotRail said it was unable to run trains in or out of the high level part of the station on Wednesday evening.

The operator said most services were running as normal on Thursday morning until the heat took hold.

Engineers painted rails white at the station so that they absorbed less heat cutting the risk of buckling - but it did not prevent Thursday's chaos.

Meanwhile a fault with the signalling system between Uddingston and Cambuslang brought disruption until 2.30pm. 

British Transport Police Scotland issued its own warning about the heat.

"The temperature today will be extremely high across the country and ergo the rail network," they said.

"Please leave additional time for your journey and if possible bring some water to ensure you remain hydrated."

A ScotRail spokesman said: “We sincerely apologise to customers affected by this disruption and completely understand their frustration when these things happen.

“Customers can get the latest service information on social media, on our website and mobile app.

“Anyone delayed by 30 minutes or more is entitled to compensation under our Delay Repay Guarantee. To claim, simply keep hold of your ticket and visit our website or mobile app.”

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