"Significant investment" is needed to update Network Rail's system of monitoring railways, a report into a fatal crash has found.

A task force was led by Lord Robert Mair - emeritus professor of civil engineering at the University of Cambridge - has been examining the management of railway cuttings and embankments in the wake of the Stonehaven train crash last year.

Its report has made a total number of 50 safety recommendations, including advice that "more regular and frequent use" should be made of helicopters and drones to identify problems.

Three people died when the 6:38am Aberdeen to Glasgow Queen Street train crashed into a landslide across the tracks near Stonehaven, Aberdeen, on August 12 last year following heavy rain. Six other people were injured.

The investigation was published alongside a study into the impact of heavy rainfall on the railway.

Network Rail’s safety and engineering director, Martin Frobisher, said: “It is clear that extreme weather presents a significant challenge to the way we safely and reliably manage railway infrastructure.

READ MORE: Stonehaven crash: Speeding trains investigated on Aberdeenshire line

“We do a vast amount to tackle the effects of climate change already but there is more to do.

"We established two independent, expert task forces led by world-class specialists to investigate the problems we face and, crucially, to guide us as we make substantial improvements.

“We will carefully consider every single recommendation and develop a science-backed improvement plan, to target available money and technology in the best possible way. This is a real breakthrough.”

HeraldScotland: Credit: PACredit: PA

Network Rail’s interim report on the crash found that the train “struck a pile of washed-out rock and gravel before derailing”.

Lord Mair’s report stated that “shortfalls in the earthwork examination and risk evaluation system need to be addressed”.

READ MOREStonehaven derailment: Bereaved families of Brett McCullough, Donald Dinnie & Christopher Stuchbury to share fund

It warned that “significant investment” was necessary to update Network Rails monitoring and surveillance methods.

A spokesman for train drivers’ union, Aslef, said: “The Government has to provide Network Rail with the funds so it can carry out the work that is needed to maintain our rail infrastructure so that passengers, and crew, can be confident of the safety of our railway.”

Transport Secretary, Grant Shapps, said: “We must do everything we can to keep our railways safe.”

He added: “These findings will inform our work as we push ahead with measures to make our railway more resilient in future, and less vulnerable to sudden tragedies like that near Stonehaven.”