Liverpool City Region mayor Steve Rotheram has demanded a "formal inquiry" into the blanket cancellation of all Merseyrail services yesterday.
On Thursday evening the service announced no trains would run on Friday (January 8) due to "adverse weather conditions."
However after a morning with no trains running, services did resume at around midday after Merseyrail engineers used "special gritters" on the tracks.
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A Merseyrail spokesman said on Friday: "Throughout [Thursday], the forecasted weather overnight and into this morning showed a combination of snow, sleet and rain which together causes problems for our electrified rail, which powers our trains.
"Rain and sleet can wash anti-ice away, while snow and sleet can create a new layer of ice on top of the rail, which electricity cannot pass through and therefore trains are unable to run."
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In a statement posted on Twitter last night, Mr Rotheram blasted the cancellations as "unacceptable."
He said: "This afternoon I have met with Network Rail and Merseyrail to convey that I believe the situation this morning was unacceptable for our City Region.
"I have also written to Network Rail asking for a formal inquiry to learn lessons and to try and prevent this from happening again."
