Labour has told the five rail operators facing strikes this week over the role of guards that the party will halt any future plans to extend driver-only operation if it wins the next general election.
Shadow transport secretary Andy McDonald said in a letter that guards are "vital" for duties such as helping passengers who need assistance.
Members of the Rail, Maritime and Transport union (RMT) on Southern, South Western Railway and Greater Anglia will strike on Wednesday and Thursday while a 24-hour walkout will be held at Merseyrail and Arriva Rail North on Wednesday.
Mr McDonald said Labour believed the railways should aspire to the safest possible method of train dispatch to ensure the maximum level of passenger service, security and safety.
The letter said: "I remain concerned that in the event of a train evacuation, derailment or incapacitated driver, the absence of a guard to assist could leave passengers at risk. Similarly, anti-social behaviour on trains could increase without the presence of a guard.
"You will appreciate that guards are also vital for accessibility both to assist passengers who require assistance on and off the train, especially at unstaffed stations, but also during their train journey.
"This is acknowledged by those train operators with disabled people's protection policies but also in the Rail Delivery Group's 2017 report 'On track for 2020 - the future of accessible rail travel'.
"I believe any changes to terms and conditions should be agreed through the proper industrial relations process and in full consultation with the relevant trade unions.
"The recent agreement between the Welsh government and trade unions on staffing arrangements for the future of the Welsh franchise highlights the vital role of dialogue and consultation in managing change.
"I also wish to advise you that an incoming Labour government will stop plans for any future roll-out of driver-only operation across the rail industry. We will examine the full range of options to realise this objective."
RMT general secretary Mick Cash said the strikes were about rail safety, adding: "All of these disputes have a common theme and that is a drive by foreign-owned rail companies to axe guards on London commuter trains in order to put private profit before public safety.
"It is sickening that Transport Secretary Chris Grayling and this Tory government are prepared to sit back and cheer on overseas operators who are robbing Londoners blind to subsidise transport services in Paris, Amsterdam and Hong Kong?.
"RMT's fight to keep the guards is about protecting the safety, security and access to rail services of the travelling public against an all-out drive to ramp up profits which are then shipped across the Channel.
"The only person politicising this rail safety issue is Chris Grayling himself, who is stopping the London commuter rail companies from negotiating deals like the ones we have successfully struck in Wales and Scotland that? guarantee a guard on the trains."