The bitter dispute over the role of guards and driver-only trains has spread to a fifth rail operator after another vote for strikes.
Members of the Rail, Maritime and Transport union on Greater Anglia backed industrial action by 9-1.
The union has staged a series of strikes on Southern Railway, Merseyrail and Arriva Rail North, while workers on the new South Western Railway franchise are to be balloted for strikes over the same issue.
The RMT said Abellio, which runs Greater Anglia, had failed to provide the union with assurances over the role and responsibilities of guards. The ballot result will now be considered by the RMT's executive who will decide on the next steps in the dispute.
RMT general secretary Mick Cash said: "Greater Anglia have been given every opportunity to give a guarantee on the future role of the guards on their services. They have failed to do so and that left us with no alternative but to move to a ballot in the interests of rail safety.
"Our members have now voted by massive majorities for action and it's now down to the company to wake up and take note and to seize the opportunity to give us the very simple assurances on the future of the guards, and the guarantee of a second safety-critical member of staff on current services."
Richard Dean, train service delivery director at Greater Anglia, said: "We are obviously disappointed with the ballot result. We're keen to talk to the RMT to try and resolve the issues involved and to avert industrial action.
"We value our conductors highly and we have guaranteed their jobs until the end of our franchise in October 2025.
"In fact, we will be recruiting additional conductors, as we are replacing all of our trains with brand new trains from 2019, which will enable us to run more services."