A strike by workers on Merseyrail in a dispute over driver-only trains was said to be "solidly supported".
Members of the Rail, Maritime and Transport union walked out for 24 hours, disrupting services.
Merseyrail is running trains for golf fans going to the last day of The Open in Southport but no services were running across the rest of its network.
The row is over plans for driver-only operation of new trains. Similar disputes have broken out across the rail industry.
The RMT and the drivers union Aslef met Transport Secretary Chris Grayling last week to try to break the deadlocked disputes and more talks are planned.