Rail services will be hit today because of the first of a series of strikes by hundreds of train drivers in a dispute over pensions.
Members of the drivers' union Aslef at East Midlands Trains will walk out for 24 hours, and are planning further stoppages on Thursday and on May 8, 10, 15 and 17.
A reduced service will be in place today, and again on Thursday, with a replacement bus services in operation on many routes.
The action follows a 3-1 vote in favour of industrial action, with Aslef complaining that the Stagecoach-run company is proposing to reduce its contributions into the pension scheme despite the current "turbulent" economic climate.
David Horne, managing director of East Midlands Trains, said they were "determined" to maintain a good service: "Pension contributions made by our employees will reduce from July this year. This is good news for our staff and will have no impact on their pension benefits. It follows recommendations from a recent pension valuation, which is an independent financial health check on the scheme.
"It makes Aslef's stance difficult to understand and we are surprised that our train drivers are planning to take industrial action over this matter.
"We cannot see how Aslef's demands, to continue with higher pension contributions when they are not required, are in the best interests of their members. It really is good news for our people that the joint contributions are reducing for all of our employees, and for drivers this will save them around £500 a year.
"Despite this action being called, we are still determined to run a good train service for our passengers."
An Aslef spokesman said the company's "cost-cutting" would have "long-term implications" for all staff: "East Midlands Trains is proposing to reduce its contributions into the scheme despite the turbulent economic climate which is likely to have reduced the fund's assets since the last valuation.
"The company's short term cost-cutting measures will have long-term implications for all staff and their pensions."
Changes caused by the strike include a reduced hourly train service from Derby to London, an hourly service from Nottingham to Leicester to connect with trains to London, a train shuttle service will run from Nottingham to Grantham, while rail replacement buses will be in operation on a number of routes including Nottingham to Lincoln, Nottingham to Mansfield Woodhouse, Derby to Matlock, Derby to Stoke-on-Trent, Nottingham to Boston, Nottingham to Sleaford and Lincoln to Sleaford.
Aslef has more than 450 members at the company.