Train services between Hertford East and Ware have been disrupted because of a signalling problem.
Bus services are running between the stations and Greater Anglia ticket holders can use their tickets on London Underground and First Capital Connect services from Hertford North.
The Transport Secretary Justine Greening has admitted that train fares could rise by inflation plus 3% next January. Regulated fares are allowed to rise by 3% above the Retail Price Index inflation figure and Ms Greening indicated the extra money would be needed to stabiliise the rail industry.
This year, the rise was reduced to just 1% above RPI inflation but Ms Greening said there was no guarantee that the money could be found to allow a similar limit in 2013.