Train services between Shrewsbury and Aberystwyth hit by flooding.
Trains between Caersws and Machynlleth were cancelled or delayed today because of flooding.
Replacement buses were being put on by Arriva Trains Wales, however the train operator warned that the flooding could also affect that travel with some roads in the area impassable.
It was hoped that the situation could improve later today.
Eryl Jones from Arriva Trains Wales said: "As a result of heavy rainfall, the railway line between Machynlleth and Caersws is currently closed, as river levels have risen beyond the safe point at Black Bridge.
"The bridge required inspection by specialist divers before the railway can be re-opened. This inspection was expected to begin after this morning. Until this inspection has been made, Arriva Trains Wales are unable to operate train services over the bridge. Services over the route between Aberystwyth and Shrewsbury are affected."
He said details of service amendmentswould be place on the Journey Check and National Rail websites.
"A limited number of replacement buses have been arranged, however many roads on the route are reported as closed due to flooding. As a result, buses may have difficulty in traversing the route. Information will be updated on the Journey Check website."
