Council bosses have spoken of their disappointment after the introduction of refurbished trains and more frequent services by a rail firm was delayed.
Passengers had been expecting refurbished trains and more frequent services from Northern Rail.
But the company has now said that service changes planned for December this year are being put back into 2019.
Councillor Amy Wilson, Sunderland City Council’s Portfolio Holder for Environment and Transportation, said: "The City Council is very disappointed that promised improvements to rail services in the North East have been deferred yet again due to delays in the delivery of infrastructure investment elsewhere.
"The knock on effect is that the promised cascade of rolling stock is delayed and the relatively modest frequency enhancements we were promised can’t be delivered on time."
In September 2017, the council urged Northern Rail to make sure that Sunderland remained a key station in the North East and on the Durham Coast line.
Coun Wilson added: "It would seem that the introduction of the Northern Connect service, that we have lobbied to be routed via Sunderland, is to be delayed into 2019.
"In addition, the rolling stock released from electrification schemes in the North West will not be available to upgrade services that call at Sunderland station.
"Good rail connectivity to the rest of the UK is essential to the future prosperity of Sunderland.
"The delay to upgrades to our local services does little to help us attract investors to the city or allow Sunderland residents to access employment opportunities in the wider region."