Detailed plans for the multi-million-pound Castle Street improvement scheme in Hull city centre are now not expected to be published until next spring.
The Highways Agency had been expected to submit a development consent order for the works on the A63 in the city centre earlier this year.
That date was subsequently changed to the autumn, but now it has been moved back again.
An agency spokesman said it would have any impact on the scheduled start on initial construction work in 2016-17.
He said: "As part of the pre-application stage for the A63 Castle Street improvement development consent order, further traffic and environmental assessments are necessary.
"We are working hard to finalise the application and will submit it as soon as these have been completed.
"We still expect to start work on this scheme in 2016-17 and to complete it in 2020."
As well as a major facelift scheme at the current Mytongate junction, the development order will also include detailed designs for a new pedestrian bridge between Princes Dock and the Marina.
Agency officials met with city council representatives and MPs earlier this week to inform them of the latest delay.
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