An extra lane could be created to ease traffic congestion on the Britannia Bridge, linking Anglesey with the mainland.
Britannia bridge carries the A55 from the mainland to Anglesey
The bridge is regularly congested, slowing traffic travelling on the A55 dual carriageway.
A detailed technical study will take place before the plans are finalised, said First Minister Rhodri Morgan.
The assembly government said it would be unlikely that work would begin before 2010.
Mr Morgan said that an initial feasability study had proved the need for a system where two lanes were open in the direction of the busiest traffic at any given time.
Ynys Mon AM Ieuan Wyn Jones has welcomed the announcement but said it would only serve as a short term measure and long term solutions were needed to traffic problems.