Mr Tremain said the proposal would have "real advantages" for the province and would improve access to the Port and move more trucks away from Marine Parade.
"It's great to see our expressway being proposed as a road of national significance - it's a big step forward and good for our local economy," he said.
"Key improvements can be made on feeder roads from Havelock North through Whakatu and Pakowhai Rd to the expressway helping to bring much of the truck traffic from this busy area direct to the expressway."
Napier-based Labour list MP Stuart Nash said if Napier wanted to keep its reputation as a "vibrant and sparkling" tourist centre it was important to keep trucks off Marine Parade. He estimated there were upwards of 700 truck journeys a day along the parade to the port, with many of those taking a shorter route along Farndon Rd.
"Anything that improves the infrastructure of Hawke's Bay is good," he said. "We know what the problem is but we have to have a full solution to make it work".
Hawke's Bay Regional Council Transport Committee chair Alan Dick said it could mean a faster route and less heavy traffic on the coastal road to the Port.
"By using the expressway the bulk of it will be taken away and it will be where it should be," Mr Dick said.
The Regional Transport Committee met this week to discuss and recommend options for the region's infrastructure and other high investment roading projects, provisionally adopting the land transport programme for 2012-2015. Key projects focused on economic growth and productivity, road safety and value for money and ensuring efficient and effective transport links through production and industrial areas to the Port of Napier.
Those included the Whakatu Arterial Link, Ford Road extension including the four laning of Prebensen Drive and upgrades of the Hyderabad Road/Prebensen Drive and Pettigrew roundabout, and a redesign of the Pakipaki intersection to direct traffic to the expressway when heading north to the Heretaunga Plains.