Major sections of the new Morpeth Northern Bypass are being put in place.
Work started last week to deliver huge U-shaped units that will create the How Burn culvert.
The six-metre by three-metre units will eventually be put together to create a six-metre square tunnel.
Six units were delivered to the site last Thursday, with lorries travelling through the town.
And motorists are being advised there may be further delays with six more units being delivered tomorrow, on Tuesday and next Friday.
On Monday, a 500-tonne crane will be arriving on site to start lifting the units into position.
Overall, 64 units will be used to complete the 60metre-long culvert. Each one weights 26 tonnes.
A total of 32 bottom units are being delivered over the next few weeks, with a further 32 arriving shortly after. Deliveries should be complete by April 26.
Mark Denham, Carillion Plc agent at Morpeth Northern Bypass, said: “How Burn culvert is a major part of the Morpeth Northern Bypass, so as we ready ourselves to set these concrete sections in place next week, we’re marking a key milestone for the project.
“It has now been a year since works started on the project and, with culvert sections arriving throughout April, progress is right on track.
“The bypass will bring huge benefits to Morpeth and the wider south of Northumberland, so it’s great to see that these gigantic deliveries have really got the local community talking and getting excited about the project.”