It will cost between $20 million and $35m to keep trucks out of Levin, the NZ Transport Agency says.
The NZTA, which manages the country's state highways, has been exploring the option of a heavy vehicle bypass for the Horowhenua town.
A potential bypass was scrapped early last year but after public feedback the NZTA said it would take a second look.
NZTA Wellington highways manager Rod James said they were yet to make a decision but had looked at several options for taking trucks away from State Highway 1 as it ran through the town.
The lowest cost option considered was just over $20m and the most expensive was nearly $35m.
"Each option would require us to purchase property to construct a new road, but this is not the main factor in the cost.
"We know it can be distressing for people whose properties are required, so we want to minimise property impacts for this reason too, not just cost.
"More work needs to be done to understand how the project will affect property owners and what the costs might be."
Mr James said improvements to the southern end of SH57 were already planned, as was a new intersection where it joined SH1.
Any bypass would use this highway, which runs to the east of Levin, before it cut back to SH1 via a road that would have to be constructed.
Any bypass would be longer than the SH1 route through Levin so even if the proposal went ahead there was no guarantee truckies would use the new road, Mr James said.
"In order to draw heavy vehicles away from the main street, the bypass would need to be straight, wide and have a higher-quality pavement to withstand the weight of the vehicles using it.
"However, this would make it attractive to other vehicles and could defeat one of the aims of the bypass, to keep through traffic on the main street.
"Therefore, if a future bypass was pursued, more work would need to be done to ensure that Levin town centre remains an attractive destination."
Bypasses for trucks in Levin have been looked at before. In 1991 the Horowhenua District Council looked at five options, with cost estimates ranging from $700,000 to $5.1m.
The cheapest option used existing roads to the east and north of Levin, as well as SH57, but included two railway crossings, several right-hand turns and the need to widen roads.
The $5.1m option went past Levin on the town's western side but would have required the purchase of land, including some held in Maori title.
The council opted not to go ahead with any of the options.
A decision from the NZTA on a possible bypass is expected later this year.
- Manawatu Standard
Should Manawatu's earthquake-prone buildings be yellow-stickered?Related story: Council won't use earthquake-risk stickers