But Regional Roads Victoria maintains the barriers will reduce the risk of death and serious injury on the stretch of road, where a number of fatalities have occurred.

Residents hosted a rally last month after learning of plans for the barriers down the road's centre and on the sides, east of Allansford, and between the dual highway from Deakin University to Allansford.

Ms Britnell has requested Roads Minister Jaala Pulford explain reasons for the planned barriers, including providing traffic counts, crash statistics, and pavement condition reports.

"There are people who are rightly concerned about this plan and are confused about why this is the option that has been taken," Ms Britnell said.

Three people lost their lives and 13 suffered serious injury on the stretch of road between 2013 and 2017.

Regional Roads Victoria (RRV) data shows between 13,000 and 15,000 vehicles use the stretch of the highway daily.

Plans include a combination of wire-rope safety barriers and guard rails on 4.5 kilometres of highway between Warrnambool and Allansford. A centreline wire-rope barrier and left-side guard rail is slated for eight kilometres between Allansford and Panmure.

The works also include a new overtaking lane between Allansford and Panmure, road widening, rumble strip line markings, and minor intersection improvements. They are set to begin by early March and due for completion by mid-2021.

RRV program delivery manager Stuart Squire said the barriers would "reduce the risk of death and serious injury from head-on and run-off-road collisions".

"As part of the design and planning phases, we consulted with local councils, emergency service providers, road users, environmental groups and impacted neighbours and took their feedback into account," Mr Squire said.

Ms Britnell, also the state opposition's rural roads spokeswoman, said wire-rope barriers had a place in road safety, but needed to be installed effectively and after consideration of other options.

"We need to be addressing the condition of the road surface first, large sections of the Princes Highway where these barriers will be installed is rutted and cracked - fixing that should be the priority," she said.

The state government is hosting an information session about the upgrades on January 24 from 4.30pm at the Summer Markets at Lake Pertobe, Warrnambool.

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