That is the question facing motorists on the unmarked western section of Pinjarra Road every day.

The Mandurah Mail has received letters from the public asking to clarify the lane situation on the busy Mandurah road.

From Dower Street onwards to the east Pinjarra Road is marked as two lanes in each direction, but authorities say the remainder of the road to the west is one lane in each direction.

The western portion of the road is also marked as two lanes at the traffic lights.

Main Roads WA regional manager Brett Belstead said Pinjarra Road was a two-lane street, one for each direction.

Mr Belstead said it was normal to have the road marked as two lanes at traffic lights, one of which is usually a turning lane, and then merging back to one lane.

A Mandurah City spokesperson said the City had future plans to upgrade Pinjarra Road and make it a dual carriageway in both directions along the entire stretch.

Peel traffic sergeant Peter Janczyk said it was legal to use the unmarked section of Pinjarra Road as two lanes in each direction so long as it was done in a safe manner.

Acting traffic sergeant Ian Hollands said the road was marked as one lane so people should keep left and overtake with caution.

Sgt Hollands said although it was alright to drive on the right hand side of the lane while driving at the legal speed limit, people generally shouldn’t use the road as two lanes.

He said during his time at the Peel traffic office he had not seen many accidents caused by lane confusion on Pinjarra Road but “when Pinjarra Road is marked as two lanes it will alleviate some of the problems”.