Perth's worst road merger spot will disappear when the Graham Farmer Freeway is reconfigured next year to make way for extra lanes in the Northbridge tunnel.
The westbound tunnel entrance is often gridlocked in morning peak hour as freeway traffic merges with vehicles from East Parade.
Under the new layout, which has been provided to _The West Australian, _ the road from East Parade will become the third lane of the tunnel, removing the need to merge.
The plans also show a new on-ramp from the Loftus Street exit to the Mitchell Freeway.
The State Government is proposing to introduce a third traffic lane in each direction of the tunnel in a $57 million project aimed at accommodating an extra 14,500 vehicles a day that will be redirected from the Perth waterfront.
The new lanes will be about 10cm narrower than existing lanes and there will be no emergency lanes.
Under the plans, the westbound lanes will go in three directions out of the tunnel. The left lane will split and head towards the Kwinana Freeway and Loftus-Thomas streets.
The middle lane will also split, with one side also heading to Loftus Street. But with the construction of a new on-ramp, traffic will be able to rejoin the Mitchell Freeway.
Transport Minister Troy Buswell told Parliament that this was designed to prevent unnecessary lane-changing in the tunnel.
"One of the big problems as cars come out of the tunnel is trying to merge across to get off the freeway," he said. "That is why it is almost at a standstill. Cars almost have to go across traffic.
"As part of the new works, as cars come out of the tunnel and head off towards Thomas Street, there will be a new ramp or slip that will whip them back down so that they will be on the other side of the freeway."
For traffic heading east, the lane from Leederville Parade will become the third lane in the tunnel.
Coming out of the tunnel, the left lane will split, with one branch heading to East Parade.
The Mitchell Freeway traffic bridges over Powis and Vincent streets and Scarborough Beach Road will also be widened.