The bus-only railway crossing at the bottom of Fitzgerald Street will be moved 250 metres west along Roe Street to avoid the big increase in the number of trains when the northern suburbs railway is up and running.
The decision to move the crossing was made at a meeting of the Perth Central City Public Transport Study steering committee.
Transport Minister and committee chairperson Pam Beggs said today the relocated crossing would incorporate a high degree of safety measures to ensure it was fail-safe.
These included special circuit loops to detect vehicles in intersections into which buses would turn.
Traffic lights along Roe Street would be synchronised to minimise delays for bus passengers and motorists.
South-bound buses on Fitzgerald Street would turn right into Roe Street and travel in a bus-only lane along Roe Street, then turn left over the crossing and enter the Wellington street bus station along the existing busway.
Out-bound buses would enter Roe Street from the busway at a new intersection controlled by traffic lights.
Mrs Beggs said the plan had been discussed with Government transport agencies, the Perth City Council and the bus drivers' union.
"The State Opposition's blatantly political action to block the proposed Fitzgerald Street bus bridge last year meant transport planners had to go back to the drawing boards to find an acceptable alternative," Mrs Beggs said.
"Finding a solution has not been easy. All the options that were examined would have involved delays for bus passengers and motorists.
"Sinking both the Fremantle and northern suburbs railway line was not an answer as it presented enormous engineering problems and would have cost an additional $14 million.
"Also, sinking both lines as proposed by the Perth City Council would have resulted in only a 50-metre strip of land being opened up to link the city north and south of the railway line.
"The relocated crossing will add between one and two minutes to bus journey times, but it will enable existing schedules to be maintained.
"A bus bridge still represents the most effective solution. Throughout the metropolitan area, people are now calling for overhead bridges to be built at more level railway crossings."
Mrs Beggs said she was pleased with the constructive way in which the bus drivers' union representatives had been involved in discussions in finding a solution.
"The bus drivers also favoured a bus-only bridge," she said.
"However, they can appreciate the almost impossible position the Opposition has created and the difficulties associated with finding an acceptable solution."
Mrs Beggs said work on the crossing would begin next month and was due to be finished in February.