Engineering clearance for Riverside Expressway.

Main Roads’ final report on Brisbane's Riverside Expressway has confirmed it is safe and structurally sound.

Minister for Transport and Main Roads, Paul Lucas, today said he had been advised by Main Roads’ chief engineer the Riverside Expressway is in good shape.

The report was prepared by Main Roads and includes independent verification by a VicRoads structural expert.

“Not only have we relied on Main Roads’ world-class engineers, we have also involved independent experts every step of the way to confirm the findings,” Mr Lucas said.

“All along I’ve said safety must come first, that’s why Main Roads moved to close the Expressway in October last year after engineers discovered movement in the Ann Street ramp.

Main Roads Director General, Alan Tesch, said the report is the result of six months of extensive investigation.

“Few structures of this type anywhere in the world have been the subject of this level of scrutiny.

“Hands-on analysis has been backed up with painstaking computer modelling which measured thousands of potential load scenarios and involved millions of individual calculations.

“Engineers tested both the whole structure, and all of the joints carrying extra bearing load because of the ramp rotation. The results were double-checked against national design codes.

"The modelling showed the Riverside Expressway is not being affected in any way structurally by the movement in the ramps. Main Roads staff have carried out detailed inspections of the joints to confirm this.

"Inspections demonstrate that at no stage over the past 35 years has the traffic load caused unexpected stress on the structure,” Mr Tesch said.

Main Roads chief engineer, Ian Reeves, said the investigations over the past six months suggested the movement in the ramps had most likely been occurring for some time.

"Analysis showed that a temperature difference of 10ºC between the top and the bottom of the structure's box girders has been enough to cause the end of them to rotate.

“That rotation means one of the bearings supporting each of the ramps is not in contact with the bottom of the structure during the hottest part of the day," Mr Reeves said.

"Temperature differences of 10ºC and more are common. From that, we know the ramps, in all likelihood, have been moving like this every day for some considerable time."

Mr Reeves said that resurfacing of 160 tonnes of asphalt on the Expressway in October last year led to the rotation being identified for the first time.

"As the report released today shows, the ramp movement is posing zero risk to the stability of the structure under current load limits."

Mr Reeves said the report also showed that, with regular maintenance, the bridge would easily meet its intended design life of 100 years.

"At some point in the future, if national heavy vehicle load limits are reviewed and significantly increased, we may to look at strengthening the joints supporting the structure at each pier," Mr Reeves said.

"But there is no need to do that in the foreseeable future.

"Over the next three to five years, Main Roads will complete an existing maintenance and refurbishment program, including replacing some of the one thousand bearings cushioning the piers with long-lasting stainless steel bearings.

“I have formally advised the Minister and the Director General of Main Roads, the Riverside Expressway is safe and structurally sound ," he said.

Media Contact: Darren Roberts 0448 184 566.