Due to its deteriorated condition, the timber bridge over the rail line at Herbert Street in Sadliers Crossing will be required to close to motor vehicles from Saturday 22 February.
Queensland Rail CEO Nick Easy said recent inspections of the bridge showed its deterioration had escalated at an unexpected rate, rendering it unsafe for motorists to use.
"For many years, we have been closely monitoring the condition of the 120-year-old timber bridge and undertaking maintenance where practicable to ensure it was fit for use," he said.
"In 2012, restrictions were placed on the bridge, reducing it to a single lane for motorists, with a load restriction of five tonnes also in place.
"While Queensland Rail completes regular maintenance and inspections of the bridge, a recent inspection by our engineers showed an unexpected rate of deterioration, which has unfortunately left us with no choice but to close it to motorists for the safety of the community and our network."
Mr Easy said from 22 February, motorists wanting to cross the rail line could use the Burnett Street overpass, 450m east of the Herbert Street Bridge, or the Gladstone Road underpass, which is approximately 750m west of the bridge.
He assured residents the bridge remained safe for pedestrians and cyclists.
"Bollards will be placed on both approaches to the bridge to prevent access by vehicles, but allow cyclists and pedestrians through," Mr Easy said.
"Queensland Rail will continue to monitor the bridge's condition to ensure this arrangement remains safe.
"While we regret any inconvenience this closure may cause to the local community, safety will always remain our number one priority."
Queensland Rail will continue to monitor the bridge and will work with Ipswich City Council in the coming months to determine future requirements at the site.