A seismic improvement works were completed on Market Road Underpass (MRU) in Auckland. The bridge consists of three structures: The Underpass, the Motorway Off-ramp and the Rail Overbridge. In the NZTA’s "Seismic Screening" of all state highway bridges MRU ranked 4th in its programme for further investigation and retrofitting. Assessment of seismic capacity of the bridge was completed by Opus in 2004 and 2008. The adopted benchmark event against which the performance of the 

bridge has been assessed is seismic shaking with a return period of 1000 years together with collapse avoidance under the 2500 year return period shaking. Seismic performance of the bridge under the above levels of shaking was determined to be inadequate, limited predominantly by the shear capacity of the beam-column joints and the abutment columns

and stability of the unreinforced masonry pier common to the Underpass and the Rail Overbridge. Seismic improvement of the bridge was successfully completed in mid 2011 and included installation of new piles at one of the abutments, new auxiliary support at the critical pier common to the Underpass and the Rail Overbridge, strengthening of the pier beam-column joints, and installation of new shear keys at the Off-ramp. Works

completed will improve the expected seismic performance of the bridge to the level required. Overall cost of the improvements was about NZ$1.5 million.