NJDOT Route 21 Viaduct

Condition Assessment, Service-life evaluation and rehabilitation strategy

When a routine visual inspection of a viaduct on New Jersey Route 21 in Newark revealed significant cracking and concrete degradation, the New Jersey Department of Transport (NJDOT) reached out to find remediation strategies.

SIMCO was hired to participate in a condition assessment of Highway 21 Southbound Viaduct performed for the NJDOT. This viaduct was built in 1953 and is located between Mount Pleasant Cemetery and Passaic River.

The investigation was focused on concrete elements and included a visual inspection of the top, bottom and lateral surfaces as well as the beams. Cores were extracted from representative locations of the structure to characterize the concrete and investigate deterioration mechanisms. The investigations allowed SIMCO’s materials experts to determine that the structure was mainly deteriorated by alkali silica reaction. The occurrence of this phenomenon is caused by the presence of a reactive aggregate and high moisture content inside the concrete.

Numerical calculations were performed using SIMCO’s STADIUM® predictive modeling tool in order to determine if it was possible to extend the service life of the viaduct by 25 years.

SIMCO’s methodology revealed that the damage was localized and future deterioration could be controlled with simple remediation strategies at minimal cost. The STADIUM® numerical simulations revealed that the structure destined for demolition could be saved and a 25-year service-life extensions was possible with a cost-effective repair and maintenance program.

“THIS ANALYSIS AND THE SUBSEQUENT RECOMMENDATIONS SAVED MILLIONS IN REPAIRS OR A TOTAL REPLACEMENT OF THE BRIDGE, ESTIMATED AT COSTING UPWARDS OF $100 MILLION. THE ANALYSIS HELPED DETERMINE THAT THIS REPLACEMENT WOULD NOT HAVE BEEN NECESSARY AND THAT INTERIM REPAIRS COULD BE MADE TO THE STRUCTURE WHICH WOULD GIVE THE NJDOT ANOTHER 25-30 YEARS OF USEFUL LIFE AT A FRACTION OF THE COST.”
Brian Strizki, New Jersey’s State Transportation Engineer