Case Study of Urban Concrete Pavement Reconstruction and Traffic Management for the I-10 (Pomona, CA) Project
A case study was performed on a Caltrans concrete rehabilitation project near Los Angeles on Interstate 10. The project was unique in that the contractor had to remove and replace 2.8 lane-km of concrete pavement in a 55-hour weekend closure. The existing cement treated base was not removed except in places where it had deteriorated, and a fast setting hydraulic cement concrete with a 4-hour opening strength was used for the surface concrete. The contractor used a concurrent working method in which demolition and concrete paving occurred simultaneously and only a single lane was removed and replaced. The contractor had only one standard width construction access lane (3.7 m) and a shoulder width of less than 3.0 m. The contractor successfully completed this 2.8 lane-km objective in 55 hours and was eligible for a $500,000 bonus per the contract. The demolition operation took 76 percent longer than planned, but it did not delay the overall progress of the project. The concrete paving activities, especially the concrete delivery and discharge, controlled the overall progress of the 55-hour weekend project. In terms of the number of slabs replaced per hour, the 55-hour weekend closure was 54 percent faster than the average nighttime closure conducted by the same contractor. The amount of the rehabilitation work performed over the 55-hour extended closure would have normally taken 2.5 weeks (16.4 days) of nighttime lane closures. If no work stoppages in the concrete paving had occurred, the maximum amount of rehabilitated road would have been 3.5 lane-km. In 10-hour nighttime closures, the contractor was able to remove and replace 50 slabs on average compared with 15 slabs for 7-hour nighttime closures. During weekend daylight hours, traffic through the construction zone was reduced by 30 to 60 percent compared with normal weekend traffic volume. During construction, the percentage of traffic diverting to other routes doubled over normal diversion in the daylight hours, but was only approximately 5 percent more than normal during the nighttime hours. The reduced traffic volumes passing the construction site indicated driver awareness of the weekend construction window and traffic lane closures. Caltrans did an excellent job of informing the public of the project through local media outlets (radio, newspapers, and television), signage, and brochures. The construction productivity data from the demolition and paving operation was used to validate a constructability and productivity analysis software coded by the University of California Berkeley (UCB). The average results from a deterministic and stochastic analysis were in agreement with the actual project productivity. The stochastic analysis showed that the expected range for the project productivity was between 2.2 and 3.4 lane-km for a 68-percent confidence interval with the average productivity being 2.8 lane-km.