By: Robert G. Packard, P.E.
The race for progressThe race for progress
Researchers at the University of California-Berkeley have documented a remarkable reconstruction project on I-10 in California—2.8 lane-km of concrete pavement was replaced in 55 hours over one weekend by the Morrison-Knudsen Corp (see Driving after 55; team races through job, January, 2000, p 23). The work involved the following: lift out and haul away slab segments previously sawcut; clean cement-treated subbase; install tiebars and dowels; place, finish and texture new concrete; cure four hours; saw joints; and open to traffic.
The segment of I-10 running through southern California, commonly called the "San Bernardino Freeway," was built in the early 1960s for a 20-year design life. Traffic volumes in this stretch of freeway, are as much as 240,000 ADT.
The objectives for the I-10 Pomona project focused on documentation of the traffic management plan and construction process for both nighttime and weekend closures, to document the techniques the contractor used to reconstruct the urban concrete pavement and to identify which construction areas were constraining the overall project productivity. Identification of the constraining activities could help improve future construction productivity by allowing contractors and agencies to focus on innovations in a particular area.
The rehabilitation project used fast-track concrete with four-hour curing time and two different construction windows (i.e. one 55-hour weekend lane closure and a series of repeated nighttime closures [7 and 10 hours]), and was completed successfully. This indicated that state agencies should be confident that 3 lane-km of pavement reconstruction on a weekend is an achievable goal.
The average production rates showed that weekend closures were 55% more productive than nighttime closures.
The overall progress of the project was found not to be controlled by the demolition activities; the maximum amount of the demolition under the contractor’s process for 55 hours of work could have been 5 lane-km. Concrete delivery to the site was found to be the constraining factor.
If the initial paving progress was maintained throughout the project length and no breakdowns occurred, the maximum amount of the rehabilitation which could be completed within a 55-hour weekend would be 3.5 instead of 2.8 lane-km.
These results may facilitate effective technology transfer to other agencies, contractors and elected officials.
About The Author: Packard is director of engineering-design for the American Concrete Pavement
Association. You may write him in care of the editor.
