By Michael Samadian, Caltrans Senior Transportation Engineer
Most of California’s state highways were built during the 1960s and 1970s and have exceeded their design lives, which has motivated Caltrans to shift focus from new highway construction to the rehabilitation of existing facilities.
The agency faces a challenge in finding economical ways to renew deteriorating roadways in metropolitan areas. Highway rehabilitation projects often cause congestion, safety concerns and limited access for road users.
In response to this dilemma, the Caltrans Division of Research and Innovation (DRI) launched a research project in 1999 to address and resolve this national problem. Through the continuous work of researchers at Caltrans and the Institute of Transportation Studies at the University of California, Berkeley, the first version of Construction Analysis for Pavement Rehabilitation Strategies (CA4PRS) was developed.
CA4PRS is a software program that analyzes traffic and construction durations for reconstruction of highway projects in congested urban zones. It determines efficient construction timeframes and selects accurate traffic management plans.
It was funded through California, Minnesota, Texas and Washington states’ departments of transportation Pavement Technology Consortium to help road agencies, pavement contractors, and engineers coordinate and conduct pavement rehabilitation and reconstruction projects efficiently.
Throughout the nation, there is growing recognition of the capabilities and benefits of CA4PRS. The new tool helps transportation officials determine the most effective and economical strategies for highway maintenance and rehabilitation projects. The program uses traffic counts, the number of highway closures and closure hours to predict how traffic will react to construction and determine the most cost-effective repair strategy. The program quantifies road-user costs and time delays — including delays on neighboring routes.
As one of the lead agencies in the development of the software, Caltrans Information Technology recently approved CA4PRS as standard software for statewide implementation. Approximately 1,000 transportation engineers in 10 state transportation departments have received CA4PRS hands-on user training.
As a recent research payoff, the International Road Federation granted CA4PRS a 2007 Global Road Achievement Award. In addition, the American Association of State Highway Transportation Officials (AASHTO) Technology Implementation Group is working on a nationwide promotion of CA4PRS for its state members. The Federal Highway Administration (FHWA) also formally endorsed CA4PRS as a “Priority, Market-Ready Technologies and Innovations” product in 2008, and recently acquired an unlimited CA4PRS group license for all 50 state transportation departments to deploy the software nationally.
The Institute of Transportation Studies of the University of California at Berkeley developed CA4PRS. It was funded through the FHWA pooled-fund, multistate consortium consisting of California, Minnesota, Texas, and Washington.
The program incorporates three interactive analytical modules: a schedule module that calculates project length, a traffic module that quantifies the delay of work zone lane closures on the traveling public, and a cost module that estimates the price.
CA4PRS users can evaluate “what if” scenarios for alternative rehabilitation strategies, including pavement cross-sections and material types, construction windows and lane closure tactics, and contractor logistics and constraints. CA4PRS has helped agencies, contractors and consultants save engineering time, improve accuracy of estimates, and streamline teamwork. CA4PRS enhancements include analyzing strategies for roadway widening and bridge/interchange replacement.
Since 1999, several major highway rehabilitation projects in California, Washington and Minnesota have confirmed the capabilities of CA4PRS. It has been successfully used on several urban freeway rehabilitation projects with high traffic volume, including projects on Interstate 10/Pomona and I-710 in Long Beach. More recently, CA4PRS was used with traffic simulation models to select the most economical rehabilitation scenario for the I-15 Devore Project. The 2.8 mile concrete pavement reconstruction project would have taken 10 months using traditional nighttime closures. However, using the CA4PRS analysis allowed construction to be completed during two nine-day periods using one roadbed, continuous closures with counter-flow traffic and around-the-clock construction. Implementing continuous closures, rather than repeated nighttime closures, resulted in significant savings: $6 million in agency costs and $2 million in road user costs in this project.
For more information, e-mail Michael Samadian