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U.S. Department of Transportation U.S. Department of Transportation Icon United States Department of Transportation United States Department of Transportation

Public Roads - Nov/Dec 1998

Urban Freeway Renewal

by David O. Cox

yellowFrequently, highway officials are faced with a situation like this: An old pavement on a heavily traveled route in the heart of an urban area has served its useful life - and more. Over the years as traffic loadings have doubled and then doubled again, the road has been patched, refurbished, and overlaid. All in all, highway engineers are very pleased with its performance, but this pavement has finally reached that inevitable point where rehabilitation just won't work any more. This pavement must be replaced! How can it be replaced in an efficient and cost-effective manner and with as little disruption as possible to the economy and to the travel patterns of the hundreds of thousands of people who depend on this route?

Sound familiar? It should because as the Interstate Highway System begins to show its age, virtually every large city in the United States has routes with pavements that match this description. Many cities have used costly maintenance-intensive "fixes" that do not fully resolve the problem and that force their citizens to live a bit longer with substandard pavements.

The 1997 issue of Highway Statistics presents the scope of this problem. In the United States, more than 34,000 kilometers of urban freeways are currently rated as being in need of replacement now or in the very near future. This is approximately 28 percent of the total length of urban freeways. Another 18,000 kilometers (15 percent) are predicted to reach that condition by the year 2005. The cost of "system preservation" in urban areas is already high and growing at a tremendous rate - from just over 42 percent of the total highway construction dollars spent in 1995 to nearly 50 percent in 1997. This means that together the states and the federal government spent almost $12 billion last year just to replace and repair some urban freeways, and still, the problem persists.

Situations like this are complex. Within the overall context of the urban freeway pavement-reconstruction problem, many specific concerns and problems must be addressed. These include problems related to work-zone capacity, materials handling and supply, the safety of both motorists and highway workers, very complicated scheduling, and public relations. Furthermore, these projects can have dramatic economic impacts and can disrupt the plans and schedules of hundreds of thousands of people for the duration of the project.

Clearly, finding cost-effective and customer-sensitive methods to reconstruct freeway pavements is an important national issue. Just as clearly, the solution to this problem will involve numerous highway disciplines and does not fit neatly into our current, more compartmentalized methods of research and study.

Test Case - I-710 in Los Angeles

In mid-1997, the Federal Highway Administration (FHWA), the Transportation Research Board (TRB), and the California Department of Transportation (Caltrans) formed a partnership to determine the best way to replace an urban pavement. The partners agreed to use Interstate 710 in Los Angeles as a test case. The partnership had two basic goals: (1) find a solution for I-710 and, in the process, identify the critical issues and provide a model for solving urban freeway problems, and (2) pioneer a new way of doing business within the highway community.

Realizing that this mission cuts across traditional lines of expertise, the partners assembled four multidisciplinary teams with experts from throughout the country and representing the entire highway industry. The typical team was made up of a chief engineer from a state department of transportation (DOT), an FHWA division administrator, a state DOT project engineer, a specialist from the asphalt- or concrete-paving industry, a highway contractor, a pavement designer, a traffic engineer, a maintenance engineer, and a member of the academic community. Two of the teams were charged with producing an asphalt pavement design, and the other two a concrete pavement design.

In addition, a team of public relations specialists and a team of life-cycle cost analysts are in the process of refining each of the recommended solutions.

I-710 in Los Angeles is an excellent test case for this project. It is a 26-kilometer-long, eight-lane freeway with concrete pavement built in the 1950s. It currently carries more than 200,000 vehicles per day. As the primary access route to the city of Long Beach and to the port of Los Angeles, I-710 is both a heavily traveled truck route and a very important commuter route.


The teams first met in February at a three-day workshop held on the campus of the University of California at Irvine. The workshop was divided into three basic activities: a fact-finding phase, including a bus tour of the project site and a public meeting; a brainstorming and analysis phase; and a presentation phase. The teams were tasked to develop and propose a project design that would:

  • Provide a renewed pavement with a service life of at least 40 years.
  • Minimize agency life-cycle cost.
  • Minimize short- and long-term user cost.
  • Minimize traffic disruption.
  • Minimize community and environmental effects.
  • Provide for the safety of both highway users and construction personnel.

Of these six criterion, the requirement for a pavement with a service life of 40-plus years was perhaps the most unusual because this is twice the design life of a typical pavement. The partners felt that a major reconstruction project on such a heavily traveled route should be a very rare event, and they wanted to be able to assure the public that, in return for enduring the inconveniences and economic impacts of reconstruction, they would not be inconvenienced to this extent again for a very, very long time.

Although the workshop recommendations are still being analyzed and refined by Caltrans (and FHWA), all four teams designed a pavement with a structural life projected to exceed 40 years. It was acknowledged that both asphalt designs would need periodic surface restoration during the 40-year period and that perhaps the concrete designs would as well. In all cases, this was envisioned as a minimal project to correct surface deviations and restore ride quality and/or skid resistance. Such work could be done at a relatively low cost and could be performed at night to minimize the effect on traffic.

Preliminary Designs

As shown in tables 1 and 2, the designs proposed by the individual teams varied considerably among themselves and with the typical Caltrans design for this type of project. Despite this variety and the innovative approach taken by the teams, all of the proposed solutions have some surprising similarities. All of the teams proposed:

  • Replacing the pavement in all four lanes in each direction as opposed to the Caltrans proposal to replace only the two truck lanes in each direction.
  • Recycling virtually 100 percent of the old pavement back into the new project, thus eliminating the need to remove waste materials from the job site and greatly reducing the quantity of new materials needed to be brought to the site.
  • A greatly accelerated work schedule, in some cases involving total closure of segments of I-710 in one direction at a time.
  • Very imaginative, traffic control plans intended to minimize the duration and negative impacts of reconstruction activities.
  • A design that emphasized constructability and contractor innovation.
  • Incentives and innovative contracting techniques to reward contractors for early completion and for exceeding specification requirements.

This table presents a summary of the reconstruction proposals of Caltrans and the four workshop teams. In making comparison be cautioned that the scope of work varies between the different proposals and the life cycle costs and the user costs have yet to be finalized. For example, while the Blue and Brown teams' proposals show the lowest initial cost, the yellow team proposal may have a lower life cycle cost and the Green team proposal may result in the lowest user costs.



Surface Type




Traffic Control Features




Lanes Replaced





3 years

Night and weekend work only

Maintain at least 2 lanes in each direction at all times

$60.8 million

Outside 2 lanes & Outside shoulders


Stone Matrix


10 months

(2 construct-ion seasons of 5 months each)

Full closure between major interchanges - one direction at a time

Truck traffic to and from port diverted to concrete lined Los Angeles River Channel running parallel to project

Non-work side restriped to carry 2 lanes of traffic in each direction

$72.3 million

All lanes and both shoulders



18 weekends

Full closure of approximately 3-4 mile sections in one direction at a time during weekends

Traffic from closed direction detoured to parallel roads

All lanes and shoulders open Monday through Friday

$87.6 million

All lanes and both shoulders



6 months

(+18 months for crossroad bridges)

Replace all crossroad structures with clear span sections

Maintain 4 lanes in each direction at all times by shifting lanes from side to side to create 2 lane wide work zones throughout the entire project length

$191.5 million

All lanes and both shoulders


Superpave Hot Mix Asphalt

42 weeks

Schedule lane closure to off peak nights and weekends only, when facility has excess capacity

Maintain 4 lanes in each direction during high volume hours

$64.9 million

All lanes and both shoulders

This table presents a summary of the reconstruction proposals of Caltrans and the four workshop teams. In making comparison be cautioned that the scope of work varies between the different proposals and the life cycle costs and the user costs have yet to be finalized. For example, while the Blue and Brown teams' proposals show the lowest initial cost, the yellow team proposal may have a lower life cycle cost and the Green team proposal may result in the lowest user costs.

























RIGHT OF WAY (Current Value)










GREEN: PCC solution 12" doweled PCC pavement over 14" of LCB (existing pavement recycled on site)

BROWN: AC solution/Rubblize existing PCC and CTB and overlay with 8" of AC (Polymer)

BLUE: Stone Matarix Asphalt (SMA) solution, ( 8 3/4" overlay) over existing PCC (localized repairs needed).

YELLOW: PCC solution. Recycle existing 8" PCC and 8" of CTB and stabilize with cement and replace on subgrade (18" to 12").

Then place PCC pavement 12"(inside lanes) to 14" (outside lanes).

Lessons Learned

By any measure, this workshop was an unqualified success. Caltrans was provided with many new ideas and options that will not only impact the I-710 project but many other projects in the years to come. Just as importantly, we learned that this concept - approaching a difficult issue with an interdisciplinary team made up of members from all facets of the industry - was highly successful. Each team generated its own synergy and enthusiasm as the team members fashioned a solution that considered the combined expertise of the team. Clearly, the special problems involved with the reconstruction of a heavily traveled urban freeway lend themselves to this approach.

While many of the engineering ideas produced by the teams are still being analyzed, some very important "general principles" emerged:

  • Short-term freeway closures (usually one direction at a time for two to three days over a weekend) are a viable technique that can dramatically lower costs and just as dramatically shorten overall construction time. (See figure 1.)
  • The traveling public will tolerate, perhaps even prefer, a relatively few short-term closures if the alternate is an extended period of congestion due to reduced lanes and construction-related delays.
  • Public relations issues should be considered in the decision-making process, even as early as the project-concept stage.
  • Careful use of "excess capacity" on nights and weekends, when combined with a public relations campaign, can create acceptable short-term work areas and still control cost and congestion. (See figure 2.)
  • It is much more cost-effective to make relatively minor modifications to the design of a current project to accommodate the future reconstruction project than it is to deal with inadequate widths and vertical clearances as a part of that future reconstruction project.
  • A 40-year (or longer) pavement design life is possible and is very cost-effective on urban freeways, considering the user costs associated with pavement reconstruction on these major routes. (See figure 3.)

Where Do We Go From Here?

Based on the initial success of the Los Angeles workshop, other states are planning their own workshops to examine special projects in their state. In addition, the FHWA Highway Operations Division has just initiated a major effort to emphasize the methods and benefits of accelerated construction and maintenance. These activities will promote concepts, materials, methods, and a customer-oriented mind set. The goals are to build projects faster with less disruption to the traveling public and to ensure the safety and the quality of the completed project. The Los Angeles workshop has shown that these goals are realistic and achievable.

David O. Cox is a senior engineer in FHWA's Office of Engineering. He deals with contract administration and innovative contracting techniques on a nationwide basis. He previously served as assistant division administrator in Tennessee, technical systems development engineer in Florida, and area engineer in Louisiana. Cox has a bachelor's degree in civil engineering from Oregon State University and a master's degree in civil engineering from Louisiana State University. He is a registered professional engineer in Louisiana.