Timing delays like relays
State DOTs study new ways to speed construction in consideration of cost to commuters
In the private sector, the axiom "time is money" has long held water
In the private sector, the axiom "time is money" has long held water.
Now, in the post-interstate erawhere reconstruction of existing roadways is complicated by the crush of staggering traffic loadsstate departments of transportation are rethinking contract structure, project scheduling and material specs to leverage time and money for their driver patrons.
Among the new permutations of the way road work used to be done is "A+B" bidding, in which user-delay costs, or so-called "lane rentals" ("B"), are added to a conventional construction bid ("A").
Another approach is "A+B+C" bidding, in which future rehabilitation, reconstruction and user-delay costs ("C") are added to the mix.
A+B contracts have the effect of spurring faster road construction because the contractor is given a quantifiable incentivebased on real economic impacts to usersto finish the job quicker. And A+B+C contracts look to the future in that they help select durable paving materials that can be restored quickly when the need ultimately arises.
Contract changes extend to project scheduling. One DOT found that complete, albeit brief, closures of a major urban expressway on consecutive weekends hurt drivers less than a drawn-out process of multiple lane closures lasting months.
In addition to their time value, fast initial and future reconstruction/rehabilitation of pavements also saves lives because the sooner a paving crew can get in and out, the sooner the barricades can come down, removing both driver and worker from the zone.
The Federal Highway Administration (FHWA) has been addressing the needs of drivers by identifying specific strategies for fighting user delay and disruption in work zones, while optimizing safety.
More than driver time is affected by road construction. Curtailed customer access during construction may harm local businesses. The Wisconsin DOT found that detours abutting highways under construction resulted in a decline in sales volume to affected businesses of as much as 17%.
Louisiana tackles A+B+C
Minimizing inconvenience to the motorist was a prime reason for Louisianas first A+B+C contract, bid and constructed in 2001 on I-10 in St. John the Baptist Parish.
"It was the first to include a factor from the life-cycle cost analysis procedure based on the FHWA model," said William Temple, P.E., chief engineer, Louisiana Department of Transportation & Development (DOTD). "When you total all those costs over a certain period of time, you see which pavement type will be the most cost-effective."
Contractors bid a conventional, "hard" figure (A), plus the number of days they estimated to complete (B), cost-out by the state at $15,000 per day in user costs. Added to this A+B sum is a figure set by the state to cover future life-cycle reconstruction costs (C). This amount is not paid or charged to anyone, but is used to distinguish hot-mix asphalt (HMA) life-cycle costs against portland cement concrete (PCC), and helps establish total costs of the project over the long term.
Of the five bids received, four were for HMA and one was PCC. The winning bidder was Barriere Construction Co. LLC, New Orleans, with a total bid of $13.1 million, including a base of $7 million (A), 95 days at $15,000/day (B), with an added "cost" of $4.6 million for HMA life-cycle costs over 30 years time (C).
"The C portion of the contract is the estimated life-cycle cost in todays dollars over the 30-year life of the project," said J. Don Weathers, executive director, Louisiana Asphalt Pavement Association. "No money changes hands. Its just added to the bid and balances with the concrete alternate."
The B portion, however, was real money. "Thats the incentive/disincentive," Weathers said. "For every day under that figure, up to a maximum amount, the contractor gets a bonus. For every day over, they are penalized."
However, due to hard work, good weather and skilled organization, Barriere was able to beat the 95-day parameter. And because the contractor exceeded the maximum bonus, the state and its taxpayers received "free" days of accelerated construction.
"We beat the maximum bonus by four days," said Bert Wilson, vice president, Barriere Construction Co. "Our project team put together a very aggressive schedule and went out to execute it."
Wilson credited project manager Matt Wood for much of the projects success.
The project ran on I-10 from U.S. 51 to the Reserve Relief Canal, a distance of approximately four miles. For the project, Barriere first cold-milled the existing HMA shoulders to a 2-in. depth prior to overlay to create a work-zone traffic lane. Then, subcontractor Hard Rock Construction repaired the existing base-failed continuously reinforced concrete pavement.
"A sub could get in to repair the concrete quicker than we could, so we used them to move the time frame up on the project," said John Victory, quality control manager of Barriere. "Then we set up to do the overlay."
Following a tack coat, an all-Superpave Louisiana Level 3 (high-traffic load) was placed in three lifts, 2.5 in., 2 in. and a 2-in. wearing course. The standard Louisiana PG 76-22M Superpave binder was incorporated, using an SBS polymer modifier. Approximately 82,000 tons of HMA were placed on the project.
The I-10 project was vetted through the Louisiana DOTD Pavement Structure Review Committee, which partnered with both pavement types to develop a consensus procedure for the life-cycle cost analysis.
Louisiana will continue with innovative contracting this year, Temple said. "Starting in July 2002, we will adopt this as a standard policy," he said. "Well be doing alternate design/alternate bid on all projects in which bids are within 20% of each other. If theyre greater than 20%, well select the least expensive bid and wont do alternates."
Temple added that the statein conjunction with Louisiana State Universityis conducting real-life testing of user delays to validate the FHWA model.
"The question has been raised whether the model predicts realistic user delay costs," Temple said. "We have initiated a research study in which we are driving through construction zoneswith GIS equipmentto monitor the time it takes to get through zones at different times of the day. Well take that data and use it to validate the model."
Asphalt speeds Kentucky rebuild
Asphalt overlays recently permitted a 3.3-mile stretch of I-64 in Louisville to be reconstructed swiftly and with minimal user delays.
About 100,000 vehicles use this stretch of highway on a typical commuter weekday. The Kentucky Transportation Cabinet (KTC) calculated that going down to one lane could back up traffic by as much as 15 miles during rush hour. So KTC officials began looking at alternatives.
One alternative was to shut down traffic entirely for two weeks and repave all lanes during that time. However, that would have congested alternative routes too much. U.S. 60, which runs through the city, would not have been able to handle the traffic, and I-71 would have been pushed to 150% of capacity during rush hour.
"We decided to take the same concept, but do it on weekends when alternate routes would be able to accommodate the diverted traffic," said Gary Sharpe, the cabinets director, Division of Highway Design.
Thus the decision was made to close the section of I-64 in both directions each weekend from 9 p.m. Friday until 6 a.m. Monday and complete the $21 million project in 16 weekends.
The project originally allowed for either concrete or asphalt to be used, but asphalt was the winning bid.
"We do [portland cement] concrete and asphalt, but we were at a loss as to how to get it done using concrete," said Dave Hardin, vice president and chief engineer of the road division for Gohmann Construction, the winning road contractor for this project.
Asphalt pavements can be put in place much more quickly than other products, said Dean Blake, executive director of the Plantmix Asphalt Industry of Kentucky.
"Newly paved asphalt roads can be opened to traffic almost immediately because no curing time is necessary," he said. "Because asphalt can be paved so quickly, it often can be done at night and on weekends, which minimizes construction delays."
The final process called for breaking-and-seating of the existing concrete pavement, followed by placement of a 6-in. Superpave base course, a 4-in. Superpave intermediate course and a 1.5-in. Superpave friction or surface course. All mainline HMA used PG 76-22 (SBS-modified) asphalt binder. The shoulder HMA was the same thickness as the main line and used PG 64-22, the commonwealths standard binder grade.
The KTC credited an aggressive, proactive community education campaign with improving satisfaction for the decision to close a 3.3-mile stretch of I-64 during the weekends.
"This is the wave of the future for road projects," said Damon Hildreth, executive assistant for the cabinets office of public affairs. "We held public meetings and got feedback that we used to make the inconveniences smaller. Then we were able to go back to the public and get them to take ownership of the project."
Fast-tracking in urban New Mexico
In New Mexico, FHWA and New Mexico State Highway and Transportation Department officials planned on only two years for the reconstruction of the only interstate interchange in New Mexico: The "Big I," located in the heart of Albuquerque.
The scope of the $225 million Big I reconstruction includes 111 lane miles of new freeway and frontage roads, 45 new and 10 rehabilitated bridges and the movement of 2 million cu yd of earth.
The commitment to a fast-track project was well understood when letting began for the designers and contractors. Constructablity was set as the No. 1 priority during the design phase.
An innovative aspect of the Big I reconstruction has been the extensive partnering between virtually every person and organization touched by the project. With a major public relations campaign at its core, the project brings together the federal and state transportation departments, the city of Albuquerque, Bernalillo County, the business community, the trucking industry, safety and emergency agencies, the media and commuters.
Fast-tracking the Big I reconstruction also has demanded the best tools for getting the roads and bridges built quickly. That meant the use of HMA for the 111 lane miles of roadways, and precast concrete segments for many of the 45 new bridges. Approximately 350,000 tons of HMA were being used in rebuilding pavements in the Big I Project.
"From day one, we were setting a record timetable of two years on the project," said Reuben Thomas, division administrator for the New Mexico Division of the FHWA. "We realized that we could only do it with asphalt."
Thomas said the need for traffic maintenance required a pavement that could be applied overnight and ready to handle the morning commute.
"We did consider bidding concrete as an alternate, but that was ruled out as we looked at the overall objectives of the project: To produce a quality project in record-setting time, minimizing the impact upon the public," said Thomas during an interview in early October. "The benefits of using asphalt have proven themselves. We have been able to maintain two lanes of traffic in both directions throughout most of the project. Were ahead of schedule. And were within budget."
User delays tip toward HMA
The promise of a speedy job and fewer user delays for time-pressed airport patrons led the city of Indianapolis to change from PCC to HMA in the reconstruction of Airport Road in 1994.
The road connects I-70 to Indianapolis International Airport, and is built to freeway standards, said Gerald Huber, P.E., Heritage Research Group, Indianapolis.
"The project called for complete reconstruction down to the subgrade," he said. "But with asphalt there is no waiting for cure time. Once youve compacted the asphalt you can open it to traffic immediately."
The original design was 12 in. of plain, jointed PCC with 7 in. of aggregate sub-base.
"We ended up designing it as 18.5-in. full-depth HMA," Huber said. "The consultant had looked at PCC and HMA options and found that asphalt was less expensive. The consultant then said we need to look at life-cycle costs, and ended up with PCC still costing more. They stated that PCC still was the better deal, because they said HMA would rut and shove in traffic."
The Asphalt Pavement Association of Indiana became aware of the controversy and was able to point out that the consultants life-cycle costing did not include user delays in the initial construction. "They also did not allow for user delays during future concrete joint repair."
The final result was an HMA savings of $1.4 million as compared to the PCC alternative, and ultimately HMA was selected by the city. The pavement has performed extremely well and the design embodies elements of todays perpetual pavements, Huber said.