The Traffic Nightmare that Wasnâ€™t: Summer Slam on SR-60 is a Slam Dunk!
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Here’s how you know the 55-hour closures of multiple lanes of the Pomona Freeway (SR-60) in July and August were a big deal: they had a name — Summer Slam on SR-60. A name elevates a closure from mere inconvenience to possible traffic nightmare. Think “Carmageddon.” “The Rampture.” Orange County’s “Bridge Bash.” All were major closures that had the potential to seriously disrupt traffic operations on multiple freeways. The names signaled to motorists that anyone who chose to brave the closure area should brace themselves for the worst.
So when District 7 held a press conference on July 10 to announce Summer Slam on SR-60 (see video below), the message was unmistakable: Be afraid. Be very afraid. These closures could slow traffic to an excruciating crawl for miles! Plan ahead! Avoid the area! Choose an alternate route! No, REALLY! We mean it!!
To be clear, the four 55-hour weekend closures, which occurred on nonconsecutive weekends in July and August, were not full freeway closures. During each weekend, two or three lanes were closed in one direction between Nogales Street and Fullerton Road. Motorists who chose to ignore the warnings and use SR-60 could squeeze by in a lane or two. Mostly, anyway. During each 55-hour closure, there were also two four-hour full freeway closures (in one direction) late at night for installation and removal of k-rail.
And that’s not all. On- and off-ramps were closed in the closure area. The northbound SR-57 connector to westbound SR-60 was closed. Speeds were reduced in the construction zone. Twenty portable changeable message signs were strategically placed across the region to direct motorists. The goal: to reduce traffic volumes by 60 percent.
The project prompting Summer Slam is a $121.5 million pavement rehabilitation on SR-60 in both directions between the San Gabriel River Freeway (I-605) and the Orange Freeway (SR-57). SR-60 is a major east-west route, carrying more than 250,000 vehicles each day. The number 3 and 4 lanes in particular take a beating from truck traffic.
Many motorists believe that freeways are basically a long slab of concrete. In reality, they’re a complex, multi-layered sandwich extending more than two feet deep. The composition of the sandwich varies, depending on factors such as location, traffic volumes and geology. But in the case of the Summer Slam segment of SR-60, the very bottom layer is filter fabric, which feels like thick felt and protects against water damage. On top of that is geogrid, a plastic webbing that helps hold the aggregate base together. Six inches of aggregate base come next, followed by six inches of lean concrete base, and then a dowel basket for strength. It’s all topped off by 13 inches of jointed plain concrete pavement (JPCP) and, of course, striping. This sandwich is what would have to be replaced during the four closures.
Resident Engineer Joe Doughly and the construction team — including Flatiron’s 120-person crew — had their work cut out for them. The team would be rebuilding almost an entire lane mile during each closure at a cost of almost $1 million. Although Doughly has over a decade of experience in freeway construction, he had never handled a 55-hour closure before. Neither had Flatiron’s project manager. This was on-the-job training, and the stakes were high.
“I was nervous at first. We knew we had to reopen the lanes to traffic by 5 a.m. Monday morning. The k-rail had to be up and the striping done,” said Doughly. “Otherwise, we’d be in trouble. There would be calls left and right.”
What could go wrong? Equipment failure. Problems with the concrete mix. Issues with the quality of the materials. A malfunction at the concrete plant. There are endless ways that a project can go awry, a myriad of reasons why 5 a.m. deadlines come and go with cones still in place. Careful planning is perhaps the best way to prevent the unexpected from derailing an operation.
Doughly might have been a 55-hour closure rookie, but he planned like the veteran he is. He had a detailed timeline mapping out when each stage of the work had to be completed. He had a backup concrete plant, and a backup for the backup. He used compaction testing consultants with a lab nearby to minimize travel time. He built extra time into the schedule to address any problems that came up.
And problems did come up, though not many and not major. During the first weekend, the challenge was the concrete mix. It was too wet. And then too dry. And then it was juuuuust right. Thanks to Doughly’s scrupulous timeline, the contractor had enough wiggle room to allow for some mix tinkering without blowing the schedule.
The aggregate base also needed some extra attention at times. Once the aggregate was down, a testing consultant measured the compaction using an instrument called a nuclear densometer. Compaction is important because if the aggregate isn’t sufficiently compacted (in this case, 95 percent), it won’t hold together well. If the compaction wasn’t at 95 percent, the contractor had to run the drum roller over the aggregate again, and then they would re-measure. When the nuclear densometer indicated acceptable compaction, the testing consultant would confirm the measurement at the nearby lab and the sandwich assembly would continue. In most cases, the compaction was fine, but a few times the drum roller had to be called into service to get the numbers up.
Another first for Doughly during Summer Slam was a new approach to freeway signage. “We used a new type of message sign on the freeway that works on remote control,” he said. “The Operations people were able to control the messages from a laptop in our office.” [Read more about District 7’s use of automated workzone information systems (AWIS) in the article on Transportation Management Plans in this issue.]
Those remote-controlled changeable message signs were especially useful during the third closure weekend, when an incident on a nearby freeway prompted many motorists to ignore the Summer Slam warnings and use SR-60 as their alternate. During the previous closures, traffic flowed fairly well at about 40 to 50 miles per hour, which may be why motorists chose SR-60 as their alternate. But with all those cars piling into the construction zone during the third closure, average speeds dropped to 20 to 25 miles per hour for part of the weekend. Operations staff used the remote-controlled message signs to direct motorists to other freeways and thereby eased congestion.
Given the magnitude of the operation and the potential for large-scale traffic disruptions, Summer Slam on SR-60 was by all objective measures a success. The work proceeded smoothly, traffic flowed reasonably well, and all closures were picked up early or on time.
“The success of the Summer Slam on SR-60 can be attributed to the vigorous work by the contractor, Caltrans Construction and all the supporting units, including Traffic Management, Public Affairs, Maintenance, Maintenance Design, Traffic Operations and Construction Safety,” said Doughly. “What surprised me most was how well it went. There were no major issues. If I have another 55-hour closure, now I know what to do.”