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Surviving Carmageddon II, I-405 Job Pushes Forward

Fri November 30, 2012 - West Edition
Jennifer Rupp

It was labeled “Carmageddon” in 2011, and “Carmageddon II” in 2012 by the Los Angeles County Metropolitan Transportation Authority (Metro); a 10 mi. (16.1 km) construction project on the nation’s busiest freeway, in Los Angeles County.

More than 250,000 motorists travel the I-405 over the Sepulveda Pass, which is only one segment of this gargantuan $1.48 billion project freeway improvements project managed by Metro.

The I-405 Sepulveda Pass Improvements Project involves the addition of a 10 mi. (16.1 kg) HOV lane and improvements for supporting infrastructure such as ramps, bridges and sound walls on the San Diego Freeway. (I-405). Additionally, lane widening is taking place from the Santa Monica Freeway. (I-10) to the Ventura Freeway. (U.S.-101).

The project will help reduce existing and forecasted traffic congestion on the I-405 and enhance traffic operations by adding freeway capacity in an area that experiences heavy congestion. In addition to these modifications, the project will improve both existing and future mobility and enhance safety throughout the corridor. Project benefits include a decrease in commuter time, reduction in air pollution, and promotion of ridesharing.

Three bridges are being completely reconstructed in a two-phase process to reduce the impact on traffic flow. The first bridge that began the reconstruction process was the Sunset Bridge in 2010, which also included the widening of under-crossings at Montana Avenue, Getty Center Drive, Church Lane and Sepulveda Boulevard.

The Sunset Bridge was reopened on Sept. 24, 2012. The newly expanded, seismically enhanced bridge is approximately 30 ft. (9.1 m) wider than its predecessor. It boasts additional lanes to improve area traffic flows, and its columns have been repositioned to accommodate the additional freeway lane created by the project. The new bridge is approximately 5 ft. (1.5 m) higher than the previous one and contains a new water line, underground power lines and other improved utility infrastructures.

Skirball Center Drive Bridge was next. Like the Sunset Bridge, Skirball was also widened by 30 ft. (9.1 m) and designed to the latest seismic standards. The new bridge will include a minimum 10-ft. (3.1 m) wide travel path on the south side of the bridge to accommodate wildlife movement. This path would function as a wildlife conduit (nighttime hours) as well as a pedestrian sidewalk. While the north side of the bridge was completed this summer, the south side expected to be open by summer 2013.

The biggest and most talked about bridge on the docket is the Mulholland Bridge over the Sepulveda Valley. The south side was demolished in July 2011, with city and county agencies preparing for Carmageddon.

Major congestion was avoided, however, and in a press release this past July, L.A. County Supervisor Zev Yaroslavsky asked the public for the same cooperation for the demolition of the north side of Mulholland in September of this year.

“During Carmageddon I, drivers proved the skeptics wrong. They heard our warnings and stayed off the roads, creating a traffic breather not seen since the free-flowing freeways of the 1984 Olympics. I have every confidence that they’ll rise to the occasion again,” said Yaroslavsky. And they did.

On Sept. 29th, the Mulholland Bridge was completely shut down for 53 consecutive hours for the demolition of the north side. Half a million motorists drive this portion of the I-405 over a typical day.

Kiewit Infrastructure West Co., with offices throughout California and the United States, is the prime contractor on the I-405 project. A number of subcontractors are working on the job, notably Pennhall Company, headquartered in Anaheim, Calif., which is performing the demolition on all three bridges.

Crews are working seven days a week, day and night.

“The main freeway work is being done almost exclusively at night, between midnight and 5 a.m., in order to impact the traffic as little as possible. It would be literally impossible to build a bridge in this area during the day. Impacts to traffic would be untenable,” said Dave Sotero, Caltrans media relations.

The contractors have found beneficial uses for excavated material on the project by recycling it to create the aggregate for the I-405 roadbed, and concrete paving on the Orange Light Extension — a bus way in the San Fernando Valley.

When this 10 mi. stretch is complete, the I-405 will have the longest HOV lane in the country. The Sepulveda Pass segment was last on the list because of the challenges it presented.

“With traveling through a canyon, there is no easy way to add a highway lane without carving out some of the canyon to make room,” said Sotero.

Accompanying the three bridge replacements is the reconstruction of the Wilshire ramps and loops. Caltrans states that nowhere is improvement needed more than at the Wilshire Boulevard/ I-405 interchange.

Accompanying the three bridge replacements is the reconstruction of the Wilshire ramp interchange. Metro states that improvements are especially at the Wilshire Boulevard/ I-405 interchange. Drivers merging on and off the I-405 jockey with drivers traveling east and west on a heavily congested Wilshire Boulevard.

This creates a potential safety hazard for commuters and causes many hours of delay each year. All eight ramps will be rebuilt to separate the traffic, eliminating cross-traffic patterns and allowing for safer and smoother transitions.

The entire project was originally slated for completion in the spring of 2013, but utility challenges and ROW acquisition has pushed the end date back about four to six months, closer to the end of 2013.

Federal stimulus funds kicked in $190 million of the total $1.48 billion bill, the remainder of which has come from state and other sources. Approximately 18,000 jobs were created during construction.

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