Strong side of the tracks

May 14, 2008

Even with its much-storied history, Rte. 66 never produced kicks quite like this. The I-215/5th Street Bridge project is the tip of the spear. This $25 million undertaking is the first phase of a larger plan to widen California’s I-215 between I-10 and State Rte. 210.

A collaboration between the San Bernardino Associated Governments (SANBAG), the California Department of Transportation (Caltrans), the Federal Highway Administration and the city of San Bernardino, the project could not happen soon enough to suit the roadway’s many users.

Even with its much-storied history, Rte. 66 never produced kicks quite like this. The I-215/5th Street Bridge project is the tip of the spear. This $25 million undertaking is the first phase of a larger plan to widen California’s I-215 between I-10 and State Rte. 210.

A collaboration between the San Bernardino Associated Governments (SANBAG), the California Department of Transportation (Caltrans), the Federal Highway Administration and the city of San Bernardino, the project could not happen soon enough to suit the roadway’s many users.

Rail and road crossing

Originally built in 1959 for far fewer vehicles, the I-215 freeway today is routinely beset with significant traffic congestion, especially during peak commuting hours. Ranked by the Texas Transportation Institute as one of the 15 most congested areas in the nation, the I-215 can only expect more traffic in years to come; it serves as a main artery through burgeoning San Bernardino County. And when it comes to heavy traffic, the section of I-215 at 5th Street in San Bernardino is certainly one of the hot spots. But this project is not only about street widening and traffic flow. A part of legendary Rte. 66, the roadway has a historical context, too, one that demands that attention be paid to aesthetic considerations as well as to the many technical design challenges. And there were other factors complicating design and construction.

“There are several major challenges on this project, but the main issue is that the bridge spans the freeway and a set of Burlington Northern Sante Fe (BNSF) railroad tracks, tracks dating back to the 1800s. And those tracks are one of the main sets of tracks leading out of the Southern California ports—the two busiest ports in the country. On average, these tracks run 100 trains per day,” explained Dennis Saylor, SANBAG’s project manager for design. “We’ve worked extensively with the railroad and Caltrans to minimize impacts to both the railroad and the freeway.

“We had the bridge designed and we are constructing it so that it could ultimately accommodate a 10-lane freeway, even though we’re still working with the current six-lane configuration. That was quite a challenge in itself. With this project we often talk about ‘threading the needle’ to get exactly the right placement; everything has to work for both the current situation and the future configuration that is already planned. But this project will provide very real benefits to the community and the region in terms of mobility and access, so we are quite willing to thread the needle to get it done.”

Given the complexity of the project, though, that needle must be threaded with great care.

“We started at the beginning of this year, and things have been going very well,” explained Andrea Nieto, SANBAG’s project manager for construction. “But we had some very complex scheduling issues that needed to be worked out up front. For example, a BNSF restriction precludes us from working over the railroad during the last quarter of the calendar year. That meant that as of Oct. 1, we could no longer work over or interfere with the railroad in any way. Obviously, scheduling was a crucial part of the project; that constraint affected contracts throughout the project timetable.

“As just one example, we had an environmental mitigation requirement to complete clearing and grubbing by Feb. 15, 2007. Because the construction contract was awarded on Dec. 6, 2006, mobilization had to be completed quickly. If that work was not completed on time, it would have pushed other schedule elements past the Oct. 1 deadline. Then we would have had to wait until next year to continue. Working out scheduling issues was extremely important for another reason: We’re going to have the same BNSF restrictions on other bridges in the larger program.”

But work restrictions were not only long-term concerns. According to Nieto, work windows over the railroad were virtually random in terms of both timing and duration.

“Work times over the railroad are dictated by BNSF’s requirements. Sometimes you only get a random, unscheduled 15-minute time span. That’s very challenging for the contractor; design and everything else must be worked out very well beforehand. And that’s exactly what we did. As a result, there have not been any big design problems and everyone has been very, very responsive.”

Fault of its own

Reconstruction of the 5th Street Bridge will facilitate the next phase of the project—widening I-215 from six to 10 lanes. The I-215 project will significantly reduce congestion and also eliminate some “merge-and-diverge” ramps that are not up to current standards. Facilitating equal access to both the east and west sides of San Bernardino, the new ramp scheme replaces existing hook ramps constructed in the 1950s. Developed in close cooperation with the city of San Bernardino, the bridge design also features unique lighting and important historical elements.

Other key project features include the development of a comprehensive traffic staging plan aimed at keeping all traffic lanes open; drainage modifications; traffic-signal improvements; ramp metering; landscaping; and right-of-way. But the project team faced another significant challenge that affected many other facets of the design—the bridge is very close to a known fault line.

“The controlling fault for the project site is the San Jacinto (SJO) fault. SJO is a strike-slip fault that is capable of a maximum credible earthquake of magnitude 7.5. The bridge site is approximately 2 km from the SJO fault,” explained Kosal Krishnan, structural department manager for DMJM Harris, the transportation firm tasked with the project’s design. “The bridge site also has a surface fault rupture potential due to the proximity to the San Jacinto fault splays and branches. So Caltrans’ geologists recommended that the bridge design incorporate offsets to cope with potential fault ruptures—specifically, a 0.5-m horizontal offset and a 0.2-m vertical offset.”

The project team and Caltrans established project-specific seismic design criteria jointly in March 2005. Consisting of three separate earthquake-loading scenarios, the design criteria aided the structural designer in evaluating bridge performance for each of the following cases:

  • Ground shaking in accordance with the Caltrans seismic design criteria;
  • Deterministic fault rupture alone; and
  • Deterministic fault rupture combined with a reduced ground shaking.

In terms of seismic considerations for the bridge itself, the team selected a traditional cast-in-place box girder bridge supported on 1.8-m-diam. multicolumn bents. The team also evaluated the use of a compact foundation that would tend to force the fault line to go around the foundation. Such foundation types can include large-diameter CIDH piles as well as driven piles on pile caps, because the cluster of driven piles densifies the surrounding soil. Ultimately, the project designers concluded that using driven piles on a pile cap was the preferred foundation type for constructability considerations.

Talking it through

Given the significant number of critical project elements and the number of stakeholders involved, the project team placed a great deal of emphasis on effective communication.

“The degree of cooperation between SANBAG, Caltrans, BNSF and the city of San Bernardino has been remarkable,” explained Mario Montes, project manager for DMJM Harris.

Citing weekly project meetings featuring the major stakeholders, Montes also pointed out that coordination and communication measures do not end with the formally recognized stakeholders. Although the project team worked hard to keep detours to a minimum, traffic has occasionally been rerouted to surface streets for such tasks as falsework construction and bridge demolition.

Targeted for completion in 2009, the I-215/5th Street Bridge project was financed through a combination of state funds and Measure I [a voter-approved half-cent sales tax]. The total cost for the I-215 corridor project is estimated at $800 million, including design, right-of-way acquisition and construction.

The I-215/5th Street Bridge project is the tip of the spear, the first of a series of projects that will ultimately transform the I-215 freeway by enhancing traffic flow and improving safety. And by all accounts, getting your kicks on Rte. 66 has never looked quite like this.

About The Author: Schurr is a New York-based freelance writer who reports on transportation infrastructure.

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