Committee Continues Designing New Bridge - The Missourian: Local News

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Committee Continues Designing New Bridge

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Posted: Saturday, May 18, 2013 1:00 pm | Updated: 12:01 pm, Wed Jun 26, 2013.

The Missouri River Bridge design team agreed that the bridge spanning from Washington to Warren County will be “magnificent” and “iconic.”

The Missouri River Bridge Enhancement Committee had a productive meeting Tuesday in which many preliminary decisions on the bridge design were made.

Members’ discussion included pier shape and lighting, the number and location of overlooks, the pedestrian/bicycle railing, overhead pier elements, girder lighting and trail lighting.

The committee is tasked with making selections of possible enhancements, then prioritizing those elements. Cost comparisons will be presented at the next meeting, in which enhancements may be deleted depending on budget.

Piers

The committee was presented with three pier options. The pier design will not be funded by enhancement funds.

Fred Gottemoeller, with Bridgescapes LLC, reminded the committee that the piers will be seen from a distance.

“The shapes that the piers present ought to be large, simple, memorable shapes that you pick up on — even at a distance,” he said.

Of the three choices, the committee unanimously favored a “gothic” option, which fits into the art deco period the group agreed fit Washington.

The option has a pointed arch cut out of the center, with raised panels on each side. The concrete looks like two martini glasses sitting next to each other, only more curved. The raised panels, the committee noted, are similar in shape to the Washington monument in Washington, D.C.

Faith Baum with Illumination Arts discussed pier lighting, which will be achieved with LED lights.

“When it comes to lighting this bridge and these different components, using juxtaposition of light and shadow becomes very important to reveal those forms.”

Baum said it’s both a beautiful way to light a three-dimensional structure and show that it’s three-dimensional, but also is more cost-effective.

“Because in doing that, you’re lighting only certain components of the bridge, not everything, and in doing so, you’re making it stand out against itself.”

Linear LED lights would be mounted along underside of the girders close to the pier cap. The effect of the lights would light the face of the pier cap while setting the raised panel in shadow, Baum said.

Because the lights are aesthetic and not for navigation, MoDOT would not be responsible for maintenance.

Judy Wagner, MoDOT area engineer, said MoDOT will partner with the city on maintenance during bridge inspections, but replacing burnt-out aesthetic bulbs would not be a priority.

LED lights typically last 50,000 to 80,000 hours. Because technology is constantly changing, the lights may even be better by the time they’re actually ordered for the bridge, Baum said.

“I think lighting of the bridge is important because we have lighting on our current bridge, and that was important when we did that,” said Mayor Sandy Lucy.

Number, Location of Overlooks

The enhancement committee agreed that one overlook near the center of the bridge (at the bridge’s high point) is a better option than two smaller overlooks.

John Griesheimer noted that taking care of two overlooks, even though they’re concrete, would be more difficult than maintaining just one. The two overlooks would have to be smaller and wouldn’t comfortably fit as many people.

The committee also felt that having one overlook would make it more special.

The design team said one overlook would be more architecturally pleasing.

The overlook would have a 16-foot radius. Seating would be built in.

Railing

The group opted for a 27-inch concrete barrier wall with vertical railing that reaches 4-feet tall. Seated drivers still would be able to see the river from the roadway.

The committee continues to favor black railing, despite the design team advising against black.

The design team said black rail wouldn’t look as nice against the blue sky and couldn’t be lit.

Photos of the railing in black, white and silver gray will be viewed at the next meeting.

Overhead Pier Elements

Four overhead pier elements were discussed. The committee unanimously favored a curved truss with a sunshade over the overlook.

The overhead truss would feature a large beacon in the center and would be reminiscent of the current bridge.

Girder/Trail Lighting

The committee agreed that a bright light that fades out would be the most suitable for the bridge.

Another option would light the full front of the bridge. The final option would be a slender line of light that would trace the underside of the bridge.

Griesheimer initially said he was disappointed that there wasn’t going to be any overhead lighting.

“This is more about enhancing the structure. Above deck lighting would detract from that,” Baum said.

“We’re replacing an icon, and with that our task is to create something that also is an icon,” said David Lisle, with Bridgescapes. “This will be one of the best-looking bridges you’ve seen in a long time. It will be a phenomenal bridge.”

The committee agreed that they would like the design team to explore lighting the entire bike trail, as opposed to only part of it. They also want the design team to look at lighting both sides of the bridge, as opposed to only the west face, which is visible from the city.

The cost difference in lighting a portion of the trail and only half of it is significant, as the difference is between lighting about 1,000 feet and lighting about 2,700 feet.

Cory Imhoff, with HDR, noted that the bridge will still be easily expandable by conventional means. The bridge will be wide enough to restripe to three lanes.

If a fourth lane is needed in the future, additional substructure and superstructure would be added. A cantilever that was originally discussed is no longer a viable option in widening.

The design team thanked committee members for their input and for making decisions together.

A full 3-D rendering of the structure of the bridge with enhancements will be presented to committee members at the next meeting, Thursday, June 20, at 8:30 a.m., at city hall.

/local_news

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