It may not be the end of the rainbow in Chippewa Falls, but it could be.

The Marsh Rainbow Arch Bridge that crosses Duncan Creek has been an East Spring Street landmark in Chippewa Falls since it was built in 1916.

“There aren’t a lot left like that in the whole Midwest,” said Rick Rubenzer, the city’s public works director.

The Marsh Rainbow Arch bridge was designed by James B. Marsh and built by the Iowa Bridge Company. It has been on the National Register of Historic Places since 1982.

But, as beautiful as the bridge is, the city wants to know if its is sturdy enough to continue handling traffic. The two lanes on the bridge are narrow for today’s traffic.

The bridge may not need to be replaced, but the traffic going over the bridge may have to be reduced.

That’s why the city’s Board of Public Works at its meeting at 5:30 p.m. Monday at City Hall will consider hiring Ayres Associates of Eau Claire for $74,248, which covers engineering services.

The total contract would be for $89,063, with the difference going for testing and doing a historical assessment. That cost is over six times the $13,950 cost to build the bridge.

Ayres would look into the following alternatives for the Rainbow bridge:

n Do nothing;

n Make Spring Street a one-way street to reduce its traffic, and do minor work to upgrade the bridge;

n Close Spring Street to vehicle traffic but keeping the bridge open for bicycle and pedestrian traffic;

n Rehabilitate the bridge to accommodate two lanes of traffic;

n Replace the bridge with a conventional concrete deck girder bridge. Its appearance would be spruced up with decorative railings. lighting and other features.

n Replace the bridge with a conventional concrete deck girder bridge but make the new one look similar to the Rainbow bridge.

n Replace the bridge with a new concrete arch bridge.

Rubenzer said the Ayres analysis would be due Oct.1, 2009. If needed, preliminary bridge plans would be due in January 2010.

Bridge safety has been at the forefront since last year’s collapse of an interstate bridge in Minneapolis, said Robbie Krejci, assistant city engineer.

City bridges are inspected on a regular basis and ratings are assigned. “When that rating reaches a certain point it enters into the bridge program for replacement,” Krejci said. That’s what happened with the Marsh Rainbow bridge.

The bridge is a 93-foot single span, and uses a typical arch form where the road is suspended from the arch.

“Eight concrete vertical intermediate posts on each side are joined by the concrete floor beams,” reads a citation by the Chippewa County Historical Society.