A project over the summer involving two single-span rural bridges in Maryland was finished quickly because of a combination of innovative construction techniques and complete road closures.
The single $4.1 million contract involved one bridge on Maryland Highway 450 and one on Maryland Highway 28. The contract was awarded to Concrete General Inc. of Gaithersburg under the direction of Butch Lundgren. It involved tearing out the old bridges and replacing them in just 67 days. The Maryland State Highway Administration (SHA) was awarded an $800,000 grant from the Highways for Life program to support its efforts in constructing the two bridges. The program encourages and rewards innovation in highway and bridge construction.
According to Robert Rager, District 5 community liaison of the Maryland SHA, the goal with both bridges was complete bridge replacement while public schools were out in order to minimize any impact on school bus routes. The MD 450 bridge was closed to through traffic on June 17, and reopened on Aug. 22, three days ahead of schedule. The MD 28 project opened in October. It took a little longer because rock sub-foundation issues necessitated additional drilling.
The contract called for the replacement of MD 28 over Washington Run in Frederick County and MD 450 over Bacon Ridge Branch in Anne Arundel County. The 450 project also included elevation of a short section of roadway east of the bridge to eliminate flooding. The MD 450 bridge slated for replacement was originally constructed in 1925 and carried about 9,000 vehicles a day.
“Balancing quality and efficiency of work with environmental stewardship was seen as a challenge initially because the roadway near the work was subject to frequent flooding from both tidal and runoff (rainwater) sources,” Rager said. “MD 450 crosses Bacon Ridge Branch in a marsh/wetland area at the head of the South River.”
However, the challenges were overcome, and the final result was a good one.
“Feedback from citizens on the MD 450 project has been overwhelmingly positive, which is no small feat where a road closure was involved,” Rager said. “This project featured an extensive community outreach effort that included radio (advance notice of pending road closure), regular project updates sent via e-mail to citizens who asked to stay informed about our progress, and project information brochures that were distributed door-to-door to area businesses.”
Rager noted that outreach partnerships included the Annapolis Mall, which provided project information in merchant bulletins and displayed project brochures at the concierge desk; and numerous civic and homeowner associations.
“Heritage Harbour, a sizeable senior-oriented community about two miles from the project, kept residents informed about the MD 450 project with updates in their newsletter and local access television,” he said. “SHA’s outreach also included a concerted effort to return citizen calls and e-mails about the project within one day, even on weekends.”
Rager noted that plans called for 3,600 cu. yds. (2,752 cu m) of fill in the floodplain to elevate the low point in the roadway by 4.6 ft. (1.4 m).
“By closing the roadway, we were able to reduce construction time from over 30 weeks (estimated) to 9 weeks (actual).” Rager said.
Each bridge was constructed with a cast-in-place concrete wearing surface.
“If you built the bridges with steel beams and a cast-in-place deck, which has to be formed, filled with reinforcing steel, and then poured, it would take at least three more weeks to build each bridge,” said Jeff Robert, project manager of the Maryland SHA. “But with precast slabs, you can place them all in a day, pour your wearing surface, let it cure for seven days, and you’re good to go.”
For the MD 28 bridge portion, a total of 250 cu. yds. (191 cu m) of material was brought in.
The biggest challenge with that bridge was what caused it to be completed later than scheduled.
“Prior to completing the drilling, we did a sub-foundation investigation, drilling in close proximity to where the piers were going to be,” explained Jerry Burgess of the Maryland SHA. “This was to verify that the rock was basically where we thought it was. There were a lot of seams and lots of layers, and the rock was not thick enough to support it until we went deeper. The depths of the shafts actually got doubled. We originally thought we would go 21 feet, but the actual average was right around 42 feet. That resulted in twice the amount of drilling, and bigger equipment was required.”
According to Burgess, the equipment list for the project included a trackhoe for removing the old bridge structure, a tracked shaft drill for drilling shafts for H-beam and the concrete piers that support the bridge footers, a 90-ton (81.6 t) crane for setting pre-cast beams between bridge abutments, and a Bidwell to place concrete and finish it for a smooth bridge deck riding surface.
(This story also can be found on Construction Equipment Guide’s Web site at www.constructionequipmentguide.com.) CEG