An overview from the Texas Department of Transportation of the U.S. 281 bridge replacement in Marble Falls:
Currently, traffic is traveling on the northbound bridge, two lanes in each direction, while the existing bridge is being demolished and rebuilt for the future southbound structure. Ultimately, each bridge will have two main lanes, two shoulders and a sidewalk for use by pedestrians or bicyclists.
• Demolition with explosives tentatively scheduled for March 17, 2013
• Demolition work expected to be complete in late April 2013.
• Construction on the new bridge expected to begin early April 2013; this work will be done concurrently while the final demolition work is taking place
• New southbound bridge expected to be complete in 18 months (fall 2014)
REASON FOR REPLACEMENT: Functionally obsolete bridge
The existing bridge was originally built in the 1930s. This project will replace the outdated steel structure with a new concrete structure.
This project will greatly enhance the safety of the bridge, not only through the addition of shoulders and sidewalks, but by preventing head-on collisions. Also, in the event that something should happen that would necessitate a closure, motorists could be re-routed to the other bridge instead of through a lengthy detour.
ESTIMATED CONSTRUCTION COST: $29.7 million
LIMITS: Project length is 0.568 miles; the bridge is about 950 feet
FREQUENTLY ASKED QUESTIONS
Q: What is taking place at the U.S. 281 bridge in Marble Falls?
A: In an effort to enhance the safety of the U.S. 281 bridge, TxDOT is replacing the bridge at the Colorado River. The department’s contractor, Archer Western, requested the use of explosives to demolish the bridge. After being reviewed by TxDOT, as well as other regulatory agencies such as the Lower Colorado River Authority, Texas Parks and Wildlife Department and the Texas Commission on Environmental Quality, this proposed method was approved.
Q: When will demolition work take place?
A: Currently, the U.S. 281 bridge in Marble Falls is tentatively set for demolition on March 17, 2013. TxDOT had to obtain a waiver from LCRA granting the department permission to use explosives on the Colorado River. The waiver is only good between March 17 and April 8; therefore, all work will take place in that timeframe. After the initial explosives work, there will be one more minor demolition blast to follow to complete the work to remove the existing piers.
Q: Besides TxDOT, what entities are involved in the demolition?
• Land and marine traffic control: Burnet County Sheriff’s Office, Marble Falls Police Department, Marble Falls Fire Department
• Aquatic resource management: Texas Parks and Wildlife Department
Q: How long will U.S. 281 traffic at the bridge be stopped? What about boat traffic?
A: Due to the type of demolition being performed, the department doesn’t anticipate needing to stop traffic for more than about 10-15 minutes. There will be electronic message boards directing traffic and alerting motorists of the temporary bridge closure.
The current plan calls for three boats to be stationed in the water at least 1,000 feet from the bridge with staff from the Marble Falls Fire Department, the Marble Falls Police Department and the Texas Parks and Wildlife Department to ensure boaters remain at a safe distance from the bridge. Boats will not be allowed in the area (up to 1,000 feet of the demolition site) for about four hours before the explosion. After the blast, east-west boat traffic will be cut off for 24 hours while the team clears a channel. After 24 hours, the same marine-traffic control that has been out for the past two years will be in place.
Q: What is the primary purpose for using a controlled explosive?
A: The purpose of using controlled explosives to demolish the bridge is to perform the work at one time, ultimately, resulting in a safer and more efficient operation. TxDOT does anticipate there to be dust associated with the demolition process, regardless of the method used. The use of explosives allows this to be taken care of all at one time, instead of prolonged exposure over the course of several months with the piece-by-piece demolition method.
Q: How do you know all the explosives have detonated?
A: All charges will be verified by the blasting technician and the area will be cleaned before giving the all clear.
Q: Will the new bridge be affected by this implosion?
The contractor will have its staff there to walk the bridge to ensure no damage has occurred and to remove any possible debris that might land on the new structure. TxDOT also will have several bridge inspectors to examine the piers and substructure of the bridge to make sure there is no damage and the bridge remains safe.
Q: What is the process for determining when explosives can or cannot be used on a project?
A: TxDOT evaluates each location independently to determine if this type of demolition method is feasible. If this is found to be the case, TxDOT will then approach the regulatory agencies (such as LCRA, TCEQ, etc.) to review and finalize the decision based on the location and circumstances of the project. Every case is unique and must be extensively reviewed before a final determination is made.
Q: What will actually go into the lake?
A: The two outside bridge spans are being manually removed; therefore, only 600 feet of the bridge would go into the water, and, of that 600 feet, only the original 1930s truss will be demolished using explosives. The concrete deck and the widening done in the late 1970s will be mechanically removed prior to the implosion.
Q: How much does this explosives demolition cost?
A: The original contract provided $1.25 million to demolish/remove the existing old structure, and that amount has not changed based on the demolition method Archer Western decided to use. TxDOT provided a demolition option in the contract; however, the department did allow the contractor to submit a revised plan for approval, which is what occurred in this instance. Archer Western is responsible for any additional demolition costs incurred.
Q: How much build time will the demolition method using explosives save?
A: The estimated time savings is about 60-90 days. The original proposed method was to remove the bridge piece by piece with cranes; the explosives option allows work to immediately begin on the new bridge while the remainder of demolition work is taking place.
Q: What kind of dust cloud might rise from the implosion?
A: We do anticipate there to be dust associated with the demolition process. Since the explosive charge will be placed underneath the bridge structure, we anticipate very little airborne debris. Dust will be present regardless of the demolition method. The use of explosives allows this to be taken care of all at one time, instead of prolonged exposure over the course of several months with the piece-by-piece demolition method.
Q: How will the blasting affect my building/property? What if something goes wrong?
A: We don’t anticipate any damage to the neighboring buildings, structures or property with this demolition. A pre-blast survey has been conducted, and vibration monitoring will be conducted to assess the blast.
Archer Western included step-by-step safety procedures in their demolition plan, so, if something does misfire, they are prepared to take appropriate action and handle any damage or clean-up as a result of the demolition. Again, we don’t anticipate any damage to the neighboring buildings, structures or property with this demolition; however, if any damage does occur, TxDOT will work to make sure all claims are handled appropriately and efficiently.
Q: How will emergency vehicles get across the river?
A: Current plans include coordination with the city of Marble Falls to stage one to two ambulances and fire trucks south of the bridge so they could quickly send someone to respond to a call, if necessary.
Q: How will the blast affect the fish in Lake Marble Falls?
A: Archer Western is working with the Texas Parks and Wildlife Department to assess the fish in the area and clear them from the blast zone prior to the implosion. TPWD will use a method called electrofishing to safely perform this task. This method does not hurt the fish. An example of how this process works can be seen in the video here: http://youtu.be/peSzPa-ynpk.
Q: Does the bridge contain lead or other toxic elements?
A: TxDOT has performed evaluations on the bridge and there was no asbestos detected. Test results did show levels of lead paint on the bridge; therefore, all lead paint in the areas where the explosive charges will be placed has been removed.
Q: Is there any question about the contractor’s ability to perform this work?
A: The contractor has provided TxDOT with its demolition plan, and, after evaluating the plan, it was determined it meets the necessary requirements to complete this work.
Q: What will happen to the steel from the bridge?
A: After retrieving the steel from the water, it will be processed and loaded onto trucks to be taken to a recycling facility.