BURKE/CALDWELL COUNTIES, NC (March 14, 2018)…Recently the NCDOT accepted bids for this project but all bids exceeded NCDOT estimates. NCDOT Bridge Program Manager Christopher D. Medlin told us “The project was let for bids on 2-21-2018. Unfortunately, all of the bids exceeded the engineers estimate and the contract is set to re-bid April 18, 2018. It is common practice to re-bid a project when contractor estimates exceed the engineers estimate.” Fortunately, the NCDOT is re-bidding the project with a more aggressive schedule of 8 months.
Here is some detailed information about the Castle Bridge Project furnished by the NCDOT…
Background
The NCDOT will be closing the Castle Bridge on Malcom Boulevard/Connelly Springs Road over Lake Rhodhiss to perform a significant bridge rehabilitation project. The Castle Bridge was built in 1961 and services approximately 9,600 vehicles per day. Work will begin this fall, and the bridge will be closed so that the deteriorating concrete deck and supporting steel beams can be replaced. Before the construction begins, a gas pipeline that is attached to the underside of the bridge will need to be relocated away from the bridge.
Reason for the project
As shown in Figures 1 and 2, a recent biannual inspection of Castle Bridge revealed that the steel beams had deteriorated to the point that they are in need of extensive repair or replacement. This deterioration occurred as water and de-icing salt applications leaked through deck joints and accumulated on the bottom flange of the beams causing accelerated deterioration. As a result, the weight limit posting for commercial trucks crossing the bridge was reduced to 19 tons (the legal load limit is 40 tons).
Course of action
Since the beams and deck need to be replaced, an underwater inspection in combination with sonar imaging (as shown in Figure 3) was used to assess the condition of the bridge foundations and concrete columns. This inspection revealed the foundation and columns to be in sound condition and able to remain in place.
Replacing the steel beams and concrete deck is estimated to cost approximately $6 million and require the bridge to be closed for approximately 8 months. It is estimated that the repairs will last 50 years, or more. In addition, the bridge deck will be widened from 28 feet to 30 feet, providing for 12 feet lanes, and the bridge rails will be upgraded to current safety standards.
Unfortunately, building a new bridge adjacent to the existing one is not feasible at this time as it would take approximately 3 years to complete the design and construction. During a period of 3 years, NCDOT would continue to monitor the bridge and there is a
high likelihood that the weight limit posting would need to be reduced again, effectively restricting all commercial vehicles, school buses, fire trucks, etc., from using the bridge. This option is unacceptable given the lengthy detour route around the bridge. In the future, if the Malcolm Boulevard widening project were to get funded, there would be enough time to secure permits, design, and build a second new bridge adjacent to the existing structure during or prior to the widening project.
The bridge rehabilitation project was recently advertised, but the contract completion date allowed 425 consecutive calendar days which could have resulted in a 14-month bridge closure. Moving forward the project will be re-advertised, with a more aggressive schedule, and a maximum of 240 consecutive calendar days (8 months) of closure time. Also, incentives will be added to the contract in an attempt to further reduce the closure time.
Additional Items
- Traffic Counts were conducted showing there are approximately 9600 vehicles per day crossing the bridge. These counts verified that approximately 6% is truck traffic. The highest count was measured between 7:30 and 7:45 which was 247 vehicles in this 15-minute period.
- Additional signs have been added to warn truck traffic of the posted weight limit on the bridge. The State Highway Patrol has agreed to patrol this area more to enforce the weight restriction.
Detour Route
A commercial truck detour route will be designated as follows: Malcolm Boulevard to US 70 to US 321 to Connelly Springs Road (Figure 4). Car traffic can utilize this route as well, but NCDOT encourages local traffic to use the route most convenient for them to reach their destination. The bridge itself will only be closed.
Figure 4. Offsite detour route for trucks.