|The Safety of North Carolina's Bridges
||Friday, May 24, 2013
RALEIGH – In light of the bridge collapse in Washington, the North Carolina Department of Transportation wants to educate our citizens and visitors about how we keep North Carolina’s bridges maintained for safe travel.
"Safety is always a top priority and every bridge that is open in North Carolina is safe for drivers," said Transportation Secretary Tata. "We have comprehensive inspection, rehabilitation, and maintenance programs in place because our bridges play a vital role in connecting people to work, school and popular vacation destinations.”
Investing in our bridges
NCDOT is investing more money than ever to improve the state's bridges. About $450 million in state funds have been invested over the past two years to replace, preserve or repair bridges, enabling the department to improve more than 1,000 bridges across the state with a focus on replacing and improving structurally deficient bridges. Additionally, proposed state budgets include about $300 million to continue the program over the next two years.
North Carolina has inspection, posting and closing procedures in place to assure public safety by closing bridges when necessary.
- Each bridge in North Carolina is inspected at least every two years in accordance with the National Bridge Inspection Standards.
- Any identified structural problem is addressed by contract repairs or by NCDOT bridge maintenance crews, which are located across the state.
- If a bridge is deemed unsafe, it would immediately be repaired or closed to traffic.
What inspectors look for in an inspection
Survey teams assess the condition of five elements on each bridge: railings, decks, expansion joints, superstructure and substructure. Inspection activities identify maintenance and repair needs to bridge items such as timber and steel handrails; timber, concrete and steel decks; expansion joints; steel and concrete beams; support piles and footings. The condition of each bridge is then summarized into a statewide bridge condition rating, along with the type and extent of repairs needed, if any. A thorough structural analysis is performed and safe load carrying capacities are determined. If necessary, weight restrictions are placed on the bridge.
- Total NCDOT Bridges – 13,500
- Structurally Deficient – Approximately 2,200. This means that while the bridge remains safe, it requires repairs and was built to design standards no longer used for bridges. A bridge is considered structurally deficient if it is in relatively poor condition, or has insufficient load-carrying capacity. The insufficient load capacity could be due to age, the original design or to wear and tear.
- Functionally Obsolete – Approximately 2,700. This means the bridge is safe, but needs to be replaced to meet current and future traffic demands. A bridge is considered functionally obsolete if it is narrow, has inadequate under-clearances, has insufficient load-carrying capacity, is poorly aligned with the roadway, and can no longer adequately service today’s traffic.
- In NC we have 35 truss-type bridges (the type involved in the Washington incident).
Working with local municipalities
NCDOT inspects all state-owned structures and municipalities are responsible for inspecting their own structures. NCDOT does offer technical assistance with municipal inspections. Municipalities have three options:
- Ask NCDOT to contract with private engineering firms to do the inspection (the municipality reimburses the department);
- The municipality handles the private engineering firm contract with NCDOT’s approval of the contract inspectors; or
- The municipality can perform their own inspection. None of the municipalities in North Carolina are currently doing so.
For more information, please visit www.ncdot.gov/projects/ncbridges.
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