Transportation departments and other tunnel owners would be required to inspect highway tunnels by prescribed standards, under a new rule being proposed by the Federal Highway Administration.
The proposed National Tunnel Inspection Standards (NTIS) would be modeled after National Bridge Inspection Standards (NBIS), the existing safety inspection program for bridges nationwide. The tunnel standards would include similar requirements for the inspection of structural and functional systems, along with a national inventory of tunnels.
Federal regulations do not currently mandate tunnel safety inspections or prescribe inspection methods, which vary significantly among the nation’s approximately 350 highway tunnels. Most of these tunnels range in age from 51 to 100 years, and some tunnels were constructed in the 1930s and 1940s, according to FHWA, an agency of the U.S. Department of Transportation.
"Safety is our highest priority, and this is an important step to make our tunnels even safer," said U.S Transportation Secretary Ray LaHood. "Establishing national standards will help us maintain a high level of safety and uniformity across the country in the inspection of tunnels."
Public comments will be accepted until Sept. 20 on the proposed rule [FR Doc No: 2010-17787], which was published July 22 in the Federal Register (Vol. 75, No. 140).
The rule would establish minimum tunnel inspection standards that apply to all tunnels constructed or renovated with Title 23 federal funds that are located on public roads and tunnels on federal-aid highways.
The standards would include requirements for inspection procedures for structural elements and functional systems, including mechanical, electrical, hydraulic and ventilation systems; qualifications for inspectors; inspection frequencies; and a National Tunnel Inventory (NTI).
FHWA says it was pursuing tunnel inspection standards before the fatal July 2006 collapse of a suspended ceiling in the Central Artery Tunnel in Boston. However, the accident reinforced the need for the measure, the agency said.
“[T]he National Transportation Safety Board (NTSB) stated in its report that, `had the Massachusetts Turnpike Authority, at regular intervals between November 2003 and July 2006, inspected the area above the suspended ceilings in the D Street portal tunnels, the anchor creep that led to this accident would likely have been detected, and action could have been taken that would have prevented this accident,’” according to the proposed rule.
The NTSB determined that the probable cause of the collapse was the use of an epoxy anchor adhesive with “exceptionally poor” creep resistance; the epoxy formulation was not capable of sustaining long-term loads. The NTSB report said the epoxy deformed and fractured over time until several ceiling support anchors pulled free and allowed a portion of the ceiling to collapse. Investigators also found that the tunnel was riddled with leaks.
The NTSB also recommended the establishment of tunnel inspection standards.
"The safety and security of our nation's tunnels are of paramount importance," FHWA Administrator Victor Mendez said in releasing the proposed rules. "Our goal is to help ensure that every inch of highway infrastructure is reliable and can support the needs of the traveling public."
The Notice of Proposed Rulemaking is available at www.regulations.gov.