If someone dumped 99 tons of sand on you, and you weren’t in good shape, you’d collapse, too.

The National Transportation Safety Board has released its fifth update of its investigation of the collapse of the I-35W bridge in Minneapolis, Minn., that killed 13 people and injured 145. The NTSB says it has not yet identified a specific cause for the collapse, only contributing factors. NTSB chair Mark V. Rosenker (speaking as cautiously as federal officials everywhere), said only “significant progress continues to be made in the investigation.” The board expects to issue a final report by year’s end.

What is known:



â€¢ In January Mr. Rosenker announced the discovery of “critical” design flaws, noting that 16 undersized gusset plates were found at eight of 112 joints on the main truss of the bridge.

â€¢ The board’s reconstruction of the collapse shows the location and weight of every car, truck and piece of construction equipment that was on the bridge including 250 pounds each for two portable toilets, for a total load of 630 tons. That included 99 tons of “sand in four mounds …, each 12 feet wide and stretching about 55 feet, in a lane between the four operating traffic lanes.”

Experts say that load was not excessive for a well-designed bridge, The Times reported. But “[s]tress at one of the two weakest points was 83 percent more than it could have handled, according to an interim report released earlier by the Federal Highway Administration,” said the newspaper.

â€¢ The NTSB won’t conduct a hearing on the I-35W collapse. Said The Times:

On Monday, the safety board voted not to hold a hearing on the collapse, but two of the five members dissented. â€œWe recognize that a political debate is raging in Minnesota about the maintenance this particular bridge received,â€ wrote the two members, Deborah A. P. Hersman and Kitty Higgins, in a statement. A well-run hearing, they said, could separate the engineering problem from the political dispute and contribute to a healthy national debate about the state of highway infrastructure.

â€¢ On Jan. 15, the NTSB recommended, on the basis of the discovery of flawed gusset plates, to the Federal Highway Administration that it require bridges of that design to be inspected nationally. S&R calls to the press office of the FHWA regarding the percentage of inspections done, the cost to do them and the influence of the I-35W bridge collapse on the proposed fiscal 2009 federal budget have not been returned.

Two weeks ago, the highway administration said it would provide an additional $195 million in emergency relief funding to rebuild the I-35W bridge. That brings the total federal payout to $377 million.

The Senate Committee on Banking, Housing, and Urban Affairs conducted a hearing this month on the Dodd-Hagel National Infrastructure Bank Act of 2007 (why it’s a bad bill). David Mongan, president of the American Society of Civil Engineers, told the panel “it would take an investment of $1.6 trillion by 2010 to bring the nation’s existing infrastructure into good working order.” [emphasis added]

The fiscal 2009 federal budget proposes a total of $40.1 billion for the Federal Highway Administration to face its “challenge … to preserve and improve the 160,000-mile National Highway System, which includes the Interstate System and other roads of importance for national defense and mobility, while also improving highway safety, minimizing traffic congestion, and protecting the environment on these and other key facilities.”

The Department of Transportation would receive $68 billion if the budget is adopted.

H.R. 3400, Rebuilding America’s Infrastructure, introduced in the House by Rep. Dennis Kucinich, was referred in August to five different subcommittees of the Committee on Transportation and Infrastructure, and then to the House Finance and Budget committees. Since Aug. 4, no further action has occurred.

Meanwhile, interstate highway closures may continue as engineers find flaws in road supports. The Pennsylvania Department of Transportation closed I-95 in Port Richmond after engineers found a 4-foot-long crack several inches wide in a 15-foot-tall concrete column (pictured above).

Enjoy your commute, people.

[Photo credit: Barbara L. Johnston, Philadelphia Inquirer]