Bridge Collapse Caused By Design Flaw, Not Maintenance

The collapse of the St. Anthony Bridge in Minneapolis started with a design flaw in the gusset plates, confirming suspicions that arose in the first week of the investigation. A source familiar with the conclusion told CNN earlier this morning that the NTSB will announce that finding later today, ending speculation that poor maintenance caused the deaths of 13 people last August:

Federal investigators have identified a design flaw as the cause of last year’s Interstate 35W Minneapolis bridge collapse that killed 13 people, a congressional official said Tuesday.
The official, who was briefed by the National Transportation Safety Board, said that investigators found a design flaw in the bridge’s gusset plates, which are the steel plates that tie steel beams together.
The official spoke on the condition of anonymity so as not to pre-empt an update being provided later Tuesday by the NTSB chairman, Mark V. Rosenker.
The findings are consistent with what the NTSB said about a week after the August 1 collapse, in which the bridge plunged into the Mississippi River.

Within hours of the collapse, some critics here and nationwide pointed to the collapse as the end result of underfunded infrastructure. One local crank blamed the head of the Taxpayers League of Minnesota for turning bridges into deathtraps six hours after the bridge failed. Others demanded a gas-tax increase to bolster the $2.2 billion annual budget for MnDOT, the agency which spends three times more than the budget for public safety every year.
Instead, we find out that the bridge design doomed it from the start. The bridge was built in a post-war period where streamlining and efficiency created a lot of questionable bridge designs; a few years later, engineers returned to the more robust pre-war concepts. This collapse showed why that was necessary, and it serves as a warning to those who skimp on redundancy as unnecessarily costly in building infrastructure.
Minnesota has already begun building the replacement bridge, which we hope will be complete by the end of the year. Everyone can learn lessons about this bridge collapse, especially those who attempted to exploit it for their own political agendas.
UPDATE: USA Today has more:

In the wreckage of the I-35W bridge, investigators found 16 gusset plates that were fractured, said one of the officials. Eight of the plates were in the location on the south side of the bridge where the collapse began, according to that official.
The fractures prompted engineers to calculate whether the plates were adequate to hold the bridge together. What they found was that the half-inch thick plates should have been an inch thick — double the size.

And without a redundant support structure, once the first gusset plate fractured, the rest would have failed as the weight of the bridge shifted and generated momentum.

Working Theory On Bridge Collapse Is Just That

The NTSB’s working theory on the St. Anthony Bridge collapse involves design flaws and overloading, according to comments by Transportation Secretary Mary Peters. That prompted questions by two state legislators about the role of maintenance and whether a lack of it didn’t also have some role to play in the collapse, but Peters said that the legislators have misinterpreted her remarks (via Mitch):

The top federal transportation official said that investigators have a “working theory” of why the 35W bridge collapsed in August: a poorly designed metal component called a gusset plate and excessive weight on the bridge that day.
U.S. Transportation Secretary Mary Peters’ comments Thursday mirrored statements she made in August, a week after the collapse, and like her previous comments immediately led to controversy. The National Transportation Safety Board, which is investigating the collapse, has said a formal finding will not be available for at least a year.
Sen. Steve Murphy, chairman of the Senate Transportation Committee, said Peters told a gathering Thursday in Washington, D.C., that he attended that “a finding of fault was not going to be lack of inspection or lack of maintenance” by state officials.
“I think it taints the findings,” he said.

The Senator jumped to a conclusion, although Peters may have inadvertently pushed him along. In any investigation of this kind, the team gathers evidence and starts testing hypotheses to see whether the evidence supports them or rules them out. A “working theory” means that the investigators have settled on one for the moment that fits the evidence seen thus far. It does not rule out that other theories will be tested, perhaps either replacing the working theory or added to it.
The NTSB says it still hasn’t ruled out any hypothesis at the moment, including maintenance or de-icing fluid issues. However, it sounds as if Senator Murphy has; any result that rules out maintenance and testing will “taint the findings”. He wants a finding of some form of incompetence with which he can beat the Pawlenty administration. A poor gusset-plate design won’t allow him to do that.
However, gusset plates seem a likely cause of the collapse. A similarly designed bridge in Cleveland had a partial collapse in 1990, and the gusset plates failed in that incident. As it turned out, the plate design was insufficient for the size and weight of the bridge. Given that history, using gusset-plate design as a starting point doesn’t seem unreasonable.
It will take several more months before the NTSB can make its decision on the cause of the collapse. Peters should probably keep her updates less specific until the investigators have their report ready. State politicians should keep their mouths shut as well, lest their desires to warp the process for their own political ends get too obvious to Minnesotans.

Minnesotans Still Don’t Want A Gas Tax

In the wake of the bridge collapse, a local television station polled Minnesotans to see whether they would support a gas tax to generate more money for roads and bridges. Despite the proximity of the collapse — it had only been a week since the St. Anthony Bridge fell into the Mississippi, killing 13 — 57% of Minnesotans opposed the tax increase. Two months later, Minnesotans haven’t changed their minds:

Minnesotans aren’t clamoring for action from state leaders in the wake of the Interstate 35W bridge collapse, a new Star Tribune Minnesota Poll has found, supporting neither a gas tax increase nor a new special session to fund bridge repairs.
The poll found 50 percent of respondents opposed raising the gas tax, while 46 percent supported it. The gap is within the poll’s margin of sampling error — 4 percentage points, plus or minus.
The poll, which surveyed 802 Minnesota adults Sept. 18 through 23, also indicates that the public doesn’t fault Gov. Tim Pawlenty or the DFL-led Legislature for not dealing with the bridge collapse in a recent special session.
Sixty-eight percent approved of the way Pawlenty handled the disaster, and 58 percent approved of the Legislature’s handling of it.

Perhaps Minnesotans have a stronger resolve than most people credit. In the wake of the collapse, politicians like Elwyn Tinklenburg, James Oberstar, and Amy Klobuchar insisted that low taxes had to go in order to make Minnesota safe. One local deranged columnist declared six hours after the collapse that David Strom of the Taxpayers League of Minnesota and Tim Pawlenty were to blame for opposing tax increases.
Minnesotans simply didn’t buy the rhetoric. They saw through all of the fingerpointing, noting eventually that Oberstar did his best to route funds away from bridge and highway repair and into bike paths and visitor centers. They also found out that MnDOT has a $2.2 billion budget, more than twice that of public safety, and that perhaps adding to that budget should take second place to verifying that its existing money gets spent properly first.
In other words, Minnesotans are smarter and more sophisticated than the New York Times, Nick Coleman, and its allies think. We want an accounting for the money already given to MnDOT and the state government before we start giving even more of it. We want to know why an agency that already gets almost 9% of the entire state budget couldn’t see the collapse coming, and we want to know why our politicians think bike paths should get priority spending ahead of bridge inspections and repairs. When the government takes itself more seriously, then perhaps we’ll look at more taxes — but then, perhaps, they’ll prove unnecessary.

Minnesota Bridge Contractor Selected

The state of Minnesota has chosen its prime contractor for the replacement of the collapsed St. Anthony Bridge, and Minnesotans may feel relieved that the state didn’t choose the lowest bidder. Instead, they selected the firm with the highest bid and the longest predicted time to completion, but included plenty of incentives for faster work:

Despite submitting the most expensive pricetag and acknowledging that it would take longer than others to do the job, a Colorado company on Wednesday won an intense competition to build the new Interstate 35W bridge in Minneapolis.
A team of companies led by Flatiron Construction, the ninth-largest transportation contractor in the country, won a four-way competition with a $233.8 million bid to replace the bridge that collapsed into the Mississippi River last month and killed 13 people.
The lead company estimated that it would need just over 14 months to complete the project, and Minnesota Department of Transportation officials said construction could start by Oct. 15 and meet the goal of having a new bridge open by the end of 2008.

The cost, even if it is the largest of the bids, still fits neatly within the $250 million grant approved by Congress. It leaves $16 million for incentive payoffs, which come at a rate of $200,000 for every day Flatiron can shave off of construction. The state will not have to pay out of its own coffers unless the bridge opens more than 81 days earlier than its delivery. The contract also includes penalties for delays, which adds $200K for every day it runs past the deadline.
The state legislature still resists the speed at which the contract was awarded. The DFL leadership called into question the confidence Minnesotans have in Governor Pawlenty and Lt. Governor Molnau to settle the bridge question. However, the commuters who have to endure the detours will undoubtedly appreciate the fast start to replacing the bridge and the speed in which the executive branch settled the questions. It has been seven weeks since the collapse, and the state has already finished the first stage of the recovery.
Minneapolis and St. Paul have an extra incentive for speeding the replacement process. The Republican National Convention will take place in the first week of September. Getting the bridge opened in time for the national spotlight would mean roughly $8 million in incentives from state coffers — but Minnesota would gladly pay it to have a trustworthy, reliable, and completed bridge spanning the Mississippi in time for the convention. Flatiron wouldn’t mind the extra cash, either. We’ll see if they can beat the clock while building to last.

Incentives Part Of New Bridge Effort

Minnesota’s plan to replace the St. Anthony Bridge will take a page from California’s expedited effort after the 1994 Northridge earthquake by incentivizing the contractors. They can earn an extra $27 million if they can complete the replacement by December 2008 — and given the economic impact of the bridge’s collapse, that may be a bargain:

In its push to replace the I-35W bridge by December 2008, the state on Thursday offered contractors up to $27 million in incentives if they finish the job early.
The team of contractors that will build the 10-lane bridge is expected to be announced three weeks from today, the Minnesota Department of Transportation said in issuing its official request for proposals on Thursday.
The cost of the bridge, which will be built strong enough to carry light-rail trains, is estimated at $220 million to $270 million. The incentives are budgeted into the project and can be paid from the $250 million in federal emergency funds allocated for bridge replacement.

Right now, MnDOT estimates that the lack of a bridge for I-35W into Minneapolis costs drivers $400,000 per day. They base that estimate on pre-collapse traffic levels and the rerouting of traffic through detours. That may overestimate the impact a bit in one sense, since at least a few travelers have started home officing more often, which actually saves money However, the lack of these people in downtown areas means secondary businesses, such as restaurants servicing lunchtime traffic, will suffer serious loss of business — so the overall impact may be even larger.
At $400K as a standard, it doesn’t take long to add up to the $27 million — just 67.5 days. If the contractors can deliver a worthy bridge two months earlier than normal, it’s paid for itself. The incentives will prompt the firms to keep working around the clock, which means good jobs and extra pay for the workers. As long as safety and quality remain high, it represents a win for everyone.
California has had no complaints from their expedited work, and the experiment there caused many of us to wonder why the state doesn’t run all of its construction projects in a similar manner. Minnesotans may have the opportunity to ask the same question.

Final Collapse Victim Found, Bush To Visit Twin Cities

Divers recovered the last body from the wreckage of the St. Anthony Bridge, just shy of three weeks after the tragedy, completing the dark but necessary mission that will allow the removal of the bridge from the Mississippi River. Construction worker Greg “Jolly” Jolstad had plunged into the water in his Bobcat:

The remains of the last person missing after a bridge collapsed into the Mississippi River nearly three weeks ago have been found, authorities said Monday, bringing the official death toll to 13 and relief to the only family still awaiting word on a missing loved one.
Gregory Jolstad, nicknamed “Jolly,” was on the construction crew that was resurfacing the bridge when it fell Aug. 1 during the evening rush hour. Mr. Jolstad, 45, was driving a skid loader, commonly known by the brand name Bobcat.
Divers had gone back in the water early Monday, and Mr. Jolstad’s wife, Lisa Jolstad, had said officials vowed to continue until they found her husband.
The recovery, announced by the Hennepin County medical examiner, ends the search for bodies and allows construction crews to proceed with removing the collapsed pieces of the bridge.

The final death toll now sits at 13, which Twin Cities residents have quietly called a minor miracle. Most of us expected that number to be much higher, considering that the collapse occurred at rush hour. Less than 100 vehicles were involved, which was a smaller number than expected, and the center section of the bridge fell straight down, fortunately limiting the carnage. Quick thinking by rescue workers and the people on the bridge itself helped limit the tragedy.
The divers will now end their work and the salvage crews will begin theirs in earnest. To that end, Governor Tim Pawlenty has requested a federal declaration of a major disaster. That would free funds from Washington immediately to start the cleanup and rebuilding process. President Bush will travel to Minneapolis today specifically to get a new briefing on the bridge and the necessities of its replacement. If Bush is inclined to declare a major disaster, it will likely come today, so that the announcement can be made from the Twin Cities.

What’s The Rush?

DFL legislators questioned the “frenzied rush” to replace the St. Anthony Bridge that collapsed in Minneapolis two weeks ago. In a joint Transportation Committees hearing, MnDOT management got the message that the state legislature wants to get a better idea of why the first bridge collapsed before building its replacement, and also to ensure that the replacement meets traffic needs for the next several decades:

State transportation officials were repeatedly told by DFL legislators Wednesday to put the brakes on their fast-track plans to replace the collapsed I-35W bridge and concentrate instead on making sure the new bridge is safe and meets the needs of Minnesotans for decades to come.
“I’m going to need a lot of assurances that building it fast equals building it right,” said Sen. Ann Rest, DFL-New Hope. “And I’m not there yet.”
She was one of three dozen members of the Joint House and Senate Transportation Committee who grilled three top officials of the Minnesota Department of Transportation Wednesday. After two hours so many legislators still had questions that the hearing was recessed until next week.

Rep Betty McCollum may have taken the chutzpah award, however. The Congresswoman from St. Paul actually had the temerity to stand up and say:

“[M]any people have expressed to me their extreme dismay at the frenzied rush to replace the bridge. A tragedy of this magnitude demands that we take a collective breath and assess the shortcomings of the old structure and the challenges of our future transportation needs. … Unfortunately, it appears haste is governing how we move forward on planning and construction.”

I wonder if Rep. McCollum happened to give this same speech to some of her DFL colleagues? For instance, she could have told this to Senator Amy Klobuchar, who announced within hours of the collapse that it was caused by a lack of funds and that new taxes were needed. Ditto for James Oberstar, the Congressman who helped lard the transportation bill with so many earmarks that one out of every seven dollars Minnesota received from Congress got redirected to a host of low-priority projects, who also demanded an increase in the federal gas tax.
Too many people have leapt to conclusions, and the leapers have little credibility to criticize those who want to take action to resolve the crisis. In this case, though, they may have a point. Expedited construction has worked well in the past, but not so for expedited design and planning. Usually that creates more problems than it resolves and winds up costing everyone more money than gets allocated. That’s been true in every private-sector project I’ve worked, and doubly true for public-sector projects for which my tax money has been spent.
Minneapolis can’t wait for years to replace this bridge, and most people understand that much. The traffic diversions put enormous stress on roads and communities that weren’t designed to handle these increased loads. Businesses in the affected areas will lose revenue while traffic gets diverted away from them, and the longer the city goes without a replacement, the more likely it will be that some of the smaller businesses close — and their jobs disappear.
We need to find some way to expedite the planning process enough to get the project started, but with enough flexibility that its planning is effective and comprehensive. It’s better to get anything done right the first time rather than regret the outcome and have to continually fix what should have been foreseen. The state legislature will have to show some flexibility as well, and avoid the impulse to posture themselves as running the show at the expense of actually making progress. So far, we’ve seen enough posturing to last us the rest of the year.

Big Dig Official To Run Bridge Rebuild

I guess we can call it the Big Bridge, but that may hit too close to home for J. Richard Capka, the federal highway official tapped by the Department of Transportation to run the Minneapolis bridge rebuilding project. Capka got terminated from that ill-starred project in 2002 and has remained a controversial figure ever since:

The federal highway official responsible for the rebuilding of the collapsed Interstate 35W bridge was dismissed in 2002 as chief executive of the Massachusetts Turnpike Authority after his leadership of Boston’s controversial “Big Dig” tunnel project came under fire.
J. Richard Capka, the nation’s federal highway administrator and a retired brigadier general in the U.S. Army Corps of Engineers, arrived in the Twin Cities on Monday night in preparation for the first public meeting today on the design and construction of the new bridge. Gov. Tim Pawlenty and state transportation officials say they are determined to complete the project by the end of 2008.
Capka, who last week viewed recovery operations in the bridge collapse, said in an interview that his short tenure with the Turnpike Authority ended with his putting together a Big Dig financial plan that held steady for the first time in the project’s history. Capka’s spokesman, Doug Hecox, said Capka was chosen to oversee the federal recovery and rebuilding effort in Minneapolis in part because he successfully handled transportation issues in New Orleans after Hurricane Katrina and played a key role in the 1997 federal disaster response to the California floods.
A graduate of West Point, Capka also oversaw an $8 billion Florida Everglades restoration.

The Big Dig is almost legendary for bloated and poor performing government projects. The former Brigadier General of the Army Corps of Engineers ran the project for eighteen months until his dismissal in June 2002. The Big Dig, a series of tunnels that pushed vehicle traffic underground in Boston, originally was supposed to take seven years and cost $2.6 billion, but wound up costing almost six times that amount in more than twice as much time.
Four years after Capka’s departure, a portion of the tunnel collapsed, killing one woman as concrete crushed her car. The DoT wanted to put Capka in charge of the investigation, but Senator John Kerry scotched that decision. Local officials also wondered why the Bush administration would have “the coach of the team referee the game,” and eventually Capka agreed to recuse himself after criticism mounted.
Capka’s other accomplishments apparently outweighed any negatives from his Big Dig connections, and even Kerry eventually signed off on his promotion to run the Federal Highway Administration. Given the nature of this project, a proven leader in engineering projects is essential, especially since the design of the bridge itself has been left fairly vague:

Unveiling vague plans for the new I-35W bridge, Minnesota Department of Transportation officials faced three hours of questioning from Minneapolis City Council members today about the replacement options. …
Project manager Jon Chiglo specifically warned against expecting a glamorous soaring cable or suspension bridge. Like the bridge that fell on Aug. 1, Chiglo said, he doesn’t “anticipate piers being in the river” on the new bridge. Such footings would trigger all sorts of questions about scour — erosion from the river current — and river traffic.
The state officials displayed a drawing of the new bridge that shows the five lanes flowing in each direction and the connections on the north and south banks of the rivers. The photo looks down at the span. Notably, the span would permanently close 2nd Street S. The plan also contemplates the closure of the rail spurs.

The insistence on using funds for a replacement bridge rather than on mass-transit options has created a stir among the council members and Mayor R.T. Rybak. Rybak and Governor Tim Pawlenty have apparently sparred over the exclusion of rail options from the new bridge, with Pawlenty insisting that the federal funding does not allow for enhancements. Watch for this debate to continue for the next few weeks, as Rybak may hold municipal consent hostage over the issue.

Fast Track On Replacement Bridge

Minnesota’s MnDOT has already decided on a conceptual bridge design and will attempt to fast-track the replacement for the St. Anthony Bridge. Rather than go through the normal process of vetting designs and then contracting for the construction, the bridge will be designed and built almost simultaneously — leading some to wonder if the state may be rushing a little too fast:

Little is known about the next Interstate Hwy. 35W bridge, but what officials do know is that the new span over the Mississippi River will go up fast.
Real fast.
An official told the Associated Press today that a preliminary design already has been selected, but would not give details. …
Under a more routine construction timeline, Beckel said, design work — drawing up and reviewing plans, pulling permits and talking with agencies such as the U.S. Army Corps of Engineers to keep them abreast of developments — would take about a year to complete.
By fast-tracking and embracing a construction strategy called “design-build,” the state will try to save time up front by choosing one contractor to oversee both designing and building the bridge.

The need for speed is obvious to those who live here. The collapse cut off the major traffic artery to most of Minneapolis, and the resultant overflow on other routes will create extraordinary traffic jams. The small businesses in the area could lose significant revenue as people avoid the area as much as possible, leading to significant economic damage and unemployment. The start of classes at the University of Minnesota will put much more pressure on traffic detours after Labor Day.
However, drivers in this area want to be assured that the bridge will be built to last, especially after this collapse. Designs will get questioned, and curtailing the selection process may be the least of the issues with the rush. The Star-Tribune notes that worker fatigue could create problems in the construction, but coordinating all of the concurrent efforts needed to build that quickly might be even more of an issue on a tight project deadline.
In California, expedited construction schedules matched with incentives for early completion helped rebuild damaged overpasses and freeways after earthquakes, both faster and better than most other road projects in the state. Those designs didn’t take into account the need to span the Mississippi, though, and used fairly standard overpass designs. The design and plans will be released for public comment tomorrow, and that will give us the first look at how Minnesota plans to accomplish a very ambitious project.
We do have one simplification already. The state will not incorporate light rail into the design, as federal rules on emergency funds prohibit it:

Lt. Gov. Carol Molnau and Metropolitan Council Chairman Peter Bell have advised the state that the new I-35W bridge won’t include light rail because of emergency federal funding rules.
At a briefing this afternoon, Lucy Kender, spokeswoman for the Minnesota Department of Transportation, said a preliminary sketch of the new bridge will be released Tuesday. A joint House and Senate committee will hold hearings on the new span Wednesday. …
Kender said that Molnau, who serves at transportation commissioner, and Bell have sent a letter to Gov. Tim Pawlenty saying that light rail does not qualify for $250 million of federal money earmarked for the new bridge.

Good. Let’s focus on replacing the highway rather than playing with more mass-transit options that people simply won’t use enough to justify the expense.

Engineers: Weight On Bridge Far Below Design Capacity

It takes a while for the Star Tribune to get to its buried lede in today’s update on the St. Anthony Bridge collapse, but engineers have thrown more cold water on the theory that construction work caused the disaster. The story focuses on the fact that MnDOT and construction crews did not consider the effect of the extra weight on the bridge, but the story answers the question itself:

As federal investigators continued to pursue evidence Thursday in the Interstate 35W bridge collapse, state officials said they had no reason to analyze the potential impact of resurfacing the bridge before authorizing that work.
The Minnesota Department of Transportation (MnDOT) said it didn’t need an analysis beforehand because the resurfacing work wouldn’t add weight to the bridge.
Construction officials and some engineers deny or doubt that the resurfacing contributed to the collapse of the steel deck truss bridge. However, an unusual federal alert was put out Wednesday to other states that have similar bridge repair projects underway.

Why didn’t they consider the weight distribution of the heavy equipment? As it turns out, the bridge design supposedly covered a much heavier load than anything a construction crew could bring. MnDOT chief bridge engineer Dan Dorgan told the Star Tribune that the bridge met military design specifications:

Kent Harries, an assistant professor of structural engineering and mechanics at the University of Pittsburgh, said that means the bridge should have been able to support a traffic jam of flatbed trucks loaded with M1 Abrams tanks.
“The loading that that bridge was seeing at the time it collapsed was considerably lower than its design loads,” Harries said.

That doesn’t mean that the weight distribution may not have played a part in the collapse. However, given the lack of any warning about the bridge’s safety, no one would have thought it dangerous to bring that equipment on the bridge, considering the reduced load from the already-milled deck and the restricted amount of traffic on the bridge. A few construction trucks and gravel loads obviously pales in comparison to a bridge full of M1A1 Abrams tanks.
Clearly the bridge failed to support the weight of the load on it at the time. The question remains as to why the bridge could not support its design load, not whether the design load got exceeded. One problem in analyzing this kind of catastrophic failure is that such failures are so rare. All factors have to be considered carefully, but it’s important not to assume anything from any one factor out of the ordinary. Correlation is not necessarily causation, and in this case it seems unlikely that a few construction trucks created the problem, although they could well have been the straw that broke the St. Anthony Bridge’s back.
Meanwhile, Minnesotans continue to look at other bridges around the state — and in Stillwater, one overpass labeled as “basically intolerable” has travelers wondering whether the state should shut it down:

Corroded strands of rebar jut from the sides and pillars of the cracked Hwy. 36 bridge near Stillwater, while jagged pieces of fallen concrete litter the ground below.
Every day, nearly 10,000 vehicles travel eastbound over the crumbling structure. Most of the people in the huge trucks, cars and school buses on the bridge are unaware that it has been listed federally as “basically intolerable.”

Its last inspection report gave the bridge a rating of 28.3, significantly below the 50 given to the St. Anthony Bridge before its collapse. This overpass runs over a highway with some significant traffic, so it could present a danger to those on it and below it. The crumbling underside of the bridge prompted a local resident to send pictures of it to his state representative. However, the good news is that MnDOT had already planned to start work on repairs next month, which will take a little over a month to complete and will require a shutdown during the construction.
This highlights the fact that MnDOT has worked on prioritizing bridge repairs and replacements for quite some time. They estimate the minimum costs at $1.4 billion over the next twenty years, which sounds like a lot of money. However, if the state maintains the spending level for MnDOT at what it has been for the last few years, MnDOT will have approximately $44 billion in funding in which to make those repairs ($2.2 billion per year). That amounts to 3.2% of MnDOT funding in 2007 dollars for that period.
It doesn’t sound like funding will be a problem, nor does that require tax hikes to acquire.