By Jeanne Aamodt

The National Transportation Safety Board Jan.15 identified the design of the Interstate 35W bridge as a surprising concern in investigation into the cause of the bridge failure.

"During the wreckage recovery, investigators discovered that gusset plates at eight different joint locations in the main center span were fractured," said NTSB Chairman Mark V. Rosenker.

"The findings announced today by the NTSB about the gusset plates are valuable not only to Minnesota but to the nation," said Bob McFarlin, assistant to Lt. Gov./Commissioner Carol Molnau.

"Because the NTSB first noted concerns about weight loads and gusset plates in August, Mn/DOT took a pro-active step to begin a review of gusset plate designs on similar truss bridges in Minnesota," he said.

Undersized gusset plates were found at eight of the 112 nodes (joints) on the main trusses of the bridge. Rosenker said investigators were shocked that these 16 gusset plates (two at each node) were roughly half the thickness required and too thin to provide the margin of safety expected in a properly designed bridge.

"The board, with assistance from the FHWA, conducted a thorough review of the design of the bridge, with an emphasis on the design of the gusset plates; this review discovered that the original design process of the I-35W bridge led to a serious error in sizing some of the gusset plates in the main truss,” he said.

Rosenker said the NTSB's investigation is still on-going. No determination of probable cause has been reached, but interim findings in the investigation have revealed a safety issue that warrants attention.

McFarlin added that as of the NTSB announcement and at the governor's direction, Mn/DOT will retain additional consultants and use department engineering staff to complete gusset checks on all 23 state highway bridges that use high truss designs regardless of future construction plans and load rates.

A list of the bridges is located at: http://www.dot.state.mn.us/i35wbridge/pdfs/trussbridges2.pdf.

More information, including the NTSB interim report and statements from Mn/DOT and the Governor's Office, can be found at www.mndot.gov.

By Craig Wilkins

Gov. Tim Pawlenty announced a $1.09 billion bonding plan that includes $416 million for transportation-related projects.

He will submit the proposal to the 2008 session of the Minnesota Legislature which convenes
Feb. 12.

The proposal calls for $965 million in general obligation bonding, with a total of $1.09 billion when user-financed bonds, trunk highway bonds, and cash amounts are included. 

Transportation accounts for nearly 40 percent of the proposal.

"Positioning Minnesota for future success means making smart decisions about where we should invest," Pawlenty said. "This proposal is fiscally responsible and sets key priorities such as replacing more than 600 local bridges."

The plan recommends $30 million for local roads and $225 million for local bridges.  This increased funding will provide the state portion of funding to replace approximately 600-700 bridges.

The local bridge amount is more than four times larger than the amount in any other bonding bill in state history. 

“This is very good news,” said Patti Loken, state aid program engineer with State Aid to Local Governments. “This level of bonding would allow us to reduce the backlog of deficient bridges and create a predictable, long-term bridge replacement program.”

There are now 70 local bridges waiting for funds that have plans approved and are ready for bid letting.

Bridges in fracture-critical status on the local road system will have the highest priority. Priority will also be given to weight-restricted bridges and those that are high on a county board’s or city council’s five-year construction plan.

High-profile and fracture-critical bridges on Mn/DOTs replacement list include:

• Lowry Avenue over the Mississippi River in Hennepin County, $25 million in bonds
• County Highway 1 over the Big Fork River in Koochiching County, $ 3 million in bonds
• County Highway 2 over the Zumbro River in Wabasha County, $2.8 million in bonds
• County Highway 17 over the Minnesota River in Redwood County (currently closed), $1.5 million in bonds
• Wheelock Parkway over the Canadian Pacific Rail Road bridge in St. Paul, $2.5 million in bonds

Mn/DOT expects to match the capacity of the contractors, designers and local governments by spending an average of $75 million a year.

Other major parts of the bonding bill include trunk highway bonds for a new district headquarters at Mankato, $24 million; a new truck station in Chaska, $8.6 million, and pre-design work for new truck stations in Rochester and Maple Grove, $2 million.

The proposal also calls for $70 million to advance the Central Corridor light rail transit line between Minneapolis and St. Paul as well as $55 million for the state’s share of the Urban Partnership Agreement awarded by the federal government.

 The state must pass this request to receive $133.3 million in federal funds for a project that will add a MnPASS-type congestion pricing lane to Interstate 35W south of downtown Minneapolis, rebuild two avenues in Minneapolis for better transit use and add park and ride facilities and buses.

Another proposal calls for $2 million for property acquisition by the St. Cloud Regional Airport.

"This bonding bill has a higher level of investment in transportation than any bonding bill in the history of our state.  This strategic focus is an important step in modernizing roads and bridges across Minnesota,” Pawlenty said.

By Craig Wilkins

After a gasoline tanker overturned as it approached Interstate 394 in Minneapolis, responders from Mn/DOT and other agencies responded in orderly waves to deal with a potentially dangerous situation.

State Patrol officers were the first to reach the scene; Mn/DOT’s Freeway Incident Response Safety Team crew units arrived just minutes later.

They were quickly joined by the Minneapolis Fire Department, sheriff’s deputies and others focused on their specific but interlocking set of responsibilities.

The incident occurred on Jan. 9 at shortly after 9 a.m. causing numerous road and ramp closures. Full access to ramps and Interstate 394 was restored at 7:15 p.m.  

Metro District maintenance crews came in right after traffic was detoured, bringing loads of sand to slow the spread of fuel leaking from the crash site.

Julie Todora and other FIRST driver quickly closed all access routes to the scene. They also shut down the mainline of Interstate 394 until the situation stabilized.

Response crews, she said, had to use extreme caution because of a possible explosion from gas fumes.

Todora said, for example, that recovery crews had to make sure their vehicles weren’t parked over manhole covers, storm sewer grates or other areas where gasoline fumes might collect and possibly ignite.

As she drove toward the scene, Todora said she focused on her part in closing access routes and preventing hazards that might result from the spill.

“We created a buffer around the site so that firefighters, hazardous materials specialists and others could do their jobs without distractions and as safely as possible,” she said.

Among those working inside the cordoned off area was Kevin Kampa, a hazardous materials specialist with Freight and Commercial Vehicles Operations.

Kampa teamed with the State Patrol, the fire department, the Metro District and other responders to mop up gasoline pooled at the crash site, transfer gas in the tanker to another truck and remove the damaged tanker from the area.

Most of the tanker’s load, about 6,500 gallon of gas, poured into the city’s storm sewer system.

The tanker was wedged into the guard rail, Kampa said, making it necessary to remove any fuel still inside before it was moved.

 Freeing the tanker from the guard rail, he said, might have ruptured the one undamaged fuel cell or caused a spark that could have ignited the fuel still inside the truck.

Doug Thies, a Metro District safety administrator, said the response was well-coordinated and recovered nearly 6,000 gallons of gasoline that entered the sewer system with only trace amounts detected in the river.  

Responders lamented the damage to the environment, but expressed relief that no one was seriously injured or killed.

The tanker’s driver suffered minor injuries.

“We had a major traffic tangle for awhile there,” Todora said, “but it could have been a lot worse.”

By Donna Lindberg

Diamonds are helping make concrete pavement quieter, safer and more durable on two test sections of Interstate 94 at Mn/DOT’s Minnesota Road Research facility near Monticello.

Diamonds used to add texture to concrete pavement, that is.

MnROAD staff led a joint study this fall with the Texas DOT, FHWA and the American Concrete Paving Association to test a new method of texturizing existing concrete pavement with a motorized, diamond-tipped cutter.

“At MnROAD, we are always looking for new and better ways to improve the texture of our roadway surfaces,” said Bernard Izevbekhai, research operations engineer.

“We’ve tested other diamond-ground concrete texturizing methods, but a new surface diamond-grinding technique, developed at Purdue University, improves tire adhesion, extends pavement durability and reduces traffic noise more effectively,” he said.

Builders have used methods such as dragging wet burlap, using brooms and, more recently, pulling inverted sections of Astro Turf over concrete to create texture since the material was first used for road building in 1891.

The new process changes the depth and patterns of tiny grooves cut into the pavement.

Izevbekhai said diamond-grinding provides a way to rehabilitate concrete pavement instead of using asphalt overlays or other methods.

The process, he said, improves performance without changing the road’s structure.
Adding texture, he said, improves safety by increasing friction between vehicle tires and the road surface. The process also slows pavement degradation, extending its effective life.  

This texturizing process also improves ride quality.

Another major benefit, Izevbekhai said, is lowering road noise levels.

Tests conducted on MnROAD’s low-volume track and on the mainline of Interstate 94 show a noise level reduction from 102 or 103 decibels to 98.5 decibels.

“That’s the equivalent of reducing traffic volume on a given roadway by 67 percent,” Izevbekhai said.

“We’ve had success with the original diamond-grinding technique on rehabilitation projects such as Highway 77 and Interstate 35W in the Twin Cities region and on a section of Interstate 94 northwest of Alexandria in the Detroit Lakes District,” Izevbekhai said.

He said a workshop discussion on the process given at this month’s meeting of the Transportation Research Board generated excitement with many officials requesting specifications for the new process.

Meanwhile, MnROAD and its partners will continue their research on the new technique.

“Safety of the roadway is the most important feature of pavement,” Izevbekhai said. “We will continue to monitor the performance of this diamond-grinding method to determine if it produces lasting friction to be safety used in practice.”

An article about the new diamond-grinding method appeared in a recent edition of “Roads & Bridges” on-line magazine: http://www.roadsbridges.com/Making-waves-not-noise-article8700.

An article also ran in the International Society of Concrete Pavements December 2007 e-newsletter.

By Nick Carpenter

Mn/DOT employees dealing with traffic accident inquiries throughout the state are seeing a spike in data requests due in large part to the availibility of the Minnesota Crash Mapping Analysis Tool.

MnCMAT, an easy-to-use software program that provides quick access to Minnesota crash data through a GIS-based mapping system, is available to approved and sponsored agencies. The most common users are county engineers, law enforcement departments and local government agencies. It is not available to the public because of limited licensing.

Before the introduction of MnCMAT, county engineers and other crash data users relied on a lengthy procedure that involved Mn/DOT traffic engineers, the Transportation Information System and computer spreadsheets.

Traffic engineers were responsible for obtaining the requested data from TIS and compiling it into a spreadsheet.

MnCMAT puts statewide crash data at the fingertips of the user, which in turn limits the amount of requests received by employees.

“The application really removes Mn/DOT from doing a lot of the day to day crash inquiries,” said Mark Vizecky, traffic safety support engineer with State State Aid to Local Transportation. “Users can probably answer about 95 percent of their own questions now.”

Besides being a quicker way to obtain data, MnCMAT is user-friendly.

“Just about anybody could sit down and use it,” Vizecky said.

Along with Loren Hill, State Aid traffic safety engineer, Vizecky is responsible for educating applicants and Mn/DOT employees about the program’s capabilities.

This past year, Vizecky and Hill met with all the counties and various law enforcement groups within the Twin Cities metro area. They also held training sessions on request of county engineers in Duluth, Detroit Lakes, and Mankato.

“Our user base is growing very quickly, well beyond our original expectations,” Vizecky said.  

Currently, Minnesota is one of four states that use their own version of the original CMAT application. New York, Pennsylvania and Iowa also have versions.

By Craig Wilkins

Mike Ginnaty, District 4’s program delivery manager, succeeds Greg Coughlin as manager of the department’s of the Cost Estimation Improvement and Organizational Integration Project.

Coughlin now serves as the Metro Distict’s state aid engineer. He will remain a contributor to the project team.

Bob Winter, Operations Division director, said the project team’s work is vital as it takes a thorough and systematic approach to develop cost-estimating, cost-management and related polices.

Ginnaty has served as a member of the project team since it was created in 2006.

He will remain based in Detroit Lakes. He will, however, make frequent trips to the Twin Cities metro area and maintain an office at the Waters Edge Building in Roseville.

Ginnaty may be reached at Detroit Lakes at 218/846-3604 and by e-mail.

A recent edition of Newsline included an article about the project: www.newsline.dot.state.mn.us/archive/07/nov/28.html.