The Fall and Rise of the I-35W Mississippi River Bridge – Part 5: Economics |

Cross-posted from The Fall and Rise of the I-35W Mississippi River Bridge – Part 5: Economics

The Fall and Rise of the I-35W Mississippi River Bridge – Part 5: Economics


At the request of Mn/DOT, shortly after the collapse, Feng Xie and I estimated the Twin Cities 7-county region daily vehicle hours of travel with and without the Bridge using a planning model under two assumptions. The first kept the trip table fixed. This means that people did not change the number of trips, or destinations, in response to the Bridge failure. This should give an upper bound to the effects of the Bridge failure. The second allowed trip destinations to vary (though keeping the number of trips fixed). This provides more of a lower bound of the effects. Clearly some people can switch destinations, or avoid trips altogether, if the cost of their previous destinations are now too high. On the other hand, not everyone can do so. The exact number of people who change destinations is not something we can easily know.

Note, these are direct model outputs, so while the precision is high, the accuracy is not nearly as high as implied by the precision. We monetize these numbers using values of time from MnDOT (The current MnDOT values of time can be found here, a the time the values given were Auto $12.63/hour and Truck $20.41 and we assumed 80 percent auto and 20 percent truck giving a composite value of time of $14.19).

I believe the OIM Value of Time for Trucks is very low, our estimates (Smalkoski, Brian, and David Levinson (2005) Value of Time for Commercial Vehicle OperatorsJournal of the Transportation Research Forum. 44:1 89-102.) put the number at closer to $50 per hour. If we used that, we would get a composite value of time of $20.14.

The results in Table below are of course estimates. However, the number is large and positive, which we expect. And the numbers lead us to conclude that letting bridges fall down is bad public policy. Which most of us already knew. The number does have uses aside from (rhetorically) beating people over the head, it tells us, for instance, how much we should reward contractors for early completion.

The problem is that those who benefit from the Bridge (or lose from the absence of the Bridge) differ from those who pay for it, and are responsible for maintaining it. If presented with the choice of paying and keeping the Bridge up and not paying and letting it fall, most users would have gladly paid more than was required to keep the Bridge up.

Scenario Time Trip Table Planning Network
0 (Base) Before N.A. Complete network
1 After Variable Crippled network
2 After Fixed Crippled network
3 After Variable Crippled network with upgrades
4 After Fixed Crippled network with upgrades


VHT Fixed Trip Table Variable Trip Table
with 1,122,342
without 1,134,355 1,131,322
loss 12,013 8,980
Value $/day $170,425 $127,390

We conducted a more thorough analysis later (Xie, Feng and David Levinson (2008)Evaluating the Effects of I-35W Bridge Collapse on Road-Users in the Twin Cities Metropolitan RegionTransportation Planning and Technology 34(7) pp. 691-703.), considering upgrades to alternative routes, such as restriping I-94 to add a lane and upgrading Mn280, with somewhat lower results.

Scenario 0 Scenario 1 Scenario 2 Scenario 3 Scenario 4
Daily VHT (10^6 veh.hrs) 1.427 1.432 (0.35%) 1.442 (1.09%) 1.431 (0.31%) 1.441 (1.00%)
Daily VKT (10^6 veh.kms) 86.53 86.27 (-0.31%) 86.58 (0.05%) 86.27 (-0.30%) 86.58 (0.06%)
Daily Economic loss ($) N.A. 71,466 220,198 62,408 203,409
Ave trip length (kms) 18.82 18.76 (-0.31%) 18.83 (0.05%) 18.76 (-0.30%) 18.83 (0.06%)
Ave trip time (mins) 18.61 18.68 (0.35%) 18.82 (1.09%) 18.67 (0.31%) 18.8 (1.00%)


Other Parts in Series: Part 1 – IntroductionPart 2 – StructurePart 3 – CommunicationPart 4 – PoliticsPart 5 – EconomicsPart 6 – TrafficPart 7 – ReplacementPart 8 – Policy Implications

The Fall and Rise of the I-35W Mississippi River Bridge – Part 4: Politics

Cross-posted from The Fall and Rise of the I-35W Mississippi River Bridge – Part 4: Politics


The Fall and Rise of the I-35W Mississippi River Bridge – Part 4: Politics


Some will say the Bridge collapse was not about money. Throwing money at the Bridge would not have kept it from falling. Others note money could have bought:

  • more inspections,
  • a structural (e.g. finite-element) model of the Bridge,
  • better, faster repairs,
  • the ability to replace the Bridge sooner.

Money could have been spent more wisely. More importantly, money is always a constraint on decision-making at MnDOT. As was noted in the Star Tribune: “Phone call put brakes on bridge repair: Plans to reinforce the Bridge were well underway when the project came to a screeching halt in January amid concerns about safety and cost.” (Article by Tony Kennedy and Paul McEnroe, Star Tribune staff writers Last update: August 18, 2007 – 4:36 PM)

Tim Pawlenty had already vetoed a legislature-passed increase in the gas tax that could have raised money to repair bridges like this one. The latest vetoed gas tax would not have solved this problem, but previous taxes that were not passed (due in part to Pawlenty’s previous veto threat) may have, had the money been spent on this kind of thing. The gas tax had not been raised in Minnesota since 1988, and thus its purchasing power had diminished significantly, while the network was expanded and aged, and traffic levels increased. Pawlenty’s campaign took pride in this veto, posting a clipping from the Star Tribune on their website:

“WEDNESDAY, MAY 16, 2007
STAR TRIBUNE: Pawlenty vetoes gas tax, income tax bills

By Patricia Lopez, Star Tribune — Gov. Tim Pawlenty struck swiftly and with strong language Tuesday to veto a gasoline tax increase and an income-tax-for-property-tax swap that were at the heart of the DFL’s agenda for the session. — DFLers accused him of protecting the state’s richest 1 percent — those who would have borne most of the income tax increase, which would pay for the proposed property tax relief — at the expense of everyone else. But they conceded that some of their top objectives are fast sliding out of reach.”

PO BOX 21887 – EAGAN, MN 55121. (This article can still be accessed. Accessed April 19, 2012)

Gas Taxes in the United States and Minnesota are dedicated to transportation (and in some cases just to roads). The 2008 Minnesota gas tax bill phased in an increase of the gas tax by 8 1/2 cents a gallon by 2014. Of that, 3 1/2 cents of the gas tax increase was dedicated to paying the debt service on $2 billion in road and bridge bonds. The bill borrowed $1 billion from 2009-2010, with $600 million earmarked for repairing or replacing the state’s 13 most dangerous bridges. In addition, the bill increased the sales tax in the seven-county metro area by 0.25 percent for transit. It also increased license tab fees on newly purchased cars and trucks (1.25 percent on sale of new cars, drops 10 percent per year).

The bill was passed by the legislature, but vetoed by Governor Tim Pawlenty. The Governor had run on a “no new taxes” pledge, and clearly had political aspirations. He was frequently mentioned as a possible Vice Presidential running mate for the 2008 GOP Presidential Nominee, John McCain, and was hosting the GOP convention in St. Paul, Minnesota that year. While in the event, the Governor of Alaska, who had more foreign policy experience, got the nod as the VP candidate, Pawlenty continued to look towards higher office, and was for a time, a candidate in the 2012 GOP party nominating process, before dropping out for lack of support and will.

The Override Six are Republicans who voted with DFL to override Gov. Pawlenty’s veto of the gas tax bill. Four of them lost their seats due to Primary challenges, while the Republicans lost two of those seats to the DFL in the 2008 General Election. This leads to the rule that voting in favor of a gas tax increase can be dangerous to your political health, if you are a Republican.

  • Representative (District) – Party Endorsement? – Primary Victor – General Election Victor
  • Bud Heidgerken (13A-Freeport) – retired – – Paul Anderson (R)
  • Rod Hamilton (22B-Mountain Lake) – Rod Hamilton – Rod Hamilton – Rod Hamilton (R)
  • Ron Erhardt (41A-Edina) – Keith Downley – Keith Downley – Keith Downley (R)
  • Neil Peterson (41B-Bloomington) – Jan Schneider – Jan Schneider – Paul Rosenthal (DFL)
  • Jim Abeler (48B-Anoka)- no endorsement – Jim Abeler – Jim Abeler (R)
  • Kathy Tingelstad (49B-Andover) – retired – – Jerry Newton (DFL)

Carol Molnau was the state’s Lieutenant Governor and the MnDOT Commissioner. While she had been confirmed in the first Pawlenty Administration, when she was reappointed, the DFL legislature did not confirm her, and her appointment expired in February 2008. That can be directly tied with dissatisfaction with her and the Governor’s performance dealing with the Bridge. Notably she was not the Department’s point person with the media in days, weeks, and months following the collapse. She was replaced by Tom Sorel, a federal civil servant who had worked on the Bridge replacement process.

The political problem is deeper than just the fate of a few politicians though. It is a classic problem in transportation funding. Ribbon cuttings on new projects are much more attractive to politicians (and newspapers and TV news) than maintaining what we have. People are also more interested in road surface than the underlying structure. Yet pavement failure, while bad, is not nearly as bad as structural failure. “Failure” in the traffic level of service sense (LOS “F”), while economically costly and personally annoying, and perhaps leading to more (or at least different) crashes, does not have anywhere near the same connotation as structural collapse.

The competing uses of funds are ultimately political decisions. Should money be spent for bread and circuses (er. football and baseball stadiums) rather than genuinely productive infrastructure? Five years later, should money be spent on new bridges with added capacity (e.g. the Saint Croix River Crossing in Stillwater) while over 1000 structurally deficient bridges remain in Minnesota (Kimball, Joe (2011) MinnPost, Report says 1,149 Minnesota bridges are deficient)?


Other Parts in Series: Part 1 – IntroductionPart 2 – StructurePart 3 – CommunicationPart 4 – PoliticsPart 5 – EconomicsPart 6 – TrafficPart 7 – ReplacementPart 8 – Policy Implications

The Fall and Rise of the I-35W Mississippi River Bridge – Part 3: Communication |

Cross-posted from The Fall and Rise of the I-35W Mississippi River Bridge – Part 3: Communication


The Fall and Rise of the I-35W Mississippi River Bridge – Part 3: Communication

The I-35W Bridge collapse occurred before the advent of Twitter, when there were only 50 million users of Facebook (as February 2012 there were 845 million users, and growth in user numbers seems to be leveling off). [I joined Facebook on November 13, 2004, so they tell me, when Facebook had fewer than 1 million users (Facebook User Growth Chart by Ben Foster)], but it was pretty much useless to me until late 2008 when enough people I knew were on to make it interesting to check in. And though I added 24 “friends” in 2007, I never posted. It did not even occur to me to update my Facebook status, which would likely be the first place many Twin Citians would go today in such an event. I did update my blog the next day.

Yet the news traveled fast. TV, radio, on-road variable message signs, phone calls, emails, all helped transmit this knowledge. We have evidence on how the news traveled by looking at traffic counts. The figure below shows the difference in counts between August 1 and a week earlier, July 25, which are otherwise similar days. As noted, behavior changed quickly that night, traffic counts were lower systemwide, but especially upstream and downstream of the collapse. In contrast the best long distance alternatives (Mn100 and I-35E saw upticks in traffic).



Other Parts in Series: Part 1 – IntroductionPart 2 – StructurePart 3 – CommunicationPart 4 – PoliticsPart 5 – EconomicsPart 6 – TrafficPart 7 – ReplacementPart 8 – Policy Implications

The Fall and Rise of the I-35W Mississippi River Bridge – Part 2: Structure |

Cross-posted from The Fall and Rise of the I-35W Mississippi River Bridge – Part 2: Structure

The Fall and Rise of the I-35W Mississippi River Bridge – Part 2: Structure


Bridges are designed to overcome gravity. They take travelers over a trench, river, or chasm of some kind to reduce the costs of travel. In their absence, travelers would need to descend, and ford a river, take a ferry, or make some other less convenient accommodation. Bridges are networks, sometimes simple, sometimes complex, for transmitting forces from the air to the ground. These networks may be of stone, concrete, wood, steel, or other materials. The network elements are connected in various ways.

The I-35W Bridge was constructed as part of the Interstate Highway System. It was not the first crossing of the Mississippi River in the City of Minneapolis, one can see many other crossings from the photos and maps. Immediately upstream we find the oldest extant crossing, the curved Stone Arch Bridge, dating from the 1883, which originally brought trains of the Great Northern Railway across the Saint Anthony Falls from Old St. Anthony on the east bank of the River to the Mill District on the West Bank, and now acts as a pedestrian crossing. Immediately downstream is the 10th Avenue Bridge, opened in 1929, and still carrying vehicles. The first river crossing in Minneapolis was the 1855 Hennepin Avenue Bridge, a tolled suspension bridge, which lasted at least 20 years.

In principle engineers know (or knew) how to build long lasting structures, that with proper maintenance could last centuries. In fact the Pons Fabricius in Rome was originally constructed in 62 BC, more than 2,000 years ago, and has remained in continuous use. So something went wrong on I-35W for it to last only 40 years, and something has gone wrong in civil engineering practice if we are designing bridges to only last 50 years.

The National Transportation Safety Board, the federal government agency for investigating failures, engaged in an extensive one-year study of the collapse. Inadequately sized gusset plates, sheets of steel that connect truss members, beams, girders, and columns in bridges and other structures, were the proximate cause. While the gusset places were too thin for the design, they were not so thin that the Bridge collapsed earlier. As can be seen from the pictures, the Bridge was undergoing some construction at the time of the collapse, only two of the four lanes were open to traffic, while the others were being resurfaced. It was the combination of the undersized gusset plate with increased weight of the Bridge over time (due to things like pavement resurfacings), and in particular, the loading of construction materials on the Bridge, above the gusset plate that day was the proverbial “straw that broke the camel’s back”. Once one gusset place cracked and could not support the loads, cascading failures led to the collapse (A summary of the NTSB report can be found at “NTSB releases report on I-35W bridge collapse” in Roads\&Bridges, November 17, 2008 (Accessed April 19, 2012)). The Bridge was fracture critical or “non-load-path-redundant”, meaning that once one critical element failed, there was no redundant element to take the load.

Tom Fisher says that fracture-critical design has four characteristics: lack of redundancy, interconnectedness, efficiency, and sensitivity to stress (Fisher, Thomas (2009) Fracture Critical.  Places: Design Observer.(Accessed April 19, 2012)). Beyond that, it has long been known the Bridge was structurally deficient, and it had been investigated for other possible failure modes.

A report by my late colleague Bob Dexter is interesting in that it said
“As a result, Mn/DOT does not need to prematurely replace this bridge because of fatigue cracking, avoiding the high costs associated with such a large project.” The report was correct as far as it went, since fatigue cracking was not the source of failure. It did not identify the problems with the gusset plates, nor did any inspections after construction. (Robert Dexter, Heather O’Connell, Paul Bergson (2001) Fatigue Evaluation of the Deck Truss of Bridge 9340. Report no. Mn/DOT 2001-10 . The full report NTSB/HAR-08/03 PB2008-916203.)

The US still has about 18,000 fracture critical bridges (America’s Broken Bridges
By Carol Wolf on March 22, 2012). Some 465 have similar designs to the I-35W Bridge. There are about 72,500 structurally deficient bridges according to USDOT, out of about 600,000 bridges (Transportation Statistics Annual Report, U.S. Department of Transportation, Bureau of Transportation Statistics, 2008). Another 80,000 are functionally obsolete, which does not imply a bridge safety problem, but means they are not to standard, for instance with narrow lanes, or are under-capacity for demand.

Bridge failures on the Interstate are not as uncommon as one might think. The list below shows major Interstate bridge failures and their causes.

  • Tampa Bay, FL – May 9, 1980 – I-275 – ship collision
  • Greenwich, CT – June 28, 1983- I-95 – metal corrosion, fatigue
  • Oakland, CA – October 17, 1989- Bay Bridge- earthquake
  • Oakland, CA – October 17, 1989- I-880- earthquake
  • Milwaukee, WI – December 13, 2000- I-794 – weather, traffic?
  • Webbers Falls, OK – May 26, 2002- I-40 – barge collision
  • Bridgeport, CT – March 2003 – I-95 – car-truck fire
  • Oakland, CA – April 29, 2007- MacArthur Maze – truck explosion
  • Minneapolis, MN – August 1, 2007 – I-35W – design, construction

Other bridges have been closed before failure, and repaired or replaced. The Sherman Minton Bridge across the Ohio River was closed in 2011 after cracks were discovered, and repaired. While some causes seem to be acts of nature (earthquakes) or difficult to predict (barge collision, truck explosion), good design will defend against even those failures, at least to a point. The trade-off inherent in all design is the amount of failure to be accepted. Will we accept one Interstate bridge failure in the US every day (no), every month (no), every year (no), every decade (yes), or every century (yes)? Nine failures in 27 years indicates about one every three years is somehow acceptable.

Each higher standard is increasingly expensive. At some point, money spent on reducing fatalities by making ever safer bridges outweighs the same money spent on reducing deaths some other way (e.g. increasing traffic safety or reducing air pollution). For instance, a billion dollars annually spent on reducing expected fatalities from bridge collapses by one person per year is 200 times more than would be spent reducing traffic fatalities (where the “statistical value of life” is on the order of 5 to 6 million dollars per person), and would be a misallocation of resources from a safety perspective.

We can of course potentially add the costs of infrastructure replacement avoided, but we currently spend more per life saved on safety in structures than on safety in traffic. As with aviation crashes, bridge collapses are highly visible and are perceived as more common than they really are.


Other Parts in Series: Part 1 – IntroductionPart 2 – StructurePart 3 – CommunicationPart 4 – PoliticsPart 5 – EconomicsPart 6 – TrafficPart 7 – ReplacementPart 8 – Policy Implications

The Fall and Rise of the I-35W Mississippi River Bridge – Part 1: Introduction |

Now at : The Fall and Rise of the I-35W Mississippi River Bridge – Part 1: Introduction


The Fall and Rise of the I-35W Mississippi River Bridge – Part 1: Introduction

C: Starting Date Wednesday August 1 2007, at 6 hours, 5 minutes and 38 seconds pm 

V1: Metro, fifty cars there’s report of some sort of collapse in the construction zone. North of University [Avenue]

V2: 437

V3: 551 I will be 10-8 [available for incidents] down here, she’s on her way doing triple A now

V4: 224

V5: Metro, West Metro’s going to be 10-33 [alarm sounding, emergency] at this time, all cars, fifty cars, we have a bridge collapse, the River Bridge over the Mississippi River Bridge is down

V5: 2500 do you copy?
[siren in background]

V6: 80 metro 60 cars being routed metro

V5: We will need southbound closed and northbound, both sides are down

V5: 2500 do you copy?

V7: In route 169 to 97

V8: 10-4 [ OK, I acknowledge] 1806

C: Ending Date Wednesday August at 6 hours, 6 minutes and 53 seconds pm

Note: C: is the computer time stamp, Vn: are the different voices heard on the recording. The 10 codes have been defined in [brackets]}“10-codes” are widely used by police and emergency personnel in the US to convey information, and were first published in 1940, though there is great debate as to their usefulness compared with plain speech. See Dispatch Magazine online for some discussion.

After spending 10 months on sabbatical in London studying the coevolution of transport and land use, on Tuesday July 31, 2007, my family and I returned home to Minneapolis. We had many things to do to restart a household, among them shopping. Relatives were in town for a conference, and they had rented a minivan. The next day we went to a warehouse club (Costco) to stock up on basic stores, filling the back of our vehicle with typical American middle class goods (paper towels, diapers, etc.). While we traveled to the store on what any online mapping service would suggest is the shortest path, on the return at about 3:00 pm we took West River Parkway instead of the highway to avoid traffic and have a more scenic view. That route runs along the Mississippi River, and passes immediately below the I-35W Bridge. I did not look up at the Bridge from below as we drove under it.

At 6:05 pm, CDT, August 1, 2007, the I-35W Mississippi River Bridge famously collapsed.

By 6:10 pm, I and the world knew about the collapse from watching both local news and CNN. People from around the world contacted me wishing well.

I didn’t know any of the 13 dead or 145 injured at the time, and was as surprised as anyone at the collapse, having driven under and on the Bridge many times. We discovered that it was an eight-lane truss arch bridge that had opened in 1967, and carried about 140,000 vehicles a day. Everyone in the Greater Minneapolis-St. Paul region has their own story, some heroic, most mundane. Everyone, though, remembers it.

The Regional Traffic Management Center (RTMC) in Roseville, Minnesota received news instantly, and had video cameras in the area, which they quickly pointed in the direction where once stood the Bridge. The recording of their audio inputs are transcribed in the opening quote. In the stream of random and mundane information coming into the center, communications were received about the collapse.

The next morning (August 2, 2007 – 8:24 AM) Paul Levy of the local Star Tribune newspaper reported an article with the headline (one which varied across the day and week)
4 dead, 79 injured, 20 missing after dozens of vehicles plummet into river .The article can be found online.

As with any tragedy, information as of August 2 was incomplete. People were missing, some of whom were found alive, others dead. The estimates of injured went up as better counts were made.

In the days following, I received some 17 media contacts asking about the traffic effects. My structural engineering colleagues received many, many more. As researchers, my transportation colleagues and I quickly proposed studies to examine the consequences of the collapse.

Users take infrastructure for granted. From the roots “infra” meaning below or underneath, and “structure” meaning building or assemblage, infrastructure is by its very nature not obvious, and is often hidden in plain sight. Yet its absence is noticed. Americans seldom complain about lack of on-demand electricity (blackouts), natural gas, or water, but often complain about lack of on-demand transportation capacity, which we call congestion. When construction or events close routes, so you cannot get from here to there, the complaints rise. But when infrastructure fails unexpectedly, it engenders shock rather than complaint.

Why did the Bridge collapse? And what does it say about the state of infrastructure in the United States, and for that matter, the developed world?

In a one-time event, blame is a useless exercise. My blaming you will not produce better future outcomes. But in a world with signals and repeated games, blame can lead people to behave better in the future, and the prospect of being blamed for failure may encourage behavior to avoid failure. Too much blame for failure, and insufficient reward for success, will lead to risk-averse outcomes. In some arenas, conventional finance, structural engineering, risk-aversion is probably a good idea. They provide a lattice on which the rest of society depends to accomplish their own work. The gains from innovation are likely small, the losses higher. In other areas, e.g. war, risk-aversion on the part of the weaker army may ensure defeat.

To answer the question on “Why the Bridge collapsed”, one can look to physics, and blame gravity. Blaming gravity, while technically correct in some sense, will not help us going forward.

One can look to structural engineering and blame undersized gusset plates. Or one can look to construction engineering practices and blame overloading. Or one can look to traffic engineering, and blame the need for all those people to get from A to B. Or one can look to politics, and ask why the Bridge which had (different) known problems, had not already been repaired. And so on. The layers of blame are worth exploring.

The collapse of the Bridge illustrates several different kinds of networks in action. The bridge itself was a structural network, a connection of steel and concrete elements designed (but in the end failing to) to transmit force safely from the Bridge deck to the ground. The Bridge was a link in the transportation network, an element of the limited access US Interstate Highway System enabling people to travel by car from point to point without stopping. The news of the collapse of the Bridge was transmitted over communications networks (both electronic and social), it was a quickly transmitted piece of information.


Other Parts in Series: Part 1 – IntroductionPart 2 – StructurePart 3 – CommunicationPart 4 – PoliticsPart 5 – EconomicsPart 6 – TrafficPart 7 – ReplacementPart 8 – Policy Implications


I-94 open to traffic

I-94 across the Mississippi restored to its 2007-2008 capacity.

– dml

Light-rail service suspended, bridge, road closed after cable problem

Star Tribune: Light-rail service suspended, bridge, road closed after cable problem : “The failure of a cable support on the Sabo bike and pedestrian bridge has resulted in closure of the bridge, suspension of light-rail service at three stops and the rerouting of vehicle traffic on Hiwatha [sic] Avenue.”

An Economic Comment on the Stillwater Bridge

Jason Scheppers writes in:


“Recently, Dr. Whitehead wrote regarding the Stillwater – St. Croix River Crossing. I have seen in your blog several mentions of the bridge and offer you the following economic comments:

I would recommend the following documents for any interested in the details of the current controversy: US House subcommittee hearing, Senate subcommittee Hearing, Record of Decision and US Court ruling vacating the National Park Service’s concurrence with the project.

I support Senators Klobuchar and Franken’s and Rep. Bachman’s right to follow the law which specifically called for override of the Scenic by-way by congress, if Congress deemed appropriate. The tremendously cumbersome process and triple flip-flopping by some federal agencies give significant cause to provide reasonable congressional relief.

But beyond the Congress’s right, the following shows that the economics constructing a new freeway bridge may not be as clear as suggested.

First, the existing bridge while currently rated in not so good condition and with load restrictions is not in any imminent state of collapse. It is also true that under build the new freeway bridge(s) would keep the existing bridge and make it a pedestrian and bicycle facility. The loading requirements for pedestrian facilities exceed those of vehicular loading due to possible densities of pedestrians during special events. The existing historic bridge is not going away.

Second, the I-94 Bridge is only 6 miles away from the current bridge. Attached are the Google directions for a path that goes over the existing bridge as compared to going over I-94, yielding 31 miles in 45 minutes, versus 34 miles in 46 minutes. The new route takes out the trip through Stillwater and straightens out some of the wiggles through Stillwater. I estimate that the time savings for the mean traveler is in the order of 10 minutes and 5 miles compared to the I35 route. Time valued at $15 per hour and cost of $0.40 per mile yields a total savings of $4.50. There actual has been a study done that found the revenue maximizing toll was $3.00. It found that the toll could cover only half the cost of the bridge.

Third, the cost benefit analysis provided in the Supplemental EIS had a very different take. It shows a 6.0 Benefits to Costs ratio. Call me old fashioned but if you can only generate enough toll revenue to pay for half of your project, it is hard to see how the B/C ratio could be greater than one. (There may indeed not be a toll on the new bridge, but the willingness to pay aspect of a toll illuminates the value of the facility.)

Fourth, the travel patterns of the residents of the area are highly dependent on what facilities are in place. Does the Minneapolis Regional model takes into account the natural barrier the river is to growth on the WI side of the St. Croix? The Toll study cited above assumed 2.0% traffic growth, but if you analyze the data in the FHWA vmt trends for Minnesota you will find an annual state wide traffic growth rate of 0.6% from 2004 to 2010. This implying that there is substantial risk to cover 50% of the costs with toll revenues. If this lower traffic growth rate were sustained over the length of the tolling not even 20% of the bridge could be financed.

So enough complaining, here are some things that I think would be reasonable. While the reports all document the danger, it is not the bridge itself where the DOTs are claiming most dangerous conditions. It is on the Minnesota side where the highway goes through the town. It is also the signals through town that impede the volume. The bridge can likely handle 18,000 vehicles a day in each direction without substantial delay. But looking at the route through

Stillwater, one possible explanation for the accidents is the on street parallel parking on this high volume road. Imagine the safeness of trying to Parallel Park during peak hour traffic.

The Supplemental EIS also discusses cut through traffic. Eliminating and compensating local business for the loss of close parking and reconfiguration of the lanes to allow some more volume is one solution. The City and MN DOT could also create one way pairs for the highway through town to allow for more traffic flow. The reality is the existence and texture of Stillwater is formed by its relationship to the river and the existing crossing. Operational improvements without the following pricing would likely significantly increase the traffic leaving the Stillwater residents with equally bad congestion in their town.

Changing the bridge to a non-motorized facility essentially changes the price for an auto to cross from zero to infinity. What if it was only changed to $5 and that it was a variable toll to address some of the Stillwater residents’ concerns about congestion. The congestion, I would guess is on Friday evenings in the summer when city dwellers rush to their weekend retreats. Such a toll reduces the traffic and also generates revenue to repair and maintain the existing bridge. The existing bridge is considered historic and historic for carrying cars across the St. Croix River. It seems the 4F work on the bridge did not respect the fact that the bridge’s vehicular history and the scenic views that were obtained by all the folks driving through Stillwater and across the bridge. To be scenic you need people to see the beauty. I would argue that removing motorized vehicles from the existing bridge is a direct and adverse impact to the scenic river and is not allowed unless otherwise approved by the US congress.

The value of the existing bridge has never been greater and capturing some of that value through tolls provides the best revenue stream to maintain the historic bridge and address its current deficiencies and pay for operational improvements on the approach roadways. I am an equal opportunity toller and encourage appropriate charges to the gondolas and sightseeing boats that pass under the lift bridge. Freight barges no longer utilize this stretch of the St. Croix. The bridge lift schedule should not be fixed but based on price. Rush hour lifts for tourists to pass under the bridge should be evaluated based on prices the “overs” versus “unders” are willing to pay. Are the pedestrians and bikers willing to pay to maintain the bridge? If motorized vehicles are prohibited, what are the implications to the very limited use the bridge will have during the November to March time frame? The reduced value of the bridge by eliminating the cars is the biggest threat to maintaining the historic structure. The current bridge also has the huge value of simply existing and not subject to the regulatory capture of the regulating agency for new structures.

The Stillwater lift bridge is a man-made bridge, historic and integral part of the scenic
river. Review of Google images of the Lower St. Croix River, show the
lift bridge may be the most popular image per linear foot of river it occupies. Why would it not be possible to build (if needed) a bridge that would age gracefully and be equally accepted into the eco-system. The current unconditional discrimination against massiveness and man-made form denies the man- made massive existing historic lift bridge, the center piece of the scenic lower St. Croix River.

Jason Scheppers
(Crossed the beautiful scenic lower St. Croix River twice in the past year (in a car))”

Weak Bridge

Suppose there were signs on each bridge saying whether or not it was “structurally deficient”.
Would this encourage people to take investment seriously?
Or would people route around structurally deficient bridges and get into more crashes, with a net increase in fatalities, given that the likelihood of dying on a bridge collapse is quite small compared to other causes of death.