Recently in Bridge Category

NY Times: Tunnel Collapses Outside Tokyo Kills Nine :

"The police said they were investigating the cause of the collapse on Sunday at the Sasago Tunnel — a three-mile passage near the city of Otsuki and about 50 miles west of Tokyo — and for evidence of negligence by the company that operates the highway.

News reports said investigators believed that supports in the ceiling of the 35-year-old tunnel might have grown brittle, allowing hundreds of the slabs to fall onto passing vehicles. Each slab weighed 1.2 tons, officials said."

David King on Bridge Collapse Causes Train Wreck:

"A train derailed in New Jersey after the bridge it was crossing collapsed. Here is a CNN story. At this point no one knows if the bridge collapse was the cause of the derailment (or was there something with the train that caused the collapse), but will this event serve as a reminder than we tolerate catastrophic failures of our infrastructure far more commonly than most people think? I am not confident that knowledge of potential failure will spur action, nor am I very confident that actual failure will change priorities to fix our infrastructure first. It seems most likely that we will continue to tolerate occasional failure even though everybody knows this is the wrong  way to go about things. Collective action problems are hard."

Pioneer Press: Timelapse video: New Hastings Bridge is floated into place:

"Watch the entire process of moving the 6.5 million pound bridge down the river and being lifted into place, which took about 60 hours from start to finish, according to the Minnesota Department of Transportation.

The roadway for the bridge won't be poured until next spring."

Now at 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"

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."

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

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.


Toronto Star:Fallen slab is concrete proof Montreal’s crumbling

MONTREAL—A huge concrete slab fell Sunday on a major expressway that runs under downtown Montreal, the latest in a series of incidents that point to the city’s crumbling infrastructure.

No one was injured in the collapse in the Ville-Marie tunnel, but the incident could have had disastrous consequences if it had occurred on Monday at the same time, during rush hour traffic, police said.

“Our officers arrived at the scene and we verified and made sure that no one was stuck underneath the rubble,” Daniel Thibaudeau, spokesman for Quebec provincial police, told reporters Sunday.

About 100,000 vehicles use the expressway during an average weekday, according to Transport Quebec.

It is somehow reassuring when infrastructure in other countries is falling apart too.

Strib writes: County wheelage tax might pay for a new bridge in Minneapolis :

Hennepin County will consider reviving a wheelage tax it hasn't used since 1975 to pay down debt on the Lowry Avenue Bridge.

Hennepin County could bring back a tax it hasn't used in 36 years to help pay its share of the Lowry Avenue Bridge, now under construction in northeast Minneapolis.

It's called a wheelage tax, and it's collected from vehicle owners in five of the seven metro-area counties able to impose it under state law. Only Ramsey and Hennepin don't have it.

That could change Tuesday, when the Hennepin County Board will take up a resolution by Commissioner Peter McLaughlin to charge $5 per vehicle (except motorcycles and some trailers) starting next year.

The $4 million that the wheelage tax would generate annually would be used to pay down most of the county's $51.7 million debt on the bridge, slated to be finished next summer.

McLaughlin said that the new tax revenue would replace the property taxes now used to finance the bridge. If the board approves the wheelage tax, he said, the property tax levy would be reduced by a corresponding amount.

"Historically, we haven't used debt backed by property taxes to pay for roads. We've used gas taxes and user fees like that," he said. "Property taxes are not how we ought to be subsidizing roads.""

OK, user fees are best of all, wheelage taxes are better than sales or income taxes, and property taxes are not as good as Transportation Utility Fees or Land Value Taxes, but if accessibility increases property value, property taxes are not an unreasonable place to start for paying for roads.

The article does mention that "Minus administrative payments, the tax would generate a little more than $4 million.", I assume it is collected by the state with annual vehicle registration. I would hate for there to be a new tax collection infrastructure for this.

Also, why aren't bicycles assessed (at half rate since they have only two wheels)? (Yes that was rhetorical).


A reader submits this: BBC News says China's record-breaking Jiaozhou bridge 'is safe'.

Here the 'scare quotes' are entirely appropriate.

The chief engineer of the world's longest sea-bridge, in China, has denied claims that its construction was rushed to allow it to open on schedule.

Shao Xinpeng told state media that the Jiaozhou bridge, opened last Thursday, was safe and ready for traffic.

Chinese media reported finding incomplete crash-barriers, missing lighting and loose nuts on guard-rails.

Reports blamed workers' haste to finish the bridge in time for the Communist Party's 90th anniversary.

In a report earlier this week, a journalist from the state-run CCTV news channel unscrewed pieces of the guard-rails and showed that the lighting system was not working properly.

Construction workers told CCTV that it would take two months before finishing all of the projects related to the bridge.

But Mr Shao said the problems highlighted in the reports were not major.

"The status of secondary features does not affect the main project or the opening of the bridge," he told the state-run Xinhua news agency.

He added that the lighting system was only aesthetic.

The structure spans 42.4km (26.3 miles), connecting the eastern coastal city of Qingdao to the suburb of Huangdao, in Jiaozhou Bay.

State media say the bridge passed construction tests last Monday and it opened to traffic on Thursday.

It is 4km longer than the previous world record-holder, the Lake Pontchartrain Causeway in the US state of Louisiana.

There are also disputes about this being the longest bridge over water in the world, since it is curved, while the Lake Pontchartrain Causeway is straight, and so goes over a longer body of water. Wikipedia writes "There is no standard way to measure the total length of a bridge. Some bridges are measured from the beginning of the entrance ramp to the end of the exit ramp. Some are measured from shoreline to shoreline. Yet others are the length of the total construction involved in building the bridge. Since there is no standard, no ranking of a bridge should be assumed because of its position in the list. " Also note many bridges are longer (and in China) but not over water.

Updated June 27, 2011 (at bottom)

The Pioneer Press reportsAnother potential shutdown casualty: Stillwater Lift Bridge

The Stillwater Lift Bridge would likely close during a state government shutdown, city officials have been told.

The employee who operates the bridge is not expected to be classified as critical, and the bridge would be left in the up position to allow river navigation.

It would close to traffic starting June 30.

About 18,000 cars use the lift bridge on an average day, said Stillwater Mayor Ken Harycki, with 25,000 or so on peak summer weekends. Traffic would be routed over the Interstate 94 bridge.

Some points:

(1) This is of course stupid for a variety of reasons, and would not occur but for the needless politicization of transportation. No other public utility would find itself shut down because of the state budget problem. Imagine they turned off electricity, or water, or even transit.

(2) This will make an excellent experiment on the importance (or lack) of this bridge. If only someone were doing before, during, and after studies. Of course with the shutdown, no one would get paid to do a "during" study.

(3) The evidence that the facility is not considered "critical" is telling about its importance.

Update June 27, 2011 with Pioneer Press article

The Stillwater Lift Bridge could remain open even if a state government shutdown occurs Friday, Minnesota Department of Transportation officials said this morning.

MnDOT is including operation of the lift bridge as a core critical function in its contingency planning efforts, pending a final court ruling.

After consulting with public safety officials and healthcare providers over the past several days, MnDOT officials have determined that the lift bridge is a "core service critical to maintaining life and health safety," said Kevin Gutknecht, a spokesman for MnDOT.

"We looked pretty hard at that, and we understand the issues so it seemed to like a good thing to do," Gutknecht said. The lift bridge will remain open primarily to allow ambulance traffic to continue between Minnesota and Wisconsin.

Republican legislators have scheduled a 1 p.m. news conference near the bridge to urge Gov. Mark Dayton to continue delivery of critical services such as the bridge in the event of a government shutdown.

The news conference was planned before MnDOT made its announcement.

I guess MnDOT reads the blog and concluded the optics of a shutdown would look bad for this and for a potential replacement bridge.

Strib reports on I-94 repairs Driving I-94 from city to city now borderline nuts:

Now, I-94 motorists are discovering that the daily rush-hour between cities is being slowed by as much as 20 to 30 minutes thanks to the $23.9 million resurfacing and repair that runs for about four miles between Cretin Avenue in St. Paul and Nicollet Avenue in Minneapolis.

The work on one of the busiest stretches of Twin Cities highway is expected to last until late fall before resuming again next spring.


Magee said the work is part of a plan to upgrade the road following the 2007 I-35W bridge collapse. Weeks after the disaster, a stretch of I-94 was re-striped to add a fourth lane in each direction as part of an emergency measure to cope with the traffic rerouted from 35W. The extra lanes were later made permanent with permission from the Federal Highway Administration, which required the state to complete the upgrades now under way, Magee said.

"Anybody who drives that road knows [the upgrades] needed to be done," said Kent Barnard, a MnDOT spokesman.

While I realize the scope is larger than what MnDOT did with I-94 after the I-35W Bridge Collapse
(1) That project was done and then undone
(2) It cost only $1,162,000 according to MnDOT 10.23.07
(3) It was done in a couple of weekends
(4) It functioned quite well at the time (i.e. this one lane in each direction reduced congestion about as much as the more expensive replacement I-35W Bridge).

I suspect this is just mostly redoing that project in more expensive way. We found that the 2007 I-94 lane restriping and some additional pavement paid off in a matter of a month. This contrasts with the reconstructed I-35W bridge, which at 3% interest rates paid off in about 23 years.

Cancelled due to adverse weather ... Rescheduled for October 18, 2011

I will extend my world tour to Rochester, Minnesota, home to the world famous Mayo Clinic, where I will talk about "Bridge Collapses, Our Journey to Work, and other Transportation Challenges" for the Sigma Xi: The Scientific Research Society

April 19, 7:30 p.m. **Leighton Auditorium, 3rd floor of Siebens Building**

Bridge Collapses, Our Journey to Work, and other Transportation Challenges
David Levinson, Ph.D.
Associate Professor, Department of Civil Engineering, University of Minnesota
Director, Networks, Economics, and Urban Systems (NEXUS) Research Group

Note, this will also be on Second Life, on which the Mayo Clinic has an island.

A bridge for Stillwater

250px Stillwater Minnesota StillwaterNew The Stillwater Bridge question is back in the news, with Governor Dayton and Representative Bachmann endorsing a new four lane bridge to connect to the future development in Wisconsin. Senator Franken is apparently undecided. Franken takes a bridge tour. MnDOT's information page is here The costs are quite high MnDOT estimates $633 M for a four-lane bridge.

We looked at the travel demands of the proposed Stillwater Bridge for MnDOT last year. The results are here. To summarize, we wrote:

"This report is prepared ... to assess the expected traveler impacts of replacing or not replacing the Saint Croix River Bridge in Stillwater, Minnesota. The model that has previously been used to evaluate different Lafayette Bridge replacement scenarios is applied, using the 20 county (“collar counties”) network from the Metropolitan Council and best estimates of 2010 land uses (population and employment). The model evaluates changes in travel cost due to network reconfigurations corresponding to different scenarios. These costs would need to be compared against construction and ongoing operations and maintenance costs, and do not account for factors such as travel time reliability, the value of a redundant network for planned or unplanned closures, or changes in land use.

It can be safely assumed that were a wider, faster bridge constructed there would be more development, and thus more travel demand from the Wisconsin side of the Saint Croix River. If no replacement bridge were built, we can assume that less growth (if any) would occur, and cross-river traffic would diminish. This model does not account for changes in land use, as we do not believe this has been accurately forecast for scenarios both with and without the bridge, but does account for changes in demand given the current land use under different network configurations. This is denoted as “Variable Trip Tables” in the report.

Compared to the baseline (a replacement 2 lane bridge in the same location) according to the model, Construction Alternative 1, a new 4 lane bridge, produces an economic gain of $1.8 million per year.

Compared to that same baseline, Construction Alternative 3, no replacement bridge at all, results in an economic loss on the order of $34.1 million per year according to the model."

Again, this comes down both to Benefit / Cost analysis (does this pass a test?) and priorities (does this count as "Fix It First"?). I think building a four lane bridge to replace a two lane bridge does not fully count as "preservation", but rather as "expansion". Given the state of the network, and the need to give priority to preservation, a four lane bridge violates that principal. As to whether a four lane bridge passes a B/C test, or better yet, a market test of whether a private firm would build it, the answer is clearly no. This four-lane bridge would not have enough demand to pay the tolls required to fund it. That should tell you something about its true necessity. The Franken article cited above suggested Wisconsin wasn't interested in funding it. Since the majority of benefits for the bridge accrue to Wisconsin land owners, it makes no sense for Minnesota to lead on this.

Bridges do not repair themselves

T4America, a pro-transportation advocacy group, is releasing a new report today on the sorry state of US bridges.
The Fix We're In For: The State of Our Nation's Bridges

The Minnesota report is available for download

The results are well known, and worth repeating, many bridges are structurally deficient. The average bridge is over 42 years old. There are insufficient funds being spent on repair/replacement/rehabilitation. Unless something is done, this will only get worse (entropy and all), bridges do not repair themselves.

Fix It First remains the battle cry.

I didn't realize Michelle Bachmann represents Wisconsin too, how regionalist of her ... Betty McCollum promises to fight Michele Bachmann's bridge (from CityPages)

(Worthington Daily Globe) From Finance & Commerce

Portion of Nobles County bridge collapses

A bridge in Nobles County is closed to traffic following a partial collapse that occurred while a contractor was working on the bridge deck.

The County State Aid Highway 1 bridge, which extends over Elk Creek near the town of Brewster, was being prepared for bituminous overlay Tuesday when a section of the span gave way under an 80,000-pound milling machine.

‘They were milling the bituminous surface off the bridge deck to get it ready for the bituminous overlay,’ Nobles County Engineer Steve Schnieder said. ‘They had milled off the entire surface’ and were making a final run when the failure happened.

The machine operator escaped without serious injury and no one else was hurt. The operator managed to jump off the machine onto a portion of the bridge deck that stayed intact, Schnieder said.

Our I-35W Bridge study is now out, the short article from CTS is below: I-35W bridge collapse had complex effect on metropolitan traffic flows, researchers find

The collapse of the Interstate 35W bridge over the Mississippi River in Minneapolis on August 1, 2007, instantly transformed the Twin Cities' transportation network. Thousands of commuters were forced to revise their daily travel routes literally overnight, resulting in dramatic changes in traffic patterns around the busy downtown area. Recognizing that the tragedy afforded researchers a unique opportunity to study real-world responses to sudden network disruption, University of Minnesota researchers including associate professor and Richard P. Braun/CTS Chair in Transportation Engineering David Levinson and civil engineering assistant professor Henry Liu initiated a suite of research projects designed to capture and analyze data on travel behavior in the immediate aftermath of an unexpected large-scale disruption. Findings from these studies may help the Minnesota Department of Transportation (which sponsored the research) and other transportation agencies prepare for and respond to catastrophic network disruptions. Levinson and graduate student Shanjiang Zhu used a variety of data sources to understand the changes in traffic flows resulting from the collapse, including traveler surveys, GPS tracking of study participants' travel, and aggregate data on traffic volumes, traffic controls, and transit ridership. Data collection incorporated both the post-collapse period and, insofar as possible, the pre-collapse period.

The researchers found that an unexpected disruption produces an avoidance response among travelers whose routes are affected. Drivers initially avoid the area around the disruption site until the perceived risk of traveling through it is reduced with time. This response produces an oscillation in travel patterns, as traffic levels on links near the disruption drop precipitously and then rebound as travelers adjust to the altered topology of the travel network.

Comparing this phenomenon to the effects of preplanned disruptions such as the closure of bridges or highway segments for reconstruction, the researchers found that the impacts of such expected closures were much smaller. The researchers speculate that the psychological shock of a sudden collapse or other catastrophic event is much more powerful than that produced by a "normal" network disruption, and suggest that rapid implementation of an effective system of detours may be key to minimizing this effect.

Network redundancy--the availability of alternate routes, including other bridges across the Mississippi--was a critical factor in accommodating the excess traffic produced by the bridge collapse. Mn/DOT was able to detour traffic along alternate freeway routes including I-94/Minnesota Highway 280 soon after the collapse, mitigating some of the negative effects of the event. However, Levinson and Zhu note in their research report, if the I-94 bridge had collapsed instead, the asymmetrical nature of the road network in the area would have made the I-35W bridge route much less able to absorb excess traffic. This finding appears to have important implications for analyses of network robustness. The addition of a temporary fourth lane on the I-94 bridge also proved to be very important to maintaining effective traffic flow in the area.

Based on their analysis of travel demand data, Levinson and Zhu conclude that the new I-35W bridge (which opened one year after the collapse with greater capacity and faster average travel speeds than its predecessor) helped reduce travel costs most of the time, but that this benefit was fairly small--on the order of 0.2 to 0.3%. This finding is consistent with a preliminary study by Levinson and graduate student Feng Xie using planning models developed at the University of Minnesota. This agreement between the models and observed travel demand data, the researchers say, suggests that forecasting models incorporating elastic demand (varying in response to travel cost) can provide good first-order estimates of the impacts caused by network disruptions. "Quick-response" travel demand models could also be useful in developing mitigation plans for planned network disruptions.

Traffic Flow and Road User Impacts of the Collapse of the I-35W Bridge over the Mississippi River (Mn/DOT 2010-21) is available from the CTS Web site. More information on University of Minnesota research on the bridge collapse is also available online.

John Adams, Shanjiang Zhu, and David Levinson

Congratulations to soon-to-be Dr. Shanjiang Zhu (September 2010- PhD Civil Engineering) for completing and successfully defending his Ph.D Dissertation -
The Roads Taken: Theory and Evidence on Route Choice in the wake of the I-35W Mississippi River Bridge Collapse and Reconstruction He will be joining the University of Maryland, College Park as a post-doc.


Route choice analysis investigates the path travelers follow to implement their travel plan. It is the most frequent, and thus arguably the most important decision travelers make on a daily basis. Long established efforts have been dedicated to a normative model of the route choice decision, while investigations of route choice from a descriptive perspective have been limited. Wardrop's first principle, or the shortest path assumption, is still widely used in route choice models. Most recent route choice models, following either the random utility maximization or rule-based paradigm, require explicit enumeration of feasible routes. The quality of model estimation and prediction is sensitive to the appropriateness of the consideration set. However, few empirical studies of revealed route characteristics have been reported in the literature. Moreover, factors beyond travel time, such as preferences for travel time reliability, inertia in changing routes, and travel experience that could also have significant impacts on route choice, have not been fully explored and incorporated in route choice modeling. The phenomenon that people use more than one route between the same origin and destination during a period of time is not addressed by conventional route choice models either.

To bridge these gaps, this dissertation systematically evaluates people's route choice behavior using data collected in the Minneapolis - St. Paul metropolitan area after the I-35W Bridge Collapse. Both aggregate traffic data and individual survey data show gaps between models based on shortest travel time assumption and traffic conditions observed in the field. This study then employs the individual GPS trajectory and GIS maps to systematically evaluate the characteristics of routes people actually use. Merits of route choice set generation algorithms widely used in practice are assessed. The phenomenon of route diversity is clearly revealed through analysis of field data. A route portfolio model is proposed to explain the rationale of choosing a portfolio of routes under uncertainty about network conditions. It is posited that a rule-based model,
comprehensively considering travelers' characteristics, additional network metrics, and previous travel experience will better replicate observed route choices than the tradi- tional assumption of simply minimizing travel time or travel cost. Findings from this dissertation could also inform other parts of travel demand modeling.

At the 28th International
System Safety Conference 2010 30 Aug-03 Sep 2010 in Minneapolis
, I will give a keynote on Aug 31 (at 8 am) on the Rise and Fall of the I-35W Mississippi River Bridge. It looks like an interesting conference. I am sure there is a lot to be learned at the intersection of system safety and network reliability.

Recent working paper
On September 18th 2008, a replacement for the previously collapsed I-35W bridge opened to the public. Consequently, travelers were once again confronted with the opportunity to find better alternatives. The traffic pattern of the Minneapolis road network was likely to readjust, because of the new link addition. However, questions arise about the possible reasons (or components in the route choice process) that are likely to influence travelers crossing the Mississippi, who had to choose among the bridge options, including the new I-35W bridge. Using GPS data and web-based survey collected both before and after the replacement bridge opened, a bridge choice model is estimated using weighted-least squares logit. In this way the proportion of I-35W trips can be estimated depending on the assigned values of the explanatory variables, which include: statistical measures of the travel time distribution experienced by the subjects, alternative diversity, and others. The results showed that travel time savings and reliability were the main reasons for choosing the new I-35W bridge.

From Gizmodo Is This the Craziest Bridge Ever Designed?

How to change from driving on the left to driving on the right:

Is This the Craziest Bridge Ever Designed?I don't know if the "Pearl River Necklace bridge is the craziest bridge ever designed, but it sure looks like the most twisted one. It's a clever solution to a very real and obvious problem, however.

The bridge is part of a proposal by NL Architects to connect Hong Kong with mainland China. To do that, they had to solve a problem: In Hong Kong, people drive on the left side of the road. In mainland China, they drive on the right side. Here's the solution: A road flipper that physically twists the roads over each other.

Is This the Craziest Bridge Ever Designed?

I hope the project goes forward, because I've always wanted to drive in a gigantic Scalextric. [Design Boom]"

From BBC Bridge collapse in western India 'kills 40'

The collapse of a bridge being built in western India is feared to have left some 40 people dead, local police say.

The lawsuits have already begun

Video available here (with really tasteless advertising)

David Levinson

Network Reliability in Practice

Evolving Transportation Networks

Place and Plexus

The Transportation Experience

Access to Destinations

Assessing the Benefits and Costs of Intelligent Transportation Systems

Financing Transportation Networks

View David Levinson's profile on LinkedIn

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