Driving I-94 from city to city now borderline nuts

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.

RESCHEDULED: Bridge Collapses, Our Journey to Work, and other Transportation Challenges (April 19, 7:30 p.m.)

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


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.

Betty McCollum promises to fight Michele Bachmann’s bridge – Minneapolis / St. Paul News – The Blotter

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

Portion of Nobles County bridge collapses

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.

I-35W bridge collapse had complex effect on metropolitan traffic flows, researchers find

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.

The Roads Taken: Theory and Evidence on Route Choice in the wake of the I-35W Mississippi River Bridge Collapse and Reconstruction

19249-thumb-400x268-56595Congratulations 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.

International System Safety Conference

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.