Archive for the ‘Traffic Reports’ Category

9/11 and the Subsequent Rise in Traffic Fatalities: More Exposure, or More Stress?

There have been a number of papers that have argued that have identified a post 9/11 uptick in traffic fatalities, theoretically based on a rise in driving, itself motivated by a fear/dread of flying (most notably, Gerd Gigerenzer, 2004, “Dread risk, September 11, and fatal traffic accidents,” in Psychological Science).

A new paper, “Driving Under the Influence (of Stress): Evidence of a Regional Increase in Impaired Driving and Traffic Fatalities After the September 11 Terrorist Attacks,” by Alexander J. Rothman, et al., also in Psychological Science, comes to a rather different conclusion.

“Although we confirmed that U.S. domestic air travel decreased significantly following September 11,” the authors write, “our analyses did not support the claim that there were notable increases in driving miles and in traffic fatalities across the United States after that date. In fact, total U.S. driving miles in the post-September months in 2001 did not differ significantly from total U.S. driving miles in the same months in 1999 and 2000, and the observed increase in total U.S. driving miles in October through December 2001 appears normative when examined within broader historical trends. The number of fatal traffic accidents in the United States did increase, albeit only marginally, in the 3 months following September 11, but there was no evidence of an overall increase in traffic fatalities.”

They did find one change amidst the data, however: “We did obtain evidence that the terrorist attacks had a systematic, but localized, effect on traffic fatalities.” The “localized” effect was on the Northeast, the region arguably the most directly impacted by the September 11th attacks. “Our analysis revealed a significant increase in traffic fatalities in the Northeast in the final 3 months of 2001.”

They continue: “To examine regional differences in traffic fatalities further, we used alcohol- or drug-related citations and reckless-driving citations as two behavioral indicators of psychological distress… [W]e found a significant increase in the number of alcohol- or drug-related citations issued in connection with such accidents during the last 3 months of 2001, but only in the Northeast. The concurrent regional increases in traffic fatalities and in alcohol- or drug-related citations lend support to our second hypothesis—namely, that behaviors impairing the quality of driving increased in those regions most affected by the terrorist attacks, and may have contributed to the observed elevation in percentage of traffic fatalities. This effect is consistent with other findings indicating that exposure to traumatic events is associated with an increased use of psychoactive substances, especially alcohol (e.g., Chilcoat & Menard, 2003; Pfefferbaum & Doughty, 2001)…”

Interestingly, they found the rate was the effect was highest in New York State, though they caution that “that meaningful operationalization of geographic proximity can be complicated and remains a task that is beyond the scope of this article.”

So, if correct, the study implies that it wasn’t a mere affect of people driving more miles to avoid airplane travel, but that their behavior on the road had in some way changed (one Israeli study found a similar increase in fatal crashes in the days following suicide bombings). My initial instinct was to think that a rise in drunk driving crashes might make sense from the perspective that more traffic enforcement officials were pulled off the roads and put into other duties in the wake of 9/11, although that wouldn’t necessarily explain the rise in citations. Another issue is to break down more specifically what kinds of roads people were driving on after 9/11, as Michael Sivak and Michael Flannagan have done, although, interestingly, this seems to potentially add weight to this study: Sivak and Flannagan found “the largest increase [in driving] occurred on local roads, not interstate highways that would be the main alternative to flying. Local roads, both urban and rural, accounted for 45 percent of the increase in traffic deaths.” Presumably, people swapping out flights for long-haul driving would be on those interstate highways, not local roads. As Rothman and his colleagues caution, “the rates of fatal traffic accidents, and hence fatalities, may have increased in the Northeast after the attacks as a result of more people driving in unfamiliar areas because of road closures and detours.”

Lastly, one can’t be certain that aggressive driving or impaired driving is a sign of “psychological distress.” Still, the pattern, localized in time and place, seems very real and suggestive.

(Horn honk to Shirl)

Posted on Monday, February 16th, 2009 at 3:24 pm by: Tom Vanderbilt
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Coming Soon to a City Near You?

Via the Tri-State Transportation Campaign is this handy round-up of congestion pricing initiatives on the horizon in any number of places across the globe:

“* Milan, Italy: The cosmopolitan city implemented the “EcoPass” cordon charge this past January to cut pollution and reduce traffic. Higher-polluting vehicles are charged more, with the revenue going towards “buses, cycle paths and green vehicles,” according to the BBC.
* Valletta, Malta: The “Controlled Vehicular Access” system, implemented in May 2007, charges non-resident cars depending on how long they stay within the charge zone, limiting long-term parking and reducing traffic in the historic capital. The plan was named a best practice case study by the European Local Transport Information Service.
* Tel Aviv, Israel: By 2009, Motorists entering Tel Aviv will be charged NIS 25-50 (US $7-$15) to enter parts of the city based on time of day, area they are driving and the amount of pollution emitted by their car. The charge is meant to tackle the city’s huge traffic problem and encourage greater use of public buses. Revenue generated would help fund a long awaited light-rail system.
* Shenzhen, China: Looming in the future with an unspecified date, Shenzhen is to introduce a congestion charge for vehicles entering its downtown. Currently, officials are figuring out where the pricing zone will be and the amount of the charge. The revenue will be used to build infrastructure for public transportation.

Cities where congestion pricing is being considered:

* Seoul, Korea: The city government has proposed legislation to charge motorists who drive to stores and buildings in Seoul’s vehicle choked center. Mostly a traffic reducing measure for the city, officials tout its benefits for energy and the environment. If passed, the charge could begin March 2009.
* Greater Manchester, England: This December, residents of the area will decide through a referendum if they want a congestion charge. If yes, the charge will be implemented in 2013. The revenue generated would expand public transportation across the areas’ 10 boroughs with extra trains, buses and improved stations, with an additional £1.5 billion (roughly $2.8 billion) in investment coming from the central government.
* Abu Dhabi, United Arab Emirates: A recent report issued by the country’s Department of Planning and Economy noted that traffic congestion and limited mass transit were inflicting a “heavy economic toll” on the city. The report lists a “demand management scenario” as one of four options to improve mobility and improve public transportation.
* Bangkok, Thailand: City government is conducting a feasibility study of implementing a congestion charge in Bangkok’s business district. The main impetus of the plan is to tackle the notorious traffic problem and encourage carpooling.
* Jakarta, Indonesia: Based on the recommendation of an outside consultant, the Governor is considering charging drivers as a way to ease traffic jams in the capital. The city is conducting feasibility studies now, but the plan could be piloted next year.”

Posted on Monday, September 8th, 2008 at 4:39 pm by: Tom Vanderbilt
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Shut Up and Drive

Often when I’m driving, I find myself entering a difficult situation — a tricky lane-change, an unfamiliar turn — and I’ll actually ask my passenger (typically my wife) to essentially stop talking for a moment (or they will voluntarily do so) as the situation resolves itself. This, of course, is one of the major problems with talking on a cell phone versus talking with a passenger: Not only are they providing another set of helping eyes, but they can sense when would be good for them to modulate their conversation in some way, whereas the person on the other end of the cell-phone will seemingly keep droning on, taking away from the driver’s workload.

This point, fairly well established by now, is made again in a new study (PDF here) by Samuel G. Charlton, University of Waikato, Hamilton, for Land Transport New Zealand. The study, as others have, found that drivers on cell phones had slower reaction times — yet drove at higher average speeds — than drivers with passengers as they went through a number of hazards in a driving simulator. Interestingly, this study also featured a person on a cell-phone who was not present in the car yet had access to the driver’s view, so they have a passenger-like view of the road.

The key to performance seemed to be what the paper calls “conversation suppression,” i.e., knowing when to shut up: “Passengers talking to drivers made shorter utterances, had more frequent pauses and were more likely to be talking about the upcoming hazard than cellphone conversors. Drivers and their cellphone conversors tended to make longer utterances than the other participants, were less likely to mention the hazards, had the poorest recall of the hazards, and had the highest crash rate.” Even when the remote cell phone conversor had access to the driving scene, they didn’t tend to adjust their conversation as much as the passenger did — maybe there’s just something ineluctable in actually being there.

The study includes one other interesting, but to my mind a bit strange, finding. Drivers did a bit better on the cell phone when an automated hazard alert message “beeped through” their call, alerting them to some upcoming traffic hazard. This gave the driver the necessary cue to break off the conversation a bit. These alerts would presumably be triggered by some sort of beacons in the road infrastructure, particularly at hazardous points. But, of course, the thing about driving is one never knows when it’s going to become hazardous, and it certainly isn’t always at the accident “black spots” (which are often just statistical aberrations in any case). There are innumerable issues here, from a driver’s over-reliance on the hazard warning system, to the idea that they may be brought back “into the loop” with not enough time to react and not enough knowledge of the situation.

Posted on Tuesday, August 12th, 2008 at 9:34 pm by: Tom Vanderbilt
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50,000 Missing Trips

I’ve had Minneapolis on my mind lately, not just because I’ve just arrived to the city, but because I’ve been reading a fascinating new paper (available here) on the large-scale traffic effects of the tragic collapse of the I-35W bridge last year.

The paper, “The Traffic and Behavioral Effects of the I-35 W Mississippi River Bridge Collapse,” is by David Levinson, Henry Liu, Shanjiang Zhu, and Kathleen Harder (Levinson, whose “Transportationist” blog is a daily must-read of mine, also figures in a number of ways in Traffic).

This paper tackles one of those fascinating traffic issues that have come up now and again in different ways: What happens when, for some reason or another, whether on purpose or not, sections of road are removed? What effects do these “network disruptions” have on the entire system? In this particular case, the paper notes, I-35W carried some 140,000 people across the bridge every day. Neighboring bridges, in the wake of the new patterns that seem to have asserted themselves a year later, are carrying only 90,000 more cars. What happened to the others? Judging by the survey results collected here, the majority that were affected did one of two things: They changed their route, or they changed the time they left home. And the rest, it would appear, simply did not make trips.

This raises interesting questions about the traffic stream during peak hours. Do all those people need to be there, or is their desire to be there equal (e.g., would they pay a premium to make that trip during that time)? It also shows the amazing flexibility and cleverness people have in staking out new routes and strategies during these disruptions. When New York City suddenly had a “plus three” car occupancy requirement in the wake of the transit strike a few years back, we were all suddenly instant car-poolers. The new routing that Minneapolis drivers quickly took on invokes a classic principal from the world of transportation: Wardrop’s equilibrium. This states (and I’m simplifying here) that a single driver cannot, by his or her own action, find a better route than the one they are on. As a New Yorker, I sort of view this in a Yogi Berra kind of way: If there was a faster way to go, everyone else would be slowing it down already.

The missing capacity in the system, the authors note, is not without costs — to the economy, to people’s individual desire to travel, to individual’s commute times. But, they add, “travelers exhibited great flexibility in dealing with the changed traffic pattern.” Some of this was aided through novel infrastructure tweaks (like adding new lanes on other bridge crossings by simply making the existing lanes more narrow), but much of it just came down to individual decisions, and people’s willingness to change. The two words in the title say it all: Traffic is behavior. In any case, the work is ongoing and promises to yield more insights.

Posted on Monday, August 4th, 2008 at 8:21 pm by: Tom Vanderbilt
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Are American Drivers Driving More Safely?

The last time the U.S. saw a substantial drop in traffic fatalities was 1974, when the double whammy of the recession and the 55 mph speed limit (a reaction to the fuel shortage) saw the number of fatalities drop by some 9000 (it’s still debated to what extent this had to do with the economy and to what extent it had to do with the speed limit).

But this year, which promises to see the first annual drop in vehicle miles traveled in 28 years, is also shaping up, if trends continue, to see fatalities drop below 40,000 for the first time since 1961.

This comes from a new preliminary report from Michael Sivak, head of the Human Factors division at the University of Michigan’s Transportation Research Institute. What’s even more interesting, notes Sivak, is that the drop in fatalities we’re seeing seems to exceed what we might expect based on the drops in fuel consumption and miles driven. It suggests a fascinating trend: U.S. drivers might not only be driving less, but driving differently.

Sivak, whose work (especially this one) has been an influence in Traffic, points out several factors that may underlie this. For one, the mileage reduction has been greater on rural highways, which are statistically riskier. Also, he suggests, the mileage of lower-income drivers, who are also statistically over-involved in crashes, may be have disproportionately dropped. And more people may be driving more slowly to save fuel, further reducing the risk of a fatal crash. I might even suggest another possible factor: Larger, higher consumption vehicles like SUVs and pickups — which pose a greater risk to other drivers — seem to be being driven less, which could also improve things for everyone.

There’s more parsing of the data to come from Sivak, so stay tuned…

Posted on Thursday, July 31st, 2008 at 6:23 am by: Tom Vanderbilt
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The Most Dangerous Place to Drive in California

According to the state’s Office of Traffic Safety, the most dangerous spot (according to 2005 stats; takes a while to tally these up and analyze presumably) to drive in California is…

Malibu. It was tops out of 105 cities of its size across the state (and based on vehicle miles traveled). I was a admittedly a bit surprised, but upon further reflection there’s little surprise. It’s not hard to puzzle out the reasons: Speed, booze, and distraction. The Pacific Coast Highway runs right through residential and often crowded areas; although the speed is marked for an already high 45 mph, as the road is engineered to highway standards there’s little immediate incentive for drivers to slow (watch here to see the speed limit compliance patterns of California drivers in action).

Then there’s the alcohol factor — people coming off the beaches are often more than a little liquored up (and let’s not forget that Mel Gibson, who told police he ‘owns Malibu,’ was busted for drunk driving after a night at Moonshadows; the fact that Gibson could have killed someone got rather overshadowed in the hue and cry over his drunken rantings to the cops).

Posted on Monday, June 23rd, 2008 at 10:41 am by: Tom Vanderbilt
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Traffic Reports

There’s one word that’s never used in this lengthy New York Times piece about the impact high-fuel prices are having in rural areas: Carpool. When will we stop treating driving to work alone as a constitutional right?

* * * *

From the FT comes this ardent defense of congestion charging, now coming to Manchester, England. Note the final line, a nice rejoinder to the typical red herring, raised in NYC and elsewhere, of congestion charging as a regressive tax. “The case for road pricing is clear: every driver on the road imposes a cost on others, through congestion, pollution, greenhouse gas emissions and the risk of accidents. The attractions of a well designed scheme are the market mechanisms that encourage drivers to travel when road capacity is cheapest and most available. By paying more for longer journeys through heavily built-up areas, motorists are encouraged to find other, quieter routes to get around. A small response from drivers can greatly improve traffic flows. Since the rich drive more than the poor, road pricing is also progressive.”

* * * *

The LA Times has been running an excellent ongoing investigation into traffic. I was struck by these sentences in particular, about a driver stuck in traffic: “He loves Los Angeles, mostly. In the last few weeks alone, he’s seen a Latin American art exhibit at the L.A. County Museum of Art, a Murakami show at the Museum of Contemporary Art, an avant-garde dance performance at UCLA, and flamenco dancing at El Cid restaurant on Sunset Boulevard. Tonight, he’ll meet friends at Papa Cristo’s Greek restaurant in L.A. to dine on fried octopus and feta.” This raises the question: How could one live a place where all those things were possible without encountering traffic? To do all these things in a place without traffic, say, Montana, you’d likely eat up the same amount of time merely driving from one far-flung locale to another in search of these activities. Angelenos can use the metro system to get to some of these events, but even those trips take longer than those by car. Traffic, like congestion itself, is a relative term.

Posted on Wednesday, June 11th, 2008 at 8:40 am by: Tom Vanderbilt
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Traffic Tom Vanderbilt

How We Drive is the companion blog to Tom Vanderbilt’s New York Times bestselling book, Traffic: Why We Drive the Way We Do (and What It Says About Us), published by Alfred A. Knopf in the U.S. and Canada, Penguin in the U.K, and in languages other than English by a number of other fine publishers worldwide.

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Upcoming Talks

April 9, 2008.
California Office of Traffic Safety Summit
San Francisco, CA.

May 19, 2009
University of Minnesota Center for Transportation Studies
Bloomington, MN

June 23, 2009
Driving Assessment 2009
Big Sky, Montana

June 26, 2009
PRI World Congress
Rotterdam, The Netherlands

June 27, 2009
Day of Architecture
Utrecht, The Netherlands

July 13, 2009
Association of Transportation Safety Information Professionals (ATSIP)
Phoenix, AZ.

August 12-14
Texas Department of Transportation “Save a Life Summit”
San Antonio, Texas

September 2, 2009
Governors Highway Safety Association Annual Meeting
Savannah, Georgia

September 11, 2009
Oregon Transportation Summit
Portland, Oregon

October 8
Honda R&D Americas
Raymond, Ohio

October 10-11
INFORMS Roundtable
San Diego, CA

October 21, 2009
California State University-San Bernardino, Leonard Transportation Center
San Bernardino, CA

November 5
Southern New England Planning Association Planning Conference
Uncasville, Connecticut

January 6
Texas Transportation Forum
Austin, TX

January 19
Yale University
(with Donald Shoup; details to come)

Monday, February 22
Yale University School of Architecture
Eero Saarinen Lecture

Friday, March 19
University of Delaware
Delaware Center for Transportation

April 5-7
University of Utah
Salt Lake City
McMurrin Lectureship

April 19
International Bridge, Tunnel and Turnpike Association (Organization Management Workshop)
Austin, Texas

Monday, April 26
Edmonton Traffic Safety Conference
Edmonton, Canada

Monday, June 7
Canadian Association of Road Safety Professionals
Niagara Falls, Ontario

Wednesday, July 6
Fondo de Prevención Vial
Bogotá, Colombia

Tuesday, August 31
Royal Automobile Club
Perth, Australia

Wednesday, September 1
Australasian Road Safety Conference
Canberra, Australia

Wednesday, September 22

Wisconsin Department of Transportation’s
Traffic Incident Management Enhancement Program
Statewide Conference
Wisconsin Dells, WI

Wednesday, October 20
Rutgers University
Center for Advanced Infrastructure and Transportation
Piscataway, NJ

Tuesday, March 8, 2011
Ontario Injury Prevention Resource Centre
Injury Prevention Forum

Monday, May 2
Idaho Public Driver Education Conference
Boise, Idaho

Tuesday, June 2, 2011
California Association of Cities
Costa Mesa, California

Sunday, August 21, 2011
American Association of Motor Vehicle Administrators
Milwaukee, Wisconsin

Wednesday, October 26, 2011
Attitudes: Iniciativa Social de Audi
Madrid, Spain

April 16, 2012
Institute for Sensible Transport Seminar
Gardens Theatre, QUT
Brisbane, Australia

April 17, 2012
Institute for Sensible Transport Seminar
Centennial Plaza, Sydney
Sydney, Australia

April 19, 2012
Institute for Sensible Transport Seminar
Melbourne Town Hall
Melbourne, Australia

January 30, 2013
University of Minnesota City Engineers Association Meeting
Minneapolis, MN

January 31, 2013
Metropolis and Mobile Life
School of Architecture, University of Toronto

February 22, 2013
ISL Engineering
Edmonton, Canada

March 1, 2013
Australian Road Summit
Melbourne, Australia

May 8, 2013
New York State Association of
Transportation Engineers
Rochester, NY

August 18, 2013 “Ingenuity” Conference
San Francisco, CA

September 26, 2013
TransComm 2013
(Meeting of American Association
of State Highway and Transportation
Officials’ Subcommittee on Transportation
Grand Rapids MI



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