Category Archives: Traffic and Safety

Warning system could protect drivers from traffic ‘shock waves’

Two summers ago, the Minnesota Department of Transportation installed electronic message boards on parts of Interstates 35W and 94 to help warn drivers of crashes and to recommend speed levels during periods of high congestion.

Now, MnDOT would like to use the devices — officially known as Intelligent Lane Control Signs (ILCS) — to advise drivers of sudden stopping or slowing of traffic.  Many crashes occur when drivers cannot react quickly enough to these changes.

The Minnesota Traffic Observatory (shown in the feature photo above) is developing a warning system to detect such problematic traffic patterns and issue automatic advisories to drivers.

Shock waves on I-94

A section of I-94 in downtown Minneapolis, where southbound I-35W and westbound I-94 converge, may have the highest crash rate in the state.

As shown in the video above, vehicles constantly slow down and speed up here during rush hour, which causes a ripple effect called “shock waves.”

“There’s a crash every two days,” said University of Minnesota researcher John Hourdos, whose students watched over a year’s worth of video footage to document every accident and near accident. “They’re not severe crashes — no one has died for as long as I can remember, and most happen at slow speeds — but they cause a lot of delays for the traveling public.”

When statistics were still being kept, this section of I-94 had the highest number of accidents in the state, with approximately 150 crashes and 400 near crashes observed in 2003.

Researchers developed a program 10 years ago to detect “shock wave” patterns in the traffic, but they couldn’t develop a practical solution until the state invested in electronic message boards.

The University of Minnesota deployed cameras and sensors on three downtown rooftops in 2002 to observe traffic patterns.  They provide seamless coverage of the entire area, allowing researchers to watch vehicles from the moment they enter and exit the area. MnDOT has added additional cameras and detectors to watch over this roadway section. For the past year, the combined efforts of MnDOT and the university have provided data from 26 cameras and 12 traffic sensors for the two-mile section that includes the high-crash frequency location.

Thanks to the message boards, Hourdos and his team can now create an automated system to warn drivers when conditions for “shock waves” are greatest, using an algorithm he developed in the previous study.

Traffic monitoring equipment on a rooftop
From downtown Minneapolis rooftops, traffic monitoring equipment detect shockwaves on Interstate 94.

Crosstown interchange 

A newer problem that researchers hope to tackle is the lineup of cars on I-35W southbound during rush hour at the newly reconstructed Crosstown interchange.

Although two lanes of traffic are provided for eastbound Highway 62 at the I-35W/62 split, these vehicles must later converge into one lane, due to the Portland Avenue exit. This causes a back-up on the 62 ramp that stretches back to 35W.

Hourdos said developing an algorithm to detect these queues is a different problem than what goes on with I-94, since there is a constant stoppage of cars and no rolling shockwaves.

“Combining the two methodologies will form a more robust solution and a single implementable driver warning system,” Hourdos said.

Researchers might target other problems areas should the state  install additional ILCS message boards elsewhere in the Twin Cities.

Three common questions about bike lanes, answered

If you’ve ever driven near a bike lane and not known what to do, you’re not alone.

A forthcoming video from the Local Road Research Board seeks to answer common questions about on-street bike lanes and help bicyclists and motorists better understand the rules. The video is due to be released this spring; in the meantime, we thought we’d give you a sneak preview by addressing three common misconceptions about bike lane rules and safety. 

1) Are bicyclists required to use a bike lane, when present?

No. Although bike lanes usually provide the smoothest, safest and most efficient method of transportation — for everybody — they are not required to use them. They are allowed to ride outside bike lanes to make turns or avoid debris, and they still have the option of using an adjacent trail where available.

2) Are vehicles allowed to enter bike lanes?

Yes, but only to park or turn onto a driveway or street. Motorists should treat bike lanes like any other lane of traffic and yield to approaching bicyclists, but they do have the right to enter bike lanes when turning.

3) Do bicyclists have to follow the same rules as motorists?

Yes. Bicycles are considered vehicles under Minnesota state law and have the same rights and responsibilities. Cyclists are required to obey stop signs and signal their turns, just like motorists.

A federal project funded 75 miles of new bike lanes in four communities, including Minneapolis.
A recent federal project funded 75 miles of new bike lanes in four communities, including the city of Minneapolis. Biking in these areas increased 50 percent; 7,700 fewer tons of carbon dioxide were emitted and gas consumption was reduced by 1.2 million gallons. (Source)

Watch for the LRRB’s new bike safety video on Crossroads this spring. In the meantime, check out MnDOT’s tips on bicycle safety.

Demonstration project helps truck drivers find safe places to park

With freight traffic increasing on U.S. roadways, commercial truck drivers often struggle to find safe and legal places to park. If parking spaces are not available at a nearby rest area or truck stop, drivers may be forced to pull over in unsafe locations or continue driving and become dangerously fatigued. Drivers may also risk violating federal hours-of-service rules, which require them to rest after 11 hours of driving.

In response to this issue, a team from MnDOT, the University of Minnesota, and the American Transportation Research Institute
 is developing a system that can identify available truck parking spaces and communicate the information to drivers—helping them determine when and where to stop. System benefits include improved safety, reduced driver fatigue, and better trip management.

The system uses a network of digital cameras suspended above a parking area to monitor space availability. Image processing software developed by researchers at the U of M’s computer science and engineering department analyzes the video frames and determines the number of available spaces.

As part of a demonstration project funded by MnDOT and the Federal Highway Administration, the project team is installing the system at three MnDOT rest areas and one private truck stop on I-94 west and northwest of the Twin Cities.

The U of M research team first installed the system in late 2012 at the the Elm Creek Rest Area, two miles north of Interstate 494 on I-94. As of early 2014, the system has been installed at an additional rest area, and a third site is in progress.

Next steps for the project include implementing several mechanisms that will communicate parking information to truck drivers. First, the team plans to install variable message signs along I-94 this spring. Also in the works are an in-cab messaging system and a website.

Overall results of the demonstration project will help the team determine whether this technology holds promise for use in other corridors throughout the nation.

Read the full article in the February issue of Catalyst.

Reducing confusion at two-lane roundabouts

Minnesotans have grown accustomed to roundabouts as they’ve proliferated throughout the state, but many motorists are still confused by the less common two-lane roundabout.

While roundabouts have been shown to reduce vehicle delay and severe crashes, the few Minnesota cities with this type of multi-lane roundabout have had a prevalence of driver mistakes.

In Woodbury, two such roundabouts were converted into smaller, one-circulating-lane designs due to driver confusion.

The City of Richfield had no such option at the high-volume Portland Avenue and 66th Street, a formerly signalized intersection that carries about 30,000 vehicles per day. (See video)

Crash-prone and congested prior to its reconstruction in 2008, a two-lane roundabout seemed to be the practical solution for this intersection. But although the roundabout reduced overall crashes, the intersection still had more fender benders than designers were comfortable with, according to City Engineer Kristin Asher.

“The crashes were primarily related to improper left-turns from the outside lane and failure to yield at the entry,” she said.

Not only were drivers unsure which lanes they should use to enter or exit the roundabout, they didn’t know how to respond to other cars inside the roundabout. (See news story)

“People don’t understand they have to yield to both lanes inside the roundabout,” explained University of Minnesota researcher John Hourdos.

In a recently completed study funded by the Minnesota Local Road Research Board, researchers from the Minnesota Traffic Observatory examined whether sign and pavement marking changes would improve performance.

The city of Richfield extended the solid lines leading up to the intersection from 50 to 250 feet to encourage drivers to choose the correct lane before entering the roundabout. It also replaced fish-hook-style roundabout signs with traditional lane designation signs and did away with complex striping patterns.

These before and after photos show the original fish-hook style pavement markings, left, which were replaced with a more traditional design. (Photos courtesy of the city of Richfield)
Before and after photos show the original fish-hook style pavement markings, left, that were replaced with a more traditional design.
(Courtesy City of Richfield)

Hourdos examined two years of traffic data to see how motorists responded to the improvements that were made in 2011.

He found 50 percent more drivers entered the correct lane from the get-go, which led to a reduction in improper turns within the roundabout. Lane violations were also reduced by 20 percent.

“One of the main problems was drivers didn’t know they have to choose one of the two lanes,” Hourdos explained. “Then once they were inside the roundabout, they were forced to either deviate from their course or commit a violation.”

The city also increased sign visibility to address yielding problems; however, these changes didn’t seem to make a difference.

With state and federal guidelines lacking much guidance for how to sign two-lane roundabouts, the LRRB is funding a new study for three other multi-lane roundabouts: in St. Cloud, at Highway 169/494 and one planned for the future realignment of County Roads 101 and 61 between Chanhassen and Shakopee.

Report: Effect of Signing and Lane Markings on the Safety of a Two-Lane Roundabout (PDF, 4 MB, 72 pages)

Update (1/30/2014): Watch the LRRB’s new video on how to navigate a multi-lane roundabout.

New technology aimed at making rural intersections safer

This video above showcases a new kind of intersection conflict warning system being developed for use primarily by local agencies at rural, two-way stop intersections. Called the ALERT System, it uses a simple but ingenious combination of radar, wireless communication and flashing LEDs to alert drivers to the presence of approaching vehicles, thereby helping them identify safe gaps in the cross traffic and avoid potentially deadly collisions.

These types of systems are nothing new; MnDOT and other state DOTs have been developing them for more than a decade under the ENTERPRISE pooled fund program. MnDOT also recently kicked off a three-year project to deploy 20–50 of its Rural Intersection Conflict Warning Systems at selected at-risk intersections across the state. The main difference with the ALERT System is that it’s designed to be cheaper and easier to deploy than existing ICWS technologies. While that might sound like an incremental improvement, the difference for cash-strapped local agencies could be huge.

Since the ALERT System uses solar power, it doesn’t have to be hooked up to the power grid — which means that, in theory, county public works crews could install it themselves. The system also uses a simplified controller that doesn’t require a traffic signal technician to install and maintain, and detects vehicles using radar rather than in-pavement sensors. These factors might encourage greater adoption of ICWS technologies, which studies have shown to reduce both the frequency and severity of crashes.

The project is now in its second phase. It still faces a number of hurdles before could be ready to deploy, but Vic Lund, the traffic engineer for St. Louis County and the project’s main champion, says the results so far have been encouraging. In the video below, Lund shares his thoughts on the project, its challenges and the future of Intelligent Transportation Systems in Minnesota.

Learn more:

Congestion-reduction measures on I-35W: How well do they work?

In an effort to combat congestion in our country’s urban areas, the United States Department of Transportation launched the Urban Partnership Agreement (UPA) program in 2007. The program infused nearly $900 million into transportation-related projects in four cities nationwide, including the Twin Cities metropolitan area. Minnesota’s projects—which include the installation of MnPASS dynamic toll lanes and variable message signs—focused on improving traffic flow in the I-35W corridor between Minneapolis and the city’s southern suburbs.

To understand the effectiveness of measures implemented under the UPA program, a team of University of Minnesota researchers examined three separate but related areas: the effects of a new variable speed limit (VSL) system, the impact of severe weather conditions on road safety, and the behavior and traffic impacts of bus rapid transit operations. Their work was funded by the Intelligent Transportation Systems Institute, a part of CTS.

Key findings included:

  • Drivers don’t typically comply with advisory speed limits posted on VSL signs along the I-35W corridor during congested conditions, but they may use them to help gauge and prepare for downstream congestion—resulting in a smoother and possibly safer traffic flow
  • Some parts of the corridor’s shoulder lanes—which are opened to traffic during specific times of the day as part of the UPA program—contain low areas that can flood during heavy rains
  • Buses traveling on the corridor underuse the MnPASS lane. In addition, bus lane changes (from stations located in the median to those located on the right side of the highway) can generate visible disturbances during moderate and heavy congestion, but they don’t seem to contribute to the breakdown of traffic flow

For more information, read the full article in the September issue of Catalyst.

CTS to lead $10.4 million regional consortium on transportation safety

In a national competition held by the U.S. Department of Transportation, CTS has been selected to lead a new $10.4 million regional University Transportation Center consortium focused on improving transportation safety.

The new Region 5 Center for Roadway Safety Solutions will be a regional focal point for transportation safety research, education, and technology transfer initiatives. The region includes Minnesota, Illinois, Indiana, Michigan, Ohio, and Wisconsin.

The two-year consortium will focus its research on regional issues related to high-risk road users and systematic safety improvements. Within these areas, the consortium will address multiple modes of transportation across a variety of topic areas, including roadway departures, urban and rural intersections, pedestrians and bicyclists, and commercial vehicle drivers. The consortium will also explore transportation safety engagement in the region’s Native American communities.

The CTS-led consortium was one of 33 federal grant recipients selected out of 142 applicants. Other consortium members in CTS’s winning proposal are the University of Akron, University of Illinois at Urbana-Champaign, Southern Illinois University Edwardsville, and Western Michigan University.

“The new consortium will allow us to bring together the diverse strengths and expertise of our members to work toward the shared goal of improving safety,” said Laurie McGinnis, director of CTS and chair of the new regional center’s Advisory Board. “Together, we can do much more to save lives on our roads than we could do alone.”

Max Donath, professor of mechanical engineering at the University of Minnesota and an internationally recognized leader in transportation safety research, will serve as the director of the new Region 5 center.

More Information

New LRRB videos focus on work zone safety

The Minnesota Local Road Research Board is a major source of funding for transportation research in the state. Occasionally, it also produces educational videos designed to raise public awareness of important transportation topics.

Two new video offerings from the LRRB (embedded above and below) are focused on save driving in work zones. While not directly research-related, they might prove a useful resource to transportation professionals. More importantly, they serve to remind us all of the very real and dramatic consequences of work zone crashes, of which there are approximately 2,000 per year in Minnesota.

You might want to also check out some of their other recent YouTube offerings, including explanations of why we need stop signs and speed limits, as well as a fascinating look at how potholes are patched.