Tag Archives: traffic

Software Tool Cuts Time to Analyze Twin Cities Congestion

Newly developed software has drastically reduced the amount of time and effort required by MnDOT’s Regional Transportation Management Center (RTMC) to analyze congestion in the Twin Cities metropolitan area.

Developing MnDOT’s annual Metropolitan Freeway System Congestion Report used to be a manual process that could be applied to only a portion of the large quantity of data generated by in-pavement sensors.

The new Highway Automated Reporting Tool now automatically imports and cleans data to produce a report about the percentage of network miles congested during peak periods as well as three new reports on other performance measures.

The tool will help MnDOT engineers and planners better develop congestion reduction strategies and determine the most cost-effective investments in the network.

From RTMC’s control room, engineers monitor and manage 400 miles of Twin Cities freeway traffic using data from thousands of in-pavement sensors.

“Before HART, it took months to analyze freeway performance using traffic data from only the month of October. Now engineers can quickly analyze data from any time period, significantly improving traffic planning,” said Jesse Larson, Assistant Freeway Operations Engineer for MnDOT’s Metro District Regional Transportation Management Center.

The tool was developed in a MnDOT-funded study led by University of Minnesota researcher John Hourdos.

Note: This article was adapted from the May–June 2014 issue of our Accelerator newsletter. Sign up for your free print or email subscription by clicking here.

Resources

MnDOT looks for solution to noisy highway rumble strips

Rumble strips alert sleepy and inattentive motorists that they are about to veer off the highway or into the opposite lane of traffic. But the grating noise that prevents collisions can also be annoying to nearby residents.

Around Minnesota, more and more counties are facing push-back as they install shoulder rumble strips on roadways in populated areas. This is because county road shoulders are narrow — leading drivers to frequently hit the rumbles.

“There is a strong concern statewide that these noise complaints will raise enough concern that legislation may be passed reducing their use,” said technical liaison Ken Johnson of MnDOT’s Office of Traffic, Safety and Technology.

A European-developed style of rumble strip, called sinusoidal, could provide Minnesota a new means of warning drivers without as much stray highway noise.

Accident reduction

Rumble strips are patterns ground into asphalt that cause a vehicle to vibrate when its tires come close to the centerline or road edge. They help prevent lane departure crashes, which account for more than 50-percent of fatalities on the road system.

The sinusoidal rumble (below) has a sine wave pattern ground into the pavement, while the traditional rumble strip (top photo) doesn’t follow a wave pattern.

Photo courtesy of the Wirtgen Group
Creation of a Sinusoidal rumble strip. Photo courtesy of the Wirtgen Group

MnDOT’s Office of Traffic, Safety and Technology plans to test different designs of the Sinusoidal rumble strips to find the one with the highest level of interior vehicle noise and lowest level of exterior vehicle noise.

The navigability of sinusoidal rumbles by motorcycles and bicycles will also be evaluated. The project was recently funded with a research implementation grant from MnDOT’s Transportation Research Innovation Group.

If sinusoidal rumble strips are found to be effective, the chosen design will be used for centerlines and road shoulders in noise-sensitive areas throughout the state highway system. It is anticipated that counties will also adopt the design.

Unlike counties, most of MnDOT’s recent complaints have been for its centerline rumbles, which are required on all rural, high-speed undivided roads in Minnesota, Johnson said.

MnDOT has considered allowing more exceptions due to residential noise concern; however, doing so could result in more fatal and serious crashes. Sinusoidal rumbles are seen as a possible alternative for these noise-sensitive areas.

The Local Road Research Board is also studying different designs of sinusoidal rumble strips in Polk County.

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.

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.

About those roundabouts

One of my unofficial duties as a MnDOT employee is to respond to a near-constant barrage of opinions from my family and friends regarding the condition of our state’s roadways. (My wife, for example, half-jokingly tries to ascribe personal responsibility to me for the congestion she faces on her morning commute.) Interestingly, one of the issues that gets brought up to me most often in private conversations is roundabouts — the circular intersections that are widely praised by engineers but often vilified by a skeptical public.

From a public interest perspective, the verdict on roundabouts is overwhelmingly positive. With very few exceptions, roundabouts have been shown to dramatically reduce both the frequency and seriousness of traffic accidents when compared to other types of intersections. One oft-cited source, the National Insurance Institute for Highway Safety, reports that U.S. intersections converted to roundabouts have experienced a 35-47 percent decrease in crashes and an 72-80 percent decrease in injury crashes (source here). Moreover, because the don’t have stop signs or traffic lights, roundabouts have been found to reduce traffic delays and pollution.

Perhaps not surprisingly, research on these potential benefits has precipitated a rash of roundabout construction. In Minnesota alone, 115 have already been built, with another 39 either planned or under construction, according to the Pioneer Press. Love them or hate them, roundabouts are becoming a fact of life here.

Of course, not everyone loves them. In spite of their stellar  record, roundabouts remain something of a political lightning rod. This article in the Mankato Free Press and this news segment from KSTP provide typical examples of the kind of skepticism officials face when proposing to put in a roundabout. The problem is persistent enough that many officials see a need to develop a public relations game plan. On June 19, the Transportation Research Board is offering a free webinar entitled “Community Outreach: Successful Outcomes for Roundabout Implementation,” designed to help transportation professionals understand and respond to political opposition to roundabouts. It’s free for employees of TRB sponsor organizations (including MnDOT); a $99 registration fee is required for employees of non-sponsors.

For those who are unfamiliar with roundabouts, there are some good resources designed to help people understand their purpose and benefits. Several years ago, the Local Road Research Board produced the video above (along with an accompanying brochure). MnDOT also has a resource page devoted to explaining the use of roundabouts.

Those with more than a passing interest in the subject might also want to check out these recent MnDOT/LRRB-sponsored studies: