Tag Archives: transportation research

Six effective low-cost safety improvements for roads

For the past 10 years, Minnesota and 37 other states have pooled their resources to test the effectiveness of roadway safety improvement strategies. The project, appropriately titled “Evaluation of Low-Cost Safety Improvements,” evaluates key strategies laid out in a national guidebook aimed at reducing the number of annual highway deaths.

Participating states say the project, which has now been extended a total of eight times beyond its original scope, has been a resounding success. MnDOT Safety Engineer Brad Estochen said the pooled-fund study has provided state DOTs much-needed evidence to gain support for implementing new safety improvements.

“Some states want to do a certain strategy, but don’t have the institutional support,” Estochen said. “Through the collaboration of the Peer Exchange, they have national results they can point to.”

We asked Estochen, MnDOT’s technical liaison for the pooled fund, to name his top strategies to come out of the study.

Traffic calming measures

Roadway

One phase of the study used simulated driving scenes to examine methods of traffic calming (i.e., getting drivers to slow down) in  rural towns. The research found that drivers were most impacted by chicanes — extra curves in the road — and the presence of parked cars on the street. An alternative strategy, curb extensions (also called “bulb-outs”), was found to offer only a small potential safety benefit or no benefit at all.

(Read more about this phase of the study.)

Nighttime visibility improvements

DSC_6498

Researchers also looked at ways of improving nighttime driver visibility on rural roads. Edge lines and post-mounted delineators were selected as the best alternatives for improving curve visibility at night, with curve detection improving 12 percent to 70 percent due to enhanced edge lines. The results are significant, since horizontal curve sections of two-lane rural roads are a major source of roadway fatalities.

(Read more about this phase of the study.)

Flashing beacons at stop-controlled intersections

One way to make drivers aware that they’re approaching a stop sign is to add a flashing beacon to the intersection. Researchers installed various configurations of flashing beacons at more than 100 sites in North and South Carolina and examined the crash data before and after installation.

Courtesy of K-Kystems
Courtesy of K-Kystems

Results indicate that standard flashing beacons, as well as some “actuated” beacons (i.e. those that only turn on when traffic is approaching the intersection), are not only effective at reducing crashes, but also economically justifiable based on cost-benefit calculations.This research helped pave the way for more widespread adoption of Minnesota’s Rural Intersection Conflict Warning Systems (RICWS).

(Read more about this phase of the study.)

Edgeline rumble strips

DSC_4106pse

Edgeline rumble strips on curves were shown to significantly improve safety in the third phase of the study, which tested a variety of techniques.

Whereas rumble strips are traditionally ground into centerline or on the shoulder, Kentucky and Florida experimented with placing rumble strips right along the white edgeline of curved sections of road. This method was shown to reduce overall crashes by 29 percent.

(Watch the FHWA website for updates on this phase of the study.)

Red light enforcement devices

Red light indicator
In Florida, crashes due to people running the red light fell by 33 percent thanks to a small light that turns on when the signal turns red. This little light bulb, which is placed on top of a signal, allows for a police officer to sit at the other end of the intersection rather than pursue a car right through the intersection. Not only is it safer, but motorists are also more likely to obey the signal if they know police might be watching on  the other side.

Researchers are also still collecting data on the other techniques studied in phase three, including surface friction treatments on curves and ramps and larger curve warning signs (called chevrons). Watch the FHWA website for updates.

Wider roads in rural areas

manufacturing

Could simply shifting the edge lines of a rural road reduce the number of accidental drive-offs?

Yes, according to this study, which evaluated the effectiveness of various lane-shoulder width configurations on rural, two-lane undivided roads using data from Pennsylvania and Washington.

In general, results were consistent with previous research, showing crash reductions for wider paved widths, lanes and shoulders. For specific lane-shoulder combinations, the study found a general safety benefit associated with wider lanes and narrower shoulders for a fixed pavement width; however, there are exceptions. The report has a chart that shows the optimal lane-shoulder combinations for different sizes of roads.

In theory, there should be no additional cost for these strategies, as an edgeline can be re-striped as part of an existing resurfacing project.

MnPASS: Two systems, both work

I-35W’s MnPASS lane, where vehicles can frequently enter and exit the high-occupancy toll lane, is just as safe as the MnPASS lane on I-394, where motorists only have a few shots to enter the system, a new study finds.

Researchers at the Minnesota Traffic Observatory undertook the MnDOT-funded study because of objections to open systems like the one on 35W.

“The federal government has very strong arguments against the open system. They’re saying it’s going to be dangerous – cause more disruption and more congestion,” said John Hourdos, director of the Minnesota Traffic Observatory. “We found that both roadways are working very well today because they were designed appropriately for their location.”

The definition of an open system is one that has more opportunity for access than restriction. On 35W, a dotted white lane means vehicles can enter the toll lane at will, and a solid line bars access.

Vehicles must have two occupants on-board or an electronic pay card to use the express lanes during rush hour.

MnPASS on Highway 35W.

The reason I-35W allows vehicles to enter MnPASS more frequently than I-394 is because there are more ramps where new vehicles are entering the freeway and might want to get on MnPASS.

Researchers studied whether accidents are more likely to occur by studying the number of accident-inducing vehicle movements along the 35W corridor. They found that areas where accidents are mostly likely to occur are also where the lane would have to allow access anyway under a closed system like 394.

The study also looked at mobility, determining that MnPASS users have just as good free-flowing traffic under the open system.

Helpful tools

Researchers also created design tools that engineers can use to determine where access points should be on MnPASS lanes.

Until now, engineers have relied on rule of thumb. For example, the general guidance for allowing access on a closed system was 500 feet for every lane between the entrance ramp and the HOT.

The tools can be used to automatically determine how fluctuations in the MnPASS fee will affect congestion within the lane.

The fee to use MnPASS depends on the time of day.

As the express lane become more congested, the fee to use it increases. This slows the number of cars entering the lane, increasing the speed of the vehicles already in the lane.

“We ran the tool on three locations on 35W and found that, for example, on Cliff Road, you can increase the traffic by 75 percent and still be okay,” Hourdos said. “You have more leeway there than north of the crossroads of Highway 62 and 35W, for instance.”

 Related Resources

Peer Exchange: Pavement researchers face similar issues, financial pressures

Soaring construction costs and a rapidly aging infrastructure will require states to revolutionize how they maintain their roadways — but without each other’s help, they won’t be successful.

That was a key message from pavement researchers last week at a MnDOT-hosted peer exchange event, where pavement experts from around North America shared their ideas and research experiences.

“You’ve got to partner with other states, the FHWA and industry,” said Research Engineer Steve Bower of the Michigan Department of Transportation. “We can’t go it alone anymore.”

Researchers at the event reviewed recent pooled-fund studies conducted at MnROAD, MnDOT’s innovative pavement testing center, to review successful implementation strategies, develop common practices to calculate benefits and help prioritize research topics for MnROAD’s  core 2016 research and reconstruction.

The pavement engineers gathered for the event face similar problems in their home states, as demonstrated by the seven pooled fund projects that were discussed. These included developing a better understanding of pavement damage caused by oversized farm equipment, knowing when to chip seal a roadway, developing a test to predict asphalt cracking , creating a national design method for concrete overlays of asphalt roadways and improvements in diamond grinding of concrete pavements.

MnROAD leading the way

State research departments often lack the time or resources to focus on innovations that could reduce future maintenance costs. If not for Minnesota leading the effort on many of these topics and providing a top-notch research facility, the peer exchange attendees said much of this research just wouldn’t happen.

“We don’t have a closed-loop facility with all these different test sections that MnROAD has; no one does,” said Larry Wiser of the Federal Highway Administration’s Turner-Fairbank Highway Research Center.

Researchers came from Missouri, Maine, Texas, Illinois, Michigan, California, Ontario, Wisconsin, Indiana and Washington for the three-day workshop.
Researchers came from Missouri, Maine, Texas, Illinois, Michigan, California, Ontario, Wisconsin, Indiana and Washington for the three-day workshop.

WisDOT Chief Materials Management Engineer Steven Krebs said the research done at MNROAD on the impact of modern farm implements on pavement was invaluable in drafting new state legislation. WisDOT was able to quantify the amount of damage done to the pavement and use the data to dispute mistruths and  misinformation. The state is now working with counties on possible remedies and weight-limit enforcement techniques.

Whereas Minnesota has taken the lead on studying such issues, it is now asking fellow states to not only participate in future such studies, but to also partner in the operations at MnROAD.  At the peer exchange, the response to this idea — especially from states closest to Minnesota — was positive, despite everyone’s lean budgets.

Peer exchange participants said more effort and funding is needed to implement research findings, which FHWA officials said costs significantly more than the research itself.

Past research also needs to be more accessible and there should be better sharing of information, particularly online, they said.

“This (peer exchange) gave us ideas to take back. Our research budget is getting tighter. It’s nice to be able to say, ‘You do a part of it and we’ll do a part of it,’ ” said California transportation researcher Joe Holland.

Further Resources

2014 Peer Exchange – Presentations

CTS Transportation Research Conference Wrap-Up (Photo Gallery)

The 25th Annual CTS Transportation Research Conference successfully concluded earlier today, wrapping up a two-day whirlwind of more than two-dozen sessions showcasing a wide range of transportation research results and innovations.

Presentations and materials from the conference, including video of the keynote speakers, will be made available on the CTS website in coming weeks. In the meantime, here are a few photos from the conference.

Center for Transportation Studies Director Laurie McGinnis
Center for Transportation Studies Director Laurie McGinnis welcomes attendees to the 25th Annual CTS Transportation Research Conference in St. Paul, Minnesota, on May 21, 2014.
MnDOT Chief of Staff Eric Davis
MnDOT Chief of Staff Eric Davis: “Research is vital to our program. It’s vital to our success as a department.”
Joe Casola, staff scientist and program director for the Center for Climate and Energy Solutions
Joe Casola, staff scientist and program director for the Center for Climate and Energy Solutions, gives the keynote address on Wednesday. Casola said transportation officials should begin incorporating the projected impacts of climate change, including more frequent extreme weather events, into their planning.
MnROAD Operations Engineer Ben Worel
On Wednesday, MnROAD Operations Engineer Ben Worel moderated a session, “Building the Future on a Solid Foundation,” focused on geotechnical research.
MnDOT Research Services & Library Director Linda Taylor and MnDOT Planning and Data Analysis Director Mark Nelson
From left: MnDOT Research Services & Library Director Linda Taylor and MnDOT Planning and Data Analysis Director Mark Nelson answer questions at a session on transportation pooled-fund research projects.
Jill Hentges, community outreach coordinator for Metro Transit
Jill Hentges, community outreach coordinator for Metro Transit, displays a tool used to help teach the public how planners optimize bus routes during a Thursday session on public engagement. Angie Bersaw, a transportation planner for Bolton & Menk, Inc., looks on.
Bruce Hasbargen, Beltrami County engineer and Local Road Research Board chairman
Bruce Hasbargen, Beltrami County engineer and Local Road Research Board chairman, answers a question at a Wednesday session on local agencies and stakeholder engagement.

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.

GPS-equipped mowers to save money, reduce noxious weeds

Putting GPS units on MnDOT highway mowers is expected to speed mowing operations and cut herbicide usage by 50-percent in metro area ditches, reducing groundwater contamination.

MnDOT’s Metro District highway maintenance division will be one of the first — if not the first — state agencies in the country to equip the majority of its maintenance tractors with Automated Vehicle Location systems.

Not only will crews be able to effortlessly track their progress — reducing paperwork and freeing time for other maintenance activities — but the AVL’s live mapping software will help them avoid noxious weed patches, thereby reducing their spread.

Last year, MnDOT tested the GPS software on five mowers.
Last year, MnDOT tested the GPS software on five mowers.

“AVL alone enables the tracking of vehicle positions, but when combined with equipment sensors and an on-board monitor with user interface, it becomes a very innovative way to reduce operation costs,” said MnDOT Project Engineer Trisha Stefanski, who applied for funding from MnDOT’s Transportation Research Innovation Group for the pilot project.

Vehicle tracking systems have been shown to reduce chemical usage by crop farmers, improve route efficiencies in truck driving and help cities and counties track snowplows.

The on-screen mapping shows the location of weed patches, so mowers can avoid them, reducing their spread.

MnDOT Metro, which tested five AVL units last year, hopes to equip as much of its remaining fleet as possible.

In the grant application, Stefanski estimated the technology will pay for itself in about a year’s time, largely due to herbicide savings.

Noxious weeds

MnDOT is required by law to manage certain noxious weeds along its highways. Each year, weed inspectors survey one-quarter of metro ditches for weeds, which enables them to concentrate eradication efforts on the worst areas.

Touch-screen maps will contain the noxious weed locations so operators can see weed patches and mow around them.

Herbicide usage is estimated to drop an estimated $100,000 to $150,000 per year. (This estimate was based on the original funding request. Final numbers haven’t been released.)

Operators can use the on-screen map to mark the location of new patches of noxious weeds.

Noxious weeds like Wild Parsnip — which can cause painful skin boils — might even be eradicated, reducing the risk for field crews, such as construction workers and Adopt a Highway volunteers.

Until now, maintenance crews have relied on paper maps to identify weed locations, which is less effective.

“What’s better, looking at a live screen when you’re going down the road and seeing where weeds are coming up, or trying to refer to a piece of paper?” Stefanski said.

Other advantages

The AVL equipment will also allow for automated reporting.

Mower operators can use the on-board AVL monitor to mark the location of guardrail hits, potholes, washed-out culverts, debris and unmarked noxious weeds.

Operators can electronically mark the location of guardrails, debris, potholes and more.
Operators can electronically mark the location of guardrails, debris, potholes and more.

Currently, operators must track their activities using hand-written forms or spreadsheets in the office.

The AVL system will also automatically track their location history, allowing operators to optimize their routes based on how long it took to mow segments in the past.

It will also be easier to answer questions from the public, who want to know the last time a certain ditch was mowed.

“Making everything geographically located adds so much analysis opportunity,” Stefanski said.

MnDOT also has AVL technology on an herbicide applicator to better track where it’s sprayed. Other future potential applications including pothole patching and road sweeping operations, Stefanski said.

Research Drives Change At Rest Stops

In an effort to encourage more use of safety rest areas and reduce drowsy driving, the Minnesota Department of Transportation is bolstering amenities and plans to install new signage at select rest areas across the state.

Drowsy driving is conservatively estimated to cause at least 1,550 deaths nationwide each year and $12.5 billion in monetary damage.

Motorists would stop more frequently at rest areas if they knew what rest areas offered, according to market research completed in 2009.

MnDOT will design and install highway symbol signs to advertise the amenities at 13 rest areas in a pilot project funded by MnDOT’s Transportation Research Implementation Group.

“We are using this as a way to entice drivers to take a break, pull over and refresh before returning to the road,” said Robert Williams, MnDOT Safety Rest Area Program Manager and the project proponent.

Rest areas in Brainerd and Cass Lake, Minn., can now offer a tourism-related gift shop, thanks to a change in state law.
Rest areas in Brainerd and Cass Lake, Minn., can now offer a tourism-related gift shop, thanks to a change in law.

Amenities differ greatly between rest areas within the state, as well as across the country; this depends on when they were built and whether they are located on an interstate, state highway or toll road.

Older, smaller rest areas may only have a bathroom and picnic area, while newer facilities often have features such as children’s play areas, staffed travel counters and dog runs.

In the future, the state may consider new amenities such as gift shops, adult exercise equipment to rejuvenate motorists, electrical vehicle charging stations and perhaps even electrification stations to allow truck drivers to power their TV or refrigerator without idling their vehicle.

Research has found that as the spacing of rest areas increases beyond 30 miles, the number of drowsy driving crashes goes up exponentially, Williams said.

Each sign will advertise up to six amenities.
Each sign will advertise up to six amenities.

Proposed Signage

Symbols on each sign will identify up to six amenities, such as in the example above, which depicts an assisted restroom, gift shop, ticket sales, EV charging stations, childrens’ playlot and adult exercise equipment.

MnDOT will evaluate the pilot project to determine if the symbol signs are effective in communicating to travelers the amenities offered at individual rest areas and if the signs were a factor that encouraged them to stop.

If the two-year project goes well, the state may add similar signs to the remaining 39 Class I safety rest areas (those rest areas equipped with flush toilets).

Some of the signs will require a request to FHWA for experimentation.  The intent is to install the signs in the summer of 2015 at rest areas on northbound I-35, eastbound I-94, as well as at the Brainerd Lakes Area Welcome Center on Hwy. 371.

Rest Area Offerings Increase

Although travelers and state DOTs would often like to introduce new amenities, state and federal laws limit what states can offer.

Toll roads and highways built before 1960 (the Interstate era), mostly in the East Coast or Chicago area, have fewer federal restrictions than rest areas in Minnesota and may feature restaurants or convenience stores.

Changes to Minnesota state law in 2005 and recent changes to federal law in MAP-21 now allow limited commercial activities, such as tourism-related gift shops and ticket sales at rest areas. MnDOT and its partners have taken advantage of some of these changes at its visitor centers in Brainerd/Baxter and Cass Lake.

In addition, the state is exploring the concept of using rest areas as transit transfer facilities, where long-distance bus carriers and regional transit lines can exchange passengers.

These transit hubs would shorten travel times for long-distance travelers and allow the rest areas to serve multiple functions while providing a comfortable waiting area for passengers.

Rest areas
Pilot locations are circled.

MnDOT announces research implementation projects

Minnesota’s next round of research implementation projects will reduce the spread of noxious weeds along state highways, improve the quality of asphalt on Minnesota roads and enhance the inspection of state bridges.

MnDOT’s Transportation Research Innovation Group (TRIG) has announced 15 projects for funding in Fiscal Year 2015. (Project descriptions below.)

Each winter, MnDOT solicits proposals from staff who want to put local or national research into practice in their day-to-day work.

“Certain departments have problems they’ve been working on for a long time and they’ve spun their wheels or not had the staff resources to get something done,” said MnDOT Research Services & Library Project Advisor Bruce Holdhusen, who helps employees develop their proposal plans.

One implementation project: Further testing and demonstration of portable traffic control devices (auto flaggers) to increase their usage by highway maintenance crews.
One implementation project will complete testing and demonstration of portable traffic control devices (auto-flaggers) to increase their usage by highway maintenance crews.

MnDOT provides the funding needed for equipment, consultant services or researcher assistance. Supervisors also must sign off that they’ll make time for the staff member to implement the practice.

“Implementation means it’s changing the way some practitioner does their job,” Holdhusen said. “It’s not just trying something new; it’s got to stick.”

Highlights of this year’s projects:

  • Installation of GPS units on MnDOT mowers to alert highway maintenance crews to areas of noxious weeds. This is anticipated to cut herbicide usage in half.
  • Purchase of 3D sonar equipment for underwater bridge inspection, which is currently performed by engineer-divers.
  • Selection of an alternative, European-branded center-line rumble strip (Sinusoidal) that produces less stray highway noise.
  • Implementation of an innovative asphalt-quality test, developed by MnDOT’s Office of Materials and Road Research, to assess the cold temperature-cracking properties of asphalt mixes proposed by contractors.
  • Advertisement of state rest area amenities on highway notification signs. This pilot project will target 13 rest stops.

The complete list of projects, by category:

Environment
Maintenance Operations and Security
Materials and Construction
Multimodal
Bridge and Hydraulics
Traffic and Safety

MnDOT leaders highlight TRB benefits at forum

As a graduate student 35 years ago, Bill Gardner attended his first Transportation Research Board Annual Meeting, and he still remembers the thrill.

“I felt like a kid in a candy shop,” recalled Gardner, who heads MnDOT’s Office of Freight and Commercial Vehicle Operations. “I was amazed at the diversity of topics… You could find people who have devoted their whole lives to the hazards of rural mailboxes.”

Gardner and other MnDOT leaders on Tuesday recounted their experiences from this year’s annual meeting — which drew more than 10,000 participants — and encouraged other MnDOT staff to get involved in the organization, which helps set national transportation guidelines, oversees collaborative research and facilitates the exchange of information.

“We’re heavily involved, but I think we could be more involved,” said Modal Planning and Program Management Director Tim Henkel, who has been part of the TRB for more than 20 years.

Henkel said TRB involvement benefits MnDOT in several ways, including access to national and international experts, the ability to keep tabs on hot-button issues and having a seat at the table in decision-making.

“It makes us a more enlightened and informed decision-making body,” Henkel said.

MnDOT has more than 60 staff serving on 114 TRB committees and contributes $125,000 annually to the TRB core program, gaining $127 in collaborative research for every $1 it contributes.

“It’s a very intense and very busy experience," said Chief MnDOT Engineer Deputy Commissioner and Chief Engineer Sue Mulvihill, who displayed the thick program book and other materials from this year’s Transportation Research Board Annual Meeting.
“It’s a very intense and very busy experience,” said MnDOT Deputy Commissioner and Chief Engineer Sue Mulvihill, who displayed the thick program book and other materials from this year’s Transportation Research Board Annual Meeting.

As part of a series of staff forums they will hold throughout the year, MnDOT leaders chose to highlight the TRB, which met in January. (MnDOT employees interested in attending next year or getting involved in the TRB should speak with their supervisor.)

State Bridge Engineer Nancy Daubenberger, who serves on a TRB subcommittee and gave a presentation at the recent conference, said it helps to hear about the challenges faced by agencies around the country.

Assistant Engineering Services Division Director Amr Jabr, who attended for the first time, said he used a smartphone app just to decide which of the approximately 3,500 sessions he wanted to attend.

“I thought it was an extremely good experience,” he said. “I picked up a lot of information and made a lot of new contacts.”