Tag Archives: Minnesota

Policy and Planning

Are energy-efficient streetlights cost-effective?

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In 2010, the City of Minneapolis installed 55 energy-efficient streetlights from nine different manufacturers along 46th Street between 34th and 46th avenues. The project, part of Hennepin County’s Minnehaha-Hiawatha Community Works program, was designed to field test various models of light-emitting diode (LED) and induction lights. Over the course of two years, researchers observed, evaluated and compared the performance of various lighting products, detailing the results in a recently published report available on the MnDOT Research Services website.

In a broad sense, the results of the study would appear to confirm what has become common knowledge regarding energy-efficient technologies: while they cost  more up front, in the long run they have the potential to save money in the form of reduced energy and maintenance costs. The study also demonstrates that  energy-efficient streetlights are capable of producing adequate light output and are well-received by residents.

However, if the big question is whether energy-efficient streetlights can save local governments money, the answer  is somewhat complicated. The study found that both the levels of light ouput and the amount of time it takes to recoup costs varies significantly by product. Page 16 of the report (page 25 of the PDF) features a table comparing various products’ light output and estimated payback time. With one notable exception, the results show that products with the highest light output (i.e. the highest performers and therefore the most desirable) tend to also have the longest payback time. The amount of time it takes to generate a cost savings from energy-efficient streetlights can be as short as 2.6 years or as long as 24 years, depending on the product.

Some other interesting tidbits from the study:

  • Researchers observed operational cost savings of 50-75 percent, depending on the product.
  • Eighty percent of the savings came from reduced maintenance costs, while only 20 percent came from reduced energy costs.
  • In a survey of area residents, 76 percent responded positively to the new, energy-efficient lights.

The study demonstrated that energy-efficient streetlighting is a feasible option for local governments, with the caveat that agencies need to research lighting products thoroughly before making a choice as to which one to use. Ultimately, considering the ever-decreasing cost of LEDs, the use of energy-efficient streetlighting technologies is likely to grow.

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Bicycling, Pedestrian, Traffic and Safety

Free webinar July 9 on best practices for bicycle trail crossings

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Intersections between trails and roadways can be dangerous places for bicyclists and pedestrians. Next week, MnDOT Research Services is offering a free webinar on a forthcoming manual designed to help make trail crossings safer.

On Tuesday, July 9, from 1:00 p.m. to 2:30 p.m. (CDT), University of Wisconsin—Madison Professor David Noyce will be conducting a workshop on his forthcoming handbook, “Decision Tree for Identifying Alternative Trail Crossing Treatments.” The project, funded by MnDOT and the Local Road Research Board, aims to identify current engineering state-of-the-practice for trail crossings and provide guidance as to appropriate crossing designs and vehicular and bicycle right-of-way hierarchies.

You can click on the link below at the specified date and time to watch the webinar. No registration is required.

http://mndot.adobeconnect.com/trailcrossing/

research

Bridging the gap between research and implementation

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The end goal of transportation research, broadly speaking, is to see the results implemented — that is, to transfer the knowledge generated through research to those who can put it to good use. Research Services and the Center for Transportation Studies use a variety of tools to help disseminate research results: our respective websites, email lists, social media, newsletters and this blog, to name a few. But what do we know about how our audiences actually interact with these various channels of communication?

At the Transportation Research Board Annual Meeting earlier this year, researchers from Nebraska presented the findings of a very interesting survey on how engineers and other transportation practitioners prefer to learn about research results. Their presentation, entitled “What Engineers Want: Identifying Transportation Professionals as an Audience for Research,” is available via Slideshare. (Unfortunately, WordPress won’t let me embed it.)

Some key takeaways from the survey:

  • Practitioners overwhelmingly prefer one- or two-page technical briefs to other types of research communication products. (Other popular formats include presentations, video highlights and webinars.)
  • By a wide margin, practitioners use search engines like Google or Bing to seek research results (compared to other options like contacting a colleague or university faculty).
  • Practitioners are mostly interested in information on how to implement findings, as well as cost-benefit analyses of implementation.

The survey results present what I think is a fairly realistic and nuanced picture of the audience for transportation research; they’re also consistent with our (Research Services) own internal research on the issue. The bottom line is that research results need to be condensed into usable bits of information and made easily accessible in a variety of formats. People want information they can use, without having to dig for it. More importantly, they want it in whatever their preferred format is, whether it be print, email, Web, RSS, social media or in-person presentations.

Interestingly, Research Services already produces the kind of two-page technical briefs described in the survey. We call them “technical summaries,” and they are among our most popular products. We generally produce a technical summary for each research project we manage, and post them on our website alongside the full research report. Reading a two-page summary, written in layman’s terms, is certainly easier than poring over research reports that oftentimes number in the hundreds of pages, so it’s not surprising that even those with a strong engineering background prefer the format.

As a side note, last Friday we published a batch of 10 new technical summaries — along with two new transportation research syntheses, which are a type of literature review. Topics range from pedestrian and bicycle safety in roundabout crossings to the effect of intelligent lane control systems on driver behavior. You can check the full list on the Research Services main page.

Now it’s your turn: What forms of communication do you think are most effective at reaching transportation practitioners? Which ones do you prefer? Let us know in the comments.

Environment, Materials and Construction

Permeable pavements could protect the environment, save taxpayer dollars

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KSTP has a nice story today on the Minnesota Department of Transportation’s ongoing research into permeable pavements at the MnROAD research facility. (The video isn’t embeddable on WordPress, but you can find a direct link here.)

Permeable pavements (also known as “porous” or “pervious” pavements) are designed to allow water to pass through roadways and infiltrate directly into the underlying aggregate and soil. Their primary effect is to reduce stormwater runoff, which carries harmful materials from the road’s surface out into waterways. Of course, reducing runoff also mitigates the need for the kinds of costly drainage structures that are normally required to manage stormwater. Permeable pavements also reduce noise and mitigate the potential for hydroplaning, among other documented benefits.

These types of pavements are already used in some areas in Minnesota — mainly in parking lots and city streets — and MnDOT has been studying their potential use for full-depth roadway pavements. As the video indicates, so far the results have been encouraging. (You can read more about MnDOT’s ongoing research on the MnROAD website.)

As a side note, the amount of water these pavements can absorb is quite impressive. Last month, we posted a new Local Road Research Board video on stormwater management. In one scene, a public works crew dumps what appears to be several hundred gallons of water onto a permeable pavement and watch as it disappears almost instantaneously. (Watch the clip here.)

Here are the results of some recent permeable pavement studies here in Minnesota:

Maintenance Operations, Materials and Construction, Traffic and Safety

‘Three Ways to Cook a Pothole’

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In April, we posted about an innovative pothole-filling technology being developed by the Minnesota Department of Transportation and the University of Minnesota, Duluth. The technique involves zapping pothole patches and the surrounding pavement with a special truck-mounted, 50,000-watt microwave. Researchers have found that heating the base and the patch material at the same time creates a stronger, longer-lasting bond that provides for a more permanent pothole fix.

Last week, the MnDOT/UMD microwave technology found its way into a new MnDOT video (above) that also explores two other experimental pothole-patching methods. One involves using a large “electric oven”-type heating element instead of a microwave. The other utilizes a new exothermic (i.e. heat-generating) asphalt mixture containing taconite from northern Minnesota mines. The video compares the potential benefits of all three of the new technologies, which the department hopes will someday lead to “more pothole-patching power for the taxpayer dollar.”

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Maintenance Operations, Materials and Construction, Traffic and Safety

The people (and machines) who fix Minnesota’s potholes

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In Minnesota, with our often wildly unpredictable weather and constant freeze-thaw cycles, potholes are a fact of life. Anyone who’s climbed into a motor vehicle in the last month or so has doubtlessly encountered countless reminders of this dismal reality. Fortunately, we have a small army of public works professionals devoted to eradicating this perennial nuisance. The Minnesota Local Road Research Board recently produced this video, which nicely explains the various methods used to combat potholes in Minnesota.

Potholes form when water invades cracks in the pavement and infiltrates the soil beneath it. When that water freezes, it stretches the road surface, causing the fractures to expand. After a few cycles of freezing and thawing, the pavement begins to buckle and eventually collapses under the weight of passing traffic, creating disruptions in the road’s surface.

Road crews use a variety of methods to fill potholes. The simplest method is the “throw-and-go” procedure, in which workers simply shovel an asphalt mixture into the pothole and pack it down until the road’s surface is smooth. A related method is “throw-and-roll,” where the patch is compacted using an asphalt roller.

Other methods include:

  • “semi-permanent” patching, in which workers clear the pothole of moisture and debris and then square the edges with a pavement saw before applying the patch;
  • “spray injection,” which involves using specialized equipment to blast water and debris out of the pothole before spray-filling it with asphalt mix and finally applying a dust coat of dry aggregate on top; and
  • “slurry” or “microsurfacing” crack filling, in which a slurry of aggregate, asphalt emulsion and mineral filler is placed over a crack in the pavement and leveled off using a squeegee.

This Asphalt Pavement Maintenance Field Guide (PDF), co-funded by MnDOT and produced by CTS, provides a handy how-to guide to pothole patching and other types of pavement repairs commonly applied by public works professionals in Minnesota.

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