In this issue:
Like many snow- and ice-control professionals, Carver County Public Works maintenance operations staff are searching for new options to reduce the amount of chloride that reaches our waters from road salt operations. Using food production byproducts such as pickle brine are among the alternatives maintenance staff have been exploring. A new video and fact sheet describe their work.
The Carver County Public Works Department began testing samples of the pickle juice in 2016 with some encouraging results. But further testing showed the brine from the pickle cannery had variable salinity and pH levels that could damage maintenance equipment. Given the variables involved, staff determined it would be difficult to manually control the manufacture of the brine into a usable liquid. VariTech Industries recommended purchase of the Brine Boss®, an automated brine-blending system to manufacture the 23.3 percent brine solution needed for effective ice control operations. In addition, staff found adding potassium hydroxide to pickle brine neutralizes the pH level.
Carver County staff received a grant through the Local Road Research Board (LRRB) Local Operational Research Assistance (OPERA) Program to help purchase the brine-making system and support further research into the viability of using pickle brine in winter maintenance operations. Staff also restored an old VariTech 600 brine maker obtained from MnDOT for the project.
After extensive testing and analysis, VariTech engineers and Carver County staff concluded that pickle brine acquired from the cannery had to be exactly the same (salinity, vinegar content, and sugar content) for each and every batch or the system sensors would fail. But it turned out that the pickle brine supplier could not provide chemically consistent batches, and the VariTech system was unable to produce a consistent blend of 23.3 percent brine solution using pickle brine. As a result, Carver County staff determined they were unable to continue using pickle brine for snow and ice control.
Nevertheless, this project benefits other agencies considering the use of food production byproducts. The Carver County project demonstrates that there can be an alternative anti-icing product. As technology continues to advance, Carver County may revisit the use of pickle brine as a viable snow- and ice-control option.
The Every Day Counts (EDC) program has developed tech sheets and a video about cost-effective pedestrian safety countermeasures. The materials are part of EDC’s Safe Transportation for Every Pedestrian Program (STEP).
STEP focuses on five treatments to help pedestrians cross the road safely:
- Crosswalk visibility enhancements—including crosswalk lighting, enhanced signing and marking, and curb extensions—can reduce total crashes by 23 to 48 percent.
- Raised crosswalks are a traffic-calming technique that can reduce vehicle speeds, encourage drivers to yield to pedestrians, and lower pedestrian crashes by 45 percent.
- Pedestrian refuge islands provide a safer place for pedestrians to stop at the midpoint of a road before crossing the remaining distance, which can decrease pedestrian crashes by 32 percent.
- Pedestrian hybrid beacons (PHBs) provide a stop control treatment for higher speed multilane roads where pedestrian volumes aren’t high enough to warrant a traffic signal. PHBs can reduce pedestrian crashes by 55 percent.
- Road diets, which reconfigure a roadway cross-section to safely accommodate all users, can decrease vehicle speeds, reduce the number of lanes pedestrians must cross, and create space for new pedestrian facilities. Road diets can cut total crashes by 19 to 47 percent.
- Read tech sheets about the countermeasures
- View a video about STEP
- Pedestrian Crossings: Uncontrolled Locations guidebook (LRRB/MnDOT, June 2014)
The National Road Research Alliance (NRRA) hosted its annual pavement workshop in May. The two-day event featured team reports and testimonials from the states and associate members. About 30 speakers represented agencies, industry, consultants, and academia. PowerPoints and recordings of the presentations are on the workshop website.
The NRRA, a pooled-fund program, provides strategic implementation of pavement engineering solutions through cooperative research. It is led by an executive committee of state DOT partners and supported by numerous agency and industry partner representatives.
The Alliance also helps direct the use of the MnROAD test track for local, regional, and national research, technology transfer, and implementation needs. The 2017 construction season at MnROAD saw construction of 35 new and unique pavement test sections. The sections, designed to address NRRA high-priority research topics, were conceived and planned by NRRA project teams. A report details development, design, and construction of each research project and the test sections supporting them.
Investigators developed a model that predicts the failure susceptibility of slopes. The GIS-based tool provides results in a readily accessible map-based format. The tool could help state and local officials plan mitigation measures more effectively to avoid costly damage.
The model was tested against a relatively small area in Carlton County to confirm that the indicated susceptibility to failure correlated well with locations in which there was observable or documented slope failure. The method was then validated by applying it to small areas in Sibley and Carver counties where slope failures had occurred. The mapping was then expanded to two full Minnesota counties (Carlton and Sibley).
“If county engineers have higher slopes adjacent to roadways, they can use this basic tool to predict slope failures and then hire a geotechnical consultant to investigate the site,” says Tim Becker, public works director with Sibley County.
A final report explains the methodology, discusses the data used, and presents the mapping results. The research was funded by the LRRB and MnDOT.
- Technical summary: County GIS Maps Help Road Departments Anticipate Slope Failure (LRRB/MnDOT, 2018-05TS, Apr. 2018)
- Final report: Storm-Induced Slope Failure Susceptibility Mapping (LRRB/MnDOT, 2018-05, Jan. 2018)
- Slope Stabilization Guide for Minnesota Local Government Engineers (MN/RC 2017-17G, June 2017)
The effectiveness of pavement markings can vary depending upon the type of materials used, such as latex, epoxy, tape, and thermoplastic. An LRRB-funded project developed pavement-marking performance metrics for Minnesota local agencies to use as a guide for choosing the most durable and cost-effective products.
Researchers designed and conducted a survey to assess pavement-marking products used by local agencies in the state. They then extracted 2010 and 2013 MnDOT pavement-marking data from a national database to analyze the performance of products that survey respondents identified as commonly used.
From the survey results, researchers learned that the majority of Minnesota local agencies use either latex or epoxy as their primary pavement marking material. However, epoxy and tape outperformed latex at all levels of conditions and provided a service life of three years or more. A few survey respondents also reported grooving as a method that seemed to extend the service life of latex paint markings.
“The findings from this research will be beneficial for Minnesota local agencies in determining which pavement marking materials are most effective,” says Kate Miner, traffic manager for Scott County and the project’s technical liaison.
- Technical summary: Using a National Database to Develop Performance Metrics for Local Pavement Markings (LRRB/MnDOT, 2017-43TS, Jan. 2018)
- Final report: Minnesota Local Agency Pavement Marking: Mining Existing Data (LRRB/MnDOT, 2017-43, Nov. 2017)
According to a report from University of Minnesota researchers, transportation investments within a county can increase the local employment rate, while investments in trunk highways surrounding a county can also enhance county and regional employment. The LRRB-funded research provides quantifiable data for use by public officials.
Researchers combined data on transportation investment, business patterns, and socio-economic conditions in Minnesota counties from 1995 to 2010. The data included the number of county business establishments, jobs in Minnesota counties by sectors, and the amount of the annual payroll. Investigators also examined spatial (GIS-map-based) data from counties. They then performed statistical analyses and created an econometric model.
Their analysis found that long-term transportation investments contribute to employment in Minnesota counties, including several positive and statistically significant relationships. However, not all areas are positively affected by these investments. The overall findings are largely driven by rural areas, while the evidence for metropolitan and micropolitan areas is mixed.
- Technical summary: Linking Transportation Investment and Job Creation in Minnesota Counties (LRRB/MnDOT, 2018-04TS, March 2018)
- Final report: Transportation Investment and Job Creation in Minnesota Counties (LRRB/MnDOT, 2018-04, Jan. 2018)