This session features a variety of winter maintenance technologies. Meet researchers working on asphalt mixes that aid ice removal, winter maintenance performance measurement, road surface condition measurement, deicer evaluations, and cost analysis of towplow operation.
Cost–Benefit Analysis of Using the Tow Plow for Winter Maintenance
Nishantha Bandara, Lawrence Technological UniversityShow Abstract
Elin Jensen, Lawrence Technological University
Several relationships between winter maintenance cost elements (direct cost such as labor, material, equipment and indirect cost such as travel delay) and snow storm severity (in terms of snow amount) were developed for two equipment fleet configurations. These configurations included Tow Plows present in the equipment fleet and Tow Plows absent in the equipment fleet. Analysis of these two equipment configurations identified the benefits of using Tow Plows in the equipment fleet for six-lane and four-lane freeways in Michigan at different winter storm severity levels. The developed relationships (based several different four- and six-lane lane freeway routes) were used to develop the most effective equipment fleet configurations for different Michigan Department of Transportation (MDOT) snow routes. Finally, the cost effectiveness of including Tow Plows in the equipment fleet was analyzed using direct cost and the total cost including delay costs. Results show substantial cost savings on the direct cost as well as total cost (including delay cost) if the recommended equipment configuration is employed. Use of Tow Plow in the equipment fleet cleared the roadways faster, and the delay costs due to winter storms were greatly reduced. The equipment fleet configuration with Tow Plows can be modified to realize direct cost savings with the use of less regular plows as recommended in this paper.
Study on the Physical and Chemical Ice Removal Effects of Asphalt Pavement
Tianqing Ling, Chongqing Jiaotong UniversityShow Abstract
This study aims at developing a new snow-melting asphalt mixture based on the physical and chemical interactions. This type of asphalt mixture (PCAM-13) has high efficiencies of physical-based ice-breaking and chemical-based ice-melting, which increases the speed of ice removing and improves the driving safety in the winter. Two types of chemical anti-freezing agent are used to replace some fine aggregates between 0 mm to 3 mm and some mineral powder for a size smaller than 0.0074 mm, respectively. Compared to the unmodified SMA-13 mixtures, the ice removing effect of PCAM-13 is significant and the most efficient temperature range is between -12˚C and 0˚C. The electrical conductivity is measured using the repeated load test on the asphalt mixture slab, which is used to determine the change of the salt dissolve rate. It is found that the more anti-freezing agent used, the more dissolved salt is observed except the temperature is below -15˚C or the thickness of the cube is larger than 10 mm. The use of PCAM-13 is found to be affected by the temperature, thickness of ice and the magnitude of loading. From the measurement of the repeated load test, under the same environmental condition and magnitude of loading, the ice on the PCAM-13 mixtures is more prone to break and become separated from the asphalt slabs compared with the SMA-13 mixtures. Meanwhile, no significant ice cube melting on the control SMA-13 is observed, which means that the advantage of PCAM-13 mixtures is remarkable.
Ice Melting Rates at −5°C, −10°C, and −15°C Using Chloride Solutions: A Physical Explanation
Johan Wåhlin, Norwegian Public Roads AdministrationShow Abstract
Alex Klein-Paste, Norwegian University of Science and Technology (NTNU)
Deicing chemicals is an important tool to keep roads passable and safe during winter. The most common deicing chemical, sodium chloride, works well at temperatures close to 0°C but its effectiveness decreases at low temperatures. One common belief is that this reduced effectiveness stems from a reduction of the ice melting rates. Previous studies have indicated that the melting rate is connected to the diffusive flux of water in a deicing solution, and the aim of this paper was to study whether this hold true also at low temperatures. An experiment was performed where aqueous solutions of sodium, magnesium and calcium chloride melted ice at three different temperatures. -5°C, -10°C and -15°C (23°F, 14°F and 5°F). Our results confirmed that the diffusive flux of water correlated well with the ice melting rate at all temperatures. The observed decrease in melting rate at low temperatures was explained by a decreased driving force for diffusion. Because of this, the eutectic temperature of a chemical becomes more important the lower the temperature becomes. The diffusive flux in deicer solutions could be a useful property. By calculating the diffusive flux of different deicing chemicals, would hence be a way to range them by their melting rates at different temperatures.
Field Validation of Salt Application Rates for Parking Lots
Taimur Usman, University of WaterlooShow Abstract
Liping Fu, University of Waterloo
Raqib Omer, University of Waterloo
Kamal Hossain, University of Illinois, Urbana Champaign
This paper describes results from the project, namely, snow and ice control for parking lots and sidewalks (SICOPS) for the winter season 2016/17. The objective of this research was to field validate salt application models for parking lots developed during our previous research under semi-controlled conditions and the optimal rates proposed therein. Data was collected from 24 parking lot sites in two different cities in the U.S. - Milton, Massachusetts and Buffalo, New York. Application of the developed model to the data shows that the developed model is capable of predicting bare pavement recovery time (BPRT) with high precision for under a wide variety of weather conditions. Model performance is compromised in the presence of snow packed conditions or under conditions when the BPRT can’t be achieved with 24 hours. Deviation of model from BPRT value of zero needs further investigation.