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Line 262: ==Parking Lot Friction Testing==[https://sustainabletechnologies.ca/app/uploads/2021/05/Friction-and-Parking-Lots.pdf LSRCA's Technical Bulletin: Alternatives to Salt]<ref>LSRCA. 2020. Friction and Parking Lots. Technical Bulletin, Volume 3 September 2020. https://sustainabletechnologies.ca/app/uploads/2021/05/Friction-and-Parking-Lots.pdf</ref> is a valuable technical brief which covers BMPs that have been developed specifically for winter maintenance in parking lots. Along with recommendations around the proper use and calibration of equipment, many of these practices relate to plowing the lot and walkways before applying salt, and applying the recommended amount of salt for the conditions. Several studies have been conducted, by industry and academia, to determine what the “right” amount of salt is, and, while “proper” application can vary depending on temperature and conditions 58 g/m2 (or 13 lb/1000 ft2) has been suggested as a reasonable rate to use for “moderate” winter events (Hossain, K. and Fu, L., 2015), while in recent studies of commercial parking lots by LSRCA, the typical real-world application rates tended to be closer to 90 g/m2 (or 18 lb/1000 ft2), and can often be much higher. This report talks about main considerations contractors face in maintaining parking lots in winter:*What application rate should be used? *What is the level of service expected by the client, for which the bare pavement return time is a common measure? **(This is the amount of time it takes after treatment to achieve a bare surface)In order to better understand these questions; in 2017 the LSRCA obtained a friction tester, with a goal of quantifying the effectiveness of various practices and salt application rates. LSRCA’s friction testing showed that bare pavement is safest, as it has the highest friction value, and that the over-application of salt does not translate to safer conditions. To read more about the friction tester results continue on below, through the rest of this section.[[File:Measuring friction LSRCA office.png|thumb|500px|This image demonstrates the two extremes of LSRCA’s friction testing: a perfectly clear and dry surface, with a µ value of 0.9 and the same surface covered in a light layer of snow, with a µ of only 0.11.]]As can be seen in the inset table, the unit for measuring friction is ‘µ’, and the closer to 1.00 the µ value, the safer the surface. A high µ, however, is not the only measure of safety – many smooth indoor floors will have low µ values, in the range of 0.3 to 0.4, and they are generally not considered unsafe. Through this study, friction of several different surfaces, which received varying treatments was measured by LSRCA staff. <br></br>{|class="wikitable"|+Friction Values and Related Road Surface Conditions|-!Measured Friction Value (µ)!Road Surface Condition|-|0.8 - 1.00|Dry, New Asphalt|-|0.50 - 0.80|Wet Asphalt|-|0.30 - 0.50|Wet Sand on Ice|-|0.25 - 0.30|Dry Sand on Ice|-|0.25 - 0.25|Dry Ice|-|0.05 - 0.15|Wet Ice|}[[File:(2)Measuring friction LSRCA office.png|thumb|500px|Friction values for a properly treated surface (left) with a small amount of residue (µ =0.63) and an over salted surface right, which has a much lower friction value (µ =0.26).]]High volumes of salt are often applied because contractors, property managers, and parking lot users feel that the more salt there is, the safer the surface is to walk or drive on. However, a surface that has been treated at an appropriate rate, (which is slightly wet with a small amount of salt residue) has a much higher friction value (μ); with the level of service achieved far more efficiently, than when compared to the same surface where rock salt has been heavily applied (over salted).[[File:(3)Measuring friction LSRCA office.png|thumb|500px|The picture above shows the same walkway where more than 10 times the generally recommended amount of salt was applied in the photo on the left, and only shoveling was done in the photo on the right, and both µ values were in the low 0.20s.]]Through this work, as referenced above - LSRCA staff documented higher friction values on untreated surfaces than on surfaces with large volumes of product; the µ value of a surface may remain low if it has only been shoveled or plowed. While shoveling is an important part of the winter maintenance process, practitioners need to consider the site and predicted conditions on a day-to-day basis to determine how to attain the safest surface for vehicle and foot traffic. In many cases the sun or traffic may melt the residual snow on a shoveled or plowed surface without any further treatment being necessary (saving both time and money); while in other cases, some salt, applied at an appropriate rate, may be necessary.====Higher Costs, Little Benefit====Friction testing has demonstrated that bare pavement is safest, as it has the highest friction value, and that the over-application of salt does not always translate to safer conditions. Simply put, applying salt at the prescribed rate for the conditions and shoveling or plowing where appropriate will attain a higher friction rate than an overapplication of salt.''What is a reasonable amount of time to achieve the desired level of service?'': *Depending on the operating hours of the property being maintained, it may be possible to reduce the salt application rate without sacrificing the desired level of service. **For example, many commercial properties keep hours between 9:00 am and 9:00 pm, which would mean that the lot does not need to be clear until shortly before 9:00 am. The table below demonstrates the time it would take to reach bare pavement at typical industry-recommended application rates, in a situation where the temperature is between -7 and -9 °C, with between 0.5 and 1.5 cm of snow on the ground. The rate may need to be increased or decreased slightly to achieve the desired level of service depending on varying factors related to traffic, sunlight, type of snow, and/or pavement type.</br>{|class="wikitable"|+Time to Reach Bare Pavement Scenario Comparison<br></br>|-!'''Difference Among Scenarios'''!'''Time to bare pavement (hrs)'''!'''Application Rate (g/m2)'''!'''<u><span title="Note: Assuming lot size of 15 ha (the approximate size of an LSRCA study lot).">Volume of salt used for each application (kg)*</span></u>'''!'''<u><span title="Note: Assuming 70 applications.">Total salt applied/season (tonnes)**</span></u>'''!'''Material costs/season (assuming $100/tonne)'''|-|'''Scenario 1'''<br></br>|2|87|13,050|913|$91,300|-|'''Scenario 2'''<br></br>|3|58|8,700|609|$60,900|-|'''Difference'''<br></br>|1|29|4,350|304|$30,400|-|}As the "''Time to Reach Bare Pavement Scenario Comparison''" above demonstrates, significant salt and cost savings could be seen in a typical big box store, commercial business or institutional building's parking lot by simply reducing the application rate of rock salt and extending the time to bare pavement by one hour. To note, this is only the material cost of the salt (which varies, but has been [https://www.cbc.ca/news/canada/ottawa/ottawa-contractors-road-salt-price-hike-1.4934369 higher than $100/tonne in recent years] (Tumilty, 2018)<ref>Tumilty, R. 2018. Rise in road salt prices hits local contractors. Available at: https://www.cbc.ca/news/canada/ottawa/ottawa-contractors-road-salt-price-hike-1.4934369 (Accessed: 24 Mar., 2022)</ref>. Over-application of salt has been noted to cause significant damage to parking lot infrastructure, including issues with concrete, corrosion of railings, damage to landscaping materials, and damage to interior buildings' flooring. Reducing the application rate would decrease the rate at which this damage occurs, as a result helping to minimize the amount needed to repair or replace at a given property each year. All of this without sacrificing the safety of parking lot users.
→Parking Lot Friction Testing
*Conductive Pavement on Walkways/Entrances: Conductive pavements consist of electrically and thermally conductive materials mixed with the dielectric aggregates typically found in standard asphalt and concrete pavements. Once connected to a power or heat source, these pavements conduct electricity and emit heat to pavement surfaces, melting ice and snow with constant and uniform heat.
*Conductive Pavement on Walkways/Entrances: Conductive pavements consist of electrically and thermally conductive materials mixed with the dielectric aggregates typically found in standard asphalt and concrete pavements. Once connected to a power or heat source, these pavements conduct electricity and emit heat to pavement surfaces, melting ice and snow with constant and uniform heat.
*Brine holding tanks: Collection of first flush (high chloride concentration) melt water runoff from a salt induced snowmelt (as opposed to rain and temperature induced snowmelt) has the potential to be beneficial if captured and reused as an anti-icing or pre wetting solution. In order to collect the first flush runoff, an electronically actuated valve controlled by an electrical conductivity sensor would be installed at the desired conveyance point to divert and collect the high chloride concentration runoff into a brine holding tank. The brine holding tank would be placed below ground and a pump could be connected to pump the brine solution into an anti-icing tank or directly used to pre-wet rock salt. <ref>LSRCA. 2015.Parking Lot Design Guidelines to Promote Salt Reduction. GHD. 11115623 (2). https://www.lsrca.on.ca/Shared%20Documents/Parking-Lot-Design-Guidelines/Parking-Lot-Guidelines-Salt-Reduction.pdf</ref>
*Brine holding tanks: Collection of first flush (high chloride concentration) melt water runoff from a salt induced snowmelt (as opposed to rain and temperature induced snowmelt) has the potential to be beneficial if captured and reused as an anti-icing or pre wetting solution. In order to collect the first flush runoff, an electronically actuated valve controlled by an electrical conductivity sensor would be installed at the desired conveyance point to divert and collect the high chloride concentration runoff into a brine holding tank. The brine holding tank would be placed below ground and a pump could be connected to pump the brine solution into an anti-icing tank or directly used to pre-wet rock salt. <ref>LSRCA. 2015.Parking Lot Design Guidelines to Promote Salt Reduction. GHD. 11115623 (2). https://www.lsrca.on.ca/Shared%20Documents/Parking-Lot-Design-Guidelines/Parking-Lot-Guidelines-Salt-Reduction.pdf</ref>
==External links==
==External links==