The idea that road salt improves safety--is a myth

.
Overuse of road salt is driven by the idea that salt clears the pavement and makes driving safer.  Basically, the public demands bare pavement, and City officials feel they must deliver, or suffer outrage from the public.

"...Perhaps surprisingly, health care and insurance costs arising from winter accidents increase with the use of road salts. Better winter driving conditions encourage increased traffic speeds with the attendant impact that, when faced with severe weather or where road clearing has been compromised by inclement weather, accidents increase on a stretch of highway."  p. 27

"...A study by the Insurance Corporation of British Columbia found that snow and ice-related accidents decreased seven percent (over the 10-year average) in the City of Kamloops following the introduction of new road salts techniques (anti-icing and pre-wetting) while also reducing the City’s snow and ice removal costs." p. 31

Beneath our radar, what's happening is that the Public is transferring responsibility for safe driving to the City.  Once the pavement is mostly clear, drivers resume normal speeds, which aren't really safe in the winter.  Then they blame the City if they have an accident.

What's needed is getting the public to accept responsibility for safety.  This report from Ontario presents a number of ways this can be accomplished--such as requiring snow tires for winter driving, or enforcing lower winter speed limits.

How Ontario is dealing with overuse of salt

.
"Here we are, at the frontier of a dilemma that echoes author Rachel Carson’s prescient warnings about pesticides—will our children in their adult years look back and ask, 'Why did the previous generation not heed the warnings about the continued use of these toxic substances?'"

Comparison of East Towne Area and Madison Street Salt Application - 2010

Note: This is the text from a report I obtained from Rick Wenta of the Public Health Dept.  No author was listed.  I was unable to reproduce the figures and table--so if you would like to see them, please email me.  I have listed the descriptions of the sample points at the end.

The objective of this study was to obtain an indication of salt application rates on private property. The study site was chosen because the mall parking lots and access roads represent a substantive area of impervious surface that is maintained by private contractor.

Three private storm drainages from the East Towne Mall area and two City storm drainages from East Springs Drive were sampled for chloride during periods of snow melt (see Figure 1). Sampling was limited by the collection method as storm sewer flows were obtained with a peristaltic pump.

Sample point 1 (see Figure 2) is a private apron end draining to the east branch of Starkweather Creek. It collects runoff from parking lots and the access road west and north of Menard’s. Sample point 2 is a City apron end (AE 6829-001) that discharges in the same location as sample point 1. It contains runoff from East Springs Drive and runoff from parking lots at Menard’s and lots and access roads to the north. Grab samples were collected at these sample points.

Sampling began in February. Sewers were inspected for flow whenever conditions were favorable. Several of the sample points were well below the street surface, requiring the use of a peristaltic pump. Consequently, samples were only taken when the flow was deep enough for the pump to draw water; standing water was not sampled.

Figure six displays the results graphically. On February 2, meltwater from the strip mall area west of Menard’s (private apron end) contained the highest level of chloride. However, the isolated street runoff (IN 6928-010) was higher than that of the combined city/private flow of AE 6829-001. This would suggest that the runoff from Menard’s parking lot and areas north diluted the street runoff significantly.

The second sampling event, on February 16, showed chloride levels from the strip mall area had dropped. The isolated street runoff sample again was higher than the combined sample at AE 6829-001. Dilution from the Menard’s parking lot sewer again appears to provide significant dilution. Subsequent sampling events yielded similar results for all sample points suggesting that the majority of the road salt had already been flushed from the system.

Although limited in scope and ability to quantify road salt application, the results suggest that large scale commercial areas probably contribute similar levels of chloride to meltwater as City deicing operations on main arterial roadways.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Sample point 1 (see Figure 2) is a private apron end draining to the east branch of Starkweather Creek. It collects runoff from parking lots and the access road west and north of Menard’s.

Sample point 2 is a City apron end (AE 6829-001) that discharges in the same location as sample point 1. It contains runoff from East Springs Drive and runoff from parking lots at Menard’s and lots and access roads to the north. Grab samples were collected at these sample points.

Sample point 3 (see Figure 3) is a City storm inlet (IN 6828-004) that collects runoff from the gutter and conveys storm water from Menard’s outside storage area.

Sample point 4 (see Figure 4) is a City storm inlet (IN 6928-003) that collects runoff from the gutter (some of which is from Menard’s parking lot) and conveys storm water from Menard’s parking lot and most of the parking lot and access roads north of Menard’s.

The final sample point (see Figure 5) is a City storm inlet (IN 6928-010) that collects street runoff and conveys storm water from: the north on East Springs Drive; Anamark Drive; High Crossing Boulevard; East Washington Avenue from about the 4700 block to the interchange.

 

Salt Recommendations for Dane County--2007

Road Salt Recommendations for Dane County

12/21/2007

Adopted by the Dane Co Lakes & Watershed Commission, 1/10/08

1. Install on-board infrared pavement/air temperature sensors on all vehicles (currently on some vehicles only)

2. Add pre-wetting capacity on all new salting vehicles (currently 21 of 58 Dane County units have pre-wetting)

3. Increase number of vehicles capable of anti-icing (applying salt brine) (currently Dane County has two units with anti-icing capability)

4. Collaborate with City of Madison to demonstrate anti-icing (salt brine) technique in Odana Golf Course pond drainage area, using County equipment

5. Implement GPS AVL technology to track trucks and collect accurate material usage

6. Create a task force of public works representatives from various municipalities, with appropriate assistance from WisDOT and other specialists, to develop county-wide:

• An employee snowplow driver training program
• A review of accuracy of weather forecasting
• A program to track salt use and promote reporting on an annual basis, including voluntary reporting by private applicators (with possible coordination through the Public Health Department for tracking and inclusion in their annual report)
•  A common advisory alert program for classifying winter weather and road conditions to be used to inform the public on expected driving conditions

7. Utilize existing education and outreach channels, including the Dane County Lakes & Watershed Commission and the Madison Areas Municipal Storm Water Partnership (MAMSWP) to

• Expand general public awareness of salt use and its impacts
• Provide educational materials to homeowners
• Provide educational material and voluntary training for private applicators
• Sponsor a workshop of experts to recommend next steps in:  *Using modeling to predict future levels of chlorides in Madison lakes and streams under different scenarios of salt use (versus other alternatives) and to estimate the ecological and economic impact of these various scenarios, and...   *Monitoring of sodium and chloride levels in storm water runoff, lakes, and groundwater to provide sufficient data for expanded modeling program (to include continuous conductivity monitoring during critical runoff times to better define acute problem areas)

9. Create a plan for implementing (over the next several years) additional demonstrations of alternatives to chloride-containing deicers and anti-icers (examples of non-chloride materials can be found here)

10. Create a process and timeline for the assessing the long-term need for developing policies or regulations for both private and public salt use, which might include requirements for training, certification, and equipment calibration.

11. Ask that municipal public works directors (and Dane County Highways) report back to the L&W on an annual basis regarding the implementation of salt reduction recommendations and programs.