1. Maine Road Salt Risk Assessment Project
University of Maine
Maine Department of Transportation

2. Project Goals
Develop among stakeholders a common understanding of the public policy issues and the relationships of funding, current research, levels of service, and risks associated with the use of road salt.
Inform the policy making process in Maine related to winter road maintenance practices.
Maine Road Salt Risk Assessment Project  University of Maine  September 2009

3. GOOD NEWS Level of Service = High
Public Safety = Improved (causal link unclear)
Environment = Less Sand/Silt in Runoff
Maine Road Salt Risk Assessment Project  University of Maine  September 2009

4. GOOD NEWS BAD NEWS Level of Service = High
Public Safety = Improved (causal link unclear)
Environment = Less Sand/Silt in Runoff
BAD NEWS
Level of Service = High Cost
Public Safety = Corrosion (vehicle/infrastructure)
Environment = Salt Effects
Maine Road Salt Risk Assessment Project  University of Maine  September 2009 4

5. UMaine Project Research Team
Per Garder, Professor of Civil Engineering
T. Olaf Johnson, Graduate Research Assistant, Department of Civil Engineering
Margaret McKee, Research Associate, Margaret Chase Smith Policy Center
Charles Morris, Senior Research Associate, Margaret Chase Smith Policy Center
Kenneth Nichols, Professor of Public Administration
John Peckenham, Director, Maine Water Research Institute & Senior Research Scientist, Senator George J. Mitchell Center for Environmental and Watershed Research
Jonathan Rubin, Professor of Resource Economics & Policy, School of Economics & Margaret Chase Smith Policy Center
Adam Stern, Graduate Research Assistant, School of Economics
Maine Road Salt Risk Assessment Project  University of Maine  September 2009

6. Project Advisory Committee
AAA
Federal Highway Administration
Federal Motor Carrier Safety Administration
Maine Auto Dealers Association
Maine Chapter of American Public Works Association
Maine Chiefs of Police Association
Maine Custom Auto Association
Maine Department of Environmental Protection
Maine Department of Inland Fisheries and Wildlife
Maine Department of Public Safety
Maine Department of Transportation
Maine Fire Chiefs Association
Maine Motor Transport Association
Maine Municipal Association
Maine State Legislature
Maine Town and City Management Association
Maine Turnpike Authority
U.S. Department of Transportation
U.S. Geological Survey, Water Resources Discipline
Maine Road Salt Risk Assessment Project  University of Maine  September 2009

7. Maine Roads 22,830 miles of public roads MaineDOT 4,164 mi. (18%)
MTA 635 lane miles
488 towns/cities
3 reservations
counties

8. Maine Winter 20-40 storms November to late April
Salt preferred chemical since 1930s
Readily available
Effective
Relatively low-cost
Maine Road Salt Risk Assessment Project  University of Maine  September 2009

9. Snow Removal Practices
De-icing
Plow after 1-2 inches. Spread sand and salt mix
Remove snow pack (salt)
Clean up sand at end of season
Disadvantages of Sand
Build up & drainage problems on roads
Siltation of waterways
Air quality issues
Benefit is temporary. No melting properties
Skidding hazard on pavement
High cost of storage, handling
Maine Road Salt Risk Assessment Project  University of Maine  September 2009

10. Anti-Icing 1996 FHWA SHRP Anti-Icing Manual of Practice Pre-Wet Solids
Pre-Treat Roads
MaineDOT initiated in late 1990s (salt priority)
Mostly salt
Requires accurate forecasting, timing
Bare pavement sooner after storms
Maine Road Salt Risk Assessment Project  University of Maine  September 2009

11. Current Practices MaineDOT Anti-icing 95%
Salt is still most effective choice above 15o
Pre-wetting salt with brine, with Ice-B-Gone, & with blend
Pre-treating small percentage of roads
Municipal/County
Practices vary widely
Sand and Salt  Liquids
De-Icing  Anti-Icing and Pre-Treating
Maine Road Salt Risk Assessment Project  University of Maine  September 2009

12. Materials Salt (NaCl) Winter Sand (mixed with salt)
Salt Brine (23% salt in water, for pre-wetting or pre-treating)
Chlorides
Calcium Chloride (CaCl2)
Magnesium Chloride (MgCl2)
Ice-B-Gone (MgCl2 blend with by-product of alcohol distillation process)
Acetates
Potassium Acetate (KA)
Calcium Magnesium Acetate (CMA)
Carbohydrate based solutions
Corn, Beet, Grains

13. Salt Usage in Maine 2008-09 * **
*estimate based on survey data
**based on national estimate (USGS)
Maine Road Salt Risk Assessment Project  University of Maine  September 2009

14. Municipal Practices: Percent Using These Materials
winter Source: survey data

15. Level of Service (MaineDOT)
Priority 1 (26%)
6 daylight hours to bare pavement, plow cycle 1 to 1 ½ hours
40-45 mph
Route length 10 centerline miles
Priority 2 (36%)
8 daylight hours, plow cycle 1 ½ to 2 hours
35-40 mph
Route length 12 centerline miles
Priority 3 (38%)
24 hours, plow cycle 1 ½ to 2 hours
35 mph
Route length 14 centerline miles
Source: MaineDOT 15

16. Level of Service: Municipal
Source: survey data
Maine Road Salt Risk Assessment Project  University of Maine  September 2009

17. Municipal Total Winter Maintenance Expenditures per Mile 2008-09
Source:l survey data

18. Municipal Practices: Winter Maintenance Budgets
Personnel
Equipment
Materials
Source: survey data
Maine Road Salt Risk Assessment Project  University of Maine  September 2009

19. Material Cost MaineDOT
Source: MaineDOT

20. Material Cost MTA
Source: Maine Turnpike Authority

21. Total Winter Maintenance Expenditures 2008-2009*
*estimate based on survey data

22. Factors in snow control policy
Level of Service
Temperature
Speed of response
Availability & amount of material
Melting properties
Cost
Equipment, training
Infrastructure & environmental impact
Driver reaction to snow clearing
Vehicle condition
Maine Road Salt Risk Assessment Project  University of Maine  September 2009

23. Road Salt Effects On Environmental Quality
Maine Road Salt Risk Assessment Project  University of Maine  September 2009

24. OUTLINE Water Cycle Fate of Road Salt Mass Balances
Environmental Receptors
Pathways
Mass Balances
Summary of Research
Water Quality
Ecosystems
Trends
Summary and Conclusions
Maine Road Salt Risk Assessment Project  University of Maine  September 2009

26. 26

27. Road Salt - Environmental Receptors
Maine Road Salt Risk Assessment Project  University of Maine  September 2009

28. Environmental Receptors
Road Salt – Pathways to
Environmental Receptors
Maine Road Salt Risk Assessment Project  University of Maine  September 2009

29. Road Salt – Mass Balances
Maine Road Salt Risk Assessment Project  University of Maine  September 2009

30. Ion Exchange NaCl + H2O Na+ + Cl- aqueous 2Na+ Ca2+ Na+ K+ Mg2+ H+
In soil
Maine Road Salt Risk Assessment Project  University of Maine  September 2009

31. Road Salt and Water Quality
Short Term
Increased Na and Cl in surface waters
Long Term
Increased Na and Cl in ground waters
Increased salinity of ponds
Soil chemistry change through ion exchange -release of Ca and Mg then H (acidification)
Soil “stores” salt and releases it over time
Trends
Increased Na and Cl in surface waters (0.2 to 2 mg/L/yr)
Increases persist for months to decades
Occurrence of high salt waters limited to near roads and storage areas
Maine Road Salt Risk Assessment Project  University of Maine  September 2009

32. Road Salt and Ecosystem Quality
Short Term
Increased attraction of salt-loving species
Foliar burning
Loss of salt sensitive species (plant and animal)
Long Term
Decrease in surface water diversity
Dominance by salt-tolerant invasive species (e.g. phragmites)
Vernal pool decline
Toxic thresholds exceeded for sensitive species
Trends
Loss of overall diversity
Increases in invasive species (plants)
Ecological footprint ~ 600 meters wide
Maine Road Salt Risk Assessment Project  University of Maine  September 2009

33. Maine Road Salt Risk Assessment Project  University of Maine  September 2009

34. SUMMARY AND CONCLUSIONS
Road Salt Affects Water Quality and Ecosystems (600 m)
Seasonal Effects- Larger Magnitude, Shorter Duration
Chronic Effects- Lower Magnitude, Longer Duration
Reversibility
Seasonal Effects are mostly reversible
Chronic Effects- Require years to decades to change
Maine Road Salt Risk Assessment Project  University of Maine  September 2009

35. SUMMARY AND CONCLUSIONS
Trends
Increase in Chloride in surface waters and ground water
Cation exchange leads to nutrient depletion and acidification of soil and water
Loss of biodiversity
Increased prevalence of invasive species
Maine Road Salt Risk Assessment Project  University of Maine  September 2009

36. Infrastructure Corrosion
Bridges
2,279 bridges in Maine
649 “structurally deficient or functionally obsolete” 28% (2007)
386 MaineDOT Watch List (2008)
Pathways of corrosion
Corrosion of steel
React with cement paste
Physical impact on cement (atmospheric)
Maine Road Salt Risk Assessment Project  University of Maine  September 2009

37. Infrastructure Corrosion
Increase # of freeze/thaw cycles.
All chlorides equally high in corrosion of rebar.
MgCl2 and acetates highest impact on paste deterioration.
All chlorides high impact on atmospheric corrosion, with CaCl2 and MgCl2 higher due to retention of moisture. NCHRP Study 577 (2008)
Maine Road Salt Risk Assessment Project  University of Maine  September 2009

38. Vehicle Corrosion Trucking Industry: “rust jacking”
Automobiles: brake lines & electrical connectors
Photo courtesy of Jeremy Williams
Maine Road Salt Risk Assessment Project  University of Maine  September 2009

39. Vehicle Corrosion Issues: Multiple types of corrosion
Variety of metals and alloys in vehicles
Environmental factors
Chemical factors
Field tests vs. laboratory tests
Maine Road Salt Risk Assessment Project  University of Maine  September 2009

40. Hexavalent Chromium Alternatives?
End-of-Life Vehicle Directive, July 2007 deadline
Eliminated:
1990s Volvo, Opel GM VW
2005 Ford
2006 Toyota, Hyundai
2007 Nissan, DaimlerChrysler
Alternatives?
Maine Road Salt Risk Assessment Project  University of Maine  September 2009

41. Conclusions
Chloride-based salts are all corrosive to motor vehicle components in laboratory tests.
Magnesium and calcium chlorides retain moisture longer.
Inconsistency of laboratory results means no risk ranking of chemicals possible. (Fay, 2009)
Diffusion of chloride into porous materials is linked to moisture.
Field conditions may contribute more to relative corrosiveness than chemical or coating. (NCHRP, 2008)
Maine Road Salt Risk Assessment Project  University of Maine  September 2009

42. Road Salt Safety
Maine Road Salt Risk Assessment Project  University of Maine  September 2009

43. Data All police reported accidents in Maine from 1989-2008.
Annual estimated vehicle miles traveled (VMT) for all individual counties in Maine as well as state totals.
Maine Road Salt Risk Assessment Project  University of Maine  September 2009

44. Crashes by Road Surface Condition 1989-2008
Maine Road Salt Risk Assessment Project  University of Maine  September 2009

45. County Crash Rates
Maine Road Salt Risk Assessment Project  University of Maine  September 2009

46. Total Crashes
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
January
February
March
April
May
June
July
August
September
October
November
December
2002
2004
2006
2008
Maine Road Salt Risk Assessment Project  University of Maine  September 2009

47. Fatality Rates Compared
Winter conditions
Dry Pavement
Maine Road Salt Risk Assessment Project  University of Maine  September 2009

48. Maine & US Crash Rates
Maine Road Salt Risk Assessment Project  University of Maine  September 2009

49. Costs of Accidents
Maine accident data shows a 10 year average cost of $1.5 billion dollars annually
Cost per accident measured in constant $2008
The total number of accidents has fallen 26% over the decade.
Possible reasons: driver behavior, vehicle technology, road way improvements, winter maintenance.
Maine Road Salt Risk Assessment Project  University of Maine  September 2009

50. Thank you University of Maine Road Salt Risk Assessment Team
Maine Department of Transportation