Weather and Surface Transportation in Canada: The Long and Winding Road

1. Weather information and surface transportation in Canada: The long and winding road Brian Mills1,2, Jean Andrey2, Susan Tighe3, and Sarah Baiz3 1Adaptation & Impacts Research Division, Environment Canada (Brian.Mills@ec.gc.ca) 2Department of Geography & Environmental Management, University of Waterloo 3Department of Civil & Environmental Engineering, University of Waterloo

2. Introduction • “Pushing the Product” • What happens after the flush? • The “Bottom-up” perspective is a necessary complement if not starting point • A few examples from road transport Impressive Gains in Predictability TIGGE thought responsible PDP complain about process DAOS target of unruly observers Shortage of planes blamed on Thorpex campaigners

3. Introduction • Economic and social activities in Canada are highly dependent on road surface transportation—by far the most important mode Source: Transport Canada 2008

4. Maintaining the mobility afforded by the highway system without compromising safety or environmental quality requires substantive investments—many of which are weather-related • Design, construction and maintenance of infrastructure • Operations • Environmental • Safety interventions Introduction

5. Introduction Andrey 2009 • Despite numerous interventions, significant risk remains • Why? Imperfect decision-making? Role of wx info?

6. Weather & Climate-related Decisions at Many Scales • Drivers • Public & commercial transport service providers • Public road authorities • Road associations • Construction & maintenance industry • Vehicle manufacturers • Vehicle repair industry • Insurers • Police/enforcement agencies • Emergency responders and healthcare industry • Weather, road weather, and hydromet service providers

7. Case 1: Weather-related collision risk • Robust estimates of the relative risks and social costs associated with driving in inclement weather are lacking at the city-region and national scales in Canada. • This information is fundamental to design and evaluate the efficacy of response measures such as the provision of weather information intended to influence driver behaviour just before and during a particular trip. D. Doiran, National Post

8. National Transportation Accident Incident Database (TRAID) collision data (1984-2000) combined with hourly and six-hourly records of precipitation (R, S, ZR/ZL, mixed) for 28 Canadian cities • Matched pair event-control analysis conducted producing ~ 36,000 entries • Relative risk calculations performed by dividing the sum of injury collisions/injuries during events by corresponding counts for controls • Further analysis facilitated the development of risk estimates disaggregated by precipitation type, amount, injury severity, region, etc. Method

9. Results • Risk of injury increases by approximately 70% during precipitation relative to dry seasonal conditions • Minimal and minor injuries tend to increase more than do major and fatal injuries • About 200-400 fatalities and several thousand injuries are attributable to weather-related motor vehicle collisions each year with an estimated social cost >CA$1 billion Andrey et al. 2005, Andrey 2009

10. Results • Comparative analysis using insurance claim data (1999-2002) for Winnipeg, Manitoba • Similar results for incidents (below) and claim costs exceptAccident Benefit Costs during snowfall events (RR=3.33) Mills et al., in press

11. Future Research • Complete RR analyses using insured loss data and weather warning/advisory information • Develop a prototype collision prediction model that can incorporate probabilistic weather prediction information and produce a normalized index • Evaluate the effect of this “impact-centric” information on stated/observed driver response relative to traditional types of weather and road weather information

12. Case 2: Seasonal Load Restrictions on Ontario Highways • Secondary roads are often subjected to heavy loads from agricultural or resource extraction (forestry, mining) operations • Where frost penetrates into the subgrade, such highways are extremely vulnerable to damage caused by brief periods of thaw-induced weakening • Seasonal load restrictions (SLR) are used by transportation agencies to reduce/increase the permissible loads carried by trucks • Fixed dates/durations are often used in establishing SLRs which provides certainty for trucking operations but can lead to tremendous damage when thaws occur outside of the period

13. Case 2: Seasonal Load Restrictions on Ontario Highways Source: MTO, 2005

14. Method • Empirical model was developed to predict frost and thaw depths as a function of simple freezing and thawing indices derived from air temperature • Model validated and calibrated against data obtained for 2 winter seasons at 2 instrumented test sites periodically evaluated for pavement strength using a portable Falling Weight Deflectometer

15. Results (Northeast Ontario Site) Where: i Number of days after the day indexed as day i = 0 i = 0 Day on which TAir first falls below 0ºC io Day of transition from Freezing to Thawing season FDi Depth of frost on day (cm) TDi Depth of thaw on day (cm) FIi Freezing Index value on day (in ºC -days) TIi Thawing Index value on day (in ºC -days)

16. Future Research • Repeat analysis and refine models using additional winter seasons and locations • Develop a damage model and SLR/WWP decision experiment using weather forecast data. Evaluate social costs and benefits as a function of accuracy.

17. Case 3: Impacts of climate change on pavement infrastructure • Current and past pavement designs generally assume a static climate whose variability can be adequately determined from records of weather conditions which normally span less than 30 years and often less than 10 years • Anthropogenic climate change challenges this assumption and raises the possibility that the frequency, duration or severity of thermal cracking, rutting, frost heave and thaw weakening may be altered leading to shifts in pavement deterioration rates if corrective actions are not taken

18. Method • Mid-century surface temperature and precipitation scenarios were developed by statistically downscaling output from the CGCM2A2x and HadCM3B21 climate experiments for 17 Canadian sites • Scenarios were applied to 2 deterioration-relevant indicators: 1) Performance Grade Asphalt Cement (PGAC) high and low temperature threshold criteria, and 2) Freeze-thaw indices • Scenarios were applied at 6 sites using the Mechanistic-Empirical Pavement Design Guide (MEPDG) model which simulates life cycle deterioration (developed by the U.S. NCHRP and AASHTO)

19. Results • Indicator analysis suggests that low temperature cracking will become less problematic; structures will freeze later and thaw earlier with correspondingly shorter freeze season lengths; and higher extreme in-service pavement temperatures will raise the potential for rutting.

20. MEPDG analysis suggests that rutting (AC and total) and cracking (longitudinal and alligator) issues will be exacerbated by climate change • Maintenance, rehabilitation or reconstruction will be required earlier in the design life • Absolute impacts of climate change are closely associated with the underlying structural, material, and traffic characteristics of a particular site thus generalizations must be considered with caution. Results

21. Future Research • Repeat MEPDG analysis using the latest AR4 climate change scenarios, more sophisticated downscaling, and a greater range of pavement structures and vehicle loads • Incorporate municipal distress data and a ravelling (pothole) indicator into the analysis • Examine utility of monthly-seasonal scale forecasts

22. Further Reading • Andrey, J, B. Mills, D. Unrau, M. Christie and S. Michaels 2005. Toward a National Assessment of the Travel Risks Associated with Inclement Weather, ICLR Paper Series, Institute for Catastrophic Loss Reduction, London, Ontario. 35 pp. • Baiz, S., S. Tighe, C.T. Haas, B. Mills, and M. Perchanok, 2008. Development of frost and thaw depth predictors for decision making about variable load restrictions, Transportation Research Record, 2053:1-8. • Mills, B., S.L. Tighe, J. Andrey, J.T. Smith, and K. Huen, 2009. Climate change implications for flexible pavement design and performance in southern Canada, Journal of Transportation Engineering, 135(10).

23. Thank you!