1. MIT Lincoln Laboratory FHWA Review Robert Hallowell 10/20/2005 Road Condition and Treatment Module Overview, Upgrades, Examples and Limitations Robert Hallowell MIT Lincoln Laboratory bobh@ll.mit.edu Presented by: Bill Mahoney, NCAR

2. MIT Lincoln Laboratory FHWA Review Robert Hallowell 10/20/2005 Outline Background Modifications for Release 4.0 Example cases Limitations Summary

3. MIT Lincoln Laboratory FHWA Review Robert Hallowell 10/20/2005 Road Condition & Treatment Module Weather Prediction Engine Road Condition & Treatment Module Time Series Weather Data Air Temperature Dew Point Wind Speed Wind Direction Insolation (direct and indirect) Precipitation Type Precipitation Rate (liquid) Generates: Pavement Temperatures Treatment Recommendations Road Condition Data Treatment Reasoning Text The RCTM can be driven by any weather time series data set!

4. MIT Lincoln Laboratory FHWA Review Robert Hallowell 10/20/2005 Road Condition-Treatment Components Weather Variables Storm Characterization Plowing Chemical Application Treatment Plan Chemical Concentration Road Weather Conditions - Pavement temp - Snow depth Rules of Practice Display / User Interface RWFS

5. MIT Lincoln Laboratory FHWA Review Robert Hallowell 10/20/2005 Storm Life Cycle Characterization In-stormPost-stormPre-storm Multiple treatments may be needed Varied precipitation types or road temperatures may change treatment strategy Pre- and Post-storm conditions may impact treatment strategy 6-12 Hour Lead Time Dry Road End of Precipitation Start of Precipitation Road Temp trends Blowing snow Road Temp trends Multi-phase precipitation (eg. Rain to snow) Multiple road temp trends (eg. Warm to in-range) Timing: stop, start, duration Precip: total frozen/liquid CAPTURE Impending storms may require pre- treatments Roads may refreeze IMPACTS

6. MIT Lincoln Laboratory FHWA Review Robert Hallowell 10/20/2005 Rules for Treatment Recommendations Perform Plow-only Operations if: –In-storm road temperatures are Too Cold or In-range moving toward Too Cold –In-storm road temperatures are In-range or Too Cold to In-range AND a Blowing Snow threshold is met –Roads are warm In-storm and Post-storm –All other In-storm road conditions AND Post-storm road temperatures are Too Cold Plow treatments clear snow in first hour and then allow snow to accumulate Perform Pre-treatment operation if: –Precipitation type starts as freezing rain –Precipitation type starts as snow and road temperatures are in-range Suppress Pre-treatment if: –Storm type starts as rain –Roads are cold AND blowing snow is present –Pre-storm roads or initial In-storm roads are warm

7. MIT Lincoln Laboratory FHWA Review Robert Hallowell 10/20/2005 In-storm recommendations: –Chemical treatments offset to start before trigger point (route time) –Blowing snow during a storm combined with below 20 o F roads will suppress chemicals and recommend plow only treatments –Cold (<14 o F) post-storm road temps will change treatment plan from chemicals to plow- only to avoid post-storm refreeze –Chemical treatments may be increased to cover short duration storms using one application Rules for Treatment Recommendations Post-storm recommendations: –Dry road time –Protect road from re-freezing

8. MIT Lincoln Laboratory FHWA Review Robert Hallowell 10/20/2005 Calculating Chemical Treatments Effective Chemical Range Ice and Salt Solution and Ice Solution and Salt Calcium Chloride Magnesium Chloride Temperature (Deg F) 0 -5 -10 30 Weight Percentage of Salt 2520 15 105 0 5 15 20 25 30 35 Sodium Chloride Splatter Traffic Precipitation Liquid runoff & Evaporation Dilution FactorsChemical Effectiveness

9. MIT Lincoln Laboratory FHWA Review Robert Hallowell 10/20/2005 Sample Treatment Recommendation / Selection

10. MIT Lincoln Laboratory FHWA Review Robert Hallowell 10/20/2005 Updates for Release 4.0 - RCTM Basic configuration of chemicals adjustable per route (instead of for the entire system) –Rates and chemical types –The form of the chemical (dry, pre-wet, liquid) – changes splatter and loss rates –Independent control of pre-treatment type (salt, MgCl 2, etc.) –Added several new chemicals: Caliber, Ice Slicer, CMag Acetate, K Acetate Added handling of multiple chemical types for user-entered treatments –For example: Start with pre-wet salt and follow-up with liquid mag-chloride (system assumes that residual salt at time of mag-chloride is treated like mag-chloride – little data exists for “stacking” of chemical types. The recommended treatments do not have the capability to produce multi-chemical recommendations

11. MIT Lincoln Laboratory FHWA Review Robert Hallowell 10/20/2005 Updates for Release 4.0 - RCTM Controlling treatment strategy: –Users can now pre-configure two types of treatment strategy: “ONTRIGGER” and “CONTINUOUS”. –Ontrigger mimics the traditional strategy of treating and then re-treating only when the first treatment becomes too weak. –Continuous is utilized for aggressive maintenance and it attempts to have trucks on the road continuously. Continuous treatments are more frequent but with lower application rates that Ontrigger events. Treatment triggers modified: –Delay treatment when rain is occurring prior to the trigger event (e.g., snow, ice). –Added additional sensitivity parameters to make fine-tuning treatment rates simpler. –The form of the chemical (dry, pre-wet, liquid) – changes splatter and loss rates. Independent control of pre-treatment type –Snow on the road at startup is now handled as a trigger for treatments.

12. MIT Lincoln Laboratory FHWA Review Robert Hallowell 10/20/2005 Updates for Release 4.0 - RCTM Miscellaneous changes –The blowing snow potential algorithm is now integrated into RCTM to: (1) Increase application rates during hours of blowing snow (2) Inhibit chemical applications when there is light snow and very cold roads –Track the phase of the water on the road (wet, chem-wet, chem-ice, snow and ice) –Added treatment explanation strings

13. MIT Lincoln Laboratory FHWA Review Robert Hallowell 10/20/2005 Sample Cases Colorado 2004-05 Available test cases –12 days total –11 treatment days Only 2 storms over 5 inches However, light snow events were critical Data capture –Snow rates not adequate –Pavement temperature Convoluted “truth” –Road condition – Snow depth comparison

14. MIT Lincoln Laboratory FHWA Review Robert Hallowell 10/20/2005 November 10-11, 2004 Colorado Protecting roads after precipitation Road still wet (icon not shown) Road temp drops below freezing Treatments triggered to protect road from freezing

15. MIT Lincoln Laboratory FHWA Review Robert Hallowell 10/20/2005 November 10-11, 2004 Colorado Snow Event 1.5 inches Road temp drops below freezing, but in-range Multiple treatments triggered to handle snow

16. MIT Lincoln Laboratory FHWA Review Robert Hallowell 10/20/2005 November 27-28, 2004 Colorado Snow Event 2.5 inches Road temp below freezing, but in- range Pre-treatment + multiple “CONTINUOS” solid treatments

17. MIT Lincoln Laboratory FHWA Review Robert Hallowell 10/20/2005 April 9, 2005 Colorado Snow Event 9.5 inches Road temp drops below freezing, but in-range Multiple “ONTRIGGER” solid treatments

18. MIT Lincoln Laboratory FHWA Review Robert Hallowell 10/20/2005 Treatment Recommendations Lessons Learned Road temperature calculation for treatment recommendations –Assume clear roads or calculate based on actual conditions? Using forecasted weather requires auto-restarts of SNTHERM each time snow is cleared. This causes instabilities in the road temperatures due to initialization Using “cleared” road conditions provides consistent road temperatures, but does not necessarily reflect actual conditions –Solution: More research. Better handling of SNTHERM restart or incorporating “slush” layer into SNTHERM. Rules verification –“Perfect” weather ingest tedious –Solution: Build playback system to allow easy ingest Mixed operations –Overwhelming snows / blowing snow (upgraded in release 4.0 to text warning that current treatment is insufficient) –Solution: Allow multiple level treatments

19. MIT Lincoln Laboratory FHWA Review Robert Hallowell 10/20/2005 Treatment Recommendations Lessons Learned (con’d) Rules for recommending multiple chemical types in a single storm –Many jurisdictions use this technique when road temperatures drop drastically in a storm. –Solution: Adjusting the algorithm to “lookup” the appropriate chemical would be straight-forward. Keeping track of the effectiveness of individual chemicals would be harder. Weak snow events –Difficult to forecast –Solution: Tactical use of radar estimated precip. & tracking Actual road conditions are inconsistent with recommended treatment logic –The system can only estimate the effect of recommended treatments –Solution: Need better feedback of actual treatments and road conditions