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Presentation . What is a Coal Severance TaxReason for the StudyStudy Work PlanPreliminary ResultsSteps Forward. What is a Coal Tax Severance?. A Tax levied against the coal industry in SW Virginia to pay for Infrastructure Improvements - roads, schools, water, etc. Tax allowed Coal Trucks to
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1. Coal Tax Severance Study - The Effects of Heavier Axle Loads on Southwest Virginia PavementsTrenton Clark, P.E. - Assistant State Pavement Engineer
2. Presentation What is a Coal Severance Tax
Reason for the Study
Study Work Plan
Preliminary Results
Steps Forward
3. What is a Coal Tax Severance? A Tax levied against the coal industry in SW Virginia to pay for Infrastructure Improvements - roads, schools, water, etc.
Tax allowed Coal Trucks to haul at higher axle loads
Started in 1980’s and affects the following counties - Buchanan, Wise, Tazewell, Russell, Dickenson, Lee and Scott.
4. Specifics of HB2209 Enacted in 1999 General Assembly Session
Amended Code of Virginia - original Coal Severance Tax
Allows trucks carrying sand, gravel or crushed stone in Coal Tax counties to haul a coal truck weight limits within 50 miles of point of origin
Trucks do not need a permit to haul at higher limits
Does not apply to VA interstates
5. Weight Limits Under HB2209
6. Purpose of Study VDOT directed by General Assembly to monitor operation of vehicles and report on condition of roadways effected by the bill.
Report to be issued to Governor and General Assembly for 2001 session
Based on report findings, General Assembly can allow bill to expire July 1, 2001, extend bill for another period of time, or enact into law
7. Objective of Study To determine if vehicles operating under the provisions of HB2209 cause pavements to deteriorate faster and therefore exacerbate maintenance, repair and rehabilitation requirements than pavements that do not support traffic operating under the bill.
8. Scope of Study 13 Month Study
Monitoring Sites - Control and Test Sites
Final Report and Recommendations
9. Work Plan Select Sites with Medium to High Traffic Volumes on Primary and Secondary Routes
Perform Pavement Condition Surveys
Visual Condition
Ride Quality
Rut Measurements
Structural Evaluation with FWD
Perform Destructive Testing
Perform Traffic Survey
Prepare Final Report with Recommendations
10. Site Selection 18 Total Monitoring Sites
10 Test Sites
8 Control Sites
Site Length - 0.3 miles
Primary or Secondary Route
11. Pavement Condition Surveys Visual Condition Surveys
Segmented sites in 0.01 mi. lengths
VDOT visual condition approach - LDR and NDR
Performed Quarterly
Ride Quality and Rut Measurement
Measured in each wheel path
South Dakota Type Profiler and Straight-edge
Calculated IRI and Rut Depth
12. Traffic Survey Performed in Spring 2000
Portable WIM station - 8 to 10 hr Monitoring
24 Hour Traffic Count
Visual counting of sand/gravel trucks for 2 hrs
Data Results - Vehicle Classifications by
Volume
Total Weight
13. Structural Evaluation with FWD Dynatest FWD
Two load levels - 9,000 and 16,000 lbs.
LTPP Sensor Spacing
Test Spacing - 50 feet
Analysis performed using VDOT developed software
Based on 1993 AASHTO Pavement Design Guide
Results in terms of Effective SN and Subgrade Mr
14. FWD Analysis Approach Test quarterly to monitor changes in structure and subgrade over time
Test in Center Lane and Outside Wheel-path
Done to see if initial differences existed
Done to compare CL and OWP over the study period
15. FWD Analysis Software
16. Sample Screens from TAG
17. Sample Screen Shots
18. Sample Screen Shots
19. Sample Screen Shots
20. Sample Screen Shots
21. Structural Analysis Results Proved Initial Fear - 13 months to short time period to see changes for most segments
Variable Pavement Structures over Short Distance
Changes in Subgrade Strength (Temperature and Moisture)
Noise in SNeff - most sections in good condition, unable to see changes due to fatigue
22. Visual Survey and Rutting Results Load and Non-Load Distress Indices faster show deterioration, as expected where heavier trucks are present
Rutting has increased on all sites, dramatically on some - 2”
23. Final Report Currently under development
Original Approach - Show increased deterioration in test vs. control sites due to increased loading.
However data does not support, why?
Pavements along coal truck routes designed for heavier loading
Structure adequate although pavement life reduced
Hard to monitor in 13 month period
24. Final Report (cont.) New Approach - Show cost to Virginia Taxpayers to accommodate increased axle weights.
Compare control site performance to test site performance
Non-coal truck routes not designed for heavier loads
To meet loading demands, structure must be increased on HB2209 effected roadways
Higher taxes needed to pay for improvements
Estimated cost to improve routes in SW Virginia and all of Virginia
25. Comments or Questions?