APWA Conference September 21st, 2011

Transkript

1 Whitetopping Colorado Style Jay Goldbaum Pavement Design Program Manager APWA Conference September 21 st, Background Concept existed since 1918 Extended to pavements in the 1960 s Asphalt is part of the pavement structure Design methodology developed in 1998 for CDOT Performance is very promising 2 Types of Whitetopping Conventional - Greater than 8 inches Thin - 4 inches to 8 inches Ultra-Thin - Less than 4 inches 3 Presented by: Jay Goldbaum 1

2 SH 68 - Harmony Road Project Data: 18,200 AADT 4% Truck Traffic 5 105,000 18k ESALs per year Inch Thick Section 1,400,000 Total 18k ESALs in the Driving Lane 6 Presented by: Jay Goldbaum 2

3 1994 Parker Road Project Data 25,900 AADT 7% Truck Traffic 180,000 18k ESALs per year Inch Thick Section 3,300,000 Total 18k ESALs in the Driving Lane Parker Road Project Data: 64,000 AADT 5% Truck Traffic 200,000 18k ESALs per year 9 Presented by: Jay Goldbaum 3

4 Inch Thick Section 1,700,000 Total 18k ESALs in the Driving Lane SH 121 Wadsworth Blvd. 12 Presented by: Jay Goldbaum 4

5 Project Data: 39,000 AADT 4% Truck Traffic 160,000 18k ESALs per year Presented by: Jay Goldbaum 5

6 US 287 Project Data: 6,000 AADT 55% Truck Traffic 16 1,000,000 18k ESALs per year Factors to Consider During Scoping Evaluate the existing pavement Evaluate the subgrade soil Estimate future traffic loads Existing curb and gutter Overhead clearance Constructability issues 17 Recommendations A good bond within the concrete/asphalt interface is essential for successful thin whitetopping performance. A minimum asphalt thickness of 5 inches after milling is recommended for thin whitetopping pavement. 18 Presented by: Jay Goldbaum 6

7 Design Parameters Factor Source Example Existing Asphalt Thickness Pavement evaluation, 6 inches cores Existing Asphalt Elastic Modulus Falling Weight 300,000 psi Deflectometer Existing Asphalt Poisson s Ratio Assumed value from 0.35 historic laboratory tests Existing Asphalt Fatigue Life Pavement Management 50% Consumed data Subgrade soil modulus Soil investigation 150 psi/in Concrete joint spacing ½ lane width 72 inches Concrete Elastic Modulus Assumed value from 3,400,000 psi historic laboratory tests Concrete Poisson s ratio Assumed value from 0.15 historic laboratory tests Concrete Flexural Strength Contract specification 650 psi Concrete temperature gradient Assumed value from historic field tests 3º F per inch Traffic loads Forecast by CDOT Traffic 18k ESALs Analysis Section 19 Thin Whitetopping Typical Joint Layout 20 Thin Whitetopping Typical Curb and Gutter Layout 21 Presented by: Jay Goldbaum 7

8 Overlaying a Vertical Curb Presented by: Jay Goldbaum 8

9 Selection process for thin whitetopping in Colorado is based on the 40-year life cycle cost analysis 25 Rehabilitation Strategies Asphalt Overlays For unmodified hot mix asphalt, the rehabilitation cycle occurs every 12 years with a 2 inch overlay. Thin Whitetopping Rehabilitation at 22 years with 1% slab replacement, grinding ¼ inch for smoothness, and joint resealing. 26 Example Project Initial construction alternatives HMA = 4 inches PCCP = 6 inches Total length = 1 mile Total width = 44 feet (12-foot lane and 10-foot shoulder in each direction) Total area = 25,800 square yards 27 Presented by: Jay Goldbaum 9

10 Initial Construction Cost Data HMA = $65.00/ton of mix PCCP = $18.00/Square Yard Based on initial construction cost only, HMA is cost effective by over $95, Rehabilitation Cost Data HMA = $65.00/ton of mix PCCP slab replacement = $150.00/Square Yard Diamond grinding = $4.50/Square Yard Sawing and sealing the joints = $1.50/Linear Foot Annual Maintenance Cost HMA = $ 1,270/Lane Mile PCCP = $ 499/Lane Mile 29 Rehabilitation Strategies HMA 2 inch overlay every 12 years PCCP ½ of 1 percent full depth repair, 50 percent diamond grinding along with sawing and resealing all the joints at year Presented by: Jay Goldbaum 10

11 Comparison of Alternatives* HMA = $683,492 NPV PCCP = $519,958 NPV PCCP is cost effective by over $160,000 Difference between the alternatives is over 31% *only material cost 31 Thin Whitetopping 32 Cost of Thin Whitetopping 33 Presented by: Jay Goldbaum 11

12 Annual Maintenance Cost 34 International Ride Index 35 Rut Depth 36 Presented by: Jay Goldbaum 12

13 Transverse Cracking 37 Longitudinal Cracking 38 QUESTIONS? Presented by: Jay Goldbaum 13

14 Year Constructed Colorado and Wyoming Thin Whitetopping Projects CDOT Region Project & Location Thickness Inches Quantity Square Yards Unit Cost Dollars/SY SH-68 Harmony Road, 3.5, 5 2,333 0 Out of service Fort Collins, CO SH-83 Franktown, CO 5 2,637 $ US-285 Santa Fe 5 2,370 $ Frontage Road SH-119 East of Longmont 4.5, 5, 6 22,300 $ US-287 South of Campo 6 25,813 $ when TOS I-70 Eisenhower Tunnel 6 1,335 $35.00 Out of service Approach US-6 Fleming to East of ,858 $ Haxton SH-83 Parker Road - Pine $ Lane to Arapahoe 1998 First Christian Church 3 11,160 $ Parking Lot, Longmont, CO 1998 Centennial Airport Jet Port 6 29,455 $ Apron SH-83 Rice to Orchard 5 91,614 $ SH-121 Wadsworth, C-470 to Parkhill 6 148,556 $ WYDOT Fox Farm & C Avenue, Cheyenne, WY 4 2, I-70 Eisenhower Tunnel 6 6,934 $ Approaches SH-83 Jamison Avenue 6 97,684 $ SH-121 Wadsworth, 6 102,013 $ th to SH SH-83 Arapahoe to Orchard 6 97,575 $ SH-83 Quincy Ave & 6 38,055 $ Parker Road SH-66 Foothills Highway to 6 243,952 $ US SH-121 Wadsworth, 88 th to 104th 6 102,650 $19.89 Age ACPA, Colorado/Wyoming Chapter S. Yosemite Ct.. Ste 100. Centennial. CO Telephone: