WY FLAP 30400(1) Gros Ventrue Pavement Report.pdf

WY FLAP 30400(1), Gros Venture Road Pavement Report

Report Prepared By

U.S. Department of Transportation Federal Highway Administration

Central Federal Lands Highway Division Lakewood, Colorado

Report prepared by: Dan Sorensen ______________________________

Dan Sorensen, Materials Engineer

Report reviewed by: Ron Andresen ______________________________

Ron Andresen, Pavements Engineer

Approved for distribution by: __________________________________

Dan Sorensen, Materials Engineer

12/4/19 ______________

Date

Distribution Project Management

Project Development

Construction

CFLHD, Central Files

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TABLE OF CONTENTS

I. INTRODUCTION

II. CLIMATE

III. EXISTING PAVEMENT

IV. EXPLORATION

V. TESTING RESULTS

VI. RECOMMENDATIONS & DISCUSSION

APPENDICES

A – Location Map B – Pavement Design Calculations

I. INTRODUCTION

During November 2017, a pavement and subgrade soil investigation was completed for WY FLAP 30400(1), Gros Ventre Road. The purpose of the pavement investigation was to determine current pavement and base thickness, as well as classify the subgrade soil.

The Gros Ventre Road project is a two-lane, resurfacing, restoration, and rehabilitation (3R) project in Teton County, WY. The proposed route is 3.79 miles long, starting at the border of the Grand Teton National Park and the Bridger-Teton National Forest at approximately MP 2.2 on of Gros Ventre Road, and running east to the Atherton Campground intersection. The existing width of the roadway varies from approximately 20ft to 22 ft, with pavement depths ranging between 5”-8”.

II. CLIMATE

The following graph displays the average temperature for Jackson Hole:

III. EXISTING PAVEMENT

Existing Pavement

The major distress in the pavement throughout the road is alligator cracking, stripping and pot-holes.

The prominent distress from approximately station 260+00 to 319+00 is pot-holes and cracking, which appears to occur due to poor drainage in combination with soils that classify as A-6 (Clayey) and A-2-6 (Sandy Clay). Station 119+00 to 260+00 appears to have less pavement distress, with soils that classify as A-4 (Silty Soil). Because of this, it is necessary to pulverize existing asphalt and base layer and construct a new pavement surface.

IV. EXPLORATION

In November 2017, a two -person crew from Jackson County Maintenance was on-site with CFL staff to conduct the pot-holing. A mini-excavator was used to pot-hole 5 locations along the route. All potholes were excavated within the roadway. Some pot-hole locations were difficult to excavate due to partially frozen pavement and subgrade. The holes were recorded by CFL. The pavement thickness and base thickness can be found in the results table below. Station 119+00 to 260+00 resulted in soils that classify as A-4 (Silty Soil). Station 260+00 to 319+00 resulted in soils that classify as A-6 (Clayey) and A-2- 6 (Sandy Clay). See Table 1 for a summary of the soils. Sta 260+00 to 319+00 appears to have received a significant amount of asphalt patching/overlays over time.

V. TEST RESULTS

Table 1 provides a summary of the drill locations and soil properties.

VI. PAVEMENT RECOMMENDATIONS AND DISCUSSION

The structural sections were designed using the 1993 AASHTO Pavement Design DARWin Pavement Design and Analysis System program. The traffic on this road is low and composed of cars, personal trucks, SUV’s, and some RV’s. The design period is 20 years, A reliability level of 85% was used to calculate the soil support value for each road.

The design R-Value was converted to a soil resilient modulus (Mr) using the following equation:

29.11

)5( 1 +

ValueRS

= 24.6 72.181

S rM

1) Gros Ventre Road Sta 119+00 to Sta 260+00: The resilient modulus, Mr, for design is 28,195 psi, corresponding to a R-value of 49. The Mr and the traffic data equates to a required structural number (SN) of 1.41 based on DARWin program.

The recommended structural section is 3” of hot mix asphalt concrete pavement (HACP) over 8” of Pulverized Pavement base on top of the existing subgrade, see figure 1:

3" of HACP

8" of Pulverized Base

Existing Subgrade

Figure 1 – Flexible Pavement Design

2) Gros Ventre Road Sta 260+00to Sta 319+00: The resilient modulus, Mr, for design is 6,550 psi, corresponding to a R-value of 10. The Mr and the traffic data equates to a required structural number (SN) of 2.53 based on DARWin program.

The recommended structural section is 3” of hot mix asphalt concrete pavement (HACP) over 6” of Pulverized Pavement base on top of the existing subgrade. The 6” pulverization is to attempt to avoid pulverizing too deep into the clayey material. see figure 2:

3" of HACP

6" of Pulverized Base

Existing Subgrade

Figure 2 – Flexible Pavement Design

Pavement Materials Recommendations:

Use 40301-0000, Asphalt Concrete Pavement Type 1. The HACP should be placed in 2 lifts.

A fog seal, bid item 40601-0000, should be included in the contract. For determining quantities use an application rate of 0.10 gal/yd2. The emulsion type can be a CSS-1, CSS-1h, SS-1, or SS-1h.

A prime coat should be applied on the base course material prior to paving. Bid Item 41102- 1000. For determining quantities use an application rate of 0.30 gal/yd2.

41201-0000, Tack coat (at 0.10 gal.yd2) is required between each lift and should either be a CSS-1. CSS-1h, SS-1, or SS-1h emulsified asphalt.

An item for blotter material, Bid Item 41105-0000 should be included at 14.75 lb/yd2.

Recommended pulverizing depth for station 119+00 to 260+00 is 8 inches. Use Bid Item 30402-5500 by the SQYD. Recommended pulverizing depth for station 260+00 to 319+00 is 6 inches. Use Bid Item 30402-5300 by the SQYD. Do not begin until the asphalt mix design has been approved.

Depending on estimated aggregate base quantities, use a 302 bid item (Method 2) if the quantity is less than 5000 tons and a 301 Bid Item if the quantity is greater than 5,000 tons.

The design unit weight for aggregate base is 139.0. lb/ft3.

APPENDICES

A – Location Map B– Pavement Design Calculations

Appendix A Location Map

Appendix B

Pavement Design Calculations

AASHTO Flexible Pavement Design

Sta 119+00 to 260+00

Standard Normal Deviate -1.037

Combined Standard Error 0.45

Design Serviceability Loss 1.70

Desired Level of Reliability (percent) 85.00

Asphalt Concrete Layer Coefficient 0.40

Aggregate Base Layer Coefficient 0.12

Aggregate Base Drainage Coefficient 0.90

Subbase Layer Coefficient 0.08

Subbase Base Drainage Coefficient 0.80

Flexible Pavement Structural Design:

Allowable 18-kip ESAL Repetitions 140,000

Resilient Modulus (psi) 28,195

Asphalt Concrete Thickness (inches) 3

Aggregate Base Thickness (inches) 8

Subbase Thickness (inches) 0

Design Structural Number 1.97

Required Structural Number 1.41

Design Life (years) 20.00

Asphalt Concrete Thickness (inches) 3.00

Aggregate Base Thickness (inches) 8.00

Subbase Thickness (inches) 0.00

AASHTO Flexible Pavement Design

Sta 260+00 to 319+00

Standard Normal Deviate -1.037

Combined Standard Error 0.45

Design Serviceability Loss 1.70

Desired Level of Reliability (percent) 85.00

Asphalt Concrete Layer Coefficient 0.40

Aggregate Base Layer Coefficient 0.12

Aggregate Base Drainage Coefficient 0.90

Subbase Layer Coefficient 0.08

Subbase Base Drainage Coefficient 0.80

Flexible Pavement Structural Design:

Allowable 18-kip ESAL Repetitions 140,000

Resilient Modulus (psi) 6,550

Asphalt Concrete Thickness (inches) 3

Aggregate Base Thickness (inches) 6

Subbase Thickness (inches) 5

Design Structural Number 2.54

Required Structural Number 2.53

Design Life (years) 20.00

Asphalt Concrete Thickness (inches) 3.00

Aggregate Base Thickness (inches) 6.00

Subbase Thickness (inches) 5.00

Distribution