Appendix D_Preliminary Pavement Recommendations.pdf

Page 1 of 6 Pages

Form FHWA-201 (Rev. 11-67)

U.S. DEPARTMENT OF TRANSPORTATION

FEDERAL HIGHWAY ADMINISTRATION

Use this form in lieu of transmittal slips within Dept. of Trans. When message comment is to be retained as file material. Do not prepare carbons. Not to be used in lieu of Form FHWA- 121 for informal correspondence. MINUTE-MEMO

SUBJECT: Preliminary Pavement Recommendations for Project NP-GWMP MVT(4)

TO MESSAGE/COMMENT FROM/DATE

Dan Weston Project Manager

And:

Tiffany Wheeler Highway Design Manager

To support developing 30% PS&E for the project, we’re submitting our preliminary findings and pavement recommendations for project NP GWMP MVT(4). The project site is located along the George Washington Memorial Parkway in Arlington County, VA.

The project consists of horizontal realignment of Bridge #31 and Bridge #32 to eliminate the “T” intersection of the two bridges, replace the bridge deck and railing. The proposed work also includes the rehabilitation of approximately 2 miles of the Mount Vernon Trail south of Theodore Roosevelt Island parking area and along the length of the Columbia Island. This memorandum presents our preliminary recommendations for the trail rehabilitation and improvement based on findings from field assessment performed by Eastern Federal Lands Highway Division (EFLHD). Please note that upon completion of further analyses, the pavement recommendations provided in this memo may be subjected to changes.

EXECUTIVE SUMMARY

The Mount Vernon Trail is an 18-mile paved multi-use trail originally constructed the MVT in the 1970s and 1980s, that stretches from George Washington's Mount Vernon Estate to Theodore Roosevelt Island. It connects with regional trails, including the Potomac Heritage, Custis, Rock Creek, Four Mile Run, and Woodrow Wilson Bridge Trails. The Mount Vernon Trail parallels the parkway between Theodore Roosevelt Island and Mount Vernon.

PAVEMENT CONDITION ASSESSMENT

EFLHD pavement engineers conducted field assessment for the trail on October 19, 2020.

It was observed that the trail varies in width, with the majority of the trail ranging from 8 to 10 feet wide (average of 9 feet), though some areas are as narrow as 6 to 7 feet, including the area of the trail under Arlington Memorial Bridge. The trail consists of an asphalt concrete (AC) pavement ranging from 2 to 4-inches in thickness with an average of 2.5-inches over aggregate base course. Pavement thickness was revealed by lightly excavating along the pavement edges to measure the thickness every 500 to 1000 ft along the trail using manual tools. Chunks of pavements from broken edges measured 3 inches (Photo 5). The existing AC surface course appears in fair to poor condition, exhibiting frequent distresses including medium to high severity transverse cracking and raveling.

Edge cracking and isolated potholes were also observed along with significant rutting mostly related to adjacent tree roots that have extended underneath the paved surface, causing the pavement to heave, crack, and create aesthetic and safety issues as uneven surface developed. Many locations along the trail require shoulder reconditioning to improve drainage, prevent shoulder erosion and pavement edge cracking (Photo 5).

Photos showing existing trail condition are provided in the Attachment.

Our field assessment began at (lat/long) coordinates 38.8951048°, -77.0664011° and ended at coordinates 38.877252°, -77.048119°.

Marc- Olivier Tschibelu Pavement Engineer

Through:

Mohammed Elias Pavement Team Leader

11/16/20

MOHA

MMED

B

ELIAS

Digitally signed by

MOHAMMED

B ELIAS

Date:

2020.11.16 11:35:39 -05'00'

MARC-

OLIVIER

TSCHIBELU

Digitally signed by

MARC-OLIVIER

TSCHIBELU

Date: 2020.11.16 11:38:44 -05'00'

Page 2 of 6 Pages

Use this form in lieu of transmittal slips within Dept. of Trans. When message comment is to

PAVEMENT RECOMMENDATIONS

Based on our field assessment and the observed existing pavement conditions, we are recommending reconstruction of the trail by removing the existing AC pavement and existing aggregate base, reconditioning the subgrade, including removal of tree roots and other deleterious material then placing the new AC pavement according to the minimum requirements provided below in Table 1. The reconstruction of the AC pavement trail and the bridge approaches will be performed in accordance with the FP-14 Standard Specifications.

Table 1. Mount Vernon Trail Pavement – Reconstruction

Layer Minimum Thickness

(in)

Comments

AC Surface Course 1.5

Asphalt Concrete Pavement, Type 1, 3/8” Nominal Maximum Size

Aggregate (NMSA), Type IV roughness, as per Section 403

Asphalt Tack Coat --- AC Tack Coat per Section 412

AC Base Course 2.5 Asphalt Concrete Pavement, Type 1, 1/2” NMSA, as per Section 403

Aggregate Base Course 4.0 Aggregate Base, Grading C or D, as per Section 301

Geotextile --- Separation and Stabilization Geotextile Class 2 – Type E, as per Section 207

Roadbed Reconditioning --- Roadbed Reconditioning, as per Section 303

Additionally, the shoulders within the limit of the project along the reconstructed trail should be reconditioned to provide adequate drainage and prevent pavement edge cracking.

Page 3 of 6 Pages

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Bridge #31 and Bridge #32 paved approaches

Based on our field assessment the bridge approaches are exhibiting minor deformation and moderate to high severity transverse cracking. We are recommending to remove the existing AC pavement and existing aggregate base and reconstruct the new bridge approaches AC pavement according to the minimum requirements provided below in Table 2.

Table 2. Bridge#31 and #32 AC pavement approaches - Reconstruction

Layer Minimum Thickness

(in)

Comments

AC Surface Course 1.5

Asphalt Concrete Pavement, Type 1, 3/8” Nominal Maximum Size

Aggregate (NMSA), Type IV roughness, as per Section 403

Asphalt Tack Coat --- AC Tack Coat per Section 412

AC Base Course 2.5 Asphalt Concrete Pavement, Type 1, 1/2” NMSA, as per Section 403

Aggregate Base Course 4.0 Aggregate Base, Grading C or D, as per Section 301

Geotextile --- Separation and Stabilization Geotextile Class 2 – Type E, as per Section 207

Attachment - Photos showing the trail existing conditions.

Page 4 of 6 Pages

(Rev. 11-67)

U.S. DEPARTMENT OF TRANSPORTATION

FEDERAL HIGHWAY ADMINISTRATION

Use this form in lieu of transmittal slips within Dept. of Trans. When message comment is to be retained as file material. Do not prepare carbons. Not to be used in lieu of Form FHWA- 121 for informal correspondence.MINUTE-MEMO

TO MESSAGE/COMMENT FROM/DATE

Photo 1: Root causing sever cracking and AC pavement heaving

Photo 2: Transverse cracking at bridge approach

Page 5 of 6 Pages

(Rev. 11-67)

U.S. DEPARTMENT OF TRANSPORTATION

FEDERAL HIGHWAY ADMINISTRATION

Use this form in lieu of transmittal slips within Dept. of Trans. When message comment is to be retained as file material. Do not prepare carbons. Not to be used in lieu of Form FHWA- 121 for informal correspondence.MINUTE-MEMO

TO MESSAGE/COMMENT FROM/DATE

Photo 3: Severe transverse cracking and deformation along trail

Photo 4: Transverse cracking and potholes repaired with cold asphalt patch

Page 6 of 6 Pages

(Rev. 11-67)

U.S. DEPARTMENT OF TRANSPORTATION

FEDERAL HIGHWAY ADMINISTRATION

Use this form in lieu of transmittal slips within Dept. of Trans. When message comment is to be retained as file material. Do not prepare carbons. Not to be used in lieu of Form FHWA- 121 for informal correspondence.MINUTE-MEMO

TO MESSAGE/COMMENT FROM/DATE

Photo 5: Severe AC pavement edge cracking along the trail. Broken asphalt concrete chunks measured 2.5 inches.