NP BLRI PVT PRES FY25(1)_PVT_Memo_adv.pdf

Page 1 of 5 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: Project NP-BLRI PVT PRES FY25(1) – Pavement Recommendations

TO MESSAGE/COMMENT FROM/DATE

S. Foronda Project Manager

R. Wright Highway Design Manager

This memorandum serves to support the PS&E development for Project NP-BLRI PVT PRES FY25(1). The project consists of pavement preservation of Blue Ridge Parkway mainline from Park Milepost (MP) 143.11 to 174.60 located in Floyd, Franklin, and Patrick Counties, Virginia. A project location map is included in Appendix A.

The recommendations presented are based on the findings from the field assessment conducted by the Eastern Federal Lands Highway Division (EFLHD) Pavement Team, as well as a review of the most recent data from the Road Inventory Program (RIP) and Highway Pavement Management Application (HPMA).

BACKGROUND

EFLHD RIP last collected pavement condition data for the Blue Ridge Parkway during Cycle 6 (C6) in 2021. This data was gathered using the Data Collection Vehicle (DCV) for roadways and ramps, while parking areas and overlooks were assessed manually. According to the data from C6 RIP, the Pavement Condition Ratings (PCR) for this section of the parkway varied from 43.4 to 98, with an average rating of 92. A visual representation of the data from C6 RIP can be found in Appendix B.

Project History

Sorted chronologically, the following projects have been completed between MP

143.11 to 174.60.

2017: BLRI PVT PRES FY16(1) project, which covered the section from Milepost 120 to 174.60, consisted of a Type 1C Chip Seal

1998: BLRI 1P11, Q12 project from Milepost 136 to 150 included a 3.5-inch Cold-in-Place Recycling, followed by a 2.0-inch overlay

1993: BLRI 1QR11 project from Milepost 150 to 165.1 involved a 1.5-inch overlay

1991: BLRI 1S12, T13 project from Milepost 165.1 to 177.8 consisted of a 1.0-inch overlay.

K. Nguyen Pavement Engineer

Through:

S. Whittemore Technical Services Branch Chief

03/13/2025

Page 2 of 5 Pages

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

PAVEMENT CONDITION ASSESSMENT

EFHLD Pavement Engineers conducted a condition survey, which involved a visual inspection, from November 19 to 21, 2024. The survey focused on the mainline areas within the project scope to assess the existing pavement conditions and evaluate the feasibility of implementing pavement preservation treatments. Appendix C includes photographs showing typical pavement conditions: Figures 1 through 3 depict segments considered beyond preservation, while Figure 4 illustrates conditions of segments deemed preservable.

The pavement condition from this 31.49-mile segment can be categorized by the following mileposts:

Milepost 143.11 to 150

The existing chip seal is in excellent condition. However, localized areas with pavement depression, approximately 1 to 2 feet in diameter, require high-severity patching.

Milepost 150 to 161 Overall, the existing asphalt is in good condition. However, localized low to moderate severity longitudinal and block cracking has been observed. Raveling of the chip seal is present in certain areas.

Milepost 161 to 163 This 2-mile segment is in poor condition. Distresses include moderate to high severity transverse, longitudinal, and block cracking. Additionally, the existing chip seal has exhibited signs of raveling.

Milepost 163 to 164.75 Localized moderate severity transverse cracking has been observed in this segment.

Milepost 164.75 to 165 This quarter-mile segment is in poor condition. Portions of the existing chip seal have delaminated, and moderate severity transverse cracking is present. Mud was observed seeping through the existing cracks during the field review.

Milepost 165 to 166 This 1-mile segment is in poor condition, with low to high severity transverse and block cracking observed.

Milepost 166 to 168 Localized moderate severity transverse cracking was noted in this 2-mile segment.

Milepost 168 to 173 High severity transverse cracking occurs at intervals of 100 feet, accompanied by moderate to high severity longitudinal and fatigue cracking. Small depressions, approximately 1 foot in diameter, were observed in the roadway.

Milepost 173 to 174.60

Page 3 of 5 Pages

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

The asphalt is in fair condition, exhibiting low to moderate severity transverse cracking.

PAVEMENT RECOMMENDATIONS

The Pavements Team conducted an evaluation of the entire Blue Ridge Parkway Mainline within the project scope. This assessment was based on a visual inspection of the existing pavement conditions and C6 RIP data to identify routes suitable for pavement preservation.

Our findings indicate that most of the original project limits would benefit from pavement preservation treatments. However, approximately 26% of the total length has segments showing conditions that are beyond the scope of preservation and require rehabilitation treatments. These segments should be excluded from preservation efforts and considered for future projects, depending on funding availability.

For localized areas with poor conditions within routes that can still be preserved, we will consider spot reconstruction (such as patching), as well as crack cleaning and sealing, prior to applying the pavement preservation treatments.

The Milepost sections recommend for preservation are the following:

MP 143.11 - 161

MP 163 – 164.75

MP 166 – 168

MP 173 – 174.60

MP 161-163, 164.75 to 166, and 168 to 173 were observed to be in poor condition and thus excluded from preservation program.

The following pavement preservation strategy and repairs (prior to placing the proposed preservation treatment) are recommended, in accordance with FP-24 Specifications, “Standard Specifications for Construction of Roads and Bridges on Federal Highway Projects”:

Chip Seal Type IC will be placed for segments deemed preservable.

Placement of the Chip Seal shall be performed in accordance with Section 407.

Fog Seal will be placed after application of the Chip Seal. The fog seal will help prevent raveling of the Chip Seal. Additionally, application of the Fog Seal will give a visual appearance similar to that of asphalt, enhancing the

Page 4 of 5 Pages

Use this form in lieu of transmittal slips within Dept. of Trans. When message visibility of paint striping. The Fog Seal application shall be performed in accordance with Section 406.

ACP Patch, Type 2, as necessary, will be performed in areas exhibiting fatigue cracking, settlement, and/or potholes. Such areas should be identified by the CO. Patch areas should be performed in accordance with Section 418.

Crack Sealing and Filling should be performed at least one week before applying the Chip Seal preservation treatment. Crack sealing is for cracks measuring between ¼ inch and less than 1 inch, while crack filling is for those wider than 1 inch. Both processes should adhere to Section 414. It is recommended to allow a timeframe of 6 to 12 months, or at least one season, between the crack sealing operation and the application of the hot surface treatment. This allows the crack sealant to set and cure under vehicular traffic, leading to better performance. If crack sealing occurs less than 6 months before the preservation treatment, it is advisable to use a recessed configuration for the sealant, ensuring it sets below the surface. This approach minimizes the risk of melting and bubbling of the sealant during subsequent hot surface treatment applications.

Table 1 provides the approximate quantities for patching and crack sealing/filling.

Crack Sealing (Linear Feet) Full Depth Patching, Type II (Square Yards)

6,000 52

Page 5 of 5 Pages

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

APPENDICES

Appendix A: Project Location Map Appendix B: Pavement Prescoping Assessment Appendix C: Photographs cc: Construction Branch, Highway Design Branch, Programs and Planning Branch

APPENDIX A – PROJECT LOCATION MAP

APPENDIX B – PAVEMENT PRE SCOPING REPORT

VA NP BLRI PVT PRES FY25(1)

PROJECT DESCRIPTION:

Preserve the Blue Ridge Parkway Mainline from Park Milepost 143.11 to 174.6 (RIP MP 143.14 to 174.74).

Prescoping Data

Park Mileposts, Start = 143.11, End = 174.6.

RIP Mileposts, Start = 143.14, End = 174.74.

Construction History A total of 2 projects were found within the limits

From MP 120 to 174.6, a Type 1C Chip Seal was placed in 2017 as part of BLRI PVT PRES FY16(1)

From MP 174.6 to 188.75, a Type 2 Microsurfacing was placed in 2020 as part of BLRI PVT PRES FY20(1).

Analyzing the 2021 RIP Cycle 6 Collection RIP has collected data from this section of the Blue Ridge Parkway in June 2021.

The PCR for this section of the mainline stays consistent throughout the limits of the project, however there is a slight downward trend in PCR post MP 159.0

At Park MP 161.38, a absolute minimum PCR for the project limit is reached at 43.4.

2021 RIP COLLECTED DATA ANALYSIS

Taking a look at the 2021 RIP data, we can then show the breakout by Surface Condition Rating (SCR) which represents the cracking/patching/rutting, as well as the Roughness Condition Index (RCI).

The mainline shows a similar trend as the RIP data, with the SCR experiencing a noticable drop at MP 161.38 and a overall downward trend after MP 159.

145 150 155 160 165 170 175

100 Inspection Date Jun 2021

Figure 1. BLRI PVT PRES FY25 - 2021 Cycle 6 RIP Data BLRI Mainline From Park MP 143.11 To MP 174.6 (RIP MP 143.14 to MP 174.74)

Park Milepost

PC

R

P ro je ct

S ta rt

P ro je cc t En d

We can further split out the SCR portion of figure 2 to see what portion of the SCR is driven by structural cracking (i.e. Alligator/Longitudinal Fatigue Cracking) and the portion that is related to transverse cracking. Transverse cracking is a age/environmental related distress unlike structural cracking, which is indicative of a insufficient pavement structure for the traffic loads or a subgrade failure.

Overall, structural and transverse cracking are in line with each other sharing an even distribution of distresses throughout the project, however there are segments in which transverse cracking composes of the majority of the SCR compared to structural cracking.

At MP 161.38, the PCR is driven primarily by transverse cracking with a index of 23.8, but is followed by structural cracking with a index of 35.8.

From MP 159 to 174.74(Project end) transverse cracking is the predominant component of the SCR.

145 150 155 160 165 170 175

100 variable pcr scr rci

Figure 2. BLRI PVT PRES FY25 - RIP Data BLRI Mainline From Park MP 143.11 To MP 174.6 (RIP MP 143.14 to MP 174.74) - Inspected 2021

Park Milepost

C on di tio n C on di tio n C on di tio n variable= rci variable= scr variable= pcr

P ro je ct

S ta rt

P ro je ct

E n

TSD Data Traffic Speed Deflectometer (TSD) data can be used to perform a structural evaluation of the pavement section to determine if it is structurally adequate.

The TSD vehicle (shown in figure 4) collects deflection of the pavement that can be used to back calculate the structural properties of the pavement. This deflection is shown in Figure 5 below.

The Effective Structural Number (SNeff) is calculated based on both pavement deflection testing by the TSD and pavement thickness data.

145 150 155 160 165 170 175

100 Crack Type Structural Cracking Transverse Cracking

Figure 3. BLRI PVT PRES FY25 - RIP Data by Cracking Type BLRI Mainline From Park MP 143.11 To MP 174.6 (RIP MP 143.14 to MP 174.74) - Inspected 2021

Park Milepost

C on di tio n

P ro je ct

S ta rt

P ro je ct

E

Figure 4 - TSD Trailer

Figure 5 - Deflection basin of TSD load impulse

Max Deflection The maximum deflection along this section of the parkway from the 2020 collection is shown in Figure 6. The maximum deflection alone may not be enough to determine the quality of a pavement structure. It is important to consider deflection data in conjunction with the pavement thickness to determine if the current pavement design is adequate. This is the purpose of calculating effective Structural Number (SNeff) shown in the next section. As these calculations are still being finalized for the BLRI, maximum deflection can still provide some useful insight.

From the chart, the Southbound lane is shown to exhibit higher deflection in comparsion to the Northbound lane.

The average deflection of the Project Limits from Park MP 143.11 to 174.6 is 25.9 mils. This falls in the 61 percentile of deflection along the parkway

The Z-Score for the project limit deflection is 0.087. This represents that the mean deflection in this section is only above 0.087 standard deviations above the mean deflection in the parkway.

145 150 155 160 165 170 175

−50

−40

−30

−20

−10 Direction Southbound Northbound

Figure 6. BLRI PVT PRES FY25 - TSD Deflection Data (Smoothed) BLRI Mainline From Park MP 143.11 to MP 174.6 (RIP MP 143.14 to MP 174.74) -Collected in Spring 2020

Park Milepost

D ef le ct io n

(m il)

P ro je ct

S ta rt

P ro je ct

E

Max Deflection (mils) Statistics (Parkway Mainline) count 85804.00 mean 24.93 std 11.66 min 0.40

50% 23.20

75% 30.70 max 199.30

Preliminary Structural Analysis Results The TSD deflection results coupled with the thickness of the Blue Ridge parkway can be used to calculate the Effective Structural Number (SNeff), which gives a good indication of the overall pavement structural condition of the existing pavement.

The Effective Structural Number of the pavement section can be compared to the Design Structural Number (i.e. what the Structural Number would be expected to be for the given pavement thickness if it were new). From this a Remaining Life (RL) and Design Life (DL) can be calculated. The ratio of RL to DL (RL/DL) gives an idea of where the pavement is in it's life-cycle.

Figure 7 - BLRI Remaining Life vs Design Life, Northbound

Source - EFL Draft Report - NT and BRP TSD Evaluation (Virginia Tech)

Figure 8 - BLRI Remaining Life vs Design Life, Southbound

Source - EFL Draft Report - NT and BRP TSD Evaluation (Virginia Tech)

Conclusions and Recommendations From the data gathered, while the majority of pavement is in good or excellent condition, there is a trend of decreasing PCR after MP 159.0. Additionally localized areas of high severity distress was identified at MP 161.38.

The PCR mainly consists of transverse cracking instead of structural, indicating temperature related distresses within the project limits.

From the data, we can predict that a pavement preservation treatment such as a chip seal is suitable from the project start at MP 143.11 to MP 159.00.

After MP 159.0, attention must be paid in the field visit to assess whether or not the existing distresses are severe enough that a preservation treatment would prove ineffective. A preservation treatment on a fair or worse condition pavement would incur the risk of early reflective cracking and not meet the 5-7 year performance standard.

APPENDIX C – PHOTOGRAPHS

Appendix C - Photographs

Figure 1: High Severity Longitudinal Cracking at MP 172.66

Figure 2: High Severity Transverse Cracking at MP 168.92

Figure 3: High Severity Transverse Cracking and Mud Seepage at MP 164.78

Figure 4: Blue Ridge Parkway MP 143.17