This document summarizes the results of the third tier of mitigation strategies analyzed as part of the Reston Network Analysis study. Key findings include: - After implementing third tier mitigation strategies, only 2 of 42 intersections were found to operate at an unacceptable level of service in 2050, a significant reduction from earlier tiers. - The recommended third tier strategies included road widening projects and new intersections along Reston Parkway and at intersections with Fairfax County Parkway. - Next steps include further analysis of phasing needs, 2030 traffic conditions, and roadway design classifications. The results support ongoing transportation improvement projects in Reston.

1. County of Fairfax, Virginia
1
Reston Network Analysis
Tier 3 Mitigation Results
September 26th, 2016
Advisory Group Meeting
Kristin Calkins
Fairfax County Department of Transportation

2. County of Fairfax, Virginia
Agenda
• Study Purpose
• Project Progress Overview
• 2050 1st and 2nd Tier Mitigation Results
• Tier 3 Alternatives
• Tier 3 Results
• Next Steps
• Questions and Answers
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3. County of Fairfax, Virginia
Purpose of Study
• Conduct a detailed analysis of the grid of streets
to determine:
– Number of lanes between and at intersections
– How to best serve pedestrians, bikes and transit
– Right-of-way needs
• Assign urban street types and modal emphasis
based on Department of Rail and Public
Transportation Multimodal System Design
Guidelines
• Conduct a phasing analysis of when larger
projects are needed
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4. Data
Collection
• Traffic
Counts in
June 2015
• Travel Time
Runs
Existing
Conditions
• Capacity
Analysis
• Level of
Service
Test Grid of
Streets (2030
& 2050)
• Traffic
Forecasting
Capacity
Analysis
• Level of
Service
Mitigation
• Signal re-
timing
• New links
• Turn lanes
• Additional
lanes
Roadway
Classification
• DRPT Design
Guidelines
• Bike lanes
• Sidewalks/
Pedestrian
routes
• On-Street
Parking
• Transit Routes
Finalize Grid of
Streets (2030
& 2050)
Based on:
• Advisory Group
input
• Stakeholder
input
• Community
input
Phasing
Analysis
• Prioritization
of larger
projects
Network Analysis Project Process
Advisory Group input, Stakeholder input, Community input
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5. County of Fairfax, Virginia
Mitigation Options
• Mitigation Measures - Tiered Approach
– Tier 1: No right of way (ROW) impact
– Tier 2: Some right of way impact
– Tier 3: Large scale mitigations
• Each grid link is initially assumed to be one
lane in each direction (with bike/ped facilities
as specified in the Comprehensive Plan)
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6. County of Fairfax, Virginia
Level of Service Standard
• LOS E (55 – 80 seconds of average delay) is the
standard for the Reston Transit Station Areas
• LOS F (greater than 80 seconds of average delay)
is considered operationally failing
• Greater than 120 seconds of delay is set as a
benchmark for problem locations in the Network
Analysis
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7. County of Fairfax, Virginia
2050 1st and 2nd Tier
Mitigation Results
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8. County of Fairfax, Virginia
2050 Tier 1 and 2 LOS Results
Of 42 key signalized intersections in the study
area, the number that are forecast to operate at
Level of Service F are shown below:
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42 Key Intersections – LOS F
Peak Hour
2050
Unmitigated
After
2050 1st Tier
After
2050 2nd Tier
AM 24 12 10
PM 26 12 12
In Both AM & PM 22 9 9
In Either AM or PM 27 14 12

9. County of Fairfax, Virginia
2050 Tier 1 and 2 Problem Locations
Of 42 key signalized intersections in the study
area, the following intersections have greater
than 120 seconds of delay:
9
Intersections – 120+ Seconds of Delay
Peak Hour
2050
Unmitigated
After 2050
1st Tier
After 2050
2nd Tier
AM 17 12 8
PM 19 7 5
In Both AM & PM 14 5 4
In Either AM or PM 20 10 7

10. County of Fairfax, Virginia
2050 Problem Locations
• Unmitigated had 22 Problem Locations
• After Tier 1: 13 Problem Locations
• After Tier 2: 9 Problem Locations
– 3 were in the Innovation TSA, which has already
been finalized
– 6 were associated with identified follow-on tasks
• Fairfax County Parkway & Spring Street
• Fairfax County Parkway & Sunrise Valley Drive
• Reston Parkway: From Lawyers Road to Baron Cameron
Avenue
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11. County of Fairfax, Virginia
Network Analysis Follow-On Tasks
Fairfax County
Pkwy. & Spring St.
Reston Pkwy.
Capacity Improvements
Fairfax County Pkwy.
& Sunrise Valley Dr.
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12. County of Fairfax, Virginia
2050 3rd Tier
Recommendations
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13. County of Fairfax, Virginia
Tier 3 Alternatives Analysis
• Options for Tier 3 mitigation were coordinated and
developed with the Advisory Group and Stakeholders
Group for:
– Reston Parkway
– Fairfax County Parkway & Spring Street/Sunset Hills Road
– Fairfax County Parkway & Sunrise Valley Drive
• Options were tested and evaluated based on LOS, cost,
ROW need and context
• The 2050 Tier 3 model incorporated the recommended
improvements for each of the follow-on tasks
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14. County of Fairfax, Virginia
Reston Parkway Options
• Option 1: Superstreets
• Option 2: Lawyers Road Connection at Fox
Mill Road
• Option 3: Flyover from WB Sunset Hills Road to
SB Reston Parkway
• Option 4: Continuous flow intersection at Sunset
Hills Road
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15. County of Fairfax, Virginia
Reston Parkway: Lawyers Road Connection
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Remove Left
Turn Bays
New
Intersection

16. County of Fairfax, Virginia
Fairfax County Parkway &
Spring Street Road /Sunset Hills Road
• Option 1: Fairbrook Drive Ramp & new signal
• Option 2: Bi-Directional Ramp
• Option 3: Ramp to NB Fairfax County Parkway
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17. County of Fairfax, Virginia
Fairfax County Parkway: Fairbrook Drive
Ramp
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18. County of Fairfax, Virginia
Fairfax County Parkway &
Sunrise Valley Drive
• Option 1: Tight Diamond Interchange; Fairfax
County Parkway overpass over Sunrise Valley
Drive
• Option 2: Single Point Urban Interchange
(SPUI); Fairfax County Parkway overpass
over Sunrise Valley Drive
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19. County of Fairfax, Virginia
Fairfax County Parkway: SPUI
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Sunrise Valley Drive

20. County of Fairfax, Virginia
Other Changes in Tier 3
Modifications to the Tier 3 Model compared to Tier 2
• Reston Parkway at Sunrise Valley Drive
– EB dual lefts, thru lane, shared thru/right
• Reston Parkway at WB Baron Cameron Avenue
– WB dual lefts
• Sunset Hills Road at Soapstone Drive Connector
– NB left turn lane & right turn lane
– WB left turn lane
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21. County of Fairfax, Virginia
Other Changes in Tier 3 (Cont.)
• Left turn lanes:
– SB Soapstone Drive at Sunrise Valley Drive
– SB Pinecrest Road extension at Sunrise Valley Drive
– NB & WB Sunset Hills Road at grid link east of
Soapstone
– EB & WB Sunset Hills Road at Michael Faraday
– EB Sunset Hills Road at Library Street extended
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22. County of Fairfax, Virginia
2050 3rd Tier
Mitigation Results
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23. County of Fairfax, Virginia
2050 Unmitigated Problem Locations
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24. County of Fairfax, Virginia
2050 1st Tier Problem Locations
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25. County of Fairfax, Virginia
2050 2nd Tier Problem Locations
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26. County of Fairfax, Virginia
2050 3rd Tier Problem Locations
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27. County of Fairfax, Virginia
2050 Problem Locations
Intersections – 120+ Seconds of Delay
Peak Hour
2050
Unmitigated
After 2050
1st Tier
After 2050
2nd Tier
After 2050
3rd Tier
AM 17 12 8 2
PM 19 7 5 1
In Both AM & PM 14 5 4 0
In Either AM or PM 20 10 7 2
Of the 42 key signalized intersections, only 2
continue to have 120 seconds of delay or
greater after Tier 3 Mitigation.
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• Reston Parkway at South Lakes Drive: PM 138 Seconds
• Centreville Road & Sunrise Valley Drive: PM 138 Seconds* In Innovation TSA.

28. County of Fairfax, Virginia
Tier 3 Problem Locations
Reston Parkway at South Lakes Drive
• 138 seconds of average delay in the AM Peak
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29. County of Fairfax, Virginia
Tier 3 LOS Results
Of the 42 key signalized intersections, only 4 continue to
have 80 seconds of delay or greater after Tier 3 Mitigation.
Of these, 3 are on Centreville Road
42 Key Intersections – LOS F
Peak Hour
2050
Unmitigated
After
2050 1st Tier
After
2050 2nd Tier
After
2050 3rd Tier
AM 24 12 10 4
PM 26 12 12 7
In Both AM & PM 22 9 9 3
In Either AM or PM 27 14 12 8
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*4 Interactions that operate at LOS F after 3rd Tier are in the Innovation Area

30. County of Fairfax, Virginia
Tier 3 LOS F Intersections
• Fairfax County Parkway at Baron Cameron Avenue
– 100 seconds of delay in the PM
• Reston Parkway at Sunrise Valley Drive
– 92 seconds of delay in the PM
• Reston Parkway at South Lakes Drive
– 123 seconds in AM & 88 seconds of delay in the PM
• Reston Parkway at Sunset Hills Road
– 83 seconds of delay in the PM
• 4 intersections in Innovation TSA
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31. County of Fairfax, Virginia
Tier 3 LOS F Intersections (Cont.)
Fairfax County Parkway at Baron Cameron Avenue
• 100 seconds of average delay in the PM Peak
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32. County of Fairfax, Virginia
Reston Parkway at Sunrise Valley Drive
• 92 seconds of average delay in the PM Peak
Tier 3 LOS F Intersections (Cont.)
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33. County of Fairfax, Virginia
Tier 3 LOS F Intersections (Cont.)
Reston Parkway at Sunset Hills Road
• 83 seconds of average delay in the PM Peak
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34. County of Fairfax, Virginia
Next Steps
• 2050 Phasing Analysis
• 2050 VISSIM for Dulles Toll Road
• 2030 VISUM Analysis of network
• Roadway classification of grid links using DRPT
Urban Street Guidelines
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35. County of Fairfax, Virginia
Schedule
Task Description 2015 May 15 June 15 July 15 Aug 15 Sep 15 Oct 15 Nov 15 Dec 15 Jan 16 Feb 16 Mar 16 April 16 May 16 June 16 July 16 Aug 16 Sep 15 Oct 15 Nov 16 Dec 16 Jan 17
1A Land Use and Networks - Task is Complete
1B Traffic Counts - Task is Complete
2A Establish Existing Conditions - Task is Complete
2B Calibrate Against Existing Conditions - Task is Complete
3A2 Analyze Future Conditions (2050) - Task complete advance
to Tier 3 Mitigation
3A1 Analyze Future Conditions (2030)
3B Simulation of the Dulles Toll Road
4A Meetings/Presentations
5A Phasing Analysis - Existing Conditions- Ths Task is complete
5B Phasing Analysis - 2050 - Optional
6 Determination of DRPT Guidelines Roadway Classification
7 Documentation
8 Reston Parkway Capacity Improvements
9 Fairfax County Parkway & Spring Street Interchange
10 Fairfax County Parkway & Sunrise Valley Drive
11 Rock Hill Bridge at Sunrise Valley Drive
12A Meetings/Presentations
07
9/26/16
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36. County of Fairfax, Virginia
Questions & Comments
For questions and comments about the study please
contact:
Kristin Calkins: Kristin.Calkins@fairfaxcounty.gov
(703) 877-5710
http://www.fairfaxcounty.gov/fcdot/restonnetworkanalysis/
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