The document summarizes the results of a traffic network analysis for Fairfax County, Virginia through 2050. It finds that without mitigation, 24 intersections will operate at unacceptable Level of Service F during morning peak hours in 2050. Implementing optimized traffic signals and signal timing reduces this number to 11 intersections. The analysis identifies locations for new traffic signals and evaluates lane reallocations and signal retiming as low-impact "1st tier" mitigation strategies. Further "2nd tier" strategies requiring more right-of-way will also be considered, such as adding turn lanes. The results help transportation planners identify needed improvements to maintain adequate mobility as development occurs through 2050.

1. County of Fairfax, Virginia
Reston Network Analysis
2050 1st Tier Mitigation Results
February 19, 2016
Stakeholders Group
Kristin Calkins
Fairfax County Department of Transportation

2. County of Fairfax, Virginia
Agenda
• Study Purpose
• Project Progress Overview
• 2050 1st Tier Mitigation Results
• Mitigation Options
• 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. County of Fairfax, Virginia
Reston Network Analysis Tasks
1. Data Collection – done
2. Existing Conditions – done
3. Future Conditions – 2050 mitigation underway
– Determine Grid of Streets
4. Phasing Analysis
5. DRPT Classifications
6. Specific Location Improvements For Additional Study
– Reston Parkway
– Sunrise Valley Drive @ Fairfax County Parkway
– Spring Street @ Fairfax County Parkway
– Rock Hill Bridge
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5. 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

6. County of Fairfax, Virginia
Reston VISUM Model
Tysons
Reston
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7. County of Fairfax, Virginia
Mitigation
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8. County of Fairfax, Virginia
Purpose of Mitigation
• Mitigation reduces vehicle congestion
• Mitigation reduces delays experienced at
intersections
• Mitigation improves the reliability of travel times
through an area (for both buses and vehicles)
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9. County of Fairfax, Virginia
Mitigation Options
• Mitigation Measures - Tiered Approach
– 1st Tier: No right of way (ROW) impact
– 2nd Tier: Some right of way impact
– 3rd Tier: Large scale mitigations if needed
– Consultation with Advisory Group and
Stakeholders
• Each grid link is initially assumed to be one
lane in each direction
– No turn lanes at new intersections
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10. County of Fairfax, Virginia
2050 1st Tier Mitigation Measures
• No ROW Impact Mitigation Measures
– Modifications to lane configurations
– Signal timing and phasing optimization
– All-way stop vs. two-way stop evaluation
– Additional traffic signals
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11. County of Fairfax, Virginia
Mitigation Measures
1st Tier: No Right of Way Impact
•Intersection Reconfiguration
– Optimized signal timing and phasing
– Lane configuration modification
Westwood Center Dr. @ Route 7 (2013) Westwood Center Dr. @ Route 7 (2015)
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12. County of Fairfax, Virginia
Mitigation Measures (Cont.)
1st Tier: No Right of Way Impact
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•Existing and Potential Future Signals
– Adding/removing traffic signals
– Adding/modifying stop control
– Modifying Parking
Westwood Center Dr. @
Sheraton Tysons Dr. (2015)
Westwood Center Dr. @
Sheraton Tysons Dr. (2013)

13. County of Fairfax, Virginia
2050 1st Tier
Recommendations
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14. County of Fairfax, Virginia
2050 1st Tier Intersection Control
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Existing Signal
Signal Proposed by
different study
Signal Proposed

15. County of Fairfax, Virginia
2050 1st Tier Intersection Control (Cont.)
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Existing Signal
Signal Proposed by
different study
Signal Proposed

16. County of Fairfax, Virginia
2050 1st Tier Signal Recommendations
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New Signalized Intersection Locations
Sunrise Valley Dr. @ Wood Oak Dr. Sunrise Valley Dr. @ Commerce Park Dr. East
Sunrise Valley Dr. @ Colts Brook Dr. Soapstone Overpass @ Indian Ridge Rd. Extension
Frying Pan Rd. @ Greg Roy Ln. Sunset Hills Rd. @ West of Town Center Pkwy.
Monroe St. @ Future Connection to Herndon Metro Town Center Pkwy. @ North of Sunset Hills
Glade Dr. @ Pinecrest Rd. Town Center Pkwy. @ Market St.
South Lakes Dr. @ Pinecrest Rd. Sunset Hills Rd. @ Library St.
Sunrise Valley Dr. @ Pinecrest Rd. Extended Sunset Hills Rd. @ Soapstone Overpass
Sunrise Valley Dr. @ Town Center Pkwy. Sunset Hills Rd. @ East of Soapstone Overpass
Town Center Pkwy. @ North of Sunrise Valley Dr. Sunset Hills Rd. @ South Lakes Overpass
West of Reston Pkwy. with grid street Reston Station Blvd. @ Metro Center Dr.
Sunrise Valley Dr. @ Roland Clarke Place Reston Station Blvd. @ Michael Faraday Dr.
Sunrise Valley Dr. @ Indian Ridge Rd. Isaac Newton Square S. @ Isaac Newton Square W.
Sunrise Valley Dr. @ Commerce Park Dr. West Wiehle Ave. @ Isaac Newton Square N.

17. County of Fairfax, Virginia
Lane Re-allocation
Sunrise Valley Drive @ Preston White Drive / S Lake Drive
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2050 Unmitigated 2050 1st Tier Mitigation

18. County of Fairfax, Virginia
2050 1st Tier Mitigation
Results
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19. County of Fairfax, Virginia
2050 1st Tier Mitigation Results
• Stop Controlled Intersections:
– Overall LOS
– Overall delay
• Signalized Intersections:
– Overall LOS
– Overall delay
– LOS by movement
– Delay by movement
– Volumes for each movement
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20. County of Fairfax, Virginia
1st Tier LOS Results
• LOS E is the standard for the Reston Transit
Station Areas
• Of 42 key signalized intersections in the study area,
the following are forecast operate at Level of
Service F:
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42 Key Intersections – LOS F
2050 Unmitigated 2050 1st Tier
AM Peak Hour 24 11
PM Peak Hour 26 11
AM & PM Peak Hour 22 9

21. County of Fairfax, Virginia
2050 Unmitigated Peak Hour LOS (Page 1)
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22. County of Fairfax, Virginia
2050 1st Tier Peak Hour LOS (Page 1)
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23. County of Fairfax, Virginia
2050 Unmitigated Peak Hour LOS (Page 2)
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24. County of Fairfax, Virginia
2050 1st Tier Peak Hour LOS (Page 2)
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25. County of Fairfax, Virginia
2050 Unmitigated Peak Hour LOS (Page 3)
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26. County of Fairfax, Virginia
2050 1st Tier Peak Hour LOS (Page 3)
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27. County of Fairfax, Virginia
2050 Problem Locations
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Intersections – 120+ Seconds of Delay
Peak Hour
2050
Unmitigated
2050 1st Tier
Mitigation
AM 17 12
PM 19 7
AM & PM 14 5
With signal re-timings and the introduction
of signals there has been a reduction in the
number of intersections experiencing delays
in excess of 120 seconds

28. County of Fairfax, Virginia
2050 Unmitigated Problem Locations
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29. County of Fairfax, Virginia
2050 1st Tier Problem Locations
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30. County of Fairfax, Virginia
2050 Unmitigated Problem Locations (cont.)
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31. County of Fairfax, Virginia
2050 1st Tier Problem Locations (cont.)
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32. County of Fairfax, Virginia
2050 Unmitigated Problem Locations (cont.)
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33. County of Fairfax, Virginia
2050 Mitigated Problem Locations (cont.)
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34. County of Fairfax, Virginia
2050 1st Tier Problem Locations
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• 2050 Unmitigated had 22 Problem Locations
• Intersections with Delay over 120 Seconds
1. Frying Pan Road & Sunrise Valley Drive
2. Frying Pan Road & Centreville Road
3. Centreville Road & Coppermine Road
4. Centreville Road & Sunrise Valley Drive
5. Monroe Street & Fox Mill Road
6. Spring Street & Herndon Parkway
7. Fairfax County Parkway & Baron Cameron Avenue
8. Fairfax County Parkway & Sunrise Valley Drive
9. Town Center Parkway & Sunset Hills Road
10. Reston Parkway & Baron Cameron Avenue
11. Reston Parkway & Bowman Towne Drive
12. Reston Parkway & Sunrise Valley Drive
13. Reston Parkway & South Lakes Drive

35. County of Fairfax, Virginia
2050 1st Tier
Available Data
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36. County of Fairfax, Virginia
2050 AM Peak Hour - Unmitigated
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37. County of Fairfax, Virginia
2050 AM Peak Hour – 1st Tier
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38. County of Fairfax, Virginia
2050 AM Peak Hour: Unmitigated vs. 1st Tier
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39. County of Fairfax, Virginia
2050 PM Peak Hour - Unmitigated
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40. County of Fairfax, Virginia
2050 PM Peak Hour – 1st Tier
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41. County of Fairfax, Virginia
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2050 PM Peak Hour: Unmitigated vs. 1st Tier

42. County of Fairfax, Virginia
AM Peak Hour Site Trips and Link Volumes
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43. County of Fairfax, Virginia
PM Peak Hour Site Trips and Link Volumes
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44. County of Fairfax, Virginia
Future Mitigation
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45. County of Fairfax, Virginia
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Mitigation Measures
2nd Tier: Some Right of Way Impact
• Turn lanes
– New Left and Right turn lanes
– Extended turn lanes: adds storage
• Additional through lane
• Additional grid link

46. County of Fairfax, Virginia
Mitigation Measures
3rd Tier: Alternative Intersection Treatment
• Median U-Turn/Superstreet
– Eliminates left turn movement for side streets
– Increases thru movement green time
– Additional needed ROW to provide turn radius
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47. County of Fairfax, Virginia
Mitigation Measures
3rd Tier: Large Mitigation Measures
• Underpass/Overpass
– Provides for an uninterrupted thru movement
• Only done in close coordination with Advisory
Group and Stakeholders after all other mitigation
measures have not worked
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48. County of Fairfax, Virginia
Next Steps
• Apply ROW impact Mitigation Measures
– Turn lanes
– Turn lane extensions
– Additional thru lane
• Develop possible mitigation measures for problem
locations that remain to discuss with Advisory Group
• Meet with Advisory Group on possible 2nd Tier
mitigation measures
• Meet with Stakeholder group on 2nd Tier
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49. County of Fairfax, Virginia
Schedule
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Task Description
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)
3A1 Analyze Future Conditions (2030)
3B Simulation of the Dulles Toll Road
3C Microsimulation - Optional
4A Meetings/Presentations
5A Phasing Analysis - Existing Conditions
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
Feb-15May-15 Jun-15 Jul-15 Aug-15 Sep-15 Oct-15 Nov-15 Dec-15 Jan-16 Sep-16 Oct-16Mar-16 Apr-16 May-16 Jun-16 Jul-16 Aug-16
2/19/16

50. 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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