TECHNICAL MEMORANDUM Central Region Traffic Engineering On Call (Task Order ) Mini Roundabout Assessment Braddock Road & Pleasant Valley Road

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1 Kittelson & Associates, Inc. T R A N S P O R T A T I O N E N G I N E E R I N G / P L A N N I N G 1850 Centennial Park Drive, Suite 130, Reston, Virginia P F TECHNICAL MEMORANDUM Central Region Traffic Engineering On Call (Task Order ) Mini Roundabout Assessment & Pleasant Valley Road Date: January 7, 2013 Project #: To: Sunil Taori, PE From: Chris Tiesler, PE and Ed Myers, PE cc: Amir Salahshoor, PE William Cutler, PE Chris Kiefer, PE At the request of the Virginia Department of Transportation (VDOT), Kittelson & Associates, Inc. (KAI) has prepared this memorandum to document its assessment of a mini roundabout intersection control at the /Pleasant Valley Road intersection in Fairfax County, Virginia. This assessment is in support of the on going alternatives analysis related to Task Order of the VDOT Central Region Traffic Engineering On Call contract considering a wide range of intersection control forms. The purpose of this memorandum is to provide additional details and findings regarding implications of the implementation of a mini roundabout at the /Pleasant Valley Road intersection. Details regarding our outreach, analysis, and findings are contained herein. MINI ROUNDABOUT DEFINITION Roundabouts can range in size, but are typically separated into three basic categories according to size and number of lanes to facilitate discussion of specific performance or design issues: miniroundabouts, single lane roundabouts, and multilane roundabouts. For this specific Task Order, only mini and single lane roundabout configurations are being considered. Mini roundabouts are small roundabouts (inscribed circle diameters [ICDs] ranging approximately feet) with a fully traversable central island. They are most commonly used in low speed urban environments with average operating speeds of 30 mph or less. Many of the same principles are used in the design of mini roundabouts as in full sized roundabouts. Key considerations include vehicle channelization, design vehicle paths, and intersection visibility. A mini roundabout is often considered as an alternative to a larger single lane roundabout due to a desire to minimize impacts outside of the existing intersection footprint. Mini roundabouts should generally be made as large as possible to achieve desired geometric deflection and accommodate large vehicles, but should generally not FILENAME: H:\PROJFILE\ CENTRAL REGION VDOT ON-CALL\TASK ORDERS\TASK 14 (12-057) - BRADDOCK RD & PLEASANT VALLEY\REPORT\FINAL\ _MINI RBT ASSESSMENT_FINAL.DOCX

2 Central Region Traffic Engineering On Call (Task Order ) Project #: January 7, 2013 Page 2 exceed a 90 foot ICD. Above 90 feet, the ICD is typically large enough to accommodate the design vehicle navigating around a raised central island. A raised central island provides physical channelization to control vehicle speeds and is more conspicuous to drivers approaching the roundabout. A fully traversable central island is typically domed or raised with a mountable curb and flat top, but in some cases painted islands or islands flush with the roadway surface may be used. In any case, it is essential that the central island be clear and conspicuous to drivers. As with larger roundabouts, splitter islands are generally used at mini roundabouts to align vehicle paths and encourage deflection and proper circulation. Single lane roundabouts are distinguished from mini roundabouts by their larger ICD ( feet) and non traversable central islands. The size of the roundabout is largely influenced by the choice of design vehicle and available right of way. Additional details regarding distinguishing characteristics between mini roundabouts and single lane roundabouts can be found in the 2 nd Edition of Roundabouts: An Informational Guide, published as National Cooperative Highway Research Program (NCHRP) Report BACKGROUND The /Pleasant Valley Road intersection currently operates as an all way stop control intersection with single lane approaches and experiences substantial congestion during peak periods of the day. During both the weekday a.m. and p.m. peak hours, the intersection operates at capacity with extensive queuing on critical approaches (eastbound during the a.m. peak hour; westbound during the p.m. peak hour). As part of Task Order , KAI is evaluating several alternative intersection control forms to address current operational deficiencies. Since a team meeting with VDOT on Tuesday, December 18 th, 2012, we ve had an opportunity further investigate the feasibility of a mini roundabout at the /Pleasant Valley Road intersection. Since this meeting, we have: Contacted Jeff Stratmeyer (Project Manager for the Harford County mini roundabout at Tollgate Road/MacPhail Road in Bel Air, Maryland) o Obtained turning movement counts and reviewed videos of the Tollgate/MacPhail mini roundabout under traffic o Reviewed operations and context 1 Rodegerdts, L., J. Bansen, C. Tiesler, J. Knudsen, E. Myers, M. Johnson, M. Moule, B. Persaud, C. Lyon, S. Hallmark, H. Isebrands, R. B. Crown, B. Guichet, and A. O Brien. NCHRP Report 672: Roundabouts: An Informational Guide, 2nd ed. Transportation Research Board of the National Academies, Washington, D.C., Kittelson & Associates, Inc. Reston, Virginia

3 Central Region Traffic Engineering On Call (Task Order ) Project #: January 7, 2013 Page 3 Considered the mini roundabout at MD 835A/Thompson Creek Road in Stevensville, Maryland for context (same mini roundabout where data were collected for the recent FHWA study that developed capacity models for mini roundabouts) o Obtained recent turning movement counts from the Maryland State Highway Administration website Further reviewed the FHWA capacity methodology for mini roundabouts Observed the critical weekday a.m. peak hour operations at the subject intersection (6:55 7:40 a.m. counts indicate peak hour is 7:00 8:00 a.m.) Conducted a year by year sensitivity analysis of a mini roundabout based on the assumed annual growth rate of two percent Tested single lane and mini roundabout configurations using the SIDRA Standard model (which is sensitive to geometric parameters such as central island size) Contextual Comparison Two mini roundabouts in Maryland were reviewed to compare against the /Pleasant Valley Road intersection. Table 1 summarizes physical, operational, and land use characteristics and Figure 1 provides aerial views of the three locations. Table 1 Contextual Conditions Location Braddock Rd / Pleasant Valley Rd (Fairfax County, VA) Tollgate Rd / MacPhail Rd (Bel Air, MD) MD 835A / Thompson Creek Rd (Stevensville, MD) Inscribed Circle Diameter (ICD) N/A 65 feet Approach Speeds 35 mph (all approaches) o Limited driveway access and no speed control in vicinity 25 mph MacPhail Rd 30 mph Tollgate Rd o Single lane roundabout 500 feet north controls speeds Surrounding Land Use(s) Rural o Agricultural o Park land Suburban o Residential o Commercial o Institutional 75 feet 25 mph (all approaches) Suburban o Commercial o Industrial Total Entering Volume (TEV) 1,552 AM 1,552 PM 690 AM 1,216 PM 500 AM 700 PM % Left Turns of TEV 27% AM 26% PM 27% AM 13% PM 12% AM 11% PM As shown in Table 1, the /Pleasant Valley Road intersection has different land use, speed, and volume characteristics than the other locations where mini roundabouts have been applied. Peak hour total entering volume (TEV) at the /Pleasant Valley Road intersection is more than double the MD 835A/Thompson Creek Road intersection and percent higher than the Tollgate Road/MacPhail Road intersection. The /Pleasant Valley Road intersection also has a higher percentage of left turn volume as compared to the MD 835A/Thompson Creek Road intersection. As seen in Figure 1, the existing mini roundabouts are in located in areas with greater development density and a more suburban character. Kittelson & Associates, Inc. Reston, Virginia

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5 Central Region Traffic Engineering On Call (Task Order ) Project #: January 7, 2013 Page 5 Fully traversable islands are appropriate in more dense/visible areas such as the Maryland sites, but given the rural nature of /Pleasant Valley Road intersection, conspicuity is an important consideration particularly under nighttime and poor visibility conditions. Conspicuity is best achieved through a raised/landscaped central island. FHWA CAPACITY MODELS FHWA recently developed capacity models for mini roundabouts which were published in the Institute of Transportation Engineers (ITE) Journal 2. Data of driver behaviors and travel characteristics at mini roundabouts were observed at the Stevensville, Maryland mini roundabout site, a microscopic traffic simulation model was developed and calibrated to simulate for multiple traffic flow scenarios, and a multiliniear regression model was developed to fit the simulated data and estimate mini roundabout capacities for both 50 foot and 75 foot ICDs. Exhibit 1 below illustrates the simulated capacity of both 50 foot and 75 foot mini roundabouts compared to a standard single lane roundabout as reported in NCHRP Report 572 based on entering and circulating volume. Exhibit 1 Comparison of FHWA Mini Roundabout Capacity Models to Single Lane Roundabout NCHRP 572 Capacity Equation 2 Institute of Transportation Engineers Journal. Mini roundabouts for the United States and Traffic Capacity Models. November Kittelson & Associates, Inc. Reston, Virginia

6 Central Region Traffic Engineering On Call (Task Order ) Project #: January 7, 2013 Page 6 As shown in Exhibit 1, the FHWA mini roundabout models predict a percent lower capacity than a traditional single lane roundabout. Recent analysis of the Gilbert s Corner roundabout (US Route 50/US Route 15) found that the default Highway Capacity Manual (HCM) capacity model was underestimating capacity, and was subsequently recalibrated. However, as noted in that report 3, the calibration is specific to Gilberts Corner due to unique conditions which include but are not limited to: Turning movement patterns (over 90 percent of all movements through movements) Roundabout geometry (190 foot ICD, horizontal and vertical alignment/features, fastest path speeds, etc.) Driver population Available sight distance While the driver population is similar in this case, virtually all other contextual conditions at Gilberts Corner are markedly different from those at the /Pleasant Valley Road intersection. As such, application of the Gilberts Corner capacity model to the /Pleasant Valley Road intersection is inappropriate. OPERATIONAL RESULTS Different capacity models were initially considered to evaluate single lane and mini roundabout configurations at the /Pleasant Valley Road intersection: FHWA 50 foot & 75 foot ICD Mini Roundabout Models SIDRA Standard (both single lane and mini) HCM 2010 Model (single lane) The SIDRA Standard model is sensitive to geometric design parameters such as ICD, but only the FHWA and HCM models are based on empirical data collected at roundabout sites in the United States. Therefore, the FHWA and HCM 2010 Models were selected to evaluate operational performance. 3 Kittelson & Associates, Inc. Gilberts Corner Roundabout. June Kittelson & Associates, Inc. Reston, Virginia

7 Central Region Traffic Engineering On Call (Task Order ) Project #: January 7, 2013 Page 7 Several scenarios were evaluated using the FHWA 75 foot ICD capacity model with recent turning movement counts the /Pleasant Valley Road intersection. The 75 foot ICD capacity model was selected as the more appropriate of the two FHWA models given the desired geometrics for the /Pleasant Valley Road intersection. These scenarios are: 2012 Existing Traffic Volumes Weekday AM & PM Peak Hours 2020 Forecast Traffic Volumes Weekday AM & PM Peak Hours A summary of turning movement volumes and total entering volumes is provided in Figure 2. A northbound right turn bypass lane was also modeled given the high turning movement demand for this movement (218 vehicles per hour during 2020 weekday a.m. peak hour conditions). The FHWA capacity model does not directly consider the effect of right turn bypasses on capacity; as such, the benefit was approximated from the HCM 2010 Model for roundabouts. Table 2 summarizes the operational results. Table 2 /Pleasant Valley Road Capacity Model Comparison Scenario Total Entering Volume Critical Approach Critical V/C Ratio (no NBRT Bypass) Critical V/C Ratio (with NBRT Bypass) FHWA Mini Roundabout Model 75 foot ICD 2012 Weekday AM 1,552 NB Weekday PM 1,552 SB Weekday AM 1,818 NB Weekday PM 1,818 SB HCM 2010 Model Single Lane Roundabout 2012 Weekday AM 1,552 NB/EB Weekday PM 1,552 SB Weekday AM 1,818 NB/EB Weekday PM 1,818 SB V/C Volume to capacity ratio NB Northbound; SB Southbound; EB Eastbound The FHWA model indicates that a mini roundabout would operate over capacity under existing 2012 traffic volumes unless a northbound right turn bypass was provided. With a bypass lane, a sensitivity analysis (assuming a compound annual growth rate of two percent) shows a 75 foot ICD miniroundabout would reach capacity by the year 2016 under weekday a.m. peak hour conditions and year 2019 under weekday p.m. peak hour conditions. A northbound right turn bypass lane affects only weekday a.m. peak hour operations because the northbound approach is critical only during that time period. Kittelson & Associates, Inc. Reston, Virginia

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9 Central Region Traffic Engineering On Call (Task Order ) Project #: January 7, 2013 Page 9 The HCM 2010 Model predicts that the critical approaches of a single lane roundabout would operate at a v/c ratio of 0.82 or better under existing 2012 traffic conditions, but by year 2017 would operate over capacity during the weekday a.m. peak hour unless a right turn bypass were constructed. With a northbound right turn bypass lane, a single lane roundabout is forecast to operate at LOC and v/c ratio of 0.88 or better under year 2020 conditions. Based on this analysis (and assumed provision of a northbound right turn bypass lane), a miniroundabout would initially operate below capacity (v/c of 0.76 or better) under existing 2012 traffic conditions and offer slightly less overall capacity (six percent) compared to a single lane roundabout. As traffic volumes grow, the mini roundabout would reach capacity (year 2016) and by year 2020 would operate over capacity (v/c of 1.64). For this location, a mini roundabout is estimated to provide 46 percent less capacity than a single lane roundabout. Attachment A contains the FHWA 75 foot ICD and HCM 2010 capacity model operational worksheets. GEOMETRIC DESIGN Geometric roundabout design requires balancing competing design objectives. Roundabouts operate most safely when their geometry forces traffic to enter and circulate at slow speeds. Poor roundabout geometry that fails to control speeds, accommodate the design vehicle, or provide adequate channelization and deflection has been found to negatively impact roundabout safety by affecting driver behavior through the roundabout. Thus, designing a roundabout is a process of determining the optimal balance between safety provisions, operational performance, and accommodation of the design vehicle. Basic geometric design parameters directly affect operations and safety at roundabouts, regardless the size. In general: As the circle gets smaller, the distance between entries/exits gets smaller. This has the effect of reducing capacity. The size of the circle and the design vehicle will dictate whether the central island can be raised/landscaped or needs to be fully traversable. o A raised island that supports landscaping is more conspicuous to drivers o A larger ICD enhances speed control through increased deflection The desire/need to avoid existing physical obstructions or utilities will affect approach alignments, and shifting the center of the roundabout from the center of the intersection increases the difficulty of keeping the ICD small to achieve appropriate speed control and deflection. As shown previously, different ICDs produce different capacity results, with a mini roundabout reaching capacity well before a single lane roundabout and providing 46 percent less capacity compared to a single lane roundabout by the year Given the rural context of the Braddock Road/Pleasant Valley Road intersection, a raised island is an important design feature to ensure the Kittelson & Associates, Inc. Reston, Virginia

10 Central Region Traffic Engineering On Call (Task Order ) Project #: January 7, 2013 Page 10 roundabout is conspicuous to drivers. In addition, a larger ICD will enhance speed control and deflection. Keeping the center of the roundabout near the center of the current intersection and reducing the need to shift approach alignments will minimize impacts in the constrained environment of the intersection, and help keep the overall size of the roundabout itself smaller. Based on this assessment, a roundabout with an ICD of approximately feet and a raised central island that is centered near the existing centerline of the intersection is expected to result in the most desirable safety and operational performance while minimizing impacts to adjacent properties. OTHER CONSIDERATIONS The /Pleasant Valley Road intersection has several constraints, including: Parkland (4f/6f property designations) in the northeast and northwest quadrants of the intersection Significant wetland areas in multiple quadrants Limited right of way availability o All prescriptive right of way with the exception of the east side of Pleasant Valley Road south of Large multi circuit utility poles (estimated $60 80k per pole for relocation) Given these constraints, minimizing the physical footprint is a key consideration in determining the appropriate intersection control. At the same time, maximizing the functional life of the improvement is another key consideration. Thinking ahead to how the selected intersection control might be revised, expanded, or replaced when it reaches the end of its functional life is yet another factor to consider. As stated previously, a mini roundabout is likely to reach capacity within a few years. Given the constrained surroundings (park, 4f/6f lands, wetlands, etc.), providing a temporary construction bypass route with a mini roundabout in place would be difficult. While a larger single lane roundabout or a traffic signal could be modified or expanded in sections and still operate under traffic, expanding a mini roundabout in its place would likely require full closure. FINDINGS AND RECOMMENDATIONS Our assessment of a mini roundabout intersection control at the /Pleasant Valley Road intersection resulted in the following findings: Kittelson & Associates, Inc. Reston, Virginia

11 Central Region Traffic Engineering On Call (Task Order ) Project #: January 7, 2013 Page 11 Operations A northbound right turn bypass lane will extend the expected functional life of a roundabout at the /Pleasant Valley Road intersection regardless of the ICD. A mini roundabout is forecast to operate at a v/c of 1.64 under year 2020 traffic conditions with a right turn bypass lane. A single lane roundabout lane is forecast to operate at a v/c of 0.88 or better under year 2020 traffic conditions with a right turn bypass lane. A 75 foot ICD mini roundabout would provide 46 percent less capacity compared to a singlelane roundabout under year 2020 traffic conditions. Context Existing traffic volumes at the /Pleasant Valley Road intersection are substantially higher (between 300 and 1,000 peak hour TEV) and have a higher percentage of left turn movements than traffic volumes present at the two mini roundabouts in Maryland that are considered in this memorandum. The rural context and 35 mph posted approach speeds of the /Pleasant Valley Road intersection suggests the need for a raised central island that includes landscaping to ensure the roundabout is conspicuous to drivers. Geometric Design As the ICD increases, deflection and speed control are enhanced, thus improving safety and operational performance. Keeping the center of the roundabout near the center of the current intersection and reducing the need to shift approach alignments will minimize impacts in the constrained environment of the intersection, and help keep the overall size of the roundabout itself smaller. This must be balanced against the desire/need to avoid existing physical obstructions, utilities, or environmental/right of way impacts. Other Considerations A mini roundabout at the /Pleasant Valley Road intersection would be more difficult (and costly) to modify/expand under traffic compared to a single lane roundabout. Based on these findings, we recommend the following treatments at the /Pleasant Valley Road intersection be incorporated as part of the design of the roundabout alternative at this location: Provide a raised central island with landscaping to increase conspicuity and improve deflection and speed control. Kittelson & Associates, Inc. Reston, Virginia

12 Central Region Traffic Engineering On Call (Task Order ) Project #: January 7, 2013 Page 12 Select a minimum ICD (approximately 95 to 120 foot range) that allows for a raised central island, accommodates the WB 40 design vehicle, provides sufficient spacing between entries and exits for capacity, and minimizes impacts to the constrained surroundings. Provide a northbound right turn bypass to maximize the functional life of the roundabout. NEXT STEPS We trust this memorandum provides additional insight into the feasibility and operational ramifications of a mini roundabout at the /Pleasant Valley Road intersection, and will assist VDOT staff in determining whether or not to carry the mini roundabout alternative forward for further evaluation. Please contact us at (703) with any questions. Kittelson & Associates, Inc. Reston, Virginia

13 Attachment A Roundabout Operational Worksheets

14 Raw Count Unserved Deman Existing 2012 VOLUMES AM Peak Hour Assumed Growth Volumes 2014 Volumes 2015 Volumes - additional demand not served in peak - added to turn movement counts for EB approach Cars 435 1% 1% 1% 282 Cars 444 1% 1% 1% 287 Cars 453 1% 1% 1% 293 Cars 462 1% 1% 1% 299 Bicycles SB Bicycles SB Bicycles SB Bicycles SB 0 City: 0 City: 0 City: 0 City: Trucks State: Trucks State: Trucks State: Trucks State: Kittelson Kittelson Kittelson Kittelson EB Pleasant Valley Rd & Associates, Inc EB Pleasant Valley Rd & Associates, Inc EB Pleasant Valley Rd & Associates, Inc EB Pleasant Valley Rd & Associates, Inc % % 1% % 1% % 1% % 7:15-8:15 a.m. 7:15-8:15 a.m. 7:15-8:15 a.m. 7:15-8:15 a.m % % 1% % 1% % 1% % % % 1% % 1% % 1% % WB WB WB WB NB NB NB NB % 1% 1% % 1% 1% % 1% 1% % 1% 1% Notes 0 Notes 0 Notes 0 Notes 0 % LT 27% Approach V C V C (PCE) C 50 C 75 Volume v/c C 50 v/c C 75 v/c C 75 w/ RT bypass Approach V C V C (PCE) C 50 C 75 Volume v/c C 50 v/c C 75 v/c C 75 w/ RT bypass Approach V C V C (PCE) C 50 C 75 Volume v/c C 50 v/c C 75 v/c C 75 w/ RT bypass Approach V C V C (PCE) C 50 C 75 Volume v/c C 50 v/c C 75 NB NB NB NB EB EB EB EB SB SB SB SB WB WB WB WB v/c C 75 w/ RT bypass Volumes 2017 Volumes 2018 Volumes 2019 Volumes Cars 471 1% 1% 1% 305 Cars 480 1% 1% 1% 311 Cars 490 1% 1% 1% 317 Cars 500 1% 1% 1% 324 Bicycles 0 SB City: Bicycles 0 SB City: Bicycles 0 SB City: Bicycles 0 SB City: Trucks State: Trucks State: Trucks State: Trucks State: 219 EB Pleasant Valley Rd & Associates, Inc EB Pleasant Valley Rd & Associates, Inc EB Pleasant Valley Rd & Associates, Inc EB Pleasant Valley Rd & Associates, Inc :15-8:15 a.m. 7:15-8:15 a.m. 7:15-8:15 a.m. 7:15-8:15 a.m. 1% % 1% % 1% % 1% % 1% % 1% % 1% % 1% % 1% % 1% % 1% % 1% % WB WB WB WB NB NB NB NB % 1% 1% % 1% 1% % 1% 1% % 1% 1% Notes 0 Notes 0 Notes 0 Notes 0 Approach V C V C (PCE) C 50 C 75 Volume v/c C 50 v/c C 75 v/c C 75 w/ RT bypass Approach V C V C (PCE) C 50 C 75 Volume v/c C 50 v/c C 75 v/c C 75 w/ RT bypass Approach V C V C (PCE) C 50 C 75 Volume v/c C 50 v/c C 75 v/c C 75 w/ RT bypass Approach V C V C (PCE) C 50 C 75 Volume v/c C 50 v/c C 75 NB NB NB NB EB EB EB EB SB SB SB SB WB WB WB WB v/c C 75 w/ RT bypass Volumes Cars 510 1% 1% 1% 330 Bicycles SB 0 City: Trucks State: Kittelson & Associates, Inc. 237 EB Pleasant Valley Rd :15-8:15 a.m. 1% % 1% % 1% % WB NB % 1% 1% Notes 0 Approach V C V C (PCE) C 50 C 75 Volume v/c C 50 v/c C 75 NB EB SB WB v/c C 75 w/ RT bypass

15 Unserved Deman Existing 2012 VOLUMES AM Peak Hour Assumed Growth Volumes 2014 Volumes 2015 Volumes - additional demand not served in peak - added to turn movement counts for WB approach Raw Count Cars 381 1% 1% 1% 195 Cars 389 1% 1% 1% 199 Cars 396 1% 1% 1% 203 Cars 404 1% 1% 1% 207 Bicycles 0 SB City: Bicycles 0 SB City: Bicycles 0 SB City: Bicycles 0 SB City: Trucks State: Trucks State: Trucks State: Trucks State: 558 EB Kittelson & Associates, Inc. Pleasant Valley Rd Pleasant Valley Rd Pleasant Valley Rd Pleasant Valley Rd EB Kittelson & Associates, Inc EB Kittelson & Associates, Inc EB Kittelson & Associates, Inc :00-6:00 p.m. 7:15-8:15 a.m. 7:15-8:15 a.m. 7:15-8:15 a.m. 1% 53 1% 50 1% 54 1% 1% 55 1% 1% 56 1% 1% % % % 1% % 1% % 1% % % % 1% % 1% % WB WB WB WB NB NB NB NB % 1% 1% % 1% 1% % 1% 1% % 1% 1% Notes Notes Notes Notes % LT 26% Approach V C V C (PCE) C 50 C 75 Volume v/c C 50 v/c C 75 v/c C 75 w/ RT bypass Approach V C V C (PCE) C 50 C 75 Volume v/c C 50 v/c C 75 v/c C 75 w/ RT bypass Approach V C V C (PCE) C 50 C 75 Volume v/c C 50 v/c C 75 v/c C 75 w/ RT bypass Approach V C V C (PCE) C 50 C 75 Volume v/c C 50 v/c C 75 v/c C 75 w/ RT bypass NB NB NB NB EB EB EB EB SB SB SB SB WB WB WB WB Volumes 2017 Volumes 2018 Volumes 2019 Volumes Cars 412 1% 1% 1% 211 Cars 421 1% 1% 1% 215 Cars 429 1% 1% 1% 220 Cars 438 1% 1% 1% 224 Bicycles 0 SB City: Bicycles 0 SB City: Bicycles 0 SB City: Bicycles 0 SB City: Trucks State: Trucks State: Trucks State: Trucks State: 604 EB Kittelson & Associates, Inc. Pleasant Valley Rd Pleasant Valley Rd Pleasant Valley Rd Pleasant Valley Rd EB Kittelson & Associates, Inc EB Kittelson & Associates, Inc EB Kittelson & Associates, Inc :15-8:15 a.m. 7:15-8:15 a.m. 7:15-8:15 a.m. 7:15-8:15 a.m. 1% 58 1% 1% 59 1% 1% 60 1% 1% 61 1% 1% % 1% % 1% % 1% % 1% % 1% % 1% % 1% % WB WB WB WB NB NB NB NB % 1% 1% % 1% 1% % 1% 1% % 1% 1% Notes Notes Notes Notes Approach V C V C (PCE) C 50 C 75 Volume v/c C 50 v/c C 75 v/c C 75 w/ RT bypass Approach V C V C (PCE) C 50 C 75 Volume v/c C 50 v/c C 75 v/c C 75 w/ RT bypass Approach V C V C (PCE) C 50 C 75 Volume v/c C 50 v/c C 75 v/c C 75 w/ RT bypass Approach V C V C (PCE) C 50 C 75 Volume v/c C 50 v/c C 75 v/c C 75 w/ RT bypass NB NB NB NB EB EB EB EB SB SB SB SB WB WB WB WB Volumes Cars 446 1% 1% 1% 229 Bicycles 0 SB City: Trucks State: 654 EB Kittelson & Associates, Inc. Pleasant Valley Rd :15-8:15 a.m. 1% % 1% % 1% % WB NB % 1% 1% Notes 0 Approach V C V C (PCE) C 50 C 75 Volume v/c C 50 v/c C 75 NB EB SB WB v/c C 75 w/ RT bypass

16 MOVEMENT SUMMARY and Pleasant Valley Roundabout Site: Braddock Rd/Pleasant Valley Rd Movement Performance - Vehicles Mov ID Turn Demand Deg. Average Level of 95% Back of Queue Prop. Effective Average Flow HV Satn Delay Service Vehicles Distance Queued Stop Rate Speed veh/h % v/c sec veh m per veh km/h South: Pleasant Valley Rd (NB) 1 L LOS D T LOS D R LOS D Approach LOS D East: (WB) 4 L LOS A T LOS A R LOS A Approach LOS A North: Pleasant Valley Rd (SB) 7 L LOS B T LOS B R LOS B Approach LOS B West: (EB) 10 L LOS C T LOS C R LOS C Approach LOS C All Vehicles LOS C Level of Service (LOS) Method: Delay & v/c (HCM 2010). Roundabout LOS Method: Same as Sign Control. Vehicle movement LOS values are based on average delay and v/c ratio (degree of saturation) per movement LOS F will result if v/c > 1 irrespective of movement delay value (does not apply for approaches and intersection). Intersection and Approach LOS values are based on average delay for all movements (v/c not used as specified in HCM 2010). Roundabout Capacity Model: US HCM HCM Delay Model used. Geometric Delay not included. Processed: Wednesday, December 26, :51:19 PM Copyright Akcelik and Associates Pty Ltd SIDRA INTERSECTION Project: K:\H_Reston\projfile\ Central Region VDOT On-Call\Task Orders\Task 14 (12-057) - Braddock Rd & Pleasant Valley\roundabout\SIDRA\2012 Existing Conditions\HCM 2010 Model\full roundabout AM Peak Hour.sip , KITTELSON AND ASSOCIATES INC, FLOATING

17 MOVEMENT SUMMARY Site: New Site - 1 and Pleasant Valley Roundabout Movement Performance - Vehicles Mov ID Turn Demand Deg. Average Level of 95% Back of Queue Prop. Effective Average Flow HV Satn Delay Service Vehicles Distance Queued Stop Rate Speed veh/h % v/c sec veh m per veh km/h South: Pleasant Valley (NB) 1 L LOS B T LOS B R LOS B Approach LOS B East: (WB) 4 L LOS B T LOS B R LOS B Approach LOS B North: Pleasant Valley (SB) 7 L LOS C T LOS C R LOS C Approach LOS C West: (EB) 10 L LOS B T LOS B R LOS B Approach LOS B All Vehicles LOS B Level of Service (LOS) Method: Delay & v/c (HCM 2010). Roundabout LOS Method: Same as Sign Control. Vehicle movement LOS values are based on average delay and v/c ratio (degree of saturation) per movement LOS F will result if v/c > 1 irrespective of movement delay value (does not apply for approaches and intersection). Intersection and Approach LOS values are based on average delay for all movements (v/c not used as specified in HCM 2010). Roundabout Capacity Model: US HCM HCM Delay Model used. Geometric Delay not included. Processed: Wednesday, December 26, :03:01 PM Copyright Akcelik and Associates Pty Ltd SIDRA INTERSECTION Project: K:\H_Reston\projfile\ Central Region VDOT On-Call\Task Orders\Task 14 (12-057) - Braddock Rd & Pleasant Valley\roundabout\SIDRA\2012 Existing Conditions\HCM 2010 Model\full roundabout PM Peak Hour.sip , KITTELSON AND ASSOCIATES INC, FLOATING

18 MOVEMENT SUMMARY and Pleasant Valley Roundabout Site: Braddock Rd/Pleasant Valley Rd Movement Performance - Vehicles Mov ID Turn Demand Deg. Average Level of 95% Back of Queue Prop. Effective Average Flow HV Satn Delay Service Vehicles Distance Queued Stop Rate Speed veh/h % v/c sec veh m per veh km/h South: Pleasant Valley Rd (NB) 1 L LOS B T LOS B R LOS B Approach LOS B East: (WB) 4 L LOS A T LOS A R LOS A Approach LOS A North: Pleasant Valley Rd (SB) 7 L LOS B T LOS B R LOS B Approach LOS B West: (EB) 10 L LOS C T LOS C R LOS C Approach LOS C All Vehicles LOS B Level of Service (LOS) Method: Delay & v/c (HCM 2010). Roundabout LOS Method: Same as Sign Control. Vehicle movement LOS values are based on average delay and v/c ratio (degree of saturation) per movement LOS F will result if v/c > 1 irrespective of movement delay value (does not apply for approaches and intersection). Intersection and Approach LOS values are based on average delay for all movements (v/c not used as specified in HCM 2010). Roundabout Capacity Model: US HCM HCM Delay Model used. Geometric Delay not included. Processed: Wednesday, December 26, :58:07 PM Copyright Akcelik and Associates Pty Ltd SIDRA INTERSECTION Project: K:\H_Reston\projfile\ Central Region VDOT On-Call\Task Orders\Task 14 (12-057) - Braddock Rd & Pleasant Valley\roundabout\SIDRA\2012 Existing Conditions\HCM 2010 Model\full roundabout w NB RT lane AM Peak Hour.sip , KITTELSON AND ASSOCIATES INC, FLOATING

19 MOVEMENT SUMMARY Site: New Site - 1 and Pleasant Valley Roundabout Movement Performance - Vehicles Mov ID Turn Demand Deg. Average Level of 95% Back of Queue Prop. Effective Average Flow HV Satn Delay Service Vehicles Distance Queued Stop Rate Speed veh/h % v/c sec veh m per veh km/h South: Pleasant Valley (NB) 1 L LOS B T LOS B R LOS A Approach LOS A East: (WB) 4 L LOS B T LOS B R LOS B Approach LOS B North: Pleasant Valley (SB) 7 L LOS C T LOS C R LOS C Approach LOS C West: (EB) 10 L LOS B T LOS B R LOS B Approach LOS B All Vehicles LOS B Level of Service (LOS) Method: Delay & v/c (HCM 2010). Roundabout LOS Method: Same as Sign Control. Vehicle movement LOS values are based on average delay and v/c ratio (degree of saturation) per movement LOS F will result if v/c > 1 irrespective of movement delay value (does not apply for approaches and intersection). Intersection and Approach LOS values are based on average delay for all movements (v/c not used as specified in HCM 2010). Roundabout Capacity Model: US HCM HCM Delay Model used. Geometric Delay not included. Processed: Wednesday, December 26, :08:01 PM Copyright Akcelik and Associates Pty Ltd SIDRA INTERSECTION Project: K:\H_Reston\projfile\ Central Region VDOT On-Call\Task Orders\Task 14 (12-057) - Braddock Rd & Pleasant Valley\roundabout\SIDRA\2012 Existing Conditions\HCM 2010 Model\full roundabout w NB RT lane PM Peak Hour.sip , KITTELSON AND ASSOCIATES INC, FLOATING

20 MOVEMENT SUMMARY and Pleasant Valley Roundabout Site: Braddock Rd/Pleasant Valley Rd Movement Performance - Vehicles Mov ID Turn Demand Deg. Average Level of 95% Back of Queue Prop. Effective Average Flow HV Satn Delay Service Vehicles Distance Queued Stop Rate Speed veh/h % v/c sec veh m per veh km/h South: Pleasant Valley Rd (NB) 1 L LOS F T LOS F R LOS F Approach LOS F East: (WB) 4 L LOS A T LOS A R LOS A Approach LOS A North: Pleasant Valley Rd (SB) 7 L LOS B T LOS B R LOS B Approach LOS B West: (EB) 10 L LOS E T LOS E R LOS E Approach LOS E All Vehicles LOS E Level of Service (LOS) Method: Delay & v/c (HCM 2010). Roundabout LOS Method: Same as Sign Control. Vehicle movement LOS values are based on average delay and v/c ratio (degree of saturation) per movement LOS F will result if v/c > 1 irrespective of movement delay value (does not apply for approaches and intersection). Intersection and Approach LOS values are based on average delay for all movements (v/c not used as specified in HCM 2010). Roundabout Capacity Model: US HCM HCM Delay Model used. Geometric Delay not included. Processed: Thursday, December 27, :00:04 AM Copyright Akcelik and Associates Pty Ltd SIDRA INTERSECTION Project: K:\H_Reston\projfile\ Central Region VDOT On-Call\Task Orders\Task 14 (12-057) - Braddock Rd & Pleasant Valley\roundabout\SIDRA\2020 Conditions\HCM 2010 Model\full roundabout - AM Peak Hour.sip , KITTELSON AND ASSOCIATES INC, FLOATING

21 MOVEMENT SUMMARY Site: New Site - 1 and Pleasant Valley Roundabout Movement Performance - Vehicles Mov ID Turn Demand Deg. Average Level of 95% Back of Queue Prop. Effective Average Flow HV Satn Delay Service Vehicles Distance Queued Stop Rate Speed veh/h % v/c sec veh m per veh km/h South: Pleasant Valley (NB) 1 L LOS B T LOS B R LOS B Approach LOS B East: (WB) 4 L LOS C T LOS C R LOS C Approach LOS C North: Pleasant Valley (SB) 7 L LOS E T LOS E R LOS E Approach LOS E West: (EB) 10 L LOS C T LOS C R LOS C Approach LOS C All Vehicles LOS C Level of Service (LOS) Method: Delay & v/c (HCM 2010). Roundabout LOS Method: Same as Sign Control. Vehicle movement LOS values are based on average delay and v/c ratio (degree of saturation) per movement LOS F will result if v/c > 1 irrespective of movement delay value (does not apply for approaches and intersection). Intersection and Approach LOS values are based on average delay for all movements (v/c not used as specified in HCM 2010). Roundabout Capacity Model: US HCM HCM Delay Model used. Geometric Delay not included. Processed: Thursday, December 27, :04:41 AM Copyright Akcelik and Associates Pty Ltd SIDRA INTERSECTION Project: K:\H_Reston\projfile\ Central Region VDOT On-Call\Task Orders\Task 14 (12-057) - Braddock Rd & Pleasant Valley\roundabout\SIDRA\2020 Conditions\HCM 2010 Model\full roundabout - PM Peak Hour.sip , KITTELSON AND ASSOCIATES INC, FLOATING

22 MOVEMENT SUMMARY and Pleasant Valley Roundabout Site: Braddock Rd/Pleasant Valley Rd Movement Performance - Vehicles Mov ID Turn Demand Deg. Average Level of 95% Back of Queue Prop. Effective Average Flow HV Satn Delay Service Vehicles Distance Queued Stop Rate Speed veh/h % v/c sec veh m per veh km/h South: Pleasant Valley Rd (NB) 1 L LOS C T LOS C R LOS C Approach LOS C East: (WB) 4 L LOS A T LOS A R LOS A Approach LOS A North: Pleasant Valley Rd (SB) 7 L LOS B T LOS B R LOS B Approach LOS B West: (EB) 10 L LOS E T LOS E R LOS E Approach LOS E All Vehicles LOS C Level of Service (LOS) Method: Delay & v/c (HCM 2010). Roundabout LOS Method: Same as Sign Control. Vehicle movement LOS values are based on average delay and v/c ratio (degree of saturation) per movement LOS F will result if v/c > 1 irrespective of movement delay value (does not apply for approaches and intersection). Intersection and Approach LOS values are based on average delay for all movements (v/c not used as specified in HCM 2010). Roundabout Capacity Model: US HCM HCM Delay Model used. Geometric Delay not included. Processed: Thursday, December 27, :02:53 AM Copyright Akcelik and Associates Pty Ltd SIDRA INTERSECTION Project: K:\H_Reston\projfile\ Central Region VDOT On-Call\Task Orders\Task 14 (12-057) - Braddock Rd & Pleasant Valley\roundabout\SIDRA\2020 Conditions\HCM 2010 Model\full roundabout w NB RT lane - AM Peak Hour.sip , KITTELSON AND ASSOCIATES INC, FLOATING

23 MOVEMENT SUMMARY and Pleasant Valley Roundabout Site: Braddock Rd/Pleasant Valley Rd Movement Performance - Vehicles Mov ID Turn Demand Deg. Average Level of 95% Back of Queue Prop. Effective Average Flow HV Satn Delay Service Vehicles Distance Queued Stop Rate Speed veh/h % v/c sec veh m per veh km/h South: Pleasant Valley (NB) 1 L LOS B T LOS B R LOS A Approach LOS B East: (WB) 4 L LOS C T LOS C R LOS C Approach LOS C North: Pleasant Valley (SB) 7 L LOS E T LOS E R LOS E Approach LOS E West: (EB) 10 L LOS C T LOS C R LOS C Approach LOS C All Vehicles LOS C Level of Service (LOS) Method: Delay & v/c (HCM 2010). Roundabout LOS Method: Same as Sign Control. Vehicle movement LOS values are based on average delay and v/c ratio (degree of saturation) per movement LOS F will result if v/c > 1 irrespective of movement delay value (does not apply for approaches and intersection). Intersection and Approach LOS values are based on average delay for all movements (v/c not used as specified in HCM 2010). Roundabout Capacity Model: US HCM HCM Delay Model used. Geometric Delay not included. Processed: Thursday, December 27, :07:24 AM Copyright Akcelik and Associates Pty Ltd SIDRA INTERSECTION Project: K:\H_Reston\projfile\ Central Region VDOT On-Call\Task Orders\Task 14 (12-057) - Braddock Rd & Pleasant Valley\roundabout\SIDRA\2020 Conditions\HCM 2010 Model\full roundabout w NB RT lane - PM Peak Hour.sip , KITTELSON AND ASSOCIATES INC, FLOATING