Traffic Analysis and Design Report NW Bethany Boulevard NW Bronson Road to NW West Union Road Washington County, Oregon May 2011
Table of Contents Table of Contents Section 1 Executive Summary... 2 Section 2 Introduction... 8 Section 3 Existing Conditions... 11 Section 4 Future 2035 Traffic Conditions... 29 Section 5 Conclusions and Recommendations... 58 Section 6 References... 63 Kittelson & Associates, Inc. iii
List of Figures List of Figures Figure 1 Site Vicinity Map... 9 Figure 2 Existing Lane Configurations and Traffic Control Devices... 13 Figure 3 Existing Traffic Conditions, Weekday AM Peak Hour... 18 Figure 4 Existing Traffic Conditions, Weekday PM Peak Hour... 19 Figure 5 2035 Future No-Build Traffic Conditions, Weekday AM Peak Hour... 32 Figure 6 2035 Future No-Build Traffic Conditions, Weekday PM Peak Hour... 33 Figure 7 Alternative 1 (5-Lane Section) Assumed Lane Configurations and Traffic Control Devices... 36 Figure 8 Alternative 1 (5-Lane Section) 2035 Forecast Traffic Conditions, Weekday AM Peak Hour... 37 Figure 9 Alternative 1 (5-Lane Section) 2035 Forecast Traffic Conditions, Weekday PM Peak Hour... 38 Figure 10 Alternative 2 (4-Lane Section) Assumed Lane Configurations and Traffic Control Devices... 41 Figure 11 Alternative 2 (4-Lane Section) 2035 Forecast Traffic Conditions, Weekday AM Peak Hour... 42 Figure 12 Alternative 2 (4-Lane Section) 2035 Forecast Traffic Conditions, Weekday PM Peak Hour... 43 Figure 13 Alternative 3 (5/3/5-Lane Section) Assumed Lane Configurations and Traffic Control Devices 45 Figure 14 Alternative 3 (5/3/5-Lane Section) 2035 Forecast Traffic Conditions, Weekday AM Peak Hour 46 Figure 15 Alternative 3 (5/3/5-Lane Section) 2035 Forecast Traffic Conditions, Weekday PM Peak Hour 47 Figure 16 Alternative 4 (3-Lane Section) Assumed Lane Configurations and Traffic Control Devices... 49 Figure 17 Alternative 4 (3-Lane Section) 2035 Forecast Traffic Conditions, Weekday AM Peak Hour... 50 Figure 18 Alternative 4 (3-Lane Section) 2035 Forecast Traffic Conditions, Weekday PM Peak Hour... 51 Kittelson & Associates, Inc. iv
List of Tables List of Tables Table 1 Existing Transportation Roadway Facilities and Roadway Designations... 12 Table 2 NW Bethany Boulevard Traffic Volumes, Speeds and Heavy Vehicle Percentages... 15 Table 3 Study Intersection Crash History (2004-2008)... 22 Table 4 Study Intersection Crash Rate (2004-2008)... 22 Table 5 Signal Warrant Analysis Results... 25 Table 6 Estimated Design Life of 3-Lane Alternative... 52 Table 7 Table 8 Summary of Delays and Levels of Service at Signalized Intersections Forecast 2035 Weekday P.M. Peak Hour... 53 Summary of Delays and Levels of Service at Unsignalized Intersections Forecast 2035 Weekday P.M. Peak Hour... 54 Table 9 2035 Queue Analysis Results and Recommended Storage Lengths... 56 Kittelson & Associates, Inc. v
Appendices Appendices Appendix A Appendix B Appendix C Appendix D Appendix E Appendix F Appendix G Appendix H Appendix I Appendix J Appendix K Appendix L Appendix M Appendix N Appendix O Appendix P Appendix Q Appendix R Appendix S Tube Count Data - Volumes Tube Count Data - Speeds Tube Count Data Vehicle Classifications Intersection Traffic Count Data Description of Level-of-Service Methods and Criteria Existing Conditions Level-of-Service Worksheets Crash Data Signal Warrant Analysis Worksheets ITE Pedestrian Crossing Methodology Calculation VISUM Model Land Use Data VISUM Model Output 2035 Travel Forecasting Worksheets 2035 No-Build Alternative Level-of-Service Worksheets Conceptual Design Drawings of Alternatives 2035 Alternative 1 Level-of-Service Worksheets 2035 Alternative 2 Level-of-Service Worksheets 2035 Alternative 3 Level-of-Service Worksheets 2035 Alternative 4 Traffic Level-of-Service Worksheets 2035 Alternative 2 Queuing Analysis Worksheets Kittelson & Associates, Inc. vi
Section 1 Executive Summary
Executive Summary Executive Summary Kittelson & Associates, Inc. (KAI) has conducted a transportation study of Bethany Boulevard between NW Bronson Road and NW West Union Road to provide background information for the NW Bethany Boulevard Corridor Improvement Project in Washington County, Oregon. This study includes an analysis of the existing 2010 and future year 2035 traffic conditions to identify existing issues or deficiencies and to develop recommended improvement concepts that meet the future transportation needs within the study corridor. The methodology and results of the transportation study are presented herein. Traffic flow within the Bethany Boulevard study area is directly affected by issues at the adjacent Highway 26 interchange, and therefore the traffic study includes the ramp terminal intersections as well as the intersections within the project area. Washington County has identified funding opportunities for interchange improvements and anticipates that the interchange improvements can be completed in conjunction with the current project. As such, those improvements have been assumed in the long term analysis of the Bethany Boulevard corridor. In addition to the interchange area issues, the traffic study identifies the need for new traffic signals at Bronson Road and Oak Hills Drive as well as capacity deficiencies at the other intersections between Bronson Road and West Union Road. The details of these deficiencies are provided herein. This analysis resulted in the following key findings and recommendations. Existing Conditions Existing Traffic Volumes Existing 2010 traffic count data on Bethany Boulevard, based on 7 day automated tube count measurements at a location just south of Oak Hills Drive, are summarized as follows: Average Daily Traffic Volumes AM Peak Hour Volumes PM Peak Hour Volumes 19,950 veh/day 1,350 veh/hr 1,500 veh/hr Truck Percentage (%) Daily 4.5% Median Speed 35 mph 85 th Percentile Speeds 40 mph Existing Levels of Service The unsignalized intersections on Bethany Boulevard at Telshire Drive, Oak Hills Drive, and Bronson Road do not meet the County s performance standards. These three intersections all operate at level of service F during both the weekday a.m. and p.m. peak hours, as motorists on the minor street approaches experience unacceptably high delays. The signalized intersection at the U.S. 26 Westbound Ramp Terminal and Bethany Boulevard does not meet ODOT s or the County s performance standard, with a volume to Kittelson & Associates, Inc. 2
Executive Summary capacity (V/C) ratio greater than 1.0 during the weekday p.m. peak hour. The over capacity condition is principally caused by the westbound right turn movement, which can result in lengthy queues extending along the westbound U.S. 26 frontage road. All other study intersections currently operate acceptably. However, the signalized West Union Road/Bethany Boulevard intersection is nearing the County s performance threshold (currently operating at a V/C ratio of 0.94 during the weekday p.m. peak hour). As a result, this intersection has little spare capacity to accommodate future growth. Queuing Issues During both the morning and evening peak hours, queuing issues occur in the vicinity of the Bronson Road and Highway 26 interchange. During the morning peak hour, southbound queues from the Highway 26 interchange spill back to Bronson Road and interfere with turning movements at the Bronson Road intersection. During the p.m. peak hour, queues in the northbound left turn lane at the Bronson Road intersection extend back to the interchange and impact traffic flow at the Highway 26 ramps. Signal Warrants Signal warrant analyses were conducted at the Bronson Road intersection and the Oak Hills Drive intersection. This analysis found: o The Bronson Road intersection meets the traffic volume criteria of Warrants #1, #2, and #3; and thus installation of a traffic signal is recommended. The signal should be interconnected and coordinated with the two existing signals at the U.S. 26 ramp terminals to minimize the likelihood of queue spillback between these three closelyspaced intersections. Furthermore, the signal should be completed in conjunction with the capacity improvements described in the Future Conditions section of this report. o Although it does not currently meet the traffic volume warrants, the Oak Hills Drive intersection meets the School Crossing criteria (Warrant #5) under existing conditions. Therefore, installation of a traffic signal is recommended at this intersection. This signal should provide pedestrian crosswalk signals and should be completed in conjunction with sidewalk enhancements between Oak Hills Elementary School and the intersection. Safety Analysis Two intersections within the project area are on Washington County s current Safety Priority Index System (SPIS), which ranks the intersections within the county in terms of crash frequency, crash rate, and crash severity. These include Bethany Boulevard/Bronson Road (ranked #188 of 262) and Bethany Boulevard/Telshire Drive (ranked #119 of 262). Signalization of the Bronson Road intersection in combination with capacity improvements at the interchange are expected to improve the overall safety of this intersection. At the Telshire Drive intersection, corridor improvements including adding a left turn lane and upgrading the roadway illumination, vertical alignment, and roadside clear zone are expected to provide safety benefits. Kittelson & Associates, Inc. 3
Executive Summary Intersection Sight Distance The intersection of Ridgetop Lane at Bethany Boulevard currently has inadequate intersection sight distance due to the horizontal curvature along Bethany Boulevard and the existing fences and vegetation along the northeastern corner of the intersection. Given the roadway geometry and right of way constraints in this area, achieving adequate intersection sight distance for left turn movements does not appear to be feasible. Therefore, it is recommended the intersection be restricted to right turn only movements. Left-Turn Lane Warrant Analysis Left turn lanes are warranted at all unsignalized study intersections along the project corridor. Therefore, left turn lanes should be provided at all unsignalized intersections at which left turn movements are allowed. Pedestrian Facilities Sidewalks are not continuously provided along the majority of the east side of Bethany Boulevard throughout the project area. A continuous sidewalk is provided along the west side of Bethany Blvd in the form of a separated asphalt path. Bicycle Facilities There are currently no bicycle lanes or other bicycle facilities on Bethany Boulevard within the project area. However, bike lanes are present along Bethany Boulevard north of West Union Road. Future 2035 Traffic Volumes The table below summarizes the projected 2035 traffic volumes on Bethany Blvd. Time Period at Bronson Road at Ridgetop Lane 2035 Average Daily Traffic Volume 39,000 veh/day 35,500 veh/day 2035 AM Peak Hour Volume 2,800 veh/hr 2,700 veh/hr 2035 PM Peak Hour Volume 3,200 veh/hr 3,100 veh/hr Future 2035 No-Build Conditions Under projected 2035 No Build conditions, every study intersection along the project corridor is expected to reach LOS F by 2035 during the weekday a.m. and/or p.m. peak hours. Therefore, capacity improvements will be needed to address future travel demands. Future 2035 Build Alternatives Analysis This study evaluated four Build alternatives that consider a range of roadway cross sections from three to five lanes for the project corridor. The key findings and recommendations for each of the alternatives are summarized as follows: Kittelson & Associates, Inc. 4
Executive Summary Alternative 1 (Five-Lane Corridor) Providing five lanes across the entire corridor would enable acceptable performance at all study intersections during the forecast 2035 weekday a.m. and p.m. peak hours, provided the following additional intersection improvements are included: o At the West Union Road/Bethany Boulevard intersection, additional eastbound and westbound through lanes and a northbound right turn lane are forecast to be needed by 2035. These lane additions are long term needs that likely will not be necessary within the next 10 15 years or more. The County could defer construction of these additional lanes until they become needed in the future. However, the County should anticipate the additional right of way needs as future projects and developments are considered. o At the signalized Oak Hills Drive intersection, the westbound approach of Oak Hills Drive should be widened to provide width for two outbound lanes (including an exclusive left turn and shared through/right turn lane). o At the signalized Bronson Road intersection, a second eastbound right turn lane is recommended on Bronson Road. o The median lane on Bethany Boulevard should be striped as a two way left turn lane at the unsignalized intersections to enable vehicles from the minor streets to perform twostage left turn movements. Alternative 2 (Four-Lane Corridor) Providing four lanes along the corridor would provide acceptable performance at all study intersections during the forecast 2035 weekday a.m. and p.m. peak hours. In addition to the corridor widening improvement, the same additional intersection improvements at West Union Road, Oak Hills Drive, and Bronson Road, as listed above for Alternative 1, are also recommended for this alternative. Additionally, raised center medians should be constructed to prevent left turn movements from Bethany Boulevard onto NW Emily Lane, NW Audrey Drive, and NW Ridgetop Lane. Alternative 3 (5/3/5-Lane Corridor) Providing a varying width along the corridor (5 to 3 to 5 lanes) results in many of the study intersections operating at LOS F and with V/C ratios greater than 1.0 under projected 2035 traffic conditions. Because this alternative fails to meet the County s performance standards and provides relatively little benefit in terms of reducing the roadway footprint, it is recommended this alternative be eliminated from further consideration. Alternative 4 (Three-Lane Corridor) If a three lane corridor were provided, all of the study intersections from NW West Union Road to NW Avondale Drive are expected to operate at LOS F during the weekday a.m. and/or p.m. peak hours. The signalized intersections at West Union Road and Oak Hills Kittelson & Associates, Inc. 5
Executive Summary Drive would be over capacity, resulting in extensive queue build ups along the corridor during the peak periods. At the unsignalized intersections, drivers at the minor street approaches will experience lengthy delays (estimated at 2 3 minutes or more for most leftturn movements). With the capacity constraints of a three lane corridor, approximately 700 vehicles during the weekday p.m. peak hour and 600 vehicles during the weekday a.m. peak hour are expected to be diverted to other streets and corridors in the area. Many of these corridors are expected to be at or over capacity by 2035 and therefore do not have the ability to accommodate additional trips. As a result, neighborhood streets may be impacted by an increase of undesirable cut through traffic. If the County elects to construct the three lane alternative as the preferred long term corridor solution, it is recommended that the impacts on the surrounding transportation network be evaluated and addressed. This system level analysis should be addressed as part of the County s upcoming update of the Transportation Plan. A design life analysis was conducted to estimate how long the three lane alternative could function acceptably as an interim solution. The intersection at NW West Union Road will likely reach capacity within approximately five years (by approximately 2015). The signalized intersection at NW Oak Hills Drive, which has lower traffic demands on the side street, is expected to function acceptably for approximately ten years (or until 2020). Sensitivity Analysis An analysis was conducted to investigate the sensitivity of the conclusions to changes in the future growth projections. This analysis showed that even if the future growth projected by the regional model is reduced by 50%, the corridor would still require a four or five lane cross section to adequately serve the future (2035) traffic demand and meet Washington County mobility standards. Kittelson & Associates, Inc. 6
Section 2 Introduction
Introduction Introduction PROJECT BACKGROUND Washington County has programmed the section of NW Bethany Boulevard between NW Bronson Road and NW West Union Road for capacity and modernization improvements. The County s 2020 Transportation Plan (Reference 1) calls for a four to five lane cross section on NW Bethany Boulevard within the project area. The County is also considering a three lane alternative as a possible interim improvement scenario. Thus, the proposed project will widen the existing two lane corridor to a new cross section consisting of between three and five lanes, depending on which alternative is ultimately selected. The project is also intended to improve pedestrian and bicycle facilities and upgrade traffic control features as needed. The project is being funded by the County s Major Street Transportation Improvement Program (MSTIP) for construction in 2013. In a separate project, Washington County and the Oregon Department of Transportation (ODOT) are jointly developing improvement plans for the interchange of NW Bethany Boulevard at U.S. 26. This project will expand the existing Bethany Boulevard overpass structure to construct additional through and turn lanes at the ramp terminal intersections. The County anticipates that the interchange improvements and the corridor improvements will be constructed at the same time. SCOPE OF THE TRANSPORTATION STUDY The scope of the currently funded MSTIP project includes the NW Bethany Boulevard corridor between NW Bronson Road and NW West Union Road. Given the proximity of the project area to the U.S. 26 interchange, the traffic study scope also includes the interchange ramp terminal intersections immediately south of the project. Operational analyses were performed at the following study intersections: NW Bethany Boulevard / U.S. 26 Eastbound Ramp Terminal NW Bethany Boulevard / U.S. 26 Westbound Ramp Terminal NW Bethany Boulevard / NW Bronson Road NW Bethany Boulevard / NW Avondale Drive NW Bethany Boulevard / NW Emily Lane NW Bethany Boulevard / NW Oak Hills Drive NW Bethany Boulevard / NW Audrey Drive NW Bethany Boulevard / NW Telshire Drive NW Bethany Boulevard / NW Ridgetop Lane NW Bethany Boulevard / NW West Union Road Figure 1 shows the location and the limits of the proposed improvement project area. Kittelson & Associates, Inc. 8
Section 3 Existing Conditions
Existing Conditions Existing Conditions The existing conditions analysis identifies field conditions and the current operational, traffic control, and geometric characteristics of roadways and other transportation facilities within the study area. KAI visited the project area and inventoried the existing transportation system to identify lane configurations, traffic control devices, bicycle and pedestrian facilities, transit stops, geometric features, sight distances, and adjacent land uses. Traffic flow during the peak hours was observed to identify existing operational issues. SITE CONDITIONS AND ADJACENT LAND USES The study corridor is approximately 0.75 miles in length and located in an area occupied primarily by single family residences. Along the west side of Bethany Boulevard, the zoning between Bronson Road and Telshire Road is designated as R9 Residential zoning per the Washington County zoning designations. To the north of Telshire Road, the designated zoning is R6 Residential. Along the east side of Bethany Boulevard for the length of the study area, the land use is designated R5 Residential. To the east of the Bethany Boulevard/Oak Hills Drive intersection is Oak Hills Elementary School. ROADWAY FACILITIES The Washington County Transportation Plan identifies six different functional classifications for roadways ranging from Local Streets to Freeways. These roadway classifications have varying roles with respect to their level of access and mobility, as illustrated below in Exhibit 1. Exhibit 1 Washington County Road Classifications Freeway Principal Arterial MOBILITY Arterial (Bethany Blvd.) Collector Neighborhood Route Local Street ACCESS Kittelson & Associates, Inc. 11
Existing Conditions NW Bethany Boulevard is classified by Washington County as an Arterial and serves as a significant north south transportation corridor serving the many neighborhoods and commercial districts between U.S. 26 and NW Germantown Road. NW Bethany Boulevard provides full access to U.S. Highway 26 via the split diamond interchange (with collector distributor roadways connecting between NW Bethany Boulevard and NW Cornell Road). South of the freeway, NW Bethany Boulevard connects to NW Cornell Road, which provides access to the commercials centers as well as the NW 158th Avenue corridor to the south. Table 1 summarizes the characteristics of the existing transportation facilities in the site vicinity. Table 1 Existing Transportation Roadway Facilities and Roadway Designations Roadway Classification 1 Section Cross- Posted Speed 2 Sidewalks Bicycle Lanes On-Street Parking NW Bethany Boulevard Arterial 2 Lanes 35 mph Partial No No NW West Union Road Arterial 2 Lanes 40 mph Partial No No NW Ridgetop Lane Local Street 2 Lanes NP Yes No Yes NW Telshire Drive Local Street 2 Lanes NP Yes No Yes NW Audrey Drive Local Street 2 Lanes NP Yes No Yes NW Oak Hills Drive Neighborhood Route 2 Lanes NP Yes No Yes NW Emily Lane Local Street 2 Lanes NP Yes No Yes NW Avondale Drive Neighborhood Route 2 Lanes 25 mph Yes No Yes NW Bronson Road Collector 3 Lanes 35 mph Partial No No 1 Classifications are based on Washington County 2020 Transportation Plan 2 NP = Not Posted The existing roadway cross section for NW Bethany Boulevard generally consists of a two lane section from Bronson Road to West Union Road, with left turn bays at Avondale Drive, Audrey Drive, and West Union Road. There are no bike lanes within the study area, and there are intermittent paved shoulders/ditches along the roadsides. Intermittent sidewalks exist on the east side, while sidewalks along the west are continuous and within the existing right of way. North of the project area, NW Bethany Boulevard maintains a three lane cross section and includes a planted median, sidewalks, and bicycle lanes. South of the project area, at the Highway 26 westbound off ramp, the width increases to a four lane cross section extending south over Highway 26 until reaching NW Cornell Road. Figure 2 shows the existing lane configurations and traffic control devices at the study intersections. Pedestrian, bicycle, and transit facilities are discussed further in the subsequent section. Kittelson & Associates, Inc. 12
Existing Conditions PEDESTRIAN AND BICYCLE FACILITIES AND ACTIVITY Continuous sidewalks are not currently provided along the east side of Bethany Boulevard throughout the project area. Sidewalks, however, are provided on the west side of Bethany, and on all side street neighborhood approaches. During the peak commuter hours, pedestrian traffic was limited, and the majority of it was observed in the vicinity of the Oak Hills Drive/Bethany Boulevard intersection, driven primarily by the Oak Hills Elementary school schedule. Designated bicycle lanes do not exist within the study area but are present along Bethany Boulevard north of West Union Road. TRANSIT FACILITIES TriMet Route 67 provides transit service along NW Bethany Boulevard within the study area. This bus route travels between the Beaverton Transit Center and Portland Community College (PCC) Rock Creek Campus. On weekdays, service runs at approximately 30 to 45 minute headways, and operates from the Transit Center to PCC Rock Creek from 6:22 a.m. to 9:06 p.m., and from PCC Rock Creek to the Transit Center from 5:58 a.m. to 9:18 p.m. On Saturdays, service runs at approximately 80 to 90 minute headways, and operates from the Transit Center to PCC Rock Creek from 9:06 a.m. to 5:20 p.m., and from PCC Rock Creek to the Transit Center from 9:38 a.m. to 5:56 p.m. No service is currently provided on Sundays. Six bus stops are currently provided within the study corridor, at the intersections of Bethany Boulevard with Bronson Road, Avondale Drive, Oak Hills Drive, Telshire Drive, Ridgetop Lane, and West Union Road. The above mentioned bus stop locations are also shown on Figure 2. No bus turnouts are currently provided on Bethany Boulevard within the project area, although extra wide shoulders are available in the southbound direction at the Oak Hills Drive and Ridgetop Lane intersections. Bus Route 89 also provides transit service at the Bronson Road/Bethany Boulevard intersection but does not enter the Bethany Boulevard study area north of Bronson Road. This route connects the Sunset Transit Center with Tanasbourne Town Center. EXISTING TRAFFIC CONDITIONS A variety of traffic data were collected and evaluated as part of this transportation analysis. Using manual count methods and automated tube counters, the following traffic information was obtained: Daily traffic volumes at key locations along the study corridor; Hourly traffic volumes at key locations along the study corridor; Vehicle travel speeds; Vehicle classifications; and, Peak hour turning movement volumes at study intersections. Kittelson & Associates, Inc. 14
Existing Conditions The remainder of this section summarizes the daily, weekly, and peak hour traffic volumes. Daily Traffic Volumes Three sets of bi directional tube counts were collected along NW Bethany Boulevard as part of this study. The first two sets were conducted in September 2009 for a 24 hour period and included counts at two locations: (1) between NW Avondale Drive and NW Bronson Road and (2) between NW West Union Road and NW Ridgetop Lane. A third tube count was conducted for a 7 day period beginning in late September 2010, at a location between NW Oak Hills Drive and NW Emily Lane. These automated tube counts all collected hourly traffic volumes in each direction, as well as travel speeds and vehicle classifications. Appendix A, B, and C contain the tube count data for volumes, speeds, and vehicle classifications, respectively. Table 2 summarizes the existing conditions traffic data. Table 2 NW Bethany Boulevard Traffic Volumes, Speeds and Heavy Vehicle Percentages September 2009 Count September 2010 Count Between Avondale Dr and Bronson Rd Between West Union Rd and Ridgetop Ln Between Oak Hills Dr and Emily Ln Average Daily Traffic Volumes 19,500 veh/day 17,300 veh/day 19,950 veh/day AM Peak Hour Volumes 1,400 veh/hr* 1,250 veh/hr* 1,350 veh/hr** PM Peak Hour Volumes 1,600 veh/hr* 1,500 veh/hr* 1,500 veh/hr** Truck Percentage (%) Daily 3.4% 4.0% 4.5% Median Speed 35 mph 35 mph 35 mph 85 th Percentile Speed 39 mph 39 mph 40 mph * Based on manual peak-hour intersection counts. ** Based on tube counts (peak-hour intersection counts not collected in September 2010) As shown in Table 2, the average weekday volume on NW Bethany Boulevard in September 2009 was approximately 19,500 vehicles per day (vpd) north of NW Bronson Road, and approximately 17,300 vpd north of NW Ridgetop Lane. In September 2010, the average weekday volume was approximately 19,950 vpd, indicating that the daily volumes have stayed relatively consistent over the past year. Further investigation of the count data reveals that traffic flows during the peak hours have also remained consistent from 2009 to 2010. Table 2 also shows the speed data, as measured by the automated tube counters along the corridor. As shown in Table 2, the median speed at all three locations along project corridor was found to be 35 mph, which is consistent with the posted speed limit. This speed represents the average running speed of the existing corridor over the course of an entire day. The 85 th percentile of the distribution of observed speeds is commonly used for design purposes as a measure of the operating speed during free flow conditions (Reference 2). As shown in Table 2, the 85 th percentile speeds were observed to be 39 mph at both the north and south ends of the project area and 40 mph at the midpoint of the corridor. Kittelson & Associates, Inc. 15
Existing Conditions Weekly Traffic Volumes Exhibit 2 shows the weekly profile of traffic flow on NW Bethany Boulevard immediately south of the NW Oak Hills Drive intersection. As shown in the exhibit, the study corridor exhibits a weekly profile that is typical of urban/suburban commuter routes, with consistent volumes on Monday through Thursday, the highest volumes on Friday, and slightly lower volumes on the weekend. 25,000 Exhibit 2 Weekly Traffic Volume Profile NW Bethany Boulevard, South of Oak Hills Drive Daily Volumes 20,000 Volume (vpd) 15,000 10,000 5,000 0 Sunday Monday Tuesday Wednesday Thursday Friday Saturday Day of Week Hourly Traffic Volume Profile Exhibit 3, below, illustrates the average weekday hourly volume profile for NW Bethany Boulevard approximately 150 feet south of NW Oak Hills Drive. Kittelson & Associates, Inc. 16
Existing Conditions 1600 1400 1200 Exhibit 3 Average Weekday Hourly Traffic Volume Profile NW Bethany Boulevard, south of NW Oak Hills Drive Northbound Southbound Total Volume (vph) 1000 800 600 400 200 0 12:00 AM 2:00 AM 4:00 AM 6:00 AM 8:00 AM 10:00 AM 12:00 PM Time of Day 2:00 PM 4:00 PM 6:00 PM 8:00 PM 10:00 PM The weekday traffic flow patterns shown in Exhibit 3 illustrate the corridor morning peak at approximately 8:00 a.m., a smaller peak at approximately noon, and an afternoon peak at approximately 5:00 p.m. The p.m. peak hour along the corridor represents the highest total volume hour of the day. These directional patterns of traffic flow are a result of the higher volume movement travels south to the Highway 26 corridor during the morning peak hours and north into the Bethany neighborhoods during the afternoon peak hours. Peak Hour Intersection Volumes Manual turning movement counts were conducted at the study intersections during a mid week day in September 2009. All study intersection were counted during the weekday morning (7:00 9:00 a.m.) and evening (4:00 6:00 p.m.) peak periods. Based on the peak period count data, the weekday a.m. peak hour (overall system volume) was found to occur between 7:20 and 8:20 a.m., and the overall weekday p.m. peak hour was found to occur between 5:00 and 6:00 p.m. Figure 3 and Figure 4 show the turning movement counts at the study intersections during the weekday a.m. and p.m. peak hours. Appendix D contains the intersection traffic count sheets. Kittelson & Associates, Inc. 17
Existing Conditions Intersection Performance Measures A number of performance measures are used to gauge the overall quality of the travel experience through an intersection or roadway segment as it is perceived by the traveler. A brief description of each performance measure is provided below: Level of service (LOS) has been the most commonly used performance measure. LOS uses an A to F ranking based on the average control delay experienced by motorists. LOS A conditions have very low vehicle delay times (10 seconds or less), while LOS F conditions have high delay times (over 80 seconds per vehicle at a signalized intersection and over 50 seconds at an unsignalized intersection) that are considered unacceptable to most drivers. A more detailed description of the LOS concept is presented in Appendix E. The appendix also indicates how LOS is measured. Volume to capacity ratio (V/C) compares the volume of traffic to the theoretical capacity of the facility to accommodate traffic. A V/C ratio of 1.0 indicates an intersection is operating at capacity. A V/C ratio over 1.0 indicates the intersection s capacity is exceeded, meaning that a vehicle may have to wait more than one signal cycle length at a signalized intersection before moving through the intersection. While overall intersection performance is calculated for signalized intersections, performance measures are only calculated for the minor approaches and the major street left turn movements at two way stop controlled intersections. No delay is assumed to the major street through movements: levels of service and volume to capacity ratios are only calculated for each minor street lane. Washington County standards allow a maximum V/C ratio of 0.99 and LOS E during peak hours for the project study area intersections. Traffic Analysis Methodology The operational analysis of each study intersection was performed using the Synchro traffic analysis software. Synchro is a software package that analyzes individual signalized and unsignalized intersections; it also enables modeling and optimizing traffic signal timings along a corridor. Synchro implements the methods outlined in the 2000 Highway Capacity Manual (Reference 3). Existing Peak Hour Traffic Performance The level of service and volume to capacity ratio results for the study intersections under the weekday a.m. and p.m. peak hours are shown in Figure 3 and Figure 4, respectively. Appendix F includes the level of service worksheets under existing traffic conditions. As shown in Figures 3 and 4, three unsignalized intersections within the project are currently operating at unacceptable levels of service during both the weekday a.m. and p.m. peak hours: NW Telshire Drive / NW Bethany Boulevard, NW Oak Hills Drive / NW Bethany Boulevard, and NW Bronson Road / NW Bethany Boulevard. Kittelson & Associates, Inc. 20
Existing Conditions Motorists on the minor street approaches at these three intersections experience unacceptably high delays during peak hours. The NW Telshire Road intersection could potentially be improved to acceptable performance by adding a center two way left turn lane on Bethany Boulevard. To address operations at the NW Oak Hills Drive and NW Bronson Road intersections, a signal warrant analysis was conducted and is discussed in subsequent sections of this report. One signalized intersection in the study area the U.S. 26 Westbound Ramp Terminal/NW Bethany Boulevard intersection does not meet the applicable performance standard, with a V/C ratio greater than 1.0 during the weekday p.m. peak hour. The over capacity condition is principally caused by the westbound right turn movement, which can result in lengthy queues extending along the westbound U.S. 26 frontage road. Field observations during the weekday evening peak hour confirmed the over capacity condition for this right turn movement. All other study intersections are currently operating acceptably. However, the signalized West Union Road/Bethany Boulevard intersection is near the upper limit of the performance standard (currently operating at LOS E and V/C ratio of 0.91 during the weekday p.m. peak hour). As a result, this intersection has little spare capacity to accommodate future growth. Additionally, queuing issues often occur on NW Bethany Boulevard between NW Bronson Road and the U.S. 26 interchange, as discussed below. Queuing Issues Field observations revealed that during both the morning and evening peak hours, queuing issues occur in the vicinity of the Bronson Road intersection and the Highway 26 interchange. During the morning peak hour, southbound queues from the Highway 26 interchange spill back to Bronson Road and interfere with turning movements at the Bronson Road intersection. During the p.m. peak hour, queues in the northbound left turn lane at the Bronson Road intersection extend back to the interchange and impact traffic flow at the Highway 26 ramps. These queuing issues are further compounded by weaving movements that occur on NW Bethany Boulevard between NW Bronson Road and the U.S. 26 ramps. There are many vehicles that turn at both the NW Bronson Road intersection and either the Eastbound U.S. 26 or Westbound U.S. 26 Ramps. Queues between the intersections often make it difficult for vehicles to enter the appropriate turn lanes and this causes vehicles to stop in the through lane while attempting to change lanes. Traffic Safety The crash histories along the study area were reviewed in an effort to identify potential segment and/or intersection safety issues. Crash records were obtained from ODOT for the five year period from January 1, 2004 through December 31, 2008. Intersection crash data as well as segment crash data were reviewed along the Bethany Boulevard corridor between West Union Road and Bronson Road. Some of the segment crashes appear in the intersection crash summary report from ODOT, while some segment crashes did not. Closer investigation of the detailed crash records revealed that 18 crashes occurred along Bethany Kittelson & Associates, Inc. 21
Existing Conditions Boulevard that were not reported in the individual intersection crash reports. However, because these crashes all occurred in the vicinity of an intersection, KAI included them together with the relevant intersection data. A summary of the 45 crashes is provided in Table 3, including the severity and type of crashes over the five year analysis period at the study intersections. Appendix G contains the crash data worksheets. Intersection Table 3 Study Intersection Crash History (2004-2008) Number of Crashes Crash Type Crash Severity Rear-End Turning Angle Other PDO 1 Injury Bethany Blvd / West Union Rd 8 6 2 -- -- 3 5 Bethany Blvd / Ridgetop Ln 7 5 1 1 -- 3 4 Bethany Blvd / Telshire Dr 7 1 2 1 3 2 5 Bethany Blvd / Audrey Dr 0 -- -- -- -- 0 0 Bethany Blvd / Oak Hills Dr 5 2 2 -- 1 2 3 Bethany Blvd / Emily Ln 3 2 1 -- -- 1 2 Bethany Blvd / Avondale Dr 1 1 -- -- -- 1 0 Bethany Blvd / Bronson Rd 14 6 5 3 -- 8 6 1 PDO: Property Damage Only To evaluate the frequency of crashes with respect to the total volumes of traffic at each intersection, crash rates were calculated. Crash rates take into account the traffic volumes at the intersections and are expressed in crashes per million entering vehicles (MEV). To calculate this rate, the weekday p.m. peak hour traffic volume of all traffic entering the intersection was factored to obtain an estimate of the annual number of total entering vehicles (TEV). Table 4 shows crash rates for the study intersections, expressed in crashes per million entering vehicles (MEV). Intersection Table 4 Study Intersection Crash Rate (2004-2008) Number of Crashes Crashes per Year Peak Hour MEV 2 / TEV 1 Year Crashes / MEV NW Bethany Blvd / NW West Union Rd 8 1.6 2370 8.651 0.18 NW Bethany Blvd / NW Ridgetop Ln 7 1.4 1518 5.541 0.25 NW Bethany Blvd / NW Telshire Dr 7 1.4 1564 5.709 0.25 NW Bethany Blvd / NW Audrey Dr 0 0 1616 5.898 0.00 NW Bethany Blvd / NW Oak Hills Dr 5 1 1675 6.114 0.16 NW Bethany Blvd / NW Emily Ln 3 0.6 1529 5.581 0.11 NW Bethany Blvd / NW Avondale Dr 1 0.2 1634 5.964 0.03 NW Bethany Blvd / NW Bronson Rd 14 2.8 2212 8.074 0.35 1 TEV = Total Entering Volume 2 MEV = Million Entering Vehicles Table 4 illustrates the crashes and calculated crash rates for each of the study intersections. As shown in the table, The Bronson Road/Bethany Boulevard, Telshire Drive/Bethany Boulevard, and Ridgetop Lane/Bethany Boulevard intersections had the highest crash rates within the project study Kittelson & Associates, Inc. 22
Existing Conditions area. Considerations for possible safety improvements at each of these intersections are discussed below. Washington County SPIS Washington County maintains the Safety Priority Index system (SPIS), which ranks the intersections within the county in terms of crash frequency, crash rate, and crash severity. A review of the most current (2006 2008) list revealed that two intersections within the project study area are listed on the SPIS: NW Bethany Boulevard / NW Bronson Road (ranked #188 of 262); and, NW Bethany Boulevard / NW Telshire Drive (ranked #119 of 262). Specific considerations and recommendations for these two intersections are discussed below. Additionally, a review of the Ridgetop Lane/Bethany Boulevard intersection is also provided. Bronson Road/Bethany Boulevard - Safety Considerations As shown in Table 4, the Bronson Road/Bethany Boulevard intersection had the highest number of crashes and the highest crash rate of all intersections within the project area. Many of the crashes are likely related to the queuing and congestion issues that occur at the intersection and the adjacent interchange ramps. Signalization of this intersection in combination with capacity improvements at the interchange (as discussed in later sections of this report) are expected to provide safety benefits. Telshire Drive/Bethany Boulevard Safety Considerations A detailed review of the crash records at the Telshire Drive/Bethany Boulevard intersection revealed no consistent trends or patterns of crashes. Five of the seven crashes appear to be a series of isolated run off the road type incidents. Two crashes occurred with fixed objects, one crash resulted when a driver used a cellular phone (and ran off the road), another was a vehicle that lost control, and yet another was a vehicle whose trailer connection broke. As a result, no specific geometric or traffic control deficiencies are identified at this time. However, corridor improvements including adding a left turn lane, upgrading the roadway illumination, improving the vertical alignment, and reducing obstacles within the roadside clear area are expected to provide safety benefits. Ridgetop Lane/Bethany Boulevard - Safety Considerations Although not listed on the county s current SPIS list, the Ridgetop Lane/Bethany Boulevard intersection had a comparable number of crashes as the Telshire Drive intersection, higher than other intersections along the corridor. The majority of these crashes were rear end collisions involving southbound vehicles. A review of field conditions found that this intersection has insufficient intersection sight distance from the westbound approach of Ridgetop Lane. The horizontal curve immediately north of Ridgetop Lane limits the ability for drivers at the intersection to view southbound traffic (i.e. traffic approaching the intersection from the north). Modifying the roadway/intersection geometry to Kittelson & Associates, Inc. 23
Existing Conditions achieve the County s intersection sight distance standards would require significant clearing of vegetation and moving of property fences along the east side of NW Bethany Boulevard that would result in significant impacts to a number of property owners. To minimize these impacts, it is recommended that a raised median be installed on Bethany Boulevard to restrict left turn movements at the Ridgetop Lane intersection. This median is expected to improve safety at the intersection by addressing the intersection sight distance deficiency and reducing the likelihood of southbound rear end collisions. Traffic Signal Warrant Analysis A signal warrant analysis was conducted to determine whether new traffic signals are justified at any of the existing unsignalized intersections within the project area. The Manual on Uniform Traffic Control Devices (MUTCD) (Reference 4) provides guidelines for justifying the installation of traffic signals based on traffic conditions, pedestrian characteristics, crash experience, and physical characteristics of the location. The MUTCD establishes the following eight traffic signal warrants: Warrant 1: Eight Hour Volumes Warrant 2: Four Hour Volumes Warrant 3: Peak Hour Volumes Warrant 4: Pedestrian Volume Warrant 5: School Crossing Warrant 6: Coordinated Signal System Warrant 7: Crash Experience Warrant 8: Roadway Network The signal warrant analysis focused on two existing unsignalized intersections on NW Bethany Boulevard: NW Bronson Road, and NW Oak Hills Drive. The results of the analysis of these two intersections are summarized below in Table 5. Detailed analysis worksheets are provided in Appendix H. Kittelson & Associates, Inc. 24
Existing Conditions Table 5 Signal Warrant Analysis Results Warrant Met? MUTCD Warrant 1. Eight-Hour Volume 2. Four-Hour Volume 3. Peak Hour Volume 4. Pedestrian Volume 5. School Crossing 6. Coordinated Signal System 7. Crash Experience 8. Roadway Network NW Oak Hills Drive at NW Bethany Boulevard No No Yes No Yes No No No NW Bronson Road at NW Bethany Boulevard Yes Yes Yes No No No No No As shown in Table 5, at least one warrant is met at both of these intersections. Additional considerations and recommendations for each location are discussed below. The NW Telshire Drive intersection was also investigated for potential signalization; however, an initial review of traffic volumes, pedestrian data, and location characteristics found that the intersection does not meet the minimum criteria. Oak Hills Drive / Bethany Boulevard As shown in Table 5, the intersection at NW Oak Hills Drive does not currently meet the traffic volume warrants for signalization (Warrants #1, #2, and #3). However, Oak Hills Elementary School is located less than 200 feet from the intersection and serves neighborhoods on both the east and west sides of NW Bethany Boulevard. MUTCD Warrant #5 provides the following guidance for when traffic signals may be justified due to school children crossing the major street. The need for a traffic control signal shall be considered when an engineering study of the frequency and adequacy of gaps in the vehicular traffic stream as related to the number and size of groups of school children at an established school crossing across the major street shows that the number of adequate gaps in the traffic stream during the period when the children are using the crossing is less than the number of minutes in the same period (see Section 7A.03) and there are a minimum of 20 students during the highest crossing hour. The 2001 ITE Traffic Control Devices Handbook (Reference 5) provides a method for estimating the probability of no vehicles arriving for the required minimum gap needed for children to cross a roadway. For a three lane roadway (assuming a 50 foot width), the time needed for small children to cross the street is approximately 17 seconds. The counted traffic volume on NW Bethany Boulevard during the one hour period after school is dismissed (2:00 3:00 p.m.) is 1,250 vehicles per hour (combined both directions). Based on the ITE methodology, it is estimated that there would be only three gaps in the traffic stream that would be of sufficient size to allow students to cross a three lane roadway. For a five lane roadway, the crossing time would be even longer (approximately 24 seconds) and the likelihood of a gap of sufficient size would likely be even lower. Kittelson & Associates, Inc. 25
Existing Conditions Therefore, the intersection meets the first criteria of the MUTCD warrant (i.e. the number of adequate gaps in the traffic stream during the period when the children are using the crossing is less than the number of minutes in the same period). Detailed calculations of the ITE methodology are provided in Appendix I. The second criteria of the MUTCD warrant is that there are a minimum of 20 students during the highest crossing hour. According to the intersection count collected in September 2009, there are currently approximately five pedestrian crossings during the morning peak school hour (7 8 a.m.) and nine pedestrians crossing NW Bethany Boulevard during the evening peak school hour (2 3 p.m.). Thus the intersection does not currently meet the requirement of 20 students during the peak hour. However, according to representatives of the Oak Hills School and residents of the surrounding neighborhoods, the low number of students crossing Bethany Boulevard is due in large part to safety concerns related to the existing intersection. Currently, the School District buses 563 students to Oak Hills School. Of those, 243 reside west of Bethany Boulevard and are within a mile of the school. Beaverton School District has indicated that if a signal were installed at the NW Oak Hills Drive/NW Bethany Boulevard intersection, these students could safely walk or bike to school and up to three buses could potentially be withdrawn. Therefore, it is very reasonable and likely that, if a signal were installed at the intersection, the number of student crossings during the peak school hours would easily exceed the MUTCD criteria of 20. A letter from Beaverton School District s Administrator for Transportation and the Oak Hills Elementary Attendance Boundary Map are provided in Appendix I. Based on the results of the analysis of pedestrian volume and gap data and the letter of support submitted by Beaverton School District, it is recommended that a signal be installed at the Oak Hills Drive/Bethany Boulevard intersection to provide safe and efficient crossing opportunities for school children. The signal should provide pedestrian crosswalk signals, should include appropriate school crossing signs, and should be completed in conjunction with sidewalk enhancements between Oak Hills Elementary School and the intersection. Bronson Road / Bethany Boulevard All three of the standard traffic volume warrants (Warrants #1, #2, and #3) are met at the NW Bronson Road/NW Bethany Boulevard intersection under today s traffic condition. Signalization of the intersection is therefore justified. Installing a signal at the Bronson Road/Bethany Boulevard intersection, however, is complicated by the proximity of the U.S. 26 Westbound Ramp Terminal intersection, which is approximately 500 feet away. Given the volume of traffic on NW Bronson Road and the lack of viable alternative routes, it is recommended that a new traffic signal be installed at this intersection. The signal should be interconnected and coordinated with the two existing signals at the U.S. 26 ramp terminals to minimize the likelihood of queue spillback between these three closely spaced intersections. Further analysis and recommendations for lane arrangements are provided later in this report under the 2035 Future Traffic Conditions section. Kittelson & Associates, Inc. 26