MEMORANDUM DATE March 1, 2012 TO Town of Milton FROM Mark Abbott, Seth Asante, and Efi Pagitsas Boston Region MPO Staff RE FFY 2011 Safety and Operations Analyses at Selected Boston Region MPO Intersections: Neponset Valley Parkway at Brush Hill Road and Milton Street in Milton INTRODUCTION This memorandum summarizes safety and operations analyses and proposes improvement strategies for the intersections of Neponset Valley Parkway at Brush Hill Road and Neponset Valley Parkway at Milton Street in Milton. It contains the following sections:  Intersection Layout and Traffic Control  Issues and Concerns  Crash Data Analysis  Intersection Capacity Analysis  Preliminary Analysis of Traffic Signal Warrants  Analysis of Traffic Signal Alternative  Review of Roundabout Alternative  Improvement Recommendations and Discussion The memorandum also includes a collection of technical appendices that contain methods and data applied in the study and detailed reports of the intersection capacity analyses. INTERSECTION LAYOUT AND TRAFFIC CONTROL The two intersections, shown in Figure 1, are owned by the Department of Conservation and Recreation. They are located in the western portion of Milton, near the Hyde Park section of Boston. Neponset Valley Parkway, the major street of the two intersections, is a two-lane roadway running in the northwest-southeast direction between Blue Hill Avenue (Route 138) and Truman Parkway; it is categorized as an urban principal arterial. Brush Hill Road in Milton is a town- owned roadway, classified as an urban collector. It runs north-south in direction, north from Blue Hill Avenue (Route 138) south of the intersections, continuing Town of Milton 2 March 1, 2012 past Milton Street, to Truman Parkway. Milton Street is an east-west street that also runs from Blue Hill Avenue, east of the intersections, to Neponset Valley Parkway. It is also town-owned and is an urban collector. Figure 1 shows the intersection layouts and the area nearby. Traffic operation at the Brush Hill Road and Neponset Valley Parkway intersection is under stop-control, with a stop sign located on the Brush Hill Road approach. Both of the Neponset Valley Parkway approaches are uncontrolled. All of the approaches are one lane that is shared by all movements. The traffic operations at the Neponset Valley Parkway and Milton Street intersection is under yield control, with a yield sign located on the northbound Neponset Valley Parkway approach. The land use in the vicinity of the intersections is mainly residential and public open space. Milton Health care, a nursing home and rehabilitation hospital, is located on Brush Hill Road, south of the Neponset Valley Parkway intersection. The two intersections are located within about 400 feet of each other. Both intersections are skewed, and a sharp roadway curve is located between them. This limits the sight distance between the intersections and sometimes causes driver confusion. There are currently no paved sidewalks along either Brush Hill Road or Neponset Valley Parkway. However, there is a pedestrian path located adjacent to Neponset Valley Parkway on the eastern side of the roadway. This pathway leads to the parking area located adjacent to the Brush Hill Road intersection. In addition to the path along Neponset Valley Parkway, there are numerous recreational trails in the area. The parking area is provided to allow access to these trails. ISSUES AND CONCERNS Staff met with Milton officials to discuss their concerns about the intersections. Their main concern was the lack of safety at the Brush Hill Road intersection. Numerous crashes have occurred at both intersections, with a majority occurring at the Brush Hill Road intersection. Another concern is the problem of a number of large trucks encroaching into the opposite lane (oncoming traffic) at this intersection. A review of the recent crash data indicates that the Brush Hill Road intersection has a high number of crashes and a crash rate higher than the average for unsignalized intersections in MassDOT Highway Division District 6 (see the next section for further analyses). The issues and concerns for this intersection can be summarized as follows:  Skewed approaches of the intersections  High number of crashes and high crash rate  Truck traffic encroaching into the lane of oncoming traffic BOSTON FIGURE 1 Safety and Operations REGION Neponset Valley Parkway/Brush Hill Road/ Improvements at MPO Selected Intersections Milton Street, Milton Town of Milton 4 March 1, 2012 CRASH DATA ANALYSIS Staff collected crash data for the most recent three years available from the MassDOT Registry of Motor Vehicles Division, from 2006 to 2008. Some additional crash reports were available for both intersections. The crash report data were used to develop a crash diagram for both intersections. This crash diagram is shown in Figure 2, and shows that there is a significant number of angle crashes at the Brush Hill Road intersection. Table 1 show that on average eight crashes occurred at the Brush Hill Road intersection each year. In total, about 30 percent of the crashes resulted in personal injuries and the rest were property damage only. The collision types consist predominantly of angle collisions and single- vehicle collisions. There were no crashes that involved pedestrians or cyclists in that period. TABLE 1 Summary of MassDOT Crash Data (2006–2008): Neponset Valley Parkway at Brush Hill Road 2006–2008 2006 2007 2008 Total Average Total Number of Crashes 10 7 6 23 8 Property Damage Only 6 4 6 16 5 Crash Personal Injury 4 3 0 7 2 Severity Fatality 0 0 0 0 0 Not Reported 0 0 0 0 0 Angle 6 1 1 8 3 Rear-end 1 0 0 1 0 Sideswipe 2 1 0 3 1 Collision Type Head-on 0 1 3 4 1 Single Vehicle 1 4 2 7 2 Not Reported 0 0 0 0 0 Roadway Wet or icy pavement 7 3 2 12 4 Conditions Dark/lighted 3 4 1 8 3 Clear 2 4 1 7 2 Weather Cloudy 2 2 1 5 1 Conditions Rain 6 1 4 11 4 Snow 0 0 0 0 0 Crashes during weekday peak periods* 4 1 3 8 3 Crashes involving pedestrian(s) 0 0 0 0 0 Crashes involving bicyclist(s) 0 0 0 0 0 * Peak periods are defined as 7:00–10:00 AM and 3:30–6:30 PM. Table 2 shows that on average two crashes occurred at the Milton Street intersection each year. Over the three-year period, the majority of the crashes resulted in property damage only. There were no predominant collision types. There were no crashes involving pedestrians or cyclists during that period. 1 1 1 1 1 2 8 1 1 4 Note: X -Number of collision diagram crashes X -Number of MassDOT crashes SYMBOLS TYPES OF CRASH SEVERITY Moving Vehicle Head On Backing Vehicle Angle Non-Involved Vehicle Pedestrian Turning Move Injury Accident Parked Vehicle Rear End Fixed Object Bicycle Sideswipe Fatal Accident Animal Out of Control BOSTON Safety and Operations FIGURE 2 REGION Improvements at Collision Diagram MPO Selected Intersections Town of Milton 6 March 1, 2012 TABLE 2 Summary of MassDOT Crash Data (2006–2008): Neponset Valley Parkway at Brush Hill Road/Milton Street 2006-2008 2006 2007 2008 Total Average Total Number of Crashes 4 1 1 6 2 Property Damage Only 3 1 1 5 2 Crash Personal Injury 1 0 0 1 0 Severity Fatality 0 0 0 0 0 Not Reported 0 0 0 0 0 Angle 1 0 1 2 1 Rear-end 1 0 0 1 0 Sideswipe 0 1 0 1 0 Collision Type Head-on 0 0 0 0 0 Single Vehicle 1 0 0 1 0 Not Reported 1 0 0 1 0 Roadway Wet or icy pavement 1 0 0 1 0 Conditions Dark/lighted 0 0 0 0 0 Clear 2 1 1 4 1 Weather Cloudy 2 0 0 2 1 Conditions Rain 0 0 0 0 0 Snow 0 0 0 0 0 Crashes during weekday peak periods* 1 0 1 2 1 Crashes involving pedestrian(s) 0 0 0 0 0 Crashes involving bicyclist(s) 0 0 0 0 0 * Peak periods are defined as 7:00–10:00 AM and 3:30–6:30 PM. Crash rate is another effective tool for examining the relative safety of a particular location.1Based on the 2006–2008 crash data and the recently collected traffic volume data, the crash rate for the Brush Hill Road intersection is calculated as 1.84, and for the Milton Street intersection the crash rate is 0.36 (see Appendix B for MassDOT intersection crash rate worksheets). The crash rate at the Brush Hill Road intersection is over three times higher than the average rate for the unsignalized intersections in MassDOT Highway Division District 6, which is estimated to be 0.57 crashes per million entering vehicles.2 1 Crash rates are estimated based on crash frequency (crashes per year) and vehicle exposure (traffic volumes or miles traveled). Crash rates are expressed as “crashes per million entering vehicles” for intersection locations and as “crashes per million miles traveled” for roadway segments. 2 The average crash rates estimated by the MassDOT Highway Division (as of July 7, 2011) are based upon a database that contains intersection crash rates submitted to MassDOT as part of the review process for an Environmental Impact Report or Functional Design Report. The most recent average crash rates, which are updated on a nearly annual basis, are based on all entries in the database, not just those entries made within the past year. Town of Milton 7 March 1, 2012 INTERSECTION CAPACITY ANALYSIS MPO staff collected turning-movement counts at the intersection on June 7, 2011. The data were recorded in 15-minute intervals for the peak traffic periods in the morning, from 7:00 to 9:00 AM, and in the evening, from 4:00 to 6:00 PM. The Brush Hill Road intersection had peak hours, which occurred between 7:00 and 8:00 AM and between 5:00 and 6:00 PM. There was observed pedestrian activity during both peak hours at this intersection—7 pedestrians and 16 pedestrians were observed during the AM and PM peak hours, respectively. The Milton Street intersection had peak hours between 7:30 and 8:30 AM and between 5:00 and 6:00 PM. There were 31 and 11 pedestrians observed during the AM and PM peak hours, respectively. The peak hour traffic volumes are shown in Figure 3. Based on the turning-movement counts and the signal timings measured on the site, the intersection capacity was analyzed by using an intersection capacity analysis program, Synchro.3 The intersections were both modeled as unsignalized intersections, with stop control at the Brush Hill Road intersection and yield control at the Milton Street intersection. Tables 3 and 4 shows the AM and PM peak hour analyses, respectively, for the existing conditions and the two alternatives provided. TABLE 3 AM Peak Hour Intersection Capacity Analysis Existing Conditions Alternative 1 Approach Mvmt LOS Delay1 V/C Q2 LOS Delay1 V/C Q2 Neponset Valley Parkway at Brush Hill Road Neponset Valley Parkway – NB LT A 0.0 0.00 0 A 0.00 0.00 0 Neponset Valley Parkway – SB TR A 0.0 0.30 0 A 0.00 0.30 0 Brush Hill Road – EB LR C 19.1 0.36 41 C 24.6 0.44 55 Neponset Valley Parkway at Milton Street Neponset Valley Parkway – NB TR F 110.2 1.14 529 A 0.0 0.38 0 Neponset Valley Parkway – EB LT A 0.0 0.00 0 A 3.7 0.15 13 Milton Street – WB LLTR A 0.1 0.41 0 D 28.0 0.68 126 Brush Hill Road at Milton Street Brush Hill Road – NB LTR B 11.7 0.10 8 B 11.1 0.05 4 Brush Hill Road – SB LTR B 11.9 0.01 0 B 11.9 0.01 0 Milton Street – EB LTR A 1.1 0.01 1 A 1.1 0.01 1 Milton Street – WB LTR A 0.1 0.00 0 A 0.1 0.00 0 1 Delay in seconds per vehicle. 2 Queue in feet. 3 Synchro Version 7 was used for these analyses. This software is developed and distributed by Trafficware Ltd. It can perform capacity analysis and traffic simulation (when combined with SimTraffic) for an individual intersection or a series of intersections. ))) 000 ((( 010 759 11) ))0 431 12( (( xxx –AM Peak Hour Volumes (xxx) –PM Peak Hour Volumes BOSTON Safety and Operations FIGURE 3 REGION Improvements at Peak Hour Traffic Volumes MPO Selected Intersections Town of Milton 9 March 1, 2012 TABLE 4 PM Peak-Hour Intersection Capacity Analysis Existing Conditions Alternative 1 Approach Mvmt LOS Delay1 V/C Q2 LOS Delay1 V/C Q2 Neponset Valley Parkway at Brush Hill Road Neponset Valley Parkway – NB LT A 0.1 0.00 0 A 0.1 0.00 0 Neponset Valley Parkway – SB TR A 0.0 0.30 0 A 0.0 0.38 0 Brush Hill Road – EB LR C 18.4 0.36 41 C 23.5 0.39 44 Neponset Valley Parkway at Milton Street Neponset Valley Parkway – NB TR F 56.9 0.95 308 A 0.0 0.30 0 Neponset Valley Parkway – EB LT A 0.0 0.01 0 A 5.6 0.25 25 Milton Street – WB LLTR A 0.1 0.57 0 E 37.2 0.71 130 Brush Hill Road at Milton Street Brush Hill Road – NB LTR B 13.4 0.14 12 B 12.3 0.09 7 Brush Hill Road – SB LTR A 0.0 0.01 0 B 0.0 0.01 0 Milton Street – EB LTR A 1.4 0.03 2 A 1.4 0.03 2 Milton Street – WB LTR A 0.8 0.01 1 A 0.0 0.00 0 1 Delay in seconds per vehicle. 2 Queue in feet. ALTERNATIVES To address the concerns about safety, two alternatives were developed to improve safety as well as traffic operations at both intersections. The two alternatives, described below, share common features. Alternative 1: Realignment of the Brush Hill Road and Milton Street Intersections Alternative 1 contains modifications to both the Brush Hill Road and Milton Street intersections, as shown in Figure 4. The intersection of Brush Hill Road and Neponset Valley Parkway is realigned to a traditional “T” intersection. The intersection is moved approximately 150 feet south of its current location. A Neponset Valley Parkway southbound right-turn lane is added to accommodate the right turns onto Brush Hill Road. A stop sign is provided on the realigned eastbound Brush Hill Road approach. Access to the existing parking area for the recreational trails is now provided via a new driveway, which uses the abandoned Brush Hill Road segment. This eliminates the problem of vehicles turning into the parking area from the roadway curve. The addition of crosswalks across Neponset Valley Parkway and Brush Hill Road are included in this alternative. The intersection at Neponset Valley Parkway and Milton Street is also realigned to provide for increased sight distance for entering Milton Street drivers. A left-turn lane is provided for the Neponset Valley Parkway left-turns onto Milton Street. The intersection is stop-sign controlled, with the stop sign being placed onto the Milton Street approach. This creates improved traffic flow through the intersection based on existing traffic volumes. The existing segment of Brush Legend Pedestrian Crosswalk BOSTON FIGURE 4 Safety and Operations REGION Alternative 1: Realignment of Brush Hill Improvements at MPO Road and Milton Street Selected Intersections