Technical Memorandum

DATE:   May 6, 2021

TO:         Maurice Goulet, Director of Public Works, Town of Medfield

FROM:   Chen-Yuan Wang and Chaopeng Hu, MPO Staff

RE:         Safety and Operations Analyses at Selected Intersections,
FFY 2020—North Meadows Road (Route 27) at West Street in Medfield

This memorandum summarizes the analyses and improvement strategies for the intersection of North Meadows Road (Route 27) at West Street in Medfield. This intersection was selected through a comprehensive review of 30 potential study locations in the region.1

The memorandum covers the following sections:

1. Study Background
2. Existing Intersection Conditions
3. Issues and Concerns
4. Crash Data Analysis
5. Existing Traffic Conditions
6. Operations Analysis
7. Proposed Short-Term Improvements
8. Long-Term Improvement Alternatives
9. Recommendations

In addition, the memorandum includes technical appendices that contain supporting data and methods applied in the study.

1          Study Background

The purpose of the “Safety and Operations Analyses at Selected Intersections” study is to examine safety, operations, and mobility issues at major intersections in the Boston Region Metropolitan Planning Organization (MPO) area’s arterial highways where many crashes occur, congestion during peak traffic periods may be heavy, or improvements for bus, bicycle, and pedestrian travel are needed.

For more than 10 years, the MPO has been conducting these planning studies with municipalities in the region. The communities find the studies beneficial, as they give them an opportunity to begin looking at the needs of problematic locations at the conceptual level, before they commit funds for design and engineering. Eventually, if the project qualifies for federal funds, the study’s documentation will also be useful to the Massachusetts Department of

Transportation (MassDOT) and its project-development process.

These studies support the MPO’s visions and goals, which include increasing transportation safety, maintaining the transportation system, advancing mobility, and reducing congestion. 

2          Existing intersection Conditions

North Meadows Road (Route 27) at West Street is a four-way signalized intersection. It is one of a few signalized intersections in Medfield, located within one mile northwest of the town center. Figure 1 shows the location of the intersection, existing street layouts, and major developments in the study area.

Route 27 is a north-south state highway running from Kingston to Chelmsford. For most of its route, it serves as an intermediate arterial between Interstate 95 and Interstate 495 and is heavily used by commuters in the region. The section of Route 27 north of Route 129 in Medfield is known as North Meadows Road. It consists of two travel lanes, one in each direction (approximately 12 to 14 feet wide) with a double yellow centerline, and a relatively wide (10 feet or greater) shoulder on both sides. There are no sidewalks on either side of the roadway. The speed limit is 45 miles per hour (mph) in both directions approaching the study intersection.2 The roadway, classified as an urban principal arterial, is under the town’s jurisdiction and is a part of the National Highway System (NHS).

West Street is an urban minor arterial owned by the town. The roadway is about one and one-quarter miles long. It connects to Harding Street and Dover Road, which continue east to Dover and west to Millis. It is a two-lane roadway that contains a travel lane approximately 11 to 12 feet wide and a shoulder of two to three feet in each direction. It has no sidewalks, except the north side of the street about 600 to 1,400 feet west of the intersection from Marsh Drive to Gatehouse Drive. The speed limit is 35 mph in both directions in the vicinity of the intersection.

Figure 1
Study Area Map
North Meadows Road at West Street, Medfield

At the intersection, all the approaches increase in width but remain a single travel lane shared by all turning movements. North Meadows Road flares to more than 30 feet wide in both approaches, which allows one or two right-turning vehicles to wait at the stop line or to turn right on red. However, there are no lane use pavement markings on these approaches. The flared areas on both approaches are also frequently used by through traffic to go around a left-turning traffic queue. West Street flares just slightly with no space for the storage of additional right-turning vehicle at the stop line. With the stop lines positioned far back (20 to 30 feet) from the intersection and wide turning radii at all corners, the intersection appears to be very large even though it has only one lane on all approaches.

The traffic signal at the intersection operates in a simple two-phase mode: one phase for both approaches of North Meadows Road and one phase for both approaches of West Street, with no pedestrian signal phases. Based on field observations, it operates at a cycle length of 74 seconds that consist of 38 seconds (30-second green time, plus 4-second yellow change interval and 4-second all-red interval) for North Meadows Road approaches and 36 seconds (30-second green time, plus 4-second yellow change and 2-second all-red interval) for West Street approaches.

Standard three-section signals are provided on all approaches of the intersection. Two overhead signals are provided for each of the North Meadows Road approaches. One overhead signal and one post-mounted signal are provided for both approaches of West Street. The post-mounted signals are not well positioned for drivers, as they are low and located far from the intersection center. All the signals at the intersection are not equipped with backplates or retroreflective borders.

There are no crosswalks at the intersection and no sidewalks on either side of all the approaches. There are guardrails present at all corners, except the northeast corner. Under the existing intersection layout, these guardrails are used to prevent the turning vehicles from driving into adjacent ditches or parking lots and to protect the roadside signal and lighting equipment. They also deter people who are walking from crossing the intersection where the traffic conditions can be complicated and compel them to cross at other locations with narrower road width or marked crosswalks with protected pedestrian signals, such as the intersection of North Meadows Road at Dale Street.

There are no dedicated bicycle accommodations on either roadway in the study area. North Meadows Road contains shoulders of approximately 10 feet wide on both sides. Some shoulder sections between Route 109 and Dale Street are marked with white hatch lines to prohibit parking. The hatched shoulders could discourage people who ride bicycles from using the shoulders and compel them to use the travel lanes. Meanwhile, in other unmarked shoulder sections, parked vehicles could occupy the space from time to time, as there are no clear regulations about parking on North Meadows Road. West Street contains narrow shoulders of approximately two to three feet wide, which are not suitable for bicycle travel. 

There are no public transit stops and no marked on-street parking spaces in the areas adjacent to the intersection.

The land uses in the vicinity of the intersection include business, industrial, residential, and school. Adjacent to the intersection, there are a number of businesses, including a fun and fitness center for children (My Gym), a landscape design company, a daycare (Medfield Children’s Center), an auto body shop, an early education school (The Goddard School of Medfield), and a veterinarian clinic. Further out, the land uses on North Meadows Road include multi-family residents and undeveloped land to the south, and mostly open space to the north. The land uses on West Street include a number of businesses and industrial offices and a nonprofit organization (American Region) to the east, and mostly residential and a hardware store (Do it Best) to the west.

The intersection is located in one of the fastest growing areas in Medfield. The Town currently is in the process of developing a new master plan. The areas adjacent to North Meadows Road have the potential for vibrant mixed-use developments, with the support of essential Complete Streets elements. A key element would be to reconstruct the intersection and improve operations and safety for users of all modes.

3          Issues and Concerns

Based on MPO staff’s field observations, discussions with the town officers, and analyses of crash data and existing operations, major issues and concerns at the intersection include the following.

• Crash severity
  The intersection is on the list of 2014–16 statewide top 200 crash locations (ranked 121). The severity of crashes at this intersection is a major concern, as nearly half of the crashes caused personal injuries.
• High frequency of red-light running
  Further analysis of crash data indicates that about 30 percent of the crashes were caused by red light violations and almost all of them resulted in injuries.
• High approach travel speeds
  Based on comments from the town and field observations, vehicles generally are traveling above the speed limit on North Meadows Road (45 mph) and West Street (35 mph).
• Inadequate intersection geometry
  Nearly unchanged from the rural highway layout, the wide single-lane approaches with wide turning radii are not suitable for walking and biking trips. Meanwhile, the current traffic volumes (with high proportion of turning movements) are increasing. Drivers are likely to be confused in the unmarked flared areas near the intersection, which also causes drivers to attempt to maneuver around turning vehicles leading to confusion and crashes at the intersection.
• Insufficient signal displays
  All the approaches of the intersection currently use the basic three-section signals, with no backplates and no retroreflective borders. They appear to be insufficient for drivers to observe from a distance, especially on the westbound approach, where the overhead signal is not aligned with the approach and the post-mounted signal is low and located too far from the intersection.
• Obsolete signal equipment and operations
  The signal control equipment is outdated. Constrained by the existing geometry, the traffic signal operates in a basic two-phase mode, with traffic running concurrently from opposing approaches. Recent intersection turning counts indicate that left-turn lanes with protected or permissive signal phases are needed at this intersection.
• No pedestrian and bicycle accommodations
  There are no crosswalks or pedestrian signals at the intersection. Meanwhile, the signal is not equipped with bicycle detection. Based on the land use and the surrounding developable area, these accommodations are needed at the intersection.

4          Crash data analysis

Crash data analysis is essential to identify safety and operational problems at an intersection. Analyzing the data on the frequency of crashes, types and patterns of collisions, and the circumstances under which crashes occur, such as the time of day and roadway surface conditions, helps to develop improvement strategies.

4.1      Collision Trends and Crash Statistics

This intersection is ranked 121 of the 2014–16 state top 200 crash locations with a high Equivalent Property Damage Only (EPDO) crash rate.3 MassDOT conducted a Road Safety Audit (RSA) for this intersection on June 15, 2019.4 The RSA analysis was based on crash data from 2014 to 2017. To further examine the intersection safety conditions with updated data, MPO staff added the recent two-year crash data (Medfield Police crash reports from January 2018 to November 2019) for this study.

In total, 46 crashes occurred during the six-year period. Table 1 summarizes the severity, collision type, pedestrian or bicycle involvement, time of day, weather, and pavement conditions of the 46 crashes by year and in total.

Nearly 40 percent (17) of total crashes at the intersection caused personal injuries. The most prevalent crash type is the angle collision, 60 percent (28) of all crashes. The second most common type is the rear-end collision, accounting for nearly 25 percent (11) of all crashes. There were a few other types of collisions, such as single-vehicle and sideswipe collisions, which account for approximately 15 percent (7) of all crashes. No crashes at the intersection involved pedestrians or bicyclists. Noticeably, 56 percent (26) occurred during the weekday peak traffic periods (7:00–9:00 AM and 3:30–6:30 PM).

Table 1
Crash Data Summary
Medfield Police Crash Reports, January 2014–November 2019

4.2      Collision Diagram

Based on police reports, staff constructed a collision diagram (Figure 2) that shows the locations and collision patterns of all the crashes at the intersection in the period of nearly six years (each indexed by chronological order of occurrence, including the 2014–17 crashes identified in the RSA). The information of each crash, including date, time, severity, collision type, weather and road conditions, driver contributing code, and police comments are listed in Appendix A.

4.3      Safety Analysis

The major severe crash type at signalized intersections is a right-angle crash, where one vehicle violates the red signal.5 The high number of angle crashes at this intersection resulted in a high injury rate.

As shown in the collision diagram (Figure 2), there were 21 right-angle crashes that can be separated into the following patterns:

• seven involving a northbound (North Meadows Road) through vehicle and an eastbound (West Street) through vehicle
• seven involving a southbound (North Meadows Road) through vehicle and an eastbound (West Street) through vehicle
• four involving a southbound through vehicle and a westbound through vehicle
• three involving a northbound through vehicle and a westbound through vehicle

Figure 2
Collision Diagram: North Meadows Road at West Street
Medfield Police Reports: January 2014–November 2019

These right-angle crashes plus another angle crash involving a westbound left-turn vehicle and an eastbound through vehicle on West Street, 22 crashes in total (accounting for nearly one-half of all the intersection crashes), were identified to be caused by a vehicle running a red light at the intersection. Further analysis indicates that the number of red-light running on the West Street approaches (14 in total, nine eastbound and five westbound) is higher than that on the North Meadows Road approaches (eight in total, six southbound and two northbound), even though the prevailing travel speeds are much higher on the North Meadows Road approaches.

There is no simple or single reason to explain why motorists run red lights at an intersection. It usually involves a number of factors and the compound effects. For this intersection, the high frequency of red-light running may occur because of one of the following reasons:

•  Speeding: The RSA noted that vehicles generally are traveling above the speed limit on North Meadows Road and West Street. Under the high-speed situation, motorists may not be able to stop in time for a red light or the clearance interval is inadequate.
• Intersection environment: The geometry of North Meadows Road (Route 27) approaching the intersection is straight and wide. The adjacent open areas may not provide sufficient visual cues for motorists to be aware of their excessive speed and that they are approaching an intersection. Though not as wide, the adjacent areas of West Street are wooded with spotty residences and businesses. Motorists, including a large portion of cross-town travelers, also tend to drive fast on West Street approaching the intersection.
• Signal visibility: The standard three-section signals with no backplates and no retroreflective borders on all approaches at this intersection may not be sufficient for motorists to see them. The two overhead signals on North Meadows Road appear to be small under the wide roadway environment. The post-mounted signal on West Street, low and far away from the intersection center, is especially difficult for motorists to see. The overhead signal on West Street, not positioned in the center with no double-up display, can be hard to see when it blends into the street’s overgrown vegetation. Meanwhile, the stop lines of all approaches are located far back from the intersection, which may reduce motorists’ visibility of signal changes.
• Signal operation: The high red-light running frequency may also occur because of inappropriate signal timing settings at the intersection. Motorists’ decision at the light-changing moment is highly correlated to the duration of the yellow change interval and the approaching speed. According to The Manual on Uniform Traffic Control Devices for Streets and Highways (MUTCD), the duration of the yellow change interval should be approximately three to six seconds, with longer intervals reserved for high-speed approaches. 6 The four-second yellow change interval on the North Meadows Road approaches may not be sufficient under the prevailing speed of 50 mph or higher (see further analysis in Section 6.2).
• Sun glare: The police reports show that a few red-light violators claimed that they were blinded by the sun glare when they were approaching the intersection. As North Meadows Road is oriented in the northwest-southeast direction, motorists are affected by the sun glare in peak traffic periods (the southbound in the morning and the northbound in the evening). The sun glare also affects motorists on West Street in peak traffic periods and in the direction with busier traffic (the eastbound in the morning and the westbound in the evening).
•  
• There were six angle crashes that can be categorized as left-turn crashes. They all involved a left turning vehicle and a through vehicle in the opposite direction. These crashes usually occurred at the intersections where left turns are operated in permissive phasing under the heavy opposite traffic. The six crashes at this intersection can be separated as follows:
• two involving a northbound left-turn vehicle and a southbound through vehicle
• two involving a southbound left-turn vehicle and a northbound through vehicle
• two involving a westbound left-turn vehicle and an eastbound through vehicle

The traffic signal at this intersection operates in permissive phasing that allows traffic in the opposite approaches to move concurrently. With no storage lane and no exclusive signal phase, left turns usually have to wait at the intersection for gaps in the opposite traffic stream. Meanwhile, approaching the intersection with no separated lanes, all the movements tend to cluster in the intersection and block each other’s views and cause driver confusion, especially during busy traffic conditions.

• Note that the left-turn crashes occurred more frequently on the North Meadows Road approaches and on the West Street westbound approaches. Both approaches of North Meadows Road are wide, which contains a flared area for through vehicles to go around the vehicle(s) waiting to turn left. However, such maneuvers create potential conflicts between the through vehicle and a left turning vehicle in the opposite direction, as the two drivers’ view to each other can be blocked by the vehicle waiting to turn left. The West Street westbound approach carries a high left-turn volume during peak traffic periods. The left-turn vehicles tend to be stuck in the intersection, especially in the morning peak hours.

There was only one right-turn angle crash that involved a vehicle turning right on westbound and a vehicle going straight on northbound. The crash did not cause injuries.

There were 11 rear-end crashes, which can be separated into the following approaches:

• five on the northbound approach
• three on the southbound approach
• two on the westbound approach
• one on the eastbound approach

Rear-end crashes at an intersection usually caused by motorists’ inattention, distraction, or not keeping sufficient distance (following too closely) to the vehicle in front. At this intersection, they were mainly caused by the sudden stop of a vehicle in front traveling fast or suddenly slowing down by a left turning vehicle. The RSA indicated that vehicles traveling in the northbound approach on North Meadows Road through the intersection are especially prone to speeding. As a result, there are more rear-end crashes occurring on this approach than the other approaches. Two of the rear-end crashes caused injuries and both occurred on the northbound approach.

The last observed collision pattern contains three single vehicle crashes at the intersection, two at the southwest corner, and one at the northeast corner. They mainly were caused by speeding motorists, turning too fast, or driving carelessly.

5          Existing Traffic Conditions

To examine the existing traffic conditions, MPO staff requested MassDOT’s assistance in collecting intersection turning movement counts (TMC) and roadway approach speeds using Automatic Traffic Recorder (ATR) counts at various locations for this study. The data collection was delayed by a snowstorm in late November 2019 and periodic snowfall in the following months. In March, just as MassDOT scheduled to collect the counts for this study, the state’s traffic data collection operations were suspended because of the COVID-19 pandemic.

Fortunately, traffic studies for recently proposed developments in the vicinity of the intersection were available for this study to evaluate the existing traffic conditions. These studies are

• Traffic Impact Assessment for Proposed American Legion Apartments, October 30, 2019 (traffic data collected on October 30, 2018);
• Transportation Impact Assessment for Medfield Green (Meadows) Residential Development, October 2018 (traffic data collected on September 28–29, 2016);
• Traffic Impact Assessment for New Apartment Building (Hillside Village) at 90 North Meadows Road, March 2018; and
• Traffic and Circulation Assessment for Proposed Daycare Facility (Medfield Children’s Center), January 2018.

5.1      Daily Traffic Volumes

Based on the ATR counts collected for the Medfield Meadows development traffic study in September 2016 and historical counts collected at the MassDOT continuous count station on Route 27 south of Hospital Road in Medfield (location ID: 39), staff estimated daily traffic volumes on the four roadway sections adjoining the intersection. The estimated volumes represent daily traffic near the intersection under normal conditions (not affected by the pandemic conditions).

• North Meadows Road south of the intersection—approximately 10,500 to 11,000 vehicles per day (vpd), with a split of 49 percent northbound/51 percent southbound
• North Meadows Road north of the intersection—approximately 8,500 to 9,000 vpd, with a split of 50 percent northbound/50 percent southbound
• West Street east of the intersection—approximately 6,000 vpd, with a split of 49 percent eastbound/51 percent westbound
• West Street west of the intersection—approximately 6,000 vpd, with a split of 50 percent eastbound/50 percent westbound

5.2      Turning Movement Volumes

Staff estimated the turning movements at this intersection based on counts from the four traffic studies but pivoting on the two recent studies, the proposed American Legion apartments and the Medfield Meadows residential developments. 7 Figure 3 summarizes the estimated 2020 AM and PM peak-hour traffic volumes by approaches. The estimation represents the optimal conditions in 2020, not the COVID-19 conditions.

The intersection is estimated to carry approximately 1,750 to 1,850 entry vehicles per peak hour during high travel months (September and October) under the normal traffic conditions. In the AM peak hour, the West Street eastbound approach carries a volume much higher than other approaches. In the PM peak hour, the West Street westbound approach carries the highest volume at the intersection. Right-turn volumes are generally low, except the North Meadows Road northbound in the morning, which carries about 100 vehicles per peak hour.

5.3      Intersection Approach Speeds

Traffic studies usually apply the observed or estimated 85^th percentile speeds to assess how fast vehicles are approaching an intersection. The 85^th percentile speed is the speed at or below which 85 percent of vehicles passing a given point are traveling, and is the principal value used to establish speed controls by the state. It can be regarded as the prevailing vehicle speed on the roadway adjacent to the specific location.

Figure 3
Estimated 2020 Weekday Traffic Volumes
North Meadows Road at West Street, Medfield

The above traffic studies provided a few observed 85^th percentile speeds at the following locations: 

• North Meadows Road just north of the intersection, at the Medfield Children’s Center (45 mph speed limit in both directions)—49 mph in the northbound and 50 mph in the southbound (observed on January 3, 2018)
• West Street just east of the intersection, at Peter Kristof Way (35 mph speed limit in both directions)—39 mph in the eastbound and 38 mph in the westbound (observed on October 30, 2018)
• North Meadows Road about a half mile south of the intersection, between Grove Street and Dale Street at the Medfield Children’s Center (40 mph speed limit in both directions)—44 mph in the northbound and 41 mph in the southbound (observed on September 28–29, 2016)

These observed 85^th percentile speeds may not be suitable to directly use as approach speeds for the intersection, as the first two locations are located too close to the intersection (about 250 to 300 feet) and the third location is too far and under a lower speed limit. Staff therefore applied 7 mph above the posted speeds as the prevailing approach speeds for the intersection’s operational analyses based on the Institute of Transportation Engineers (ITE) guideline. 8

6          intersection operations analysis

Based on the estimated turning movement volumes, staff conducted the intersection capacity analysis by using the Synchro traffic analysis and simulation program.9 Staff also reviewed the signal settings of the yellow change and all-red clearance intervals and the issue of pedestrian and bicycle accommodations.

6.1      Intersection Capacity Analysis

In general, the intersection operates at an acceptable level of service (LOS) on all approaches in both the AM and PM peak hours. Field observations indicated that there were no extensive traffic queues during the peak hours, except the eastbound approach in the morning and the westbound approach in the evening.

Table 2 summarizes the estimated LOS, average delay, and volume to capacity ratio (V/C) for all the approaches at the intersection in the AM and PM peak hours. The estimation is based on an observed cycle length of 74 seconds that consist of 38 seconds (30-second green, plus 4-second yellow, and 4-second all-red) for North Meadows Road approaches and 36 seconds (30-second green, plus 4-second yellow and 2-second all-red) for West Street approaches.

Table 2
Summary of Intersection Capacity Analyses
Estimated 2020 AM and PM Peak-Hour Traffic Conditions

Notes:

Approach: NB = Northbound; SB = Southbound; EB = Eastbound; WB = Westbound

All movements share a single lane on all approaches

AM Peak Hour = 8:00–9:00; PM Peak Hour = 5:00–6:00

Delay = Average delay per vehicle (seconds)

LOS = Level of Service. V/C = Volume to capacity ratio.

Appendix B contains the Synchro reports of the AM and PM intersection capacity analyses underestimated existing conditions. Note that these analyses do not include safety concerns and impacts from the shared single-lane operations (analyzed in the section of crash data analysis).

6.2      Yellow Change Interval and Red Clearance Interval

To further examine the issue of red-light running at this intersection, staff conducted a quick analysis of the yellow change and all-red (red) clearance intervals at this intersection. The yellow change and red clearance intervals compose the two parts of the traffic signal change period. The determination of the intervals depend on a number of factors, including the intersection and approaching roadway characteristics, and traffic conditions.

Appendix C summarizes the estimation of yellow change and red clearance intervals for all the approaches at the intersection, based on the guidelines recommended by ITE. It also includes the existing yellow change and red clearance intervals observed in the field for comparison. Appendix D contains details of the ITE method and formula for calculating the two intervals.

The calculation for the yellow change interval provides the minimum interval to allow time for a motorist to see the yellow signal indication and decide whether to stop or to enter the intersection. This time includes the motorist’s perception-reaction time, generally one second. It should be sufficient time for motorists that are too close to the intersection to decelerate comfortably to a stop and thus reach the intersection before the right-of-way terminates. The calculation for the red clearance interval allows motorists that enter the intersection before the yellow change interval terminates time to continue through to the far side of the intersection before conflicting traffic enters.

Currently, North Meadows Road approaches operate with a signal change period of eight seconds that consists of four seconds of yellow change interval and four seconds of red clearance interval, and West Street approaches operate with a signal change period of six seconds that consists of four seconds of yellow change interval and two seconds of red clearance interval. The yellow change interval for North Meadows Road approaches is slightly short, compared to the estimated five seconds. The red clearance interval for West Street approaches is slightly short, compared to the estimated 2.5 seconds. In terms of the total signal change periods for both roadway approaches, they are close to the estimated 7.5 seconds for North Meadows Road approaches and 6.5 seconds for West Street approaches.

The signal change setting is critical for traffic safety at an intersection. Note that this is a quick estimation based on some assumptions and approximations, including the estimated 85^th percentile speeds. In the short term, a further engineering study should be conducted with radar-measured 85^th percentile speeds on all approaches and surveyed intersection geometry, before making adjustments to the existing yellow change and red clearance intervals.

In the long term, the intersection should be redesigned with lower approach speeds, reduced turning radii, and signal vehicle detection to minimize dilemma zones. 10 Under the new intersection design, the intersection would operate at the usual range of yellow change interval (three to four seconds) and red clearance interval (one to two seconds).

6.3      Pedestrian and Bicycle Accommodations

There are insufficient pedestrian and bicycle accommodations at the intersection and its adjacent areas. Both North Meadows Road and West Street have no sidewalks, except an 800-foot section on the north side of West Street west of the intersection. The intersection has no crosswalks on all approaches.

Both roadways have no dedicated bicycle accommodations. Although North Meadows Road has shoulders of approximately 10 feet wide in both directions approaching the intersection, it has no consistent treatment in accommodating bicycles as parking on the shoulders is not explicitly prohibited and some sections are hatch-marked.

During the recent development of the Medfield town-wide master plan, residents strongly supported more sidewalks and bikes to reduce the dependence on cars and buses and prioritizing walking and biking in the transportation system to enhance the health and wellness of residents. Meanwhile, the intersection was described as a location with major safety and congestion concerns and new developments in the area have generated and will generate more walking trips. Pedestrian and bicycle accommodations should be prioritized in the redesign and reconstruction of the intersection.

7          Proposed short-term improvements

Based on the above analyses, MPO staff developed a series of short- and long-term improvements to address safety and operational problems at the intersection. The proposed short-term improvements generally can be implemented within two years at a relatively low cost (usually under $30,000). The proposed long-term improvements are more complicated and cover larger areas, thus requiring intensive planning and design, and significant funding. They are analyzed in the next section. The proposed short-term improvements are summarized below, from the lowest to the highest cost:

• Reinforce speed regulations on the roadways approaching the intersection. 11
• Restripe the stop lines of all approaches to at least 1.5 feet wide and consider relocating the stop lines on both approaches of North Meadows Road and the eastbound approach of West Street approximately five to 10 feet toward the intersection.
• Install MUTCD Signal Ahead warning sign (W3-3) on both approaches of North Meadows Road to increase motorists’ awareness and readiness to stop.12
• Consider installing solar-powered speed feedback (Your Speed) warning signs in conjunction with the posted speed regulation at suitable locations approaching the intersection.
• Consider and examine the feasibility of reducing the speed limit from 45 MPH to 40 MPH on both approaches of North Meadows Road.13
• Examine the feasibility of installing backplates with retroreflective borders on the existing signal heads or new signal heads.14
• Consider adjusting the yellow change intervals and red clearance intervals based on a further engineering study and retiming the traffic signal after the study.15
• Consider striping all travel lanes from 12 to 11 feet wide approaching the intersection and striping the 10-foot shoulders on North Meadows Road to six-foot bike lanes with a four-foot buffer from traffic.16

8          long-term improvement alternatives

The proposed long-term improvements would require intensive planning and design and significant funding. Staff developed a number of long-term improvement alternatives for this intersection and its immediate areas. Based on the goals of maximizing safety and operational benefits for all transportation modes and minimizing land-taking and construction impacts, staff identified three alternatives that are more feasible than others.

Staff also analyzed traffic operations for the alternatives and the base case (no-build scenario) under the projected 2030 traffic conditions. For comparison purposes, the analysis includes a future year no-build scenario that contains only signal retiming with no geometry modifications and no signal system upgrade.

Key elements of the no-build scenario and the three alternatives are summarized as below.

No-Build Scenario

The no-build alternative assumes that the intersection would remain the same as the existing conditions, which include a single lane for all approaches, no crosswalks, no bicycle detection, and no signal system update. The only improvement included is to retime the signal with the estimated yellow change and red clearance intervals (Section 6.2) and a slight reduction of overall cycle length.

Alternative One

Alternative 1 proposes to modify the intersection layout and upgrade the signal system for adding protected left-turn operation, protected pedestrian crossing, and bicycle detection. Figure 4 shows the conceptual plan of the alternative. Key elements of the alternative include  

• adding a left-turn exclusive lane on all approaches;
• reducing turning radii at all corners;
• installing crosswalks on all roadways;
• installing six-foot sidewalks on both sides of all approaches with Americans with Disabilities Act (ADA) compliant wheelchair ramps connected to the crosswalk;
• upgrading the signal system to include accessible count-down pedestrian signals, bicycle detection, and new signal indications; 17
•  
• installing six-foot bike lanes on North Meadows Road in both directions;18 and
• making West Street a bike shared road.

Alternative Two

Alternative 2 proposes to modify the intersection layout and upgrade the signal system for adding protected/permissive left-turn operation, protected pedestrian crossing, and bicycle detection. The alternative would require a similar layout to Alternative 1 (see Figure 4 for the conceptual plan).19 Key elements of the alternative include  

• adding a left-turn exclusive lane on all approaches;
• reducing turning radii at all corners;
• installing crosswalks on all approaches;
• installing six-foot sidewalks on both sides of all roadways with ADA compliant wheelchair ramps connected to the crosswalk;
• upgrading the signal system to include accessible count-down pedestrian signals, bicycle detection, and new signal indications;
• installing six-foot bike lanes on North Meadows Road in both directions; and
• making West Street a bike shared road.

Alternative Three

Alternative 3 proposes to convert the intersection into a single-lane modern roundabout. Figure 5 shows the conceptual plan of the alternative. Key elements of the alternative include  

• designing and constructing a single-lane modern roundabout with an inscribed circle of at least 130 feet in diameter;
• adding a right-turn exclusive lane on the northbound approach;
• installing six-foot sidewalks on both sides of all roadways;
• installing crosswalks on all approaches;
• installing 10-foot shared-use paths encircling the roundabout with ADA-compliant wheelchair ramps connected to the crosswalk;20
• Installing six-foot bike lanes on North Meadows Road in both directions;
• making West Street a bike shared road; and
• installing sharrow makings on West Street and in the circulatory roadway for bicycle travel.

Table 3 summarizes the intersection capacity analyses for the no-build scenario and the three alternatives under the predicted 2030 AM and PM peak-hour traffic conditions.21 Appendix E contains Synchro intersection capacity analysis reports that detail input volumes, lane configurations, signal timing settings, and analysis results of the various alternatives.

In terms of the overall intersection operation, all three alternatives would operate at acceptable levels of services in both the AM and PM peak hours.22 In terms of individual approaches, all three alternatives would operate at acceptable levels of services in the AM peak hour, except the left turns on the West Street westbound in Alternative 1 and the entire approach of West Street eastbound in Alternative 3. In the PM peak hour, all approaches in the three alternatives would operate acceptably.

Note that these capacity analyses do not explicitly indicate the safety benefits of the three alternatives. Alternatives 1and 2 would reduce left-turn crashes and right-angle crashes and thus reduce the crash severity and improve safety for users of all modes at the intersection. Alternative 1 would provide more protection for left turns than Alternative 2 but would also increase average delay per vehicle on all approaches. Alternative 3 would slow down all the traffic through the roundabout and would reduce the crash severity most significantly.

Figure 4
Proposed Long-Term Improvement Alternatives 1 and 2
North Meadows Road at West Street, Medfield

Figure 5
Proposed Long-Term Improvement Alternative 3
North Meadows Road at West Street, Medfield

Table 3
Intersection Capacity Analysis
No-Build and Long-Term Improvement Alternatives
2030 Projected Traffic Conditions

However, Alternatives 1 and 2 can be constructed within the existing roadway layout without any land takings. Alternative 3 would require a much larger footprint and require some land takings on the east side of North Meadows Road. In addition, Alternative 3 would require significant landfill and drainage rearrangements, as the roundabout would take up the ditched areas on the west side of North Meadows Road. All of these should be further investigated at the functional design stage.

9         Recommendations

This study performed a series of safety and operations analyses, identified issues and concerns, and proposed short- and long-term improvements at the intersection. The proposed short-term improvements would enhance safety and operations for the intersection under the existing conditions. With a relatively high benefit/cost ratio, they should be implemented as soon as resources are available from highway maintenance or local Chapter 90 funding.

The proposed long-term improvements, such as reconstructing the intersection by adding necessary turning lanes; installing sidewalks, crosswalks, and bicycle accommodations; and renovating the signal system to include pedestrian signals and bicycle detection, would significantly address the safety and operational problems at the intersection. At this preliminary planning stage, staff recommend Alternatives 1 or 2, considering that Alternative 3 would require land takings and major landfill and drainage rearrangements and thus may have some impacts to the surrounding areas. However, all three proposed alternatives should be included and further investigated at the functional design stage.

The Town of Medfield has jurisdiction of the intersection and roadways in the study area, and is responsible for renovation of the intersection to improve safety, mobility, connectivity, and operations. The Town is currently in the process of developing a new master plan. North Meadows Road and its adjacent areas have the potential to accommodate vibrant mixed-use developments with Complete Streets design. Improving safety and operations at this intersection is one essential component in successfully developing the areas.

This study gives the Town an opportunity to address the needs of the intersection and plan for design and engineering. The next steps would be to select the preferred alternative that is sensitive to the goals and needs of stakeholders and advance the project through the planning process. These steps will depend upon cooperation between MassDOT, the Town, and the MPO to begin the project notification and review process, and complete the project initiation form. After completing the initial steps, the Town and MassDOT can start preliminary design and engineering to place the project in the Transportation Improvement Program. Project development is a complicated process that takes transportation improvements from concept to construction and is influenced by factors such as financial limitations and agency programmatic commitments (see Appendix F for an overview of this process).

This study supports the MPO’s visions and goals, which include increasing transportation safety, maintaining the transportation system, advancing mobility and access, reducing congestion, and expanding the opportunities for walking and bicycling, while making them safer. If implemented, the improvements proposed in this report would modernize the roadway and significantly improve safety and mobility of all users.

cc:       Sarah Raposa, Town of Medfield

Joseph Frawley, MassDOT Highway Division District 3

Appendices

Medfield Intersection Study Appendices