Mixing pedestrians and bicycles in a limited space is generally problematic, as explained in the Massachusetts Highway Department’s Project Development & Design Guide (2006):
11.4 Shared Use Path Design
It is important to identify the intended users of a path early in the design process to the extent possible, to provide appropriate accommodation and address potential conflicts. A mix of users on a shared use path is not always a desirable situation because the potential for conflicts is high. For example, commuting bicyclists are slowed by users on recreational strolls. The safety and enjoyment of a path can decline when conflicts among users occur. For these reasons, the designer should avoid creating situations in which sidewalks are used as shared use paths. Conflicts between users stem from many sources including:
It is important to identify the intended users of a path early in the design process to the extent possible, to provide appropriate accommodation and address potential conflicts. A mix of users on a shared use path is not always a desirable situation because the potential for conflicts is high. For example, commuting bicyclists are slowed by users on recreational strolls. The safety and enjoyment of a path can decline when conflicts among users occur. For these reasons, the designer should avoid creating situations in which sidewalks are used as shared use paths. Conflicts between users stem from many sources including:
- Personal expectations;
- Overcrowding;
- Clashes between different users;
- Various levels of ability and experience; and
- Differences in speed.
An 8-foot path is recommended only in rare cases where usage is expected to remain low. From Chapter 5 of the American Association of State Highway and Transportation Officials’ Guide for the Development of Bicycle Facilities, 4th Edition (2012):
5.2.1 Width and Clearance
The usable width and the horizontal clearance for a shared use path are primary design considerations. Figure 5-1 depicts the typical cross section of a shared use path. The appropriate paved width for a shared use path is dependent on the context, volume, and mix of users. The minimum paved width for a two-directional shared use path is 10 ft (3.0 m). Typically, widths range from 10 to 14 ft (3.0 to 4.3 m), with the wider values applicable to areas with high use and/or a wider variety of user groups. In very rare circumstances, a reduced width of 8 ft (2.4 m) may be used where the following conditions prevail:
The usable width and the horizontal clearance for a shared use path are primary design considerations. Figure 5-1 depicts the typical cross section of a shared use path. The appropriate paved width for a shared use path is dependent on the context, volume, and mix of users. The minimum paved width for a two-directional shared use path is 10 ft (3.0 m). Typically, widths range from 10 to 14 ft (3.0 to 4.3 m), with the wider values applicable to areas with high use and/or a wider variety of user groups. In very rare circumstances, a reduced width of 8 ft (2.4 m) may be used where the following conditions prevail:
- Bicycle traffic is expected to be low, even on peak days or during peak hours.
- Pedestrian use of the facility is not expected to be more than occasional.
- Horizontal and vertical alignments provide frequent, well-designed passing and resting opportunities.
This is confirmed in Chapter 6 of the Federal Highway Administration’s Shared Use Path Level of Service Calculator (2006):
TRAIL WIDTH
The findings of this study provide strong support for the standard trail width guidance provided in the AASHTO Guide for the Development of Bicycle Facilities. Trails having 8.0-ft width, which AASHTO recommends only in “rare instances,” were found to have poor LOS [Level of Service], except at very low volumes or with user mixes that included few pedestrians and runners. The findings of this research support AASHTO’s minimum “recommended paved width for a two-directional shared-use path of ten feet.”
The findings of this study provide strong support for the standard trail width guidance provided in the AASHTO Guide for the Development of Bicycle Facilities. Trails having 8.0-ft width, which AASHTO recommends only in “rare instances,” were found to have poor LOS [Level of Service], except at very low volumes or with user mixes that included few pedestrians and runners. The findings of this research support AASHTO’s minimum “recommended paved width for a two-directional shared-use path of ten feet.”
Residents on South Main St. already make regular (“more than occasional”) use the existing sidewalk for exercise and dog-walking. In many sections, the proposed 8-foot path will be up against fences, reducing opportunities to step off the path for passing purposes.
Regardless of path width, warnings about problems with anything but low levels of pedestrian and bicycle mixing can be found in numerous planning guides. From the Chapter 4 of the New Jersey Department of Transportation’s Bikeway Planning and Design Guidelines:
1. Planning Issues in Designating Bicycle Paths
a. Shared Use of Multiple Use Paths
As indicated, off-road paths are rarely constructed for the exclusive use of bicyclists, but instead must be shared with other non-motorized users. Just as conflicts can occur between bicycles and pedestrians on sidewalks, or between motor vehicles and bicycles on highways not constructed to compatible standards, heavy use of trails and other multiple use paths can create conflicts between different user groups. Among bicyclists, basic riders and young children who travel at speeds below 9 mph will conflict with more advanced riders travelling at speeds greater than 12 mph. Pedestrians, in-line skaters and bicyclists, both basic and advanced, will wish to travel at substantially different speeds. So long as the volume of users is low, the conflicts between different groups can be kept manageable. However, even moderate volumes may result in substantial deterioration in level of service and can expose users to substantial safety risks. Conflicts between users are especially likely to occur on regionally significant recreational trails which attract a broad diversity of users.
a. Shared Use of Multiple Use Paths
As indicated, off-road paths are rarely constructed for the exclusive use of bicyclists, but instead must be shared with other non-motorized users. Just as conflicts can occur between bicycles and pedestrians on sidewalks, or between motor vehicles and bicycles on highways not constructed to compatible standards, heavy use of trails and other multiple use paths can create conflicts between different user groups. Among bicyclists, basic riders and young children who travel at speeds below 9 mph will conflict with more advanced riders travelling at speeds greater than 12 mph. Pedestrians, in-line skaters and bicyclists, both basic and advanced, will wish to travel at substantially different speeds. So long as the volume of users is low, the conflicts between different groups can be kept manageable. However, even moderate volumes may result in substantial deterioration in level of service and can expose users to substantial safety risks. Conflicts between users are especially likely to occur on regionally significant recreational trails which attract a broad diversity of users.
Keeping pedestrians and bicycles separate (as recommended by Fuss & O’Neill in 2015) and providing safe accommodation for bicycles to ride in the road is the most effective way of smoothly handling a wide range of pedestrian and bicycle usage levels on a quiet neighborhood street such as Haydenville's South Main Street.