Outdoor dining has been a lifeline for many local businesses this year, while providing much needed relief, enjoyment, and new destinations for Cambridge residents and visitors. The proliferation of outdoor dining has also helped us pilot and re-envision how our streets can be used to expand our public space for people rather than being exclusively for cars and parking. Cambridge Bicycle Safety supports these new uses and notes that such outdoor dining uses are fully compatible with continuous protected bike lanes and can be implemented alongside safety improvements for cyclists and pedestrians. In fact, a varied streetscape that includes outdoor dining is safer for everyone, by calming traffic and reducing pedestrian crossing distances.
The majority of on-street outdoor dining installations in Cambridge are fully contained within the bounds of adjacent standard parallel parking spaces (7’ wide). Thus, from a basic dimensional perspective, on-street outdoor dining and parking spaces take up the same width of the street’s cross section.
On-street outdoor dining installations do have two major differences from parking spaces that actually make it easier to design protected bike lanes. First, on-street outdoor dining installations do not have car doors, and thus there is no need for a “door zone” buffer, which typically takes up 3’ of space between parking and a protected bike lane. Instead, a smaller buffer can be used in some situations. Second, unlike parking spaces which need to allow regular vehicle movement, on-street outdoor dining installations are typically built in place and do not move for several months, and thus it is possible to build protected bike lanes (with physical barriers) around them.
Concretely, there are two basic on-street outdoor dining configurations that have been shown to work well with protected bike lanes: (1) curbside on-street outdoor dining, and (2) floating on-street outdoor dining. Dimensionally, these designs require equal or lesser space as compared to parking-protected bike lanes, and thus, they can be used in all the same situations, plus additional situations. These two designs are detailed below.
Curbside on-street outdoor dining is compatible with protected bicycle lanes
With curbside on-street outdoor dining, the outdoor dining is located next to the curb, with the bike lane next to it, followed by a physical barrier (such as flexible delineator posts or a jersey barrier), and finally the motor vehicle travel lane. Protected bike lanes outside the dining provide a further buffer between diners and motor vehicles, improving the dining experience.
This configuration is illustrated schematically in Figure 1, and a photo of how it is presently implemented in Cambridge on Mass Ave in Central Square is shown in Figure 2.
As shown in Figure 1, the configuration of a curbside on-street outdoor dining with a protected bike lane takes up 15’ (3’ buffer, 5’ bike lane, 7’ outdoor dining). This is the same amount of space as a standard parking-protected bike lane configuration (7’ parking space, 3’ buffer, 5’ bike lane).
 Figure 1. Schematic diagram of curbside on-street outdoor dining with a protected bike lane in a typical configuration. |
  Figure 2. Examples of curbside on-street outdoor dining with a protected bike lane as implemented on Mass Ave in Central Square, Cambridge. |
Note, since outdoor dining installations do not have car doors in them and thus do not create a dangerous “door zone”, the required 15’ of space can actually be decreased. In constrained situations, the buffer separating the bike lane from the motor vehicle travel lane could be reduced from 3’ to as little as 0.5’ (provided a vertical delineator such as a flexpost is still present). This increases the range of scenarios where this option can be used even beyond those where a parking-protected bike lane is feasible.
One example where this dimensional flexibility would be of value is on Cambridge Street across from the King Open School. There is an on-street outdoor dining installation in front of Atwood’s Tavern on Cambridge Street. Due to the curb-separated school bus loading/parking lane/bike lane next to the school, there are fewer options for rearranging the cross-section here to integrate a protected bike lane into the outdoor dining installation compared to most other places along Cambridge Street. However, a safe protected bike lane could be implemented next to the outdoor dining by using a 0.5’ buffer and either reducing the bike lane from 5’ to a slightly substandard 4.5’ or reducing the motor vehicle lane from 11’ to a still-standard 10.5’. This cross section is illustrated in Figure 3.
 Figure 3. Schematic diagram of curbside on-street outdoor dining with a protected bike lane in a dimensionally constrained environment, such as on Cambridge St in front of Atwood’s Tavern. |
Floating on-street outdoor dining is compatible with protected bicycle lanes
In floating on-street outdoor dining, the outdoor dining is located next to the motor vehicle travel lane, and the bike lane is between the outdoor dining and the curb (Figure 4). As shown in Figure 4, the configuration of a curbside on-street outdoor dining with a protected bike lane takes up 15’ (7’ outdoor dining, 3’ buffer, 5’ bike lane,). This is exactly the same as a standard parking-protected bike lane configuration (7’ parking lane, 3’ buffer, 5’ bike lane).
This configuration is widely implemented in New York City, with examples shown in Figure 5, with successful results. A benefit of this configuration (compared to a curbside outdoor dining) is that if parking and outdoor dining are intermingled along a stretch, less parking capacity is lost in transitioning between dining and parking uses. Additionally if the outdoor dining space is no longer required, it is easier to convert that space into parking space.
 Figure 4. Schematic diagram of floating on-street outdoor dining with a protected bike lane in a typical configuration. |
  Figure 5. Examples of floating on-street outdoor dining with a protected bike lane. |
Other Considerations and Configurations
In some places in the city, more substantial changes have been made, e.g., Inman Square. In these situations, the basic concepts described above still apply, and often there can be additional options to create a high quality protected bike lane that is integrated with the outdoor dining installation due to increased available space.
For example, the outdoor dining in Inman Square between Springfield St and Oak Street replaced both a parking lane and an adjacent right turn lane, occupying approximately 17’ of the cross section. An unprotected bike lane was installed adjacent to this outdoor dining. By re-allocating only a foot or two of space from the outdoor dining, this bike lane could have been designed as a fully protected bike lane, and the outdoor dining installation would still have been over twice as wide (15’) as most other on-street outdoor installations in Cambridge (which are usually 7’ wide). This is illustrated in Figure 6 below.
  Figure 6. (Top) Schematic diagram of current on-street outdoor dining installation in Inman Square, with only an unprotected bike lane. (Bottom) Schematic diagram of a slightly modified on-street dining installation that does include a protected bike lane. Note, even in the modified version, the outdoor dining is over twice as wide as typical on-street outdoor dining in Cambridge. |