Having worked in communities big and small across the continent, we’ve had ample opportunity to test ideas and find approaches that work best. Urban design details. Outreach tactics. Implementation tricks. Many of these lessons are transferable, which is why, beginning today, you’ll find a new feature here every Thursday — “Back of the Envelope” — where we’ll make note of things you might find useful.
The B-Grid: A traditional city building pattern common in early western settlements, particularly on the more rectilinear grid-iron pattern of streets.
Typically, Main Street was the “A” street: a high quality, pedestrian-oriented space lined with continuous shopfronts and important civic buildings. But what about larger parking areas, vehicular services, and other uses not appropriate in such a context? Enter the B-Grid, adjacent streets running parallel, where a less pedestrian-friendly environment allowed for automobile-oriented uses to take place without detracting from high-quality public space.
With today’s refocussing on pedestrian-friendly places, the B-Grid once again finds its place as an important tool. Commonly used in Form Based Codes and other urban-oriented development regulations, the B-Grid allows special exceptions for automobile-oriented uses, automobile-focused arterials and highways, and larger commercial uses that require sizable parking lots at their front door.
While arterial streets and gas stations are an obvious use for the B-Grid, the more important and perhaps more controversial is the allowance for larger retailers with front parking lots. Keeping in mind that not all developers are out to build A-level urbanism, when faced with the difficult choice of project viability vs. an uncompromised plan, the B-Grid offers a compromise. Most importantly, this compromise takes into consideration the evolution of urbanism over time by ensuring a connected street network and the formation of urban blocks.
Here’s how to get them right:
- Start the conversation from the standpoint of an all A-Grid plan, and then work backward to identify strategic B-Grids.
- Get all of your small retail onto an A-Grid. If you’re up against more conventional developers, diagonal parking will usually do the trick, though parallel parking makes for a better pedestrian environment.
- Connect the A-Grids to A-Grids forming an A-Grid network for pedestrians throughout the neighborhood. In theory, a pedestrian should not have to enter the B-Grid.
- Install walkable streets on the B-Grid, setting the seeds for future redevelopment, and acknowledging that pedestrians emerge from parking lots and need to walk safely to the A-Grid.
- Ensure that B-Grid utilities are installed along block perimeters, not through parking lots.
- Where parking isles intersect the B-Grid, anticipate the street that might be built in the future. Provide a continuous sidewalk that trumps the drive isles. Plant trees and install light standards so that they don’t have to be moved in the future.
- Up to 20% is an acceptable standard for B-Grid thoroughfares within any given neighborhood.
–Geoff Dyer
One reason for demand for “B” grids is that people in parking lots–perhaps rightly–worry about being invisible from the street. If the parking is open to the side, then they may feel safer. It’s an interesting question as to whether this is a real or perceived problem, or whether it can be mitigated by security.
Geoff – have to be the guy to disagree a bit.
First, B-streets in grids were not a historical pattern. They happened after the advent of the automobile culture and its overlay on existing towns. Some of those towns had blocks that weren’t optimized size-wise for auto-oriented uses, so many back streets were effectively turned into alleys. The original intent, however, was that those were all walkable streets. Sure, there was often a “main” street, but it doesn’t mean the back blocks were parking lots or vehicle service – that didn’t really exist as we know it today.
As to the technique itself, I find it’s useful in some limited applications, such as retrofitting a block structure that has dimensional issues. For new construction or greenfield projects, there’s no need to worry about A & B streets – simply design the block structure more flexibly to begin with.
Lastly, while this was a technique used to excellent effect in some early New Urbanist projects, I wonder about its viability today in the world of smaller projects, infill, and small interventions. Methinks we will increasingly have more opportunities to take some of those “less optimal” block sizes, and occupy them more fully for walkability on all sides. The future’s so bright, you gotta wear shades.
Love and kisses,
Kevin
I suspect as with alleys in denser cities, where laneway housing and mews type housing are becoming more common, that the notion of B-streets that we are content to relegate to a secondary auto-oriented status will become an artifact of the automobile age.
Given that particular example, I might have continued the existing street just to the right of middle of the upper block and found a way to integrate some of the existing street language into the site vs. introduce a new street simply in the middle. Then the value coming from the “boulevard” in the lower area is extended up into more than just the block you are redeveloping – it could also help transform the parking lot on the adjacent block as well. It may also allow for a slightly unique block layout – which is particular important in cities to help continue the overall uniqueness of their patterns which in turn give identity and sense of place in a given district.
Geoff, A useful article for planners, developers and most of all, policy makers. Too many try to make all streets A quality resulting in a general dumbing down. All cities have a B street, somewhere, as they are ever evolving living animals. I would add that B streets should be planned to grow into A streets. Andres Duany was the first to make this observation.
I use the following list of thoroughfares, listed from highest to lowest Pedestrian Propulsion:
Main Street
Front Passage
Front Street
Side Street
Mews
Side Passage
Alley
Back Street, which is essentially a B Street
Back Streets primarily serve parking lots, loading docks, waste receptacles, and utility areas of adjacent buildings. They are not meant to be walkable. They therefore have a negative Pedestrian Propulsion factor. The best businesses to front onto Back Streets is the Live/Workshop Unit. Other unit types that can front onto Back Streets are the most affordable residential units (assuming they’re near an intersection where the cross street has positive Pedestrian Propulsion) and Live/Service Units.
BTW, really glad to see you guys doing these Thursday posts… could be really useful stuff.
Kevin — alleys for vehicle service date back to the horse-and-buggy era. They weren’t thoroughfares, but they sure were for parking lots and garages. To that extent the concept is old.