Why biking can’t just happen on side streets

A common question about protected bicycle lanes is why they need to be added on major streets like Mass Ave. Why not direct people on bikes to parallel side streets like Oxford St. or Orchard St.?

There are a few reasons why this approach doesn’t work well in Cambridge:

To begin with, there are no streets that are fully parallel to all of Mass Ave. In other cities that have a more consistent grid, this sometimes works differently, but in Cambridge, the main streets historically evolved into being the main ones precisely because they are the only ones that connect all the way through between the most common origin/destination pairs that people want to go to. For example:

  • Orchard St dead ends on both ends, pushed people back onto Mass Ave or Elm Street, especially on the Porter Square side.
  • Many people currently traveling on Mass Ave want to ultimately go across the Mass Ave Bridge, but Harvard St ends up a number of blocks away from the Mass Ave Bridge and does not really leave you with an obvious safe route to get there.

The problem with circuitous and non-intuitive routes isn’t just that they are inconvenient to people biking, but also that if people have trouble finding and following the routes, they won’t use them. For example, the city has a signed bike route going North]South that is supposed to be an alternative to Prospect St; they do not want to put upgraded bike facilities on Prospect St. because it is a major route from the Mass Pike/Mem Drive/etc to parts of Cambridge and Somerville. But Nate, a member of CBS, notes: “After all the years I have lived here, I rarely use that route because I can never keep track of where it is, and also, it only works for a fraction of the trips I’d otherwise use Prospect St for.”

Many or most of the destinations people want to go to are on the major streets like Mass Ave, not side streets like Orchard, Oxford, or Harvard St. For example, this includes many of the local businesses in the Cambridge Local First Network. Because of the way one way streets work, it ends up being very likely that one will end up on streets like Mass Ave for part of a trip, bringing us back to our first problem.

Even if parallel streets were a practical choice, making them safe for cyclists of a wide range ages would also require very substantial changes to those streets, which would also result in vocal pushback by a minority of residents. It is not sufficient just to put up a sign and say “bicyclists, ride here.” Specifically, in order to provide a high quality facility without physical separation from motor vehicles:

  • One needs very significant traffic calming (e.g., frequent speed bumps or making the travel lane very narrow, both of which the Fire Department is strongly opposed to).
  • One needs to ensure that traffic volumes are low (e.g., through diverting all through traffic to other streets, which residents on the target street often strenuously oppose).
  • In addition, if one wants to create a connected network that allows bicyclists to go through, it will often be necessary to change the direction of traffic flow or allow bicyclists to go against motor vehicle traffic flow for at least short stretches to allow connecting movements.

An example of traffic diversion is to put physical barriers every block or every few blocks that force all motor vehicles to turn. Thus, motor vehicle access to each block is preserved, but through traffic is precluded. Bicycles and pedestrians are allowed to continue through. This has been implemented widely in Portland, OR.

Unfortunately, even modest changes to side streets’ traffic configurations (on a scale much smaller than what would be required) have resulted in pushback from some residents. For example, as part of the Inman Square redesign the city proposed changing the direction of Antrim St to reduce cut through traffic and simplify the intersection a bit. A subset of Antrim St residents were upset by this change, and managed to kill the direction change. In the case of Antrim, the direction change was actually proposed to help the residents of Antrim St itself by discouraging cut-through traffic, and yet it was still strenuously opposed and shot down. Putting aside who was right in this case, experience has shown again and again that any change to street configuration results in pushback by some residents.

In short, using side streets as an alternative to major roads for biking would:

  • be less useful for people who ride bikes,
  • would therefore not be used much,
  • and would still result in pushback from a subset of residents.

In order to ensure safer streets for people who ride bikes, we need to implement infrastructure changes on the roads that people want to use, the major connecting roads of Cambridge.