It’s time for PBOT to stop spending more for less.
By northeast Portland resident and bike bus leader, Sam Balto.
Portland prides itself on being a leader in biking and sustainable transportation, yet the city’s approach to traffic calming on our Neighborhood Greenways is both outdated and unnecessarily expensive. The Portland Bureau of Transportation (PBOT) continues to rely heavily on speed bumps to slow down drivers when a more effective, affordable, and bike-friendly solution exists: modal filters (a.k.a. diverters).
For years, PBOT has installed speed bumps along our greenways in an attempt to reduce cut-through driving and keep speeds below 20 mph. But speed bumps don’t solve the core problem—cars still dominate streets that are supposed to prioritize biking and walking. Worse yet, speed bumps don’t actually prevent drivers from using greenways as shortcuts. Instead, they just make the experience mildly more annoying, often leading to aggressive driving between bumps.
Meanwhile, speed bumps cost taxpayers around $3,500–$7,000 each. A series of them along a stretch of greenway can easily add up to $50,000 to $100,000. That’s money spent on a solution that doesn’t address the root issue.
Modal filters, on the other hand, are a cost-effective way to truly prioritize greenways for people biking and walking. By restricting through traffic at key intersections, modal filters reduce the number of cars using greenways in the first place. They don’t just slow drivers down; they eliminate the need for most of them to be there at all. A simple concrete planter or curb modal filter costs a fraction of what PBOT spends on multiple speed bumps, while achieving a greater safety impact.
This has been playing out in my neighborhood of Beaumont-Wilshire where PBOT recently installed 11 speed bumps at a cost of over $50,000 on NE 37th between Fremont and Prescott instead of a modal filter which was presented to the neighborhood association board members before the project. To top it off, the issue on NE 37th is too many drivers, not too many people speeding. So why did PBOT choose the more expensive option? In conversation with PBOT staff, the modal filter was removed based on neighborhood association feedback.
PBOT has a chance to not repeat the same mistake. Since PBOT delayed the implementation of Mason/Skidmore Neighborhood Greenway Project until this summer, the agency could opt to forgo building five expensive speed bumps on NE Skidmore between 37th and 42nd (which sees 85th percentile speeds at 21 & 23 mph) and instead implement the modal filter design at NE 37th and NE Skidmore. This would help PBOT meet its own guidelines by reducing peak-hour traffic counts and create a more bike-bus friendly neighborhood greenway for two nearby schools. The modal filter should cost about $10,000 (even less without drawn-out neighborhood association meetings which eat up city budgets), instead of up to $35,000 for speed bumps.
The proof is in the numbers. When PBOT installed modal filters on SE Clinton Street in 2016, it resulted in a reduction of 35-75% of annual car trips on the greenway. The decrease in drivers was so significant that most bicycle users gushed about the improvement to the street. Compare that to streets with speed bumps, where car volumes remain a persistent issue.
It’s time for PBOT to stop spending more for less. This is especially important given their ongoing budget crisis, which will not slow down in the coming years. Modal filters aren’t just a better solution—they’re the fiscally responsible one.
— Sam Balto
