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The City of Portland, Oregon

Portland Bureau of Transportation

Phone: 503-823-5185

Fax: 503-823-7576

1120 SW Fifth Ave, Suite 800, Portland, OR 97204

More Contact Info

Project Q and A

Answers to questions about this project that we have received.

Project Q and A

1. I don’t like biking over speed bumps. Why does Tillamook need speed bumps?

2. Is it possible to get bike-friendly speed bumps on Tillamook?

3. I don’t like the look and feel of speed bumps. Can Tillamook have more traffic diversion or 4-way stops instead?

4. Can new traffic diverters be included in this project to reduce vehicle volumes on the greenway?

5. Could there be 4 way-stops at Tillamook and Vancouver and Tillamook and Williams?

6. Can the traffic circle at 7th and Tillamook be removed? It is difficult for bikes to navigate and the tree blocks visibility for both drivers and bikers.

7. I don’t live on Tillamook, but I’m concerned about vehicle speeds on my street.

8. I’m concerned that living on or near a neighborhood greenway will negatively impact the value of my property.

NE 21st and Tillamook Q and A

9. What are the corner islands in the NE 21st and Tillamook design? Will these do enough to slow down traffic at this unique intersection?

10. Can there be a 4-way stop at NE 21st and Tillamook?

11. I feel the street markings proposed on NE 21st and Tillamook create visual noise on the street that negatively impacts the historic nature of the neighborhood. Can the project improve safety with fewer visual impacts to the street?

12. Can there be speed bumps added to the NE 21st and Tillamook design to slow vehicles down further at this intersection?

 


 

Project Q and A

1. I don’t like biking over speed bumps. Why does Tillamook need speed bumps?

While we recognize that some people on bicycles prefer roads without speed bumps, speed bumps are the city’s most effective tool for obtaining slower vehicle speeds on neighborhood greenways. Slower vehicle speeds create neighborhood greenways that are comfortable for all ages and abilities of people walking and biking.

The reason speedbumps are included in this project is because vehicle speeds on Tillamook are currently higher than the speeds recommended by the operational performance guidelines set by Portland’s Neighborhood Greenway Assessment Report. The vehicle speed target on all the city’s neighborhood greenways is 85th percentile vehicle speeds of 20 mph, with a maximum of 23 mph. Tillamook between Flint and 28th currently has 85th percentile speeds of 23-27 mph.

Lowering speeds creates a more comfortable and less stressful environment for people of all ages and abilities to walk and bike on neighborhood greenways. The 20 mph speed guideline is supported by traffic engineering and safety research indicating that a person who is struck by a vehicle at 20 mph has less than 15 percent risk of fatality or serious injury. When cars travel 30 mph, the risk of fatality or serious injury rises to 40 percent. Faster cars, posing a well-understood and documented jump in risk, depress bicycle use. Speed bumps are the most effective and cost-effective tool to slow speeding auto traffic, and PBOT has had good success with speed bumps over the years.  

We are also including speed bumps in this project because we will be turning eight stop signs on Tillamook. While turning the stop signs allows people walking and biking to travel more efficiently along the greenway, it can also attract new drivers to use the street as a short-cut. The speed bumps help keep vehicles off of Tillamook.

2. Is it possible to get bike-friendly speed bumps on Tillamook?

PBOT is currently planning to test a speed bump design on SE Clinton that includes narrow gaps wide enough for bike wheels to move through without going over a bump. However, this design is not approved for city-wide use. At this time, Tillamook will receive the typical 14-foot speed bump treatment.

3. I don’t like the look and feel of speed bumps. Can Tillamook have more traffic diversion or 4-way stops instead?

PBOT has had good success with speed bumps over the years.  Speed bumps are the most effective tool to slow speeding auto traffic.  It has been suggested that more diverters, maybe every ¼ mile (about every 5 blocks) could also lower vehicle speeds to 20 mph 85th percentile speeds. PBOT’s experience shows that 5 blocks are enough distance for people driving to accelerate faster than 25 or 30 mph. This amount of traffic diversion construction is expensive, and these resources are better directed elsewhere in the city.  

While 4-way stops are one of the safest intersection designs, many studies have shown that stop signs are not an effective measure for reducing midblock speeds. People driving trend to increase their speed between stop signs to regain their perceived time spent at the stop sign.  Stop signs can also increase rear end collisions and auto emissions.

In addition, PBOT wants neighborhood greenways to be streets that are excellent places to bicycle, and stop signs along neighborhood greenways increase travel time for bicyclists. The Neighborhood Greenway Assessment Report recommends removing stop signs on bikeways.

4. Can new traffic diverters be included in this project to reduce vehicle volumes on the greenway?

As part of its assessment of Neighborhood Greenways, PBOT identified a set of traffic volumes as a measurement of success.  When an existing or proposed greenway route has car volumes below 1,000 vehicles per day, diversion of auto traffic is typically not proposed.  When a proposed greenway route has more than 1,500 auto trips per day, diversion may be considered. If auto volumes on a proposed greenway exceed 2,000 per day, diversion of auto traffic shall be considered.

Vehicle volumes on Tillamook between NE Flint and Martin Luther King are in the 1,200-1,450 vehicles per day range, which is near the threshold for considering traffic diversion. We are exploring possible traffic diversion designs for this section of Tillamook.

On Tillamook between NE Martin Luther King and NE 28th, vehicle volumes are already under 1,000 vehicles per day. Instead of constructing new diversion on this stretch of Tillamook, PBOT will direct these resources to the needs of other areas of the city.

5. Could there be 4 way-stops at Tillamook and Vancouver and Tillamook and Williams?

Since Vancouver and Williams are Neighborhood Collector streets, they are intended to move higher volumes of traffic.  Stop signs at Local Service street intersections, like Tillamook, would add delay to the higher order streets, which may cause long lines of vehicle queuing and diversion of traffic into the neighborhood.  It would also imply that Tillamook is the same kind of street as Vancouver or Williams, attracting more drivers to use Tillamook.

6. Can the traffic circle at 7th and Tillamook be removed? It is difficult for bikes to navigate and the tree blocks visibility for both drivers and bikers.

Removal of this traffic circle is not included in this project due to the route planning currently underway for the Lloyd to Woodlawn Neighborhood Greenway. Evaluation is now taking place to determine whether this greenway will follow NE 7th or 9th. A decision is expected in Fall 2018. That alignment decision will impact the future needs and design of the intersection of NE 7th and Tillamook. The traffic circle at this intersection will be examined at that time.   

7. I don’t live on Tillamook, but I’m concerned about vehicle speeds on my street.

The focus of this project is the Tillamook Neighborhood Greenway, but all other traffic concerns can be reported to (503) 823-SAFE, or the PBOT web site. If diversion is considered at a particular intersection, PBOT gathers data along alternative routes for several blocks in each direction of the proposed diverter to evaluate how the change affects nearby streets.

8. I’m concerned that living on or near a neighborhood greenway will negatively impact the value of my property.

Research by Portland State University has found that advanced bikeways like neighborhood greenways have a positive effect on home values. For single family home sales, being a quarter mile closer to an advanced bikeway translated to a $686 premium, while increasing the bikeway density by a quarter mile represented a $4,039 premium. Learn more: Better bikeways associated with higher home values.  

9. What are the corner islands in the NE 21st and Tillamook design? Will these do enough to slow down traffic at this unique intersection?

The purpose of the corner islands is to slow vehicles to 10-15 miles per hour around the curves of the off-set intersection at NE 21st and Tillamook. Minimizing turning speeds is crucial to the safety of people walking, biking, and driving in this intersection. Corner radii directly impact vehicle turning speeds.

This intersection also needs to accommodate commercial trucks that have a wider turning radius than cars. Large trucks are able to slowly mount these islands to navigate the curves.  

A similar design is in place at SE 11th and Clay. The corner radii slow down cars, while still enabling commercial trucks to navigate the turns.  

10. Can there be a 4-way stop at NE 21st and Tillamook?

While 4-way stops are one of the safest intersection designs, vehicle volumes are too high on NE 21st for this design to function properly. A 4-way stop on NE 21st will create a long line of vehicle queuing during peak travel hours.

11. I feel the street markings proposed on NE 21st and Tillamook create visual noise on the street that negatively impacts the historic nature of the neighborhood. Can the project improve safety with fewer visual impacts to the street?

Intersections are the most dangerous places for travelers of all modes. We’ve heard from residents living at this intersection that crashes and unsafe behaviors are happening frequently. PBOT’s priority is to make this intersection safer by using research-based design standards and best practices.  

The purpose of using green and white paint at intersections and painted bike lanes on the road is to give people driving a visual cue to expect to see bicycles and pedestrians crossing. The visual markings aim to eliminate conflicts between users. The green color is mandated by the Federal Highway Administration.

We want streets where all Portlanders, from the oldest to the youngest, and including all physical abilities, can move safely. We are considering aesthetics as much as we can when placing street markings.

12. Can there be speed bumps added to the NE 21st and Tillamook design to slow vehicles down further at this intersection? 

Additional speed tables can be considered on NE 21st. NE 21st north of Stanton already has speed tables, and since NE 21st is a Local Service street and not designated for higher order emergency response, the addition of speed tables south of Stanton to Broadway is possible.