top of page

Improve the 17th Street Project Design: Eight Steps

Many thanks to SFMTA and the 17th Street Project team for the proposed designs. In addition to bike lanes separated from traffic by either a painted buffer and plastic posts or parked cars, the designs contain a number of additional positive details including:


  • Seven foot wide bike lanes in some sections. This is particularly valuable as wider mobility devices gain popularity including family bikes, cargo bikes and adult tricycles which provide an important option for those less confident on two wheels. 

  • Corner wedges that increase safety at intersections

  • A bikeshare station relocated convenient at the bike lane

  • Plastic posts located to prevent parking in daylighting safety zones


Thank you SFMTA for these features. There are also a several key areas where the current designs need to be improved: 


1. Eliminate the four mixing zones between San Bruno and Potrero Avenue. Modular speed bumps can be placed along the bike lane in these areas to deter cars from driving or parking in the bike lane. The SFMTA Proposed designs include a solid green bike lane just east of Vermont St in front of the auto spa to deter parking in the bike lane. This design of solid green paint is also needed on the north side of 17th between Utah and Potrero, The combination of the solid green paint and modular speed bumps is particularly important near Potrero Ave where drivers frequently use the mixing zone not to turn right but rather to pass the car in front of them. A protected intersection would also help move the bike lane to the right against the crosswalk and further reduce the danger of right hooks. 


2. Install modular speed bumps at driveways for example just east of Potrero Ave, at the Whole Foods loading bays, 76, UPS and the Friends of SFPL. Modular speed bumps are already in use at driveways along the Embarcadero and on Battery St. 


3. Install a Protected Intersection at Potrero Ave. Crash data presented on the SFMTA 17th St project page appropriately shows a bullseye on the Potrero Ave. intersection because of the disproportionate number of past crashes there. The solution is a protected intersection such as this dutch style design prepared by Mobycon for this specific intersection. 

An objection raised in the past to this design has been the perceived need to relocate of the curb cut ramps resulting in a path for pedestrians that is not perfectly straight. The significant safety gain from a protected intersection design at Potrero Ave warrants this relocation of the curb ramps. However for a quickbuild, having the new bike lane (cross ride) right up against the existing yellow ramps in their existing locations in the Potrero intersection would still provide a significant setback and safety improvement by enabling a larger corner island. 


There are a number of locations around the city where the crosswalk is not lined up with the property line and curb. Market at Polk is a prime example. The crosswalks crossing Market are not lined up with the sidewalk. In fact the northeastern crosswalk appears to have been pushed away from the intersection in order to create space for a bike turn box. 

The NACTO guide, Don't Give Up at the Intersection, also presents a similar design with a bend out and sidewalk that has been pushed out from the intersection. Note how the two curb ramps are not located the same distance from the corner. One has been pushed away from the intersection to create a greater setback.

There are many other examples of this bend out treatment in San Francisco where a crosswalk has been pushed away from the intersection including 9th and Division, Hayes at Polk and Townsend at 7th. Pedestrians heading north on the east side of Townsend at 7th must make a 90 degree turn at the end of the crosswalk because the path of travel moves far to the left, on the opposite side of the bike lane. A great protected corner has been created and in order to do so the crosswalk could not point directly at the pedestrian path of travel. The crosswalks at Potrero Ave and 17th St should also be moved in order to gain similar safety improvements. 

4. Paint a green protected two stage left turn at Mississippi, not a bike box (aka murder box). Many people on bikes heading east on 17th will turn left onto Mississippi in order to continue east on 16th. If the new concrete protected bike lanes on Mississippi north of 17th will be completed before the 17th Street project the addition of a painted solid green bike lane (cross ride) through the intersection would provide important direction as to the correct and safe path for bikes to take when turning left at that intersection. The row of parked cars newly protecting the bike lane on the south side of 17th west of Mississippi will prevent eastbound people on bikes from continuing the current practice which is to shift lanes north into the vehicle travel lane and then turn left like a car. A solid green 6' wide bike lane cross ride hugging the crosswalks along the southern and eastern sides of the intersection with a curved corner would clearly show the path eastbound cyclists should take when turning left onto Mississippi. This is similar to the design on Townsend for north/east bound cyclists turning left onto 7th. Note again the location of the cross ride right against the edge of the yellow curb ramp.

5. Target initial enforcement at blocked bike lane illegal parking. Past experience in San Francisco suggests that there may be illegal parking in the bike lane particularly at the driveways such as Friends of SFPL, Whole Foods and east of Potrero Ave. Similar to what SFMTA plans for Valencia St, there should be an initial period of two or more weeks where there is vigilant targeted enforcement along 17th so that people who park in these driveways receive citations and thus word spreads that violators will be cited. 


6.  Make 17th and Missouri safer for pedestrians. Pedestrian counts have found that 16th and Missouri is one of the most heavily used intersections for pedestrians in the area. Many of these pedestrians also continue and cross 17th and Missouri. There is a need for additional treatments to improve pedestrian safety at 17th and Missouri. Perhaps this is a good candidate for art painting the full intersection. 


7. Repeat the NE San Bruno corner wedge and bend out at Arkansas, DeHaro and Missouri. The SW corners of Arkansas and DeHaro each have a skinny corner wedge. It appears that a similar wedge could be installed at the SW corner of Missouri. Parking on the side street is at 90 degrees making this possible. A wedge would reduce the likelihood of a right hook. 


Even better is the larger wedge at the NE corner of San Bruno and the “bend out” of the bike lane away from the vehicle travel lane increasing the setback and improving visibility for turning vehicles to reduce danger right hooks. It seems that the SW corners of Arkansas, DeHaro and Missouri could each have the same larger corner wedge treatment and bend-out as the treatment at the NE corner of San Bruno. The bend-out of the bike lane can be increased further by moving the crosswalk further away from the intersection. This would mean extending the crosswalk beyond the width of the sidewalk. However such an alignment has been used in countless locations in San Francisco as discussed above including at 7th and Townsend, Market and Polk and more. 


8. Fill two nearby gaps in connections. The 17th Street project should include two critical segments to fill adjoining gaps and address safety on the connections to the rest of the network. If these two segments cannot be included in the current 17th St project without significant delay they should be quickly addresses in separate follow-on mini-projects:

a. Kansas between 16th and 17th. Kansas is the route connecting 17th to the north however vehicles frequently double parked in the bike lane by Starbucks present serious danger. A number of merchants on this block are in favor of a parking protected bike lane on the east side of Kansas. 

b. 17th between Potrero Ave and Bryant. The bike lane between Bryant and Harrison is already separated from vehicle traffic by paint and plastic posts. In addition, the developer PNC and SFMTA have announced that the bike lane will be protected by concrete curbs on 17th between Hampshire and Bryant as part of the Potrero Yard project. However there is a gap on the small segment between Potrero Ave and Hampshire. By protecting the bike lane on one side of one block between Potrero Ave and Hampshire we would extend the overall connected 17th segment on both sides of six blocks.  


Next Steps


The 17th Street project highlights three important next step priorities: 

  1. The intersection at 16th and 7th, used by those continuing east from 17th St is not safe, particularly in the westbound direction. 

  2. SFMTA plans to upgrade bike facilities on Cesar Chavez. This welcome development underscores the need to create protected bike lanes on Illinois so that people can safely travel north/south between the soon to be safer 17th St and Cesar Chavez east west corridors. 

  3. A safe connection is needed between 17th at Mississippi and the future Mariposa bike bridge, located above the train tracks just north of Mariposa Street.

bottom of page