Beware Highway 1’s new “bicycle friendly” rumble strips

I was just riding along last weekend when I nearly bit it on the recently installed rumble strips along Highway 1 north of Santa Cruz, California.

Highway 1 rumble strip Santa Cruz County

I was southbound on Highway 1 approaching Wilder Ranch State Park. Because sightlines are bad for people pulling out of the Wilder Ranch Parking Lot, I and many other cyclists habitually pull waaay out into the lane if there’s no other traffic behind us.

Sure enough, an SUV with mountain bikes mounted on top was edging out of the driveway as I zoomed past at 28 MPH.

With a car now approaching from behind at 60 MPH, I begin to move into the shoulder and SURPRISE! RUMBLE STRIPS START IMMEDIATELY AFTER THE DRIVEWAY AND THEY’RE NOW UNDER MY TIRES DON’T FREAK OUT EVEN THOUGH THAT CAR IS NOW PASSING AT SPEED! It was a pretty near thing as I scrubbed my speed whilst staying upright and avoiding passing traffic.

After the public meeting in 2012 at which cyclists were invited to give their feedback regarding this project, I was perhaps a little less reflexive than other cyclists in opposing these rumblestrips. Two cyclists have been killed by cars in classic “run-off-the-road” crashes since that meeting, after all, and rumble strips may have saved their lives. I believed Caltrans when they said they would install more “bicycle friendly” rumble strips, and only in locations that wouldn’t overly inconvenience cyclists.

Ha. I really should have known better. There’s no way these rumble strips are safe for the typical road cyclist traveling at speed along the North County coast. They also violated their own standards by installing these dangerous traps at locations where the shoulder is less than five feet wide.

Local cycling author Jim Langley, who was always less credulous of Caltrans good intentions than I, documented the danger points and sent them to the Santa Cruz County Regional Transportation Commission for their discussion at tonight’s Bicycle Advisory Committee. He notes the numerous locations where the rumblestrips are milled in where the shoulder is less than five feet wide. There are numerous locations where the cyclist is squeezed into a narrow, two foot bottleneck between the rumblestrip and a drain grate. Langley also mentions the various places where people use the dirt area off of the road as highway-side parking, which results in a debris-filled shoulder.

In addition to these shoulder rumblestrips, Caltrans added centerline rumblestrips on Highway 1. Besides the well-known problem of motorists who fail to move over for cyclists (because cyclists are less bumpy than rumblestrips?), Langley points out a new hazard created by the centerline rumble strip: flying hubcaps!

Oversize RVs and tour buses, frequent Hwy 1. Right away, I noticed that some of these oversize vehicles refuse to move left for fear of hitting the center rumble strips. Instead they come perilously close to me on my bike. This was never an issue before rumble strips. Any safe driver could move over and not worry about hitting anything in the middle of the road.

Safer drivers in normal vehicles are sometimes now crossing the center rumble strips to give more room, which is nice. HOWEVER, recently the rumble strips knocked the hubcap off one of these cars and it rocketed past me at 50mph!! So, rumble strips are even more dangerous than we already knew. Think about gravel trucks or logging or firewood/agricultural, etc. and what might be thrown at cyclists from these vehicles should they hit the rumble strips. Not safe.

Caltrans now plans to install another set of rumblestrips along the portion of Highway 9 that goes through Castle Rock State Park south of Skyline in Santa Cruz County. Caltrans will be at the RTC meeting tonight to discuss the proposed Highway 9 rumblestrips and the already installed Highway 1 rumblestrips. Bring your metaphorical pitchforks to the Santa Cruz County Bicycle Advisory Committee at 6 PM tonight at the Regional Transportation Commission office on Pacific Avenue in Santa Cruz. Meeting details, including location and agenda with Langley’s photos and notes, are available at the RTC BAC web page.

Highway 1 rumblestrip photo above courtesy of Jim Langley and used with his permission.


  1. At first I thought, thats cool, they put the rumble strip in the lane of vehicle traffic. Here in Washington it’s to the right of the line on the shoulder. But looking closer, it appears they moved the white line over making the shoulder even narrower to accommodate the rumble strip on the left of the line.

    I have experienced the same thing with centerline rumble strips. Vehicles are less likely to cross strips to pass at a safe distance. Another indication that sitting in a steel cage numbs drivers to the vulnerability of pedestrians and cyclists.

  2. Why not stay in the rightmost travel lane and let the passing motorist use the passing lane?

  3. Caltrans is also planning to install shoulder rumble strips on Niles Canyon Rd. between Fremont and Sunol in Alameda County (Caltrans District 4), as part of an imminent “Short-Term Safety Improvements [sic] Project” that doesn’t require an EIR and thus can be implemented before the EIR is complete:

    Objections should be sent to “” – If anyone has better contacts at Caltrans District 4 or statewide, please let us know.

    (I went to the Caltrans outreach meeting in Sunol last week. Caltrans staff tried to play down the significance of the short-term project, including the rumble strips. When I pressed, they said that rumble strips would improve safety for bicyclists *riding on the shoulder*. They were adamantly unwilling to consider cyclists riding anywhere other than the shoulder, and insisted that there are “many studies” showing that rumble strips can be “comfortable” for cyclists.)

    FHWA recommends that any shoulder rumble strips on roads “where bicycles are expected” (which in California should mean any road except certain limited-access expressways) should be intermittent, with gaps of at least 10-12 feet every 40-60 feet to permit cyclists to cross the rumble strips:

    That would only slightly mitigate the danger caused by rumble strips, of course. You can’t predict that if a motorist passes too close or cuts back in too soon after passing, and you need to move onto the shoulder, you will chance to be alongside one of the gaps in the rumble strips. Nor can you wait 40 feet to move to the shoulder if you are getting sideswiped or cut off. Similarly, you can’t readily watch *behind* you for a gap in passing traffic to merge back off the shoulder after pulling out to allow motorists to pass, while looking *ahead* for a gap in the rumble strip. Nor will the gap in passing traffic necessarily coincide with a gap in the rumble strips.

    But Caltrans has ignored even this minimal mitigation recommendation from the Feds. Every shoulder rumble strip I have seen in California is continuous.

    This needs to be addressed at some systemic and probably state-wide level with Caltrans.

  4. Same thing happening in Niles Canyon. Excellent comments here, which I believe are public record

    From: Edward Hasbrouck
    To: nilescany…
    Subject: Issues for EIR *and* issues with “Short-Term Safety Improvements Project”
    Date sent: Fri, 16 Oct 2015 14:21:21 -0700

    The comments below are intended to amplify what I could fit on a “comment card” at the “Public Scoping Meeting” in Sunol on 14 October 2015.

    As a bicyclist who uses Niles Canyon Rd. and would use it more often if it were made less dangerous to cyclists, I have the following comments and recommendations regarding both the environmental impact review and the “Short-Term Safety Improvements Project” (which I was told is not subject to an EIR and is intended by Caltrans for execution by Caltrans at an unspecified but much earlier date than the project subject to the EIR):

    (1) Shoulder rumble strips should not be installed on Niles Canyon Rd.

    Shoulder rumble strips would make this road much more dangerous for
    cyclists, slow down motor vehicle traffic, and contribute to unnecessary
    conflict between bicyclists and motorists. They are contraindicated by
    best practices and recommendations.

    I agree with the position on this issue of the East Bay Bicycle Coalition (since renamed Bike East Bay), as stated in its 2010 letter to Caltrans:

    “Rumble strips are a safety risk to cyclists. Rumble strips reduce the
    surface area that cyclists have to adequately control their bicycle, which increases the risk of fall, loss of control, and collision. Rumble strips also gather debris, which can become a secondary cause a crash. Special consideration should be given to cyclists using the roadway in evening hours, during wet and windy conditions, loaded with camping and commuting gear, with narrow high performance road bike tires, and being physically tired.”

    I also agree with the League of American Bicyclists and the Alliance for
    Biking and Walking, which jointly identify as a “best practice”:

    “Not installing rumble strips on designated bicycle routes and other roads where bicycling is expected.”

    In California, bicycling is expected on all roads except certain sections of some limited-access highways. Bicycling certainly should be expected on Niles Canyon Rd.

    Because many bicyclists cannot safely cross rumble strips at speed in
    traffic, many bicyclists simply will not ride on roads with shoulder
    rumble strips demarcating lanes too narrow for motor vehicles to pass
    bicycles safely within the same lane. On such roads, shoulder rumble
    strips operate as de facto bicycle exclusion devices.

    (2) On a road with narrow lanes shared by cyclists and motor vehicles,
    such as this one, shoulder rumble strips will slow motor traffic

    By law, cyclists must use pullouts to allow faster vehicles to pass, when more than five faster vehicles are following and pullouts are available.

    Typically, cyclists on Niles Canyon Rd. or similar roads — where there
    are no marked pullouts — use the shoulder.

    But cyclists are not required to use a deficient shoulder as a pullout,
    and most will not pull out onto the shoulder across a rumble strip. By
    denying cyclists who would like to pull out to allow motorists a chance to pass any safe space to do so, shoulder rumble strips will make motorists wait much further and longer for places where cyclists can pull out.

    Unfortunately, prolonged backups behind cyclists tend to lead to “road
    rage”, harassment, and assault against cyclists by motorists, mainly
    taking the form of passing too fast and too close to cyclists when
    motorists eventually do get a chance to pass. Cyclists will bear the
    brunt of the delay for motorists that will result from shoulder rumble

    (3) If shoulder rumble strips are installed, they should be *mitigated* by being intermittent, not continuous, with gaps at least 10-12 feet long at intervals of no more than 40-60 feet, in accordance with FHWA Technical Advisory T 5040.40, Rev. 1 (November 7, 2011):

    “Where any width paved shoulder exists beyond the rumble strip and
    bicycles are allowed to ride, recurring short gaps should be designed in
    the continuous rumble strip pattern to allow for ease of movement of
    bicyclists from one side of the rumble to the other. A typical pattern is gaps of 10 to 12 feet between groups of the milled-in elements at 40 to 60 feet.”

    But it is critically important to understand that intermittent breaks in
    shoulder rumble strips can only slightly mitigate the inherently adverse
    effects of shoulder rumble strips on road usability and safety for
    cyclists. No shoulder rumble strips can “accommodate” cyclists safely.

    It’s possible for most reasonably competent cyclists to ride a slalom
    course and hit 10′ gaps, on a closed course and not in traffic. But that’s not the same as doing so in traffic and where the rumble strip is likely to cause a serious crash if the cyclist misses the gap.

    It should go without saying that cyclists are not required, and should not be expected, to ride on shoulders, much less to do so primarily or
    exclusively. Shoulders are not built, maintained, or cleaned to the same standards as travel lanes (or designated bike lanes). Especially where sight lines are poor (as they are on much of Niles Canyon Rd.), or at night on a road without street lights (ditto), a cyclist who attempts to ride on the shoulder cannot predict where, without warning, the shoulder will end, become unpaved, run into the end of a guardrail or a bridge abutment, or be obstructed by fallen rocks or branches, overgrowth, debris, or parked or stopped vehicles.

    Cyclists use shoulders — especially intermittent shoulders such as those on Niles Canyon Rd. — in two ways. Neither of these uses is meaningfully accommodated by shoulder rumble strips with recurring gaps.

    First, as discussed above, cyclists use shoulders as de facto pullouts to allow motor vehicles to pass: Where a cyclist can see that there is a
    sufficiently long, sufficiently wide, section of shoulder ahead to permit doing so safely, a cyclist can drift right onto the shoulder, allow motorists to pass, and then merge back into traffic.

    It’s much safer if a cyclist can do this while maintaining speed, to
    minimize any speed differential when merging back into traffic.

    If a cyclist can pull out only at (typically short) marked pullouts, and
    thus has to pull out and stop to permit motor vehicles to pass, the
    cyclist then has the more difficult and dangerous task of merging back
    into moving traffic from a standing (stopped) start.

    A cyclist cannot safely watch the position and speed of following or
    overtaking traffic behind, and the status and condition of the shoulder
    ahead, *and* simultaneously be expected to watch for and hit the breaks in the rumble strips when she crosses onto and back off of the shoulder.

    There’s no way to guarantee the break in following traffic where a cyclist can most safely merge back in before the shoulder ends, narrows, or is obstructed will coincide with one of the breaks in the rumble strips.

    Second, cyclists use the shoulder as a literal “margin: of safety — a
    space to move right in an emergency, most often when a motorist passes too close and/or too fast alongside or pulls back in too soon after
    overtaking. Swerving or even just drifting onto the shoulder allows a
    bicyclist to avoid being side-swiped.

    But a cyclist who needs to veer onto the shoulder to escape being
    sideswiped doesn’t have time to wait 40′ for the next break in the rumble strip, or even to check whether they are alongside such a break. If the alternative is to be sideswiped, a cyclist will probably risk going right anyway. Even with intermittent rumble strips, the odds are that they will hit the rumble strip, and may well fall. And the falls produced by rumble strips are likely to be at the worst possible time: When there is already a motor vehicle too close alongside. The “failure mode” and safety cost that must be assessed prior to installing any shoulder rumble strips is that cyclists will hit the rumble strip and fall back to the left under the rear wheels of a motor vehicle, especially a truck.

    As I understand from the outreach meeting, although I have found no map of exactly where rumble strips are proposed, Caltrans is proposing to grind in shoulder rumble strips “only” in those places where there is at least 4′ of paved shopper beyond the rumble strips. But this would deny cyclists safe access to and from the shoulder in precisely the places where without rumble strips the shoulder would be most useful to cyclists.

    (4) Caltrans should consider, as one of the options in the EIR, *lowering* the speed limit on Niles Canyon Rd. from the present 45 mph. Caltrans should assess what (if any) legal changes or changes in the status of the road, by what decision-makers, this might require; what it would cost (presumably, only very modest cost for new signs); and the safety benefits and likely reduction in crash rates (likely huge).

    I believe that this would be the locally preferred alternative to any or
    all of the other changes proposed by Caltrans.

    Since not all of the road is equally unsafe at the present speed limit,
    Caltrans should consider two alternatives, one to reduce the speed limit for the entire segment between Niles and Sunol, and the other to reduce the speed limit for only perhaps the more dangerous half of that stretch.

    While I’m sure that there would be a variation in preferred speed limits (some might prefer 25 mph, some might prefer 35 mph), I would recommend a 30 mph speed limit throughout this stretch of road as sufficiently slow to permit safe sharing of the road by motorists and cyclists.

    (5) When changes to a road are being contemplated, notice of the proposed changes should be posted on the road itself, so that road users will have an opportunity for input before decisions are made.

    Where road users include cyclists (as they do on all roads in California except some, but not all, limited-access expressways), and especially where the changes are intended to benefit or likely to impact cyclists, notices should include signs directed to cyclists.

    It’s normal, and in many jurisdictions required, to post on-site notices of proposals for zoning changes, tree removal, etc. It would be easy and inexpensive to post similar on-site notices for road-related proposals.

    For example, 8 1/2″ by 11″ flyers, laminated to resist rain and weather, could be affixed to posts or existing sign poles alongside intersections or endpoints of the project road, where cyclists would normally stop.

    I recommend that *on-route* posting of proposals, including postings
    specifically directed to cyclists and pedestrians on all roads not closed to them, be added to your standards and templates for public outreach.

    If this is not the proper point of contact, particularly with respect to
    the shoulder rumble strips contemplated as part of the “Short-Term Safety Improvements Project”, please forward this message to the responsible decision-making individual or body, and let me know who that is and how I can contact them.


    Edward Hasbrouck
    GPC-talk mailing list

  5. Do not expect Caltrans to install rumble strips with regard to what they tell you. They will install them in many places they shouldn’t be installed. I have yet to see shoulder rumble strips installed without mistakes in California.

    They are about to do a median post guardrail project on SR-18 from the the base of the mountain to 138. This project will include shoulder rumble strips which they say will be installed within the lane where the shoulder is less than 4 feet. The main problem is there is a lack of shoulders along much of this section and where there are shoulders, dirt from the mountain is covering it, so no bicyclists can ride in the shoulder anyway.

    Bicyclists should work to make rumble strips an unrecommended practice in the same way that bollards are now unrecommended for preventing motor vehicles from entering bike paths at intersections.

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