Bike/Walk Tennessee directors Bruce Day and Tom Evans on January 15 tested how compatible grooved thermoplastic edge lines are with cycling, using road bikes with 700x25 tires on a stretch of US 246. The grooved lines presented no problem whatsoever, and they rode on and across them numerous times. Although the lines can be felt, they did not present anything other than the ordinary for a road cyclist.
Grooved thermoplastic road markings may present a more bike-friendly alternative to rumble strips in terms of reducing run-off road crashes. The markings gently alert drivers to reaching the line, and they're not as loud. As an additional benefit, pavement longevity is not adversely affected by them, unlike the case with rumble strips. Bike/Walk Tennessee is proud to have assisted TDOT with this assessment. Click here for copy of the report.
US 70 Bike Route in Watertown was resurfaced and rumbled last week (early November 2010). This stretch of highway runs to the Dekalb county line and is used for the annual Big Hill Challenge sponsored by the Veloteers. The grooving was applied in accordance with the March 2010 TDOT specifications.
On a recent ride we encountered this bit of rumbling along TN SR 290 in Bedford Co between Chapel Hill and Shelbyville. The part in Marshall Co was not rumbled, had the same shoulder and same traffic. The part in Marshall Co felt perfectly safe but the part in Bedford Co did not. The bit of shoulder that was left was too narrow to ride, especially when there was a multi foot drop off from pavement to grass. After almost falling when being chased off the travel lane by a horse hauling truck and trailer having to move back to the right to accommodate oncoming traffic, we searched and found a usable side road. This road has no special merit except for being direct and easy to follow and in the future I will avoid 290 entirely. However it does highlight several issues.
I was riding the Mississippi River Trail just south of Grafton, Illinois this weekend when I came upon this use of Rumble Strips. It shows a way that rumble strips can be made to benefit BOTH motorists and bicyclists.
What are rumble strips?:
. . Rumble strips are raised or grooved patterns in a road’s shoulder designed to alert drivers with noise and vibrations that they are drifting off the roadway. They can be an effective safety measure to prevent run‐off‐the‐road (ROR) crashes, especially on limited‐access highways and rural two‐lane highways with long straight sections.(Rumble strips placed on the centerline can help prevent head‐on crashes.)
How do rumble strips impact cyclists? . . Rumble strips are virtually impossible to ride a bicycle on or over– they are at best uncomfortable, even for a very short distance, and at worst can cause a cyclist to lose control of their bike and fall. They can damage a bicycle wheel, can cause a flat tire, and/or shake lose parts off a bicycle. Consequently, cyclists will avoid riding over themii – and when rumble strips leave no room on a shoulder, the cyclist will have no other option than to ride in the travel lane. While rumble strips do not deter car, truck or bus travel, they have a severe impact on bicycling travel, and have ruined popular cycling routes.
. . The negative impact of rumble strips on the ride‐ability of a roadway has prompted American Association of State Highway and Transportation Officials (AASHTO) and the Federal Highway Administration (FHWA) to provide guidance to follow when considering rumble strips on roadways used by cyclists. They recommend that rumble strips should not be used indiscriminately on roadways that are not limited‐access. Rumble strips should be used where there is a history of run‐off‐the‐road crashes; especially where there is sufficient recovery room for a motorist to react to the alert provided by the rumble strip; and when the impact cyclists can be minimized. This means that at least four feet of unobstructed roadway shoulder remains after the rumble strips have been installed.
. . States should train and monitor contractors to ensure best practices are followed. Advocates should work with their state DOTs, Municipal Planning Organizations (MPOs), and county road commissions to verify that unnecessary rumble strips are not installed and that preferred bicycling routes, especially, are kept free of rumble strips. It is important to get it right the first time. Improperly installed rumble strips are expensive to repair – often costing many times more than the original installation – and usually cannot be repaired without leaving behind an uneven surface or a shoulder prone to early failure.
Specific Elements to Address . . 1. Too wide – many rumble strips are excessively wide, removing limited space on the shoulder for bicyclists to travel.
. . 2. Too deep – most rumble strips are ground‐in to depths that are excessive and dramatically more dangerous for cyclists.
. . 3. Continuous – rumble strips without gaps in the strip do not allow a safe way for cyclists to cross, merge or turn without hitting rumble strips.
. . 4. Placement – the lateral placement in a shoulder can make a shoulder that was once very comfortable to a bicyclist unusable.
. . The League of American Bicyclists, the Alliance for Biking And Walking, and Adventure Cycling call for a National Strategy on dealing with safety rumble strips. The Alliance is hosting a teleconference. Click here to Register.
. . Although Bike Walk Tennessee has reached a reasonable compromise with TDOT on this matter, we must remain vigilant and engaged. Board Members have elevated this matter to these three organizations and insisted on their involvement.
. . Bike Walk Tennessee will be assisting TDOT and their contractor RPM Transportation Consultants in identifying routes important to bicycling. Please visit our Web Page that provides instructions on how bicyclist can help in this effort.
For your interest and amusement, I found some really good rumble strips in Florida. They were ~3 inch discs, ~1 inch in height, glued into the middle of the right-hand paint stripe and appeared to be composed of small glass beads (like the paint stripe) glued into a matrix and put down at the same time as the stripe I think. A periodic break in their sequence every 20 feet or so would have been the only improvement I would want.
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