Key changes Effective March 1, 2010: (Provided by Jessica Wilson, 1/20/10)
1) There are now 4-inch and 8-inch wide alternatives to the standard 16-inch strip in order to accommodate cyclists where the available paved shoulder may be limited. Additionally, these alternatives will be installed as stripes, meaning the rumble will included as part of the white edgeline.
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2) The new standards utilize a 30’-10’ gap pattern. This means that for every 30’ of continuous rumble stripe, there will be a 10’ break to serve as a gap for cyclists who may need to enter/exit the travel lane
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3) TDOT adapted a more bicycle-friendly 5” rumble/7” space pattern instead of the more common 7” rumble/5” space. This was taken from research provided by the University of Missouri for MoDOT (report No. RDT 03-007, Refer to table 4-4 on page 7 for performance rankings. http://library.modot.mo.gov/RDT/reports/Ri01057/RDT03007.pdf
4) The depth of the rumble used will be the midpoint of 3/8” to 1/2” (most common depth adopted by other states) with a +/- 1/16” tolerance. This means that the depth of the new rumble stripe will be somewhat shallower than the ½” depth we’ve used in the past.
All resurfacing projects will be review by the TDOT Bike/Ped Coordinator for sensitivity to bicycle routes
The following analysis results from reading the Notes block on the three Engineering Drawings for the Spec's
Rumbling Stripping will NOT BE USED on roads with bicycle traffic
Rumble Strips will be used ONLY on the following two road classes:
- Controlled Access Road - These roads are generally off-limits to bicyclist so the spec is not applicable.
- Non-controlled Access Roads with a minimum shoulder width of 8-feet on which bicycle traffic is not
permitted.
Rumbling Striping will BE USED on roads with bicycle traffic
Although STRIPING significantly reduces the damage rumbling does to shoulder for cyclists,
it does not eliminate the problem on roads not signed as Bike Routes
The primary benefit of the new spec is on the many state roads with 3- to 4-foot shoulder widths. Past practice of stripping nearly down the center of this shoulder eliminated its use for a bicyclist, who was then forced to ride in motor traffic creating issues for eveyone. The new 8-inch-wide design placed over the fog line (and not in the center of the shoulder) now leaves sufficient room to ride.
On roads with shoulders of 2-foot or less, the 4-inch-width may or may not leave room for the bicyclist. In many of these cases the bicyclist for safety reasons chooses to take-the-lane and does not attempt to ride the shoulder. Motor traffic tends to squeeze bicyclists off-the-road. The narrower and shallower road cut in t he new spec is a benefit in that it allows the cyclist to cross the rumble with less risk of loss of control should that become necessary.
Rumble Strip construction is LET as part of Resurfacing Projects. A list of LET projects by county can be found here
Key changes, May 18, 2011: (Provided by Jessica Wilson)
FHWA sent out new guidance to the states regarding rumble strips (see attached). These guidelines replace the Roadway Shoulder Rumble Strips from December 2001. Essentially it talks about the effectiveness of rumbles and then advises states on a number of issues, with one issue being that states should use mitigation strategies for rumbles in instances where a shoulder is less than 4'. It practically mirrors the standards that TDOT adopted last year.
