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Demonstration of Milled Rumble Strips on Asphalt Shoulders in The State of Kansas.
Kansas DOT / FHWA.
One of the latest advancements in the construction of Asphalt Shoulder rumble strips is the use of computer-controlled milling machines. In 1999 the Kansas DOT and FHWA Division Office sponsored a field demonstration using this technology to construct rumble strips. For more than 15 years Kansas DOT has been using rolled-rumble strips on asphalt shoulders on rural highways. The FHWA and KDOT arranged for a large milled-rumble strip contractor Surface Preparation Technologies to mill shoulder rumble strips over existing rolled rumble strips on the section of highway US 75 north of Topeka.
The purpose of this demonstration to compare the placement and the operational characteristics of the milled rumble strips to the rolled rumble strips. The milling machine has a single head that hydraulically lifts up and down as the machine travels down the shoulder. Doug Johnson of Surface Preparation Technologies says it is a continuous operation that moves in the rate of 9 to 13 shoulder miles in an 8-hour day on asphalt and 2 to 5 shoulder miles in an 8-hour day on concrete. Other milling machines may have different rates of production. The milling machine knows the rumble strip pattern and is followed by a sweeper that sweeps the millings off the shoulder. The milled rumble strip has been developed as an alternative to the formed and rolled rumble strips. Rolled rumble strips can only be placed during construction, but milled rumble strips are place after the surface is completed. As we can see the milled rumble strip is clearly distinguishable from the longer rolled rumble strip. Both the gapped and continuous milled rumble strips were constructed and evaluated using several test vehicles as part of the field test.
[Sound of the 1st test vehicle (sedan) driving on the shoulder with milled
rumble strips.]
[Sound of the 2nd test vehicle (compact car) driving on the shoulder with milled
rumble strips.]
[Sound of the 3rd test vehicle (truck) driving on the shoulder with milled rumble
strips.]
[Sound of the 4th test vehicle (motorcycle) driving on the shoulder with milled
rumble strips.]
Mike Crow, Bureau Chief of Traffic Engineering: "I was concerned at first because the rumble strips look wider, I know they only half-inch deep and because they are wider they look deeper. And I was concerned that the rumble strips would giggle the tires and the handlebars too much for me to control it. I saw cars and trucks go over it without any problem but I was concerned about motorcycles. Well, after I rode over it [on a motorcycle] it was a pleasant surprise, because it did not take the control away from me did give me a good rumble and quite a bit of noise. They really work, I can see if a cycle-rider had drifted off asleep then they [rumble strips] would definitely alert them [riders] that they are off the road but I do not think that they would throw them at all. I think these are good rumble strips, they did the job and provided the warning that they are supposed to."
[Sound of the 4th test vehicle (motorcycle) driving on the shoulder with milled rumble strips]
Tom Walsh, Retired Yellow Freight Systems, Inc. Driver: "In my 34 years as a professional driver, I believe that drifting off the roadway is a serious problem not just for truck drivers but for all drivers. When the FHWA asked me to participate in the demonstration of an improved type of shoulder rumble strip I quickly accepted. My hope of course was to support any roadway feature that I thought would enhance the safety of all drivers. When I drove over the current Kansas design where the shoulder rumble strips are rolled into the asphalt and compared them to the new milled rumble strips I immediately knew that the milled rumble strip test section was definitely superior in both feel and sound. In fact I could barely notice the rumble effect of the rolled-in strips in the cab of my truck. I hope Kansas and other states quickly will put this into force."
The milled rumble strips offer an effective and vibration to alert the vehicle leaving the lane and traversing onto the shoulder where the rumble strips are located. In addition it was concluded that the milled rumble strips did not adversely impact the control of any of the test vehicles. With this information, the KDOT intends to further evaluate the milled rumble strips by including them on some construction projects.
For further information on the milled rumble strips please refer to the following:
Contacts at KDOT:
Scott King,
Road Squad Leader, Bureau of Design - Road Section
785-296-3091
email: sking@ksdot.org
Mike Crow
Bureau Chief of Traffic Engineering
785-296-3618
email: mikec@ksdot.org
Robert Alva
Safety Traffic Engineer FHWA Kansas Division
785-267-7284
email: Robert.Alva@fhwa.dot.gov
Demonstration of Milled Rumble Strips on Asphalt Shoulders in the State of Kansas, December 23, 1999.