By Wayne E. Rivet

Staff Writer

At a time when motorists can be distracted by cell phones and other factors, center-line rumble strips are considered an effective measure to reduce the number of head-on collisions.

Center-line rumble strips are primarily used to warn drivers whose vehicles are crossing center lines of two-lane, two-way roads. The noise and vibration produced by rumble strips alert drivers when they leave the traveled way.

According to the U.S. Department of Transportation Federal Highway Administration, the percent reduction in crash frequency from before-to-after rumble strip implementation — 45% on rural two-lane roads, and 64% on urban two-lane roads.

Milled rumble strips are made by a machine with a rotary cutting head, which creates a groove into the pavement. Tires passing over milled rumble strips drop into the groove, which causes tire noise and vehicle vibration. According to the federal transportation website, the wider and deeper the rumble strip, the more sound and vibration. “Research indicates that different dimension milled rumble strips provide different amounts of sound and vibration in the passenger compartment.”

Typical milled rumble strip widths are 5 to 7 inches with 12-inch spacing and approximately 0.5 inch depth. A typical length is 12 to 16 inches, but smaller versions have become more popular on two-lane roadways.

Maine has jumped on the center-line rumble strip bandwagon. New construction projects in western Maine have included installation of these strips, and possibly more are coming this way.

At a past Bridgton selectmen’s meeting, officials were informed that rumble strips are scheduled for installation on major portions of Route 302, including the Moose Pond Causeway.

“The unusual noise tires make as they cross over rumble strips keeps drivers alive, but it may also keep neighbors awake,” the federal transportation website says. “To fulfill their purpose, rumble strips must make enough noise inside the vehicle and tires must drop into the rumble to cause enough vibration to get the driver’s attention.”

Bill and Incy Muir, who reside on Brewster Circle in Bridgton, are concerned about that noise level.

They have discussed the matter with Maine Department of Transportation officials, and have reached out to other residents through an online survey.

“I wanted to reach out to everyone who lives around Moose Pond with regard to a recent issue that developed back in November 2016. The issue arose when the Maine Department of Transportation created rumble strips along the south side of the Causeway on Route 302,” said Bill Muir in a e-mail to The News. “The rumble strips have the effect of creating substantial disruptive background noise when cars or trucks intentionally or unintentionally hit the strips. Most people have not had the opportunity to hear this noise due to the timing of the installation of the rumble strips, which were installed at a time when most residents around the lake had left for the winter. The best way to describe the noise, for those who have not heard it yet, is very similar to the noise made by a tractor-trailer going down a steep grade and shifting into low gear. The noise is of a very low frequency and quite loud and has a tendency to carry down the lake. I know from personal experience that it could be heard inside our home quite clearly even with all windows closed.”

As a result of this noise and the potential impact it has on the enjoyment/environment of the lake, Incy Muir decided to reach out to the MDOT and asked officials about the rumble strips and what necessitated their installation.

She was told by the highway program manager and the lead “PE” at the safety office for MDOT that they would be happy to look into potential alternatives or maybe simply removing the rumble strips altogether, Bill Muir said

The highway program manager suggested that the Muirs should contact residents who are potentially impacted by the noise created by the rumble strips and try to get a group of people together who would support the idea that these rumble strips and the noise created by them should be looked into.

“The idea is that the MDOT would take the request more seriously provided it was supported by more than one individual,” Bill Muir said. “I would request that any resident who shares this concern regarding the noise created by the rumble strips and is interested in having the highway program manager/safety officer look into ways that the rumble strips might be made quieter, reply to the survey.”

According to the U.S. Department of Transportation Federal Highway Administration’s website, “the typical noise level inside a passenger vehicle without additional interior noise sources such as a radio playing is 60 decibels. It is not clear what combination of noise level increase and amount of vibration is necessary to alert a drowsy driver, but numbers from 6-15 decibels are mentioned in various studies. The increase in noise inside the passenger compartment typically correlates to an increase in noise outside the vehicle, which is why neighbors object to rumble strips. Proximity also greatly affects the amount of noise heard by neighbors.”

Road agencies have experimented with several alternatives to reduce exterior noise. Some simply ban their use in residential areas, while others try other alternatives to improve safety before considering rumble strips. And when rumble strips are placed near residences, agencies may discontinue the rumble strips where residences are very close to the road or around tight curves where large vehicles are more likely to have a wheel go beyond the edge line.

Survey Questions

1. Do you believe the noise created by the rumble strips may have a negative impact on residents’ enjoyment of the lake?

Yes‬ or No‬

1. Do you think that the noise created by the rumble strips could have a negative impact on the lake environment and wildlife?

Yes or No

1. Would you like the Highway Program manager/Maine DOT to look into the possibility of modifying or eliminating the rumble strips to reduce the noise they create?

Yes or No

1. Are there any other observation you would like to comment on with regard to the other improvements to the (Moose pond) Causeway.

Your answer

May we include your name as a respondent to this survey? Yes or No

The survey link:

https://docs.google.com/forms/d/e/1FAIpQLScmc4fhrWr4LYJRFt-dzJLEhi10M41oobhWariIZS5WW1iQfA/viewform