6. Staff Report PW Washington Co. Mumble strip 2024-2025
Staff Report
Date of Meeting: 7-1-20
To: Mayor, City council
From: Adam Hawkinson, Director of Public Works
Re: Washington County adding mumble strip on Manning Tr. 2024-2025
Information:
Washington County will be pursuing an application to implement MUMBLE strips along the
CSAH 15 (Manning Avenue) centerline from CSAH 12 north to the county line. Like rumble
strips, mumble strips create vibration as a car rolls over them – alerting the driver that they are
veering into oncoming traffic. However, they do so while also muffling the sound, which means
less noise for surrounding communities. This particular stretch of Manning Avenue has seen
several deadly head-on collisions in the last decade, and mumble strip s reduce the frequency
and severity of that type of crash.
If funded, the mumble strips could be installed in 2024 or 2025, which may result in minor,
temporary traffic disruptions during installation. There will be no cost -participation required
from the City of Scandia as part of this project.
HSIP
Highway Safety Improvement Program (HSIP) is a federal program facilitated by MnDOT that is
designed to fund projects that enhance safety by reducing the frequency and/or severity of
crashes. An example of a previous Washington County project that received HSIP funding was
the addition of turn lanes on County State Aid Highway (CSAH) 15 (Manning) at Mendel Rd N in
Grant and Stillwater Township.
HSIP funding for this solicitation is for state fiscal years 2024 and 2025, and we can apply for up
to $2.0 million per project. After analyzing the program requirements, County staff determined
that centerline rumble strips along CSAH 15 (Manning) from CSAH 12 (75th St N) to 240th St N
could be a competitive application.
Project Background
There is a history of serious and fatal crashes on this stre tch of CSAH 15 – several involving
head-on collisions. MnDOT crash data collected from 2016-2018 shows 92 crashes during that
3-year period, including 14 moderate-injury crashes, 1 serious-injury crash, and 3 fatal crashes.
29 of those crashes occurred in Scandia – including a fatal head-on collision between two
vehicles in 2018. This stretch of CSAH 15 is also amongst the highest priority rural segments
recognized in the 2013 Washington County Roadway Safety Plan, and rumble strips emerged as
one of the top recommended strategies to address safety concerns for this segment.
The proposed centerline rumble strips – in addition to reflective striping – would reduce the
frequency and severity of head-on collisions along CSAH 15. This is an important goal for the
county – we need to figure out a way to reduce these head on crashes – and centerline rumble
strips seem to be a cost-effective solution. We are aware of the concern over noise related to
rumble strips – therefore we are NOT proposing to add shoulder rumble strips at this time.
Additionally, we are evaluating a new rumble strip design – called sinusoidal rumble or
“mumble” strips. Mumble strips still vibrate the steering wheel of the vehicle, providing the
driver feedback we are looking for, but they produce less external noise.
The proposed project is estimated to cost $124,063 and the City of Scandia is NOT responsible
for any cost-sharing related to this project. If we are successful in this application, these
projects will be programmed in the County CIP for years 2024-2025. If we are NOT successful,
then the project would likely be deferred.
Next Steps
While the application does not require any formal letter of support from the City Council, we do
want to work with Scandia to make sure the City is supportive of this project. The project is in
its earliest stages of planning, and should we receive funding County staff looks forward to
continuing discussions with Scandia.
If there is something you would like to discuss further, we can set up a conference call with the
City to discuss the project in more detail. Let us know!
Video on Mumble Strip vs. Rumble strips:
https://mntransportationresearch.org/2014/06/10/rumble-strips-vs-mumble-strips-noise-comparison-
video/
Please let me know if you have any questions or concerns regarding this project or application.
Washington County Public Works staff are copied here, and are available to discuss.
Options:
1. Inquire more information from Washington Co.
2. Support the measure with no concerns and have PW Director reply to Washington
County of that fact.
Recommendation:
Option #2