HomeMy WebLinkAbout17-3944 ExE Traffic analysisMEMORANDUM
TBPLS Firm No. 10074302
Date: May 17, 2017
Re: 2520 Shadywood Rd., Orono, MN – Access Considerations
File R0010413.00
To: Tom Goodrum, Westwood
From: Steve Manhart, P.E. PTOE, PTP
Per your request, I have reviewed the access considerations for the proposed 40-unit
apartment use at 2520 Shadywood Road in Orono. The following are some of my
observations and reactions:
The posted speed limit on Shadywood Road south of Shoreline Drive (Co. Rd.
15) is 40 mph.
Shadywood Road is functionally classified as an “A-Minor Expander” roadway
by the Metropolitan Council.
The 2015 MnDOT Metro Traffic Volume Map does not provide a specific
Annual Average Daily Traffic (AADT) for this segment of Shadywood Road.
Nevertheless, one may estimate the daily volume by averaging the given
volumes to the north and south of this site. Therefore, one may assume the
AADT for this segment of Shadywood Road is approximately 7,950 veh/day.
According Land Use Code 230 of the ITE Trip Generation Manual, Ninth
Edition, the 40-unit condominiums will generate approximately 232 trips per
weekday (116 entering and 116 exiting); 18 trips in the a.m. peak hour (3
entering and 15 exiting), and 21 trips in the p.m. peak hour (14 entering and 7
exiting).
According Land Use Code 230 of the ITE Trip Generation Manual, Ninth
Edition, the 40-unit condominiums will generate approximately 226 trips per
day on a Saturday (113 entering and 113 exiting), and approximately 194 trips
per day on a Sunday (97 entering and 97 exiting). The Saturday peak hour will
Council Exhibit E
17-3944
May 17, 2017
Page 2
generate 19 trips (10 entering and 9 exiting), while the Sunday peak hour will
generate 18 trips (9 entering and 9 exiting).
The MnDOT Access Management Manual provides guidance on offset
driveways and streets. According to the manual, “On undivided highways,
high-volume (Type 3) driveways and public street connections on opposite
sides of the a highway should be aligned with one another to the extent
practicable, or they should be offset to minimize overlapping left turns and
other maneuvers that could result in safety or operational problems.”1
o A Type 3 driveway is a driveway designed to provide access to a large
development area encompassing multiple properties or structures served
by a clearly-defined system of internal streets.
o The access driveway proposed for this apartment use does not measure
up to the scale of a Type 3 driveway. This would be a minor driveway.
o It is advisable to provide an offset driveway across from the Baywind
Christian Church driveway on the west side of Shadywood Road, as
illustrated below. Overlapping driveways with the church should be
avoided, due to back-to-back left-turn lanes.
Figure 1 – Overlapping Driveways
(Source: MnDOT Access Management Manual, 2008, and Westwood Professional Services, 2017)
1 Section 3.4.5., Offset Driveways and Streets, MnDOT Access Management Manual, Minnesota
Department of Transportation, Saint Paul, MN, January 2, 2008, p., 35.
CHURCH NEIGHBORHOOD CHURCH
FRESHWATER FRESHWATER FRESHWATER
CONDOS CONDOS CONDOS
Aligned Offset Overlapping
May 17, 2017
Page 3
Conclusion
o Given the modest trip generation during peak hours, the apartment use
will increase AADT along Shadywood Road by approximately 3%.
o Either an aligned or offset driveway between the apartment use and the
church will operate safely and efficiently. An overlapping driveway
should be avoided, regardless of the low turning volumes.
o It is my engineering judgment that the potential vehicular turning
conflicts between the proposed apartment use and the Baywind
Christian Church will be relegated to Sunday mornings and possibly
one evening a week.
Please contact me if you have further questions or comments regarding this review.