F-006 Preliminary Sight Distance Letter C EMERIO
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October 13, 2022 c r
DocuSigned by:
City of Lake Oswego
Engineering Review Staff s R GD
380 A Avenue 0�10,
Lake Oswego, OR 97034 �(/q v . P _-
Attn: Engineering Review Staff EXPIRES: 12/31/2023
RE: Baleine Street Development at Tax Map 251E 07CA, Tax Lots 100, 2902, 3000
- Preliminary Sight Distance Certification
This letter is to address the City of Lake Oswego Municipal Code Section 50.06.003.2.b.i(4)
concerning sight distance for driveway approaches, specifically for 5 future single-family
homes to be proposed on the southeast corner of Kimball Street & Baleine Street.
Location and Project Description:
The two proposed driveway approaches for this project are located between 108 and 130 feet
south of the intersection of Kimball Street & Baleine Street. Both approaches are accessed
from east side of Kimball Street. The north proposed shared drive (driveway "A") will serve
three single-family homes, and the south proposed shared drive (driveway"B") will serve two
single-family homes.
Road Classification: Kimball Street is classified as a local street by the City of Lake Oswego
and is a two-lane roadway approximately 18 to 21 feet wide with a posted residential speed
limit of 25 MPH. No sidewalks, curbs, or bike lanes are provided for the either side of the
road. Intersection sight distance for this project requires analysis of vehicles traveling in the
south and north directions on Kimball Street.
Object and Driver Eye Heights: Measurements are based on a driver's eye height of 3.5 feet
above the anticipated driveway finish grade and an object height of 3.5 feet above the existing
roadway. The front of a stopped vehicle is assumed to be 10 feet from the near edge of the
travel lane pavement (Kimball Street). Measurements to the driver's eye are referenced from
the existing edge of pavement of Kimball Street to 15 feet back to the location of the driver.
Left Turn from Minor Road:
Northbound Vehicles on Kimball Street
Case B1, Left Turn from Stop is the controlling case for determination of intersection sight
distance at this driveway. With a design speed of 25 MPH, the required sight distance for a
left turn from a stop is 280 feet per Table 9-7, 9-46 in the AASHTO "A Policy on Geometric
Design of Highways and Streets, 2018" manual.
Vehicles approaching from the south can be seen along a sight distance over 450 feet from
each proposed driveway. The code is satisfied by showing a measured sight distance greater
than the required 280 feet for approaching vehicles from the south.
Southbound Vehicles Approaching from Baleine Street Intersection
Vehicles approaching from the north while still on Baleine Street to the west can be seen along
a sight distance of at least 149 feet from driveway"B" and 137 feet from driveway"A". The
AASHTO manual indicates the speed range for turning motorists is typically 10-15 MPH. The
upper limit design speed of 15 MPH will be sued for vehicles turning from Baleine Street onto
Kimball Street. With a design speed of 15 MPH, the required intersection sight distance for a
6445 SW Fallbrook Place,Suite ioo • Beaverton,OR 97008 • emeriodesign.com
2
left turn from a stop is 170 feet per Table 9-7 in the AASHTO manual. While intersection sight
distance to the minimum of 170 feet could not be measured due to the proximity to the
intersection, the minimum stopping sight distance of 80 feet (149 feet and 137 feet
measured) is available for approaching vehicles from Baleine Street.
Due to existing vegetation/trees in front of the existing lot in the ROW, the sight distance to
the east and west for the proposed approaches at the driver's eye height is obstructed. Sight
distance was obtained by standing in front of the vegetation and taking measurements along
the sight lines.
Conclusion:
I hereby certify that sight distance is available at the two proposed driveway approaches.
Sight distance conforms to the requirements as set forth by AASHTO, subject to the following
improvements:
a. Construction of the accesses as designed
b. Clearing of existing vegetation onsite and in the right-of-way in the site frontage
If you have any questions please do not hesitate to send an email to
joshua@emeriodesign.com or call at 503-746-8812.
Sincerely,
Emerio Design, LLC
Joshua Ayers, PE
Project Engineer
6445 SW Fallbrook Place,Suite ioo • Beaverton,OR 97008 • emeriodesign.com