PZ - Collector-Traffic-Engineer-Memo Kimley>>>Horn
January 10, 2022
Ms. Kelli Black
Walsh Group
(208) 329-5715
Re: Jamestown Ranch Subdivision, Meridian, ID
Dear Ms. Black:
As requested, we have performed a review relative to the location and traffic operations associated
with the proposed Grand Lakes Way and McMillan Road access serving the Jamestown Ranch
residential development in Meridian, ID.This review is predicated on data provided by the Walsh Group,
LLC as well as the previously prepared Traffic Impact Study for Jamestown Ranch Subdivision,
Meridian, ID, CR Engineering, Inc., revised October 14, 2021.
Background
Jamestown Ranch is a proposed residential development comprised of 294 single-family homes. The
development is located south of McMillan Road, between Black Cat Road and Joy Street. A proposed
access, known as Grand Lakes Way, is located 1336.98 feet east of Black Cat Road and 983.48 feet
west of Joy Street. Grand Lakes Way was originally planned to align with Joy Street. However, due to
an existing power pole(high mast transmission tower)and a residence in close proximity to this location
on the south side of McMillan Road, an alternative alignment approximately 980 feet to the west of Joy
Street was selected. This location preserves a '/4 mile separation from Black Cat Road. Further, ACHD
found this proposed location to be acceptable due the constraints noted previously.
Access Spacing
Per ACHD Policy 7205.4.6, a minimum separation of 1320 feet is required for unsignalized collector
streets away from a signalized intersection. The proposed location of Grand Lakes Way is
approximately 1340 feet away from Black Cat Road (future multi-lane roundabout) and thereby meets
this requirement. Spacing to Joy Street is approximately 985 feet.
Traffic Operations
Under two-way-stop-control, the intersection of Grand Lakes Way and McMillan Road operates at LOS
B or better without and with a (warranted) westbound left turn lane under 2025 build-out (total) traffic
conditions. No further improvements are anticipated at this location to accommodate forecast traffic
conditions.
Sight Distance
At 50 mph on McMillan Road, 555 feet of sight distance is needed to the right (east) in order to make
a northbound left turn from Grand Lakes Way and 530 feet is needed to left (west) in order to make a
northbound right turn. As terrain is relatively flat within these limits and the profile along McMillan Road
is as well, meeting these sight distance requirements can be accomplished as long as obstacles such
Kimley>>>Horn Page 2
as vegetation, aboveground utilities, and structures are not located within the sight distance triangle.
The vertex of the sight distance triangle extends 14.5 feet from the edge of McMillan Road, along Grand
Lakes Way. Within the sight triangle, vegetation, structures and other features should be restricted to
3.5 feet or less.
Other Considerations
North of McMillan Road, Joy Street continues for approximately 750 feet before it terminates at Milano
Street. Aligning Grand Lakes Way with Joy Street would do very little to enhance north-south travel in
this area other than to connect two separate subdivisions. South of McMillan Road, Grand Lakes Way
offers a curvilinear collector street centrally located to planned subdivision lots and connecting local
streets. The inherent geometry of Grand Lakes Way should offer some degree of traffic calming within
the Jamestown Ranch neighborhood, as well as offer efficient ingress and egress to associated lots.
While an access alignment at Joy Street would likely require another access on McMillan Road serving
the the westerly lots.
Conclusion
The location of the Jamestown Ranch Subdivision access at Grand Lakes Way and McMillan Road
meets ACHD access requirements and does not create adverse operational or safety conditions.
We appreciate the opportunity to provide these services to you. Please contact me if you have any
questions (208.510.6265).
Very truly yours,
KIMLEY-HORN AND ASSOCIATES, INC.
By: Robert Beckman, P.E., PTOE
Attachments: Jamestown Ranch site plan