HomeMy WebLinkAbout012_AccessDeviationLetter
August 8, 2024
Lucian Hand
Altos Photonics, Inc.
201 S Wallace Ave
Bozeman, MT 59715
Reference: Traffic Deviation Analysis – Altos Photonics
Project No. 24141.1
Dear Lucian:
The purpose of this letter is to provide a summary of traffic engineering services
completed in support of the Altos Photonics project in Bozeman, MT. A deviation is
requested per the City’s Uniform Development Code (UDC) (38.400.090.H) to permit
an approach to the proposed surface parking lot on Tamarack Street that is closer to
the Rouse/Tamarack intersection than the UDC allows based on the City’s
classification of Tamarack Street as a collector.
Access to Altos Photonics is proposed via one (1) existing approach on Rouse Avenue
and one (1) existing approach on Tamarack Street. The access point on Rouse Avenue
is located 129-feet north of Tamarack Street. The access point on Tamarack Street is
currently located 131-feet east of Rouse Avenue. In the proposal, the Tamarack Street
access will be moved 10 feet west, which will place it 121-feet east of Rouse Avenue.
Adjacent to the site development, Rouse Avenue is classified by MDT as a minor
arterial with a 25-mph speed limit. Additionally, Tamarack Street is classified by the
City of Bozeman as a collector with a 25-mph speed limit adjacent to the site. The
roadway section for Rouse Avenue is a 3-lane typical with a center two-way left-turn
lane. Rouse Avenue is an MDT maintained/responsible roadway (P-86) on their
primary roadway system. The roadway section for Tamarack Street is a 2-lane typical
that has left- and right-turn lanes at its intersection with Rouse Avenue.
The City of Bozeman’s UDC (TABLE 38.400.090-1) outlines the required distance for
full access spacing on collector streets, as Tamarack is classified adjacent to the
site, to be 330-feet. The minimum separation for access locations on collector streets
is noted as 150-feet in the same referenced table. The proposed access on Tamarack
Street has a distance from the intersection of 120-feet, which falls short of the
minimum. A deviation is requested per the UDC, Section 38.400.090.H, for the
Tamarack Street access. UDC 38.400.090.H.3.a through 38.400.090.H.f are addressed
in this letter.
Lucian Hand
August 8, 2024
Page 2
Intersection capacity was evaluated with site trips added to future volumes. This
Future (2038) + Site scenario was found to operate at LOS C or better on all legs for
both peak periods. Table 1 below presents the capacity results for this scenario.
Projected queueing on the east leg of the Rouse/Tamarack intersection is 28-feet
during the AM peak hour and 55-feet during the PM peak hour for the Future (2038) +
Site scenario. This equates to three (3) vehicles and would not interfere with
operations at the proposed parking lot approach location on Tamarack Street.
Intersection Sight Distance (ISD) was evaluated at the proposed approach location
using criteria from AASHTO’s A Policy on Geometric Design of Highways and Streets,
Chapter 9.5.3.2. Both a passenger car and single unit truck were evaluated as design
vehicles, and only one (1) single unit truck is expected to deliver to the site each day.
For a left-turn movement out of the site, a passenger car and a single unit truck
require 240 and 315-feet to the west, respectively. For an egress right-turn movement,
a passenger car and single unit truck require 280 and 350-feet to the east,
respectively. Street vision triangles were also evaluated according to UDC
38.400.100C. There do not appear to be any vision restrictions within the sight
triangles. Clear sight triangles should be evaluated during construction for any
temporary traffic control restrictions.
Table 1. Existing and Future + Site Capacity Calculations Summary
Avg
Delay
(s/veh)
LOS
95th %
Queue
(veh)
Avg
Delay
(s/veh)
LOS
95th %
Queue
(veh)
EB 20.8 C 2 19.4 B 2WB20.7 C 1 21.7 C 2NB8.6 A 7 9.3 A 10SB7.9 A 8 9.7 A 10Intersection10.4 B --11.4 B --
EB 21.4 C 2 19.6 B 3WB20.9 C 2 22.3 C 3NB10.9 B 12 12.3 B 15SB9.9 A 12 13.2 B 17Intersection12.3 B --14.2 B --
Intersection Control Signalized
Tamarack Street &
North Rouse Avenue
Future (2038) + Site
Tamarack Street &
North Rouse Avenue
Intersection Control Signalized
Intersection Approach
Existing (2023)
AM Peak PM Peak
Lucian Hand
August 8, 2024
Page 3
While the location of the proposed Tamarack access point does not meet the
minimum separation from the Rouse intersection, it is located as far east on the site
as possible. Additionally, increasing the number of access point on the site to two (2)
is preferred for commercial sites by the City for fire access and other safety reasons.
Ingress and egress site traffic flow will primarily be right turns at the location of the
Tamarack access point based on the parking orientation, location of Rouse access in
proximity to the adjacent traffic signal and external site distribution.
It is recommended that the Altos Photonics access deviation request be approved as
it is not anticipated to impact the health, safety or welfare of the public. Please feel
free to contact me if you have any questions.
Sincerely,
Joey Staszcuk, PE, PTOE, RSP1
Associate Principal/Community Transportation Studio Manager
KRK/jhs/SG
Enc.
P:\24141_01_411_E_Tamarack_Site_Plan_&_Inf_Plan\TRAFFIC\Access
Deviation\E_Tamarack_Access_Deviation
ROUSE AVE2
3
1 2 3
0
(0)
(3)
7
(0) 2
1 (1)
7 (4)
3
(2)
1 TAMARACK ST
12 (6)
6 (2)
12
(4)
(3)
1
(6)
11
(2) 3 10 (4)
(4)
6
KEY
XX
(XX)
[XX%]
AM Peak Hour
PM Peak Hour
Distribution
XX
(XX)
[XX%]
AM Peak Hour
PM Peak Hour
Distribution
KEY
[35%][35%][25%][5%]
0
(0)
(0)
0
(0) 0
(0) 0
0
(0)
0 (0)
(0)
0
(0)
0
(0) 0 0 (0)
AASHTO PC ISDLEGENDAASHTO SU TRUCK ISDUDC STREET VISION TRIANGLE95TH QUEUE LENGTH