Appendix D Traffic Impact Analysis - westplainseis.com

Background/Introduction
This document serves as an addendum to the TIA dated April 28, 2011 prepared in support of the Draft
EIS prepared by AES, Inc. for the Spokane Tribe’s proposed West Plains Development. This addendum
does not revise or supersede the fundamental assumptions used in the TIA related to the site
development, trip generation, distribution and assignment or the overall operational analysis results.
This addendum focuses on the following items:
1. Suggested changes by WSDOT and Spokane County to site access locations and intersection
control along the HWY 2 project site frontage.
2. Roadway connectivity
3. Bike, pedestrian and transit facilities
4. Cummulative (2032) Condition Corridor Impacts
5. Alternatives mitigations for the Hayford/HWY 2 intersection
6. Revised Analysis/Mitigation at HWY 2/Fairchild AFB Intersection
7. Approach to Mitigation (timing/phasing of mitigation improvements and proportional share)
HWY 2 Site Access
The TIA examined three site development alternatives all with the same proposed site access locations
along HWY 2 (see Figures 2A-2C of the TIA). These site plans proposed one full movement access at
about the midpoint of the project site frontage along HWY 2 about 1/3 mile west of Craig Rd.
Additionally, two right-in/right-out (RI/RO) access were proposed; one west of the primary access and
one east of the primary access.
The full movement main access was analyzed with both roundabout and signalized intersection control.
The analysis indicated that a roundabout would likely operate better under most analysis scenarios,
provide greater capacity and have less of an impact on HWY 2 corridor operations.
WSDOT staff has reviewed the operational analysis and also independently developed a VISSIM model
to compare roundabouts to signalized intersection control at the Main Site Access(Middle Dwy)/HWY 2
intersection as well as the HWY 2/Craig intersection.
Additionally, WSDOT and Spokane County staff developed a schematic alternative plan for site access
locations and control for the project’s HWY 2 frontage. The schematic plan is included as Attachment
A. This document will refer to the revised access as the ‘Two Roundabout Access’ scheme. It suggests
having two full movement accesses on the HWY 2 site frontage using roundabout intersection control,
along with a roundabout at the HWY 2/Craig intersection. The three roundabouts would be more or less
equally spaced just less than a ¼ mile apart. The westerly access would be positioned near the westerly
property of the Spokane Tribe site providing access to the overall site as well the existing Spoko Fuel
facility. The middle roundabout would be located somewhat east of the previously proposed main
access.
It is DEA’s opinion that this access scheme would function well and disperse traffic more evenly to the
access points compared to the original access scheme and have less impact to HWY 2 corridor traffic
flow and operations.
This alternative access scheme would require some minor revisions to the location and layout of the
commercial/retail pads along the HWY 2 frontage as well as to on-site the circulation road on southerly
portion of the site. However, the core of the development (casino/hotel/entertainment facility) and
West Plains Development – Spokane Tribe Page | 1
Traffic Impact Analysis Addendum July 18, 2011