MODELING WY-22 FUTURES

The Teton County Travel Demand model developed by the county was used to evaluate the four alternatives for WY-22. The model was developed by Cambridge Systematics for Teton County; the same modeling team that developed the County's model conducted the analysis for this report. The travel demand model is a tool that can be used to estimate changes in how and where people travel based on future land use conditions (in this case 2035 was modeled) and what mode of travel people are likely to use (focus is on transit, HOV, or SOV). No model can predict the future, but the Teton County model is an important tool to inform local residents and stakeholders about potential future outcomes. Importantly, it is likely that WYDOT will use similar tools in its WY-22 corridor planning and environmental process. Understanding what models are likely to reveal informs future decisions and tradeoffs.

More detail on the Teton County Travel demand model is available in Appendix B.

Transportation Demand Management

Table 1 illustrates the major zones designated in the travel demand model and what impact a suite of TDM measures would likely have in reducing trips between zones.

Transit Service Assumptions

After discussions with representatives of START, the 2035 transit network in the model was adjusted to reflect transit system improvements that represented implementation of the START Routing Plan (2020 – 2025) and reasonable growth in service over the following 10 years (2025 – 2035). These transit improvements include addition of service to and from the Airport. The forecast year models also increase frequency on existing fixed route bus service by a factor of three over existing service levels (less compared to full implementation of the START Routing Plan). These transit system improvements are included in all forecast year model runs, including the no-build alternative.

In Vancouver, WA, C-Tran operates bus on shoulder on State Highway 14. Buses operate on the shoulder only in congested conditions speeds are capped at 35 miles per hour.

The speed of transit vehicles varies depending on the alternative:

• No Build: assumes buses operate in traffic and travel speeds are dictated by levels of congestion.

• Shoulder-Running Transit: assumes buses travel at a maximum speed of 35 miles per hour when utilizing the shoulder transit lane (consistent with policies set by agencies that operate running transit). Buses can travel faster when in general traffic lanes during uncongested periods.

• Transit + HOV 2+ Lane: assumes buses operate at travel speeds dictated by use and flow of the HOV lane (set by model)

• Four Lane: assumes buses operate at travel speeds dictated by use and flow of general traffic lane.