Future Employment Estimation

Introduction

For Oregon modeling work there is no official (mandated) source or control for total workers / employment for future years, as there is with population. ODOT-TPAU staff have historically used a variety of methods to develop future year employment inputs to travel demand models. In the past, trip-based model future employment development usually focused just on the employer side (employment), and typically did not include a detailed review / alignment with the number of workers (the household side). The ABM requires a much stricter review / development process, where both the number of workers and the jobs (employment) need to be consider at the same time. This additional level of detail requires an updated approach to building the future population.

Historically with trip-based model work, future employment was allocated at the TAZ level (using various methods) and then totaled up and compared to the population for reasonableness (one could think of this as a bottom up approach). The ABM is approach with a top-down method. Where overall job and worker totals for the region are established and then allocated down to the zones (in this case MAZs). There is no required source of information to build the regional totals; ODOT-TPAU has opted to use the 10-year employment forecasts published by the State of Oregon Employment Department (OED) and then continue the 10 year growth assumptions linearly out to the model's future year. ODOT's Statewide Integrated Model (SWIM) can also be used to assess future employment estimates. In the case of SOABM, SWIM was reviewed, but ultimately the team decided to use OED's 10-year forecast as a more official and statewide consistent approach. The use of that data to inform the future year employment development is further described in the steps below.

Future Year Employment Development Steps