New! System-Wide Transit Corridor Plan for the San ... - Omnitrans

Chapter 4
Travel Demand Forecasting and Future
Conditions
This chapter examines the future travel markets
in the major transit corridors and the growth
potential in transit ridership that might be
achieved with the introduction of premium transit
service and good connections to other corridors
and other operators.
Route 1 Bus at Stop
The examination of growth potential in each
corridor will be demonstrated with demographic
forecasts and the projected magnitude of future
trip-making.
4.1 Model Methodology
This section summarizes the methodology used
and the validation of the San Bernardino Valley
Focus Model (SBVFM) that was used to produce
travel forecasts for the Long Range Transit Plan.
This information is intended to demonstrate the
model’s ability to replicate existing transportation
and transit ridership behavior, and the utility of
the model for forecasting future ridership and
comparing transit alternatives in San Bernardino
County.
This document provides a summary of the
development and derivation of the SBVFM from
the SCAG regional model, followed by a
summary of the model validation effort
specifically required for the analysis of transit
services in the San Bernardino Valley. The
regional nature of the remainder of the model
(outside of the San Bernardino Valley) also
allows for future transit analysis of the remainder
of San Bernardino County, to a sketch planning
lower level of accuracy.
The forecasting tool employed for the Long
Range Transit Plan is the San Bernardino Valley
Focus Model, which is a focused model derived
from the Southern California Association of
Governments (SCAG) regional model. The
SCAG model was updated in conjunction with the
2008 Regional Transportation Plan (RTP), using
a Year 2003 validation year. Elements of the
SCAG regional mode are documented in 2003
SCAG Model Validation and Summary –
Regional Transportation Model (January 2008).
The San Bernardino Valley Focus Model uses
the basic structure of the SCAG model, with the
mode choice model customized for use in the
San Bernardino Valley, and an increased level of
definition based on the networks and zone
systems found in the San Bernardino Valley.
The SBVFM employs the traditional 4-step
modeling process used in the SCAG model.
Special features of the SBVFM include:
• All person trips are modeled (including nonmotorized)
• Auto-ownership is tied to transit accessibility
• Person trip data is split into peak and off-peak
trips before application of distribution models
• Feed-back loops are used for highway and
transit skims
• Log-sums are used to estimate composite
impedance for application within trip
distribution models for home-based work trip
purpose
• Vehicle trip data is split into four time periods
and converted to origin-destination format
using time-of-day models
• Transit trip data is assigned to peak (AM) and
off-peak (midday) time periods in productionattraction
format
System-Wide Transit Corridor Plan 73