Sonoma Marin Area Rail Transit (SMART)
Analysis on the Effectiveness
of the Proposed Rail System
MS&E 220 – Probabilistic Analysis
Professor Samuel Chiu
December 4, 2008
Prepared By:
Samuel Gambrell
Paul Jones
David Williams
Executive Summary
Project Overview
This analysis addresses the issue of whether one should support the proposed Sonoma-Marin Area Rail Transit (SMART)
commuter rail system that was on the ballot in November 2008. The methodology of the analysis was to use the tools of
probability to examine the uncertainties surrounding the decision making process. The key uncertainties in this decision
scenario are ridership, expenses, and revenues. These uncertainties have been modeled and combined with a personal
preferences matrix resulting in a decision model. The decision model is valuable for understanding why an individual or
organization supports or rejects the SMART project.
Background
The SMART District is planning the development of a 70-mile long passenger railroad along an existing but currently unused
freight railroad corridor. The railway will serve as a travel alternative to commuters on Highway 101 which is congested
during commute hours from San Francisco, through Marin County, and far into Sonoma County. The project’s construction
and operation costs will be funded by commuter fares, government funds, and a ¼ percent sales tax increase for the two
counties served. The budget measure was approved by a two thirds majority on November 4 th, 2008 to proceed with the
SMART project. The train is expected to be ready for use in 2014. The project has been controversial because of the
uncertainties related to ridership levels and project costs.
Recommendation
As evidenced by a 69% yes vote for SMART on November 4th, 2008, there is strong community support for the commuter
rail project. Even though only a fraction of 1% of the community is expected to ride the train on a daily basis, voters
accepted the ¼ percent sales tax hike with the hope that traffic conditions will improve, air quality will improve, and the train
project will bring economic benefits to the community as a result of new development surrounding the stations.
Due to the uncertainties in key factors driving the project, it is difficult to predict whether the SMART system will be viewed
as a success or failure over the course of 20 years. Commute patterns, gas prices, and environmental awareness can be
expected to change over the next two decades and they each have a significant impact on the ridership of a commuter rail
system. The cost to build and operate the system and the revenue anticipated from sales taxes are also uncertain.
A probabilistic analysis was performed by Williams, Gambrell & Jones (220 project team) to model key attributes of the
SMART system and to validate or discredit reports conducted by the SMART organization that were based primarily on
deterministic estimates of ridership, expenses and income. The probabilistic model provides more information on what the
possible ranges of parameters can be expected to be.
The analysis conducted by the SMART project coordinators can be viewed as conservative with respect to ridership
expectations and revenue from the sales tax increase. The SMART project coordinators estimated construction and operation
costs and then increased that estimate by a 20% buffer. Each of these three estimates from SMART reports fell at the low
end of the probability models created by our team.
The decision to support or not support the SMART project is heavily influenced by personal preferences and attitude towards
risk. To aid an individual or organization in making this decision, a decision tree and preference matrix has been created to
assist with understanding the parameters involved with assigning a success or failure status to the SMART project.
The recommendation from Williams, Gambrell & Jones is to support the SMART project while instituting stringent cost
control measures on construction and operational costs. Our model projects that the minimum actual ridership will exceed
the SMART’s official estimate and could possibly be up to three times higher. It is understood that the positive impact on
traffic conditions and the environment will be slight relative to the overall vehicle traffic on Highway 101. However, the ¼
percent sales tax increase is not a significant burden on individual citizens and the completed train system will spur economic
growth and encourage environmentally sound development near city centers as opposed to urban sprawl.