Scenario Planning:
U.S. Experience
CIVITAS Open Academy
Ljubljana
15 April 2010
Eric N. Schreffler, Transport Consultant
San Diego, California USA
Overview

What is Scenario Planning (U.S. context)

Example: Envision Missoula

Performance Measures

Travel Demand Modeling
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WHAT ARE SCENARIO PLANNING AND VISIONING?
THE BASICS
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U.S. DEFINITION: Scenario Planning
“Scenario planning is a process in which
transportation professionals and citizens
work together to analyze and shape the
long-term future of their communities. Using
a variety of tools and techniques,
participants assess trends in key factors
such as transportation, land use,
demographics, health, etc. Participants bring
the factors together in alternative future
scenarios, each of these reflecting different
trend assumptions and tradeoff
preferences.”
Federal Highway Administration definition
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VISIONING

Scenario planning
complements and follows
community visioning

Community visioning
helps experts project
future growth, economy,
funding

More importantly, it
establishes important
community values that
define livability
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Scenarios

Typically, scenarios include alternative
growth futures and alternative investment or
funding strategies

Differs from alternatives analysis, which
assumes one static future

Scenario planning provides a framework for
developing a shared vision for the future

It does this by analyzing various forces that
affect growth and testing various future
alternatives that meet area needs
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Scenarios

Common assessment of forces that
influence growth, including:
• Mobility
• Economy
• Health
• Land use
• Environment

Common assessment of factors that
influence available funding

Development of transportation strategies to
meet future scenarios, including
consideration of trade-offs
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Inclusive Planning

Successful plans come from early
involvement of a variety of stakeholders:
• The public (as residents, voters and travelers)
• Politicians (local elected officials)
• Government administrators
• Special interest groups (e.g. bicycle advocates)
• Private business, including land developers
• Transportation providers (e.g., public transport)
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Six Steps of Scenario Planning
1.
Define driving forces of change
2.
Determine patterns of interaction
3.
Create scenarios
4.
Analyze implications
5.
Evaluate scenarios
6.
Monitor indicators
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Benefits of Scenario Planning

Provides an analytical framework and process for
understanding complex issues.

Facilitates consensus building by giving
communities the capacity to participate actively in the
planning process.

Includes tools and techniques to assess the
impact of transportation and other public policy
choices on a community.

Allows an opportunity to recognize the impact of
trade-offs among competing goals.

Yields an enhanced decision-making framework by
bringing together many viewpoints.

Helps to improve management of increasingly
limited resources.
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Why Develop Scenarios?
“ If you don t know where
you re going, you’ll
probably end up
somewhere else. “
Yogi Berra
New York Yankees
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ENVISION MISSOULA
U.S. EXAMPLE
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Envision Missoula Scenarios
Missoula, Montana (population 100,000)
Scenario Planning Used to Update Longrange Transportation Plan
Three Scenarios Developed:
1.
Business as Usual (no vision)
2.
Suburban Satellites (multi-centers)
3.
Focus Inward (city center)
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Role of Scenarios
According to plan, scenarios were:
“not intended to represent project lists for the
plan, but rather to suggest problem-solving
approaches for how Missoula can address
its transportation challenges in the long
term.”
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Visioning Exercise

Used “chips”
and “tapes”

Chips represented desired
land uses

Tapes represented transport modes
• Different classes of roads
• Public transport services
• Bicycle and pedestrian paths
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Envision Missoula Analysis
Modeling and analysis used to
show how different strategies for
managing travel demand while
investing in targeted infrastructure
can support future system
performance.
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Outcome of Focus Inward Scenario

Single In-Town Mobility District with one priority
corridor (rather than many multimodal corridors)

Increase density in city core

Priority to bicycles and bike access to public
transport

Multimodal center in city center

ITS improvements giving priority to pedestrians

Electric circulator buses

Commuter rail focused on city center destination

One-way street couplets

Preferential parking and commuter shuttles
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GOING BEYOND CONGESTION AND TRAVEL TIME
PERFORMANCE
MEASURES
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Multi-modal Performance Measures
Policy Objectives
1.
Congestion
2.
Mobility
3.
Accessibility
4.
Sustainability
5.
Livability
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Multi-modal Performance Measures
Examples
• Travel time reliability (managing congestion)
• VHT – Vehicle Hours of Travel (congested
conditions)
• VKT reduction (effectiveness of non-auto modes)
• Person Throughput – travelers per mile, all modes
• Average speed across corridor by all modes
(mobility)
• Multi-modal Level of Service (bus and bike)
• User satisfaction with travel modes
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Envision Missoula Indicators
Scenario
Key Strategic Elements for
Managing Congestion and
Travel
Demand
2005
Conditions
Mobility Performance
VMT
(millions)
% VMT
Congested
VHT
% VHT
Congested
3.09
0.5%
72,992
3%
Business as
Usual
•Increase Infrastructure Supply
Only
• Limit transit expansion to
current
plans
• Low Density Development
• Build and Expand Roads to
Meet Demand
10.00
33.0%
712,523
78.8%
Suburban
Satellites
• Invest in Multi-Modal Corridors
• Manage Travel Demand in
Town
Centers Along Key Multi-Modal
Corridors
• Invest primarily in Currently
Committed Roadway Projects
10.13
40.4%
965,596
85.6%
Focus
Inward
• Invest in Amenities Downtown
• Support One Multi-Modal
Corridor
• Invest primarily in Currently
Committed Roadway Projects
8.50
24.5%
364,444
60.5%
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THE
END
Thank You!
Eric N. Schreffler
[email protected]
www.estc-tdm.com
Scenario Planning – Ljubljana Workshop
SOME CONSIDERATIONS AND CAUTIONS
USING TRAVEL
DEMAND MODELS
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Why Do We Use Travel Models?

To project travel demand into the future in
order to plan for future

To assess where that travel might occur

To project car and public transport use

To assess unmet needs

To justify large infrastructure investments
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Four Step Travel Demand Model
Starts with land use analysis to project population and
employment
Step 1 – Trip Generation – frequency of O & D by trip purpose
Step 2 – Trip Distribution – spatial distribution of travel by zone
Step 3 – Mode Choice – matches modes to personal attributes
Step 4 – Route Assignment – distributes travel to roads
Often used in Benefit/Cost Analysis and Environmental
Impact Studies to evaluate projects
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Activity-based Models

Unit of travel is journey rather than trip

Microsimulation framework is used to track
journeys of each individual in the study area

Stop frequency and locations are modeled

Non-motorized analyzed as a separate mode

Multimodal assignment is conducted

Very data intensive
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Criticism of Traditional Modeling

Focus on car and public transport, not bike/walk

Reduces evaluation to time and cost factors

Cannot handle mobility management strategies

Presumes we can project 20 years out (or more)

Based on population forecasts, which are inaccurate

Revealed preference presumes past behavior
continues

Used as “black box” with aura of wizardry

Can be misused to justify desired projects
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Issue: Lack of Validation

Validation is comparing forecasted (a priori)
impacts to actual results (ex post)

For nine out of ten railway projects the study
found that passenger forecasts were
overestimated, with an average overestimate
of 106%,

For half of all road projects, including bridges
and tunnels, the study found that the
difference between actual and forecast traffic
was more than 20%, while for 25% of road
projects the difference was more than 40%.
Flyvbjerg, Holm, and Buhl (January 2006)
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Forecasting vs. Results

“Evaluation” can imply both prediction of
outcomes based on modeling AND
measurement of actual results based on
monitoring

Very important to set objectives and then
evaluate programs, projects and policies to
gauge fulfillment of or progress toward
objectives

This is at the heart of “objective-driven,
performance-based planning”
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Appropriate Use of Models

Modeling is only one tool in planning
process

Modeled forecasts should be used to
compare scenarios on a relative, not
absolute basis

Off-model tools, such as TDM models and
meta-simulation tools can improve
projections

Limitations and uncertainty inherent in
modeling should be acknowledged
Scenario Planning – Ljubljana Workshop
THE
END
Thank You!
Eric N. Schreffler
[email protected]
www.estc-tdm.com
Scenario Planning – Ljubljana Workshop