FOCUS MODEL OVERVIEW
Denver Regional Council of Governments
June 24, 2011
This presentation
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Ask Erik, Shahida and me questions throughout
General Concepts
Break model into four “stages”
Then several steps within each stage
Describe each step- it’s inputs and outputs
Review stage inputs and outputs
Move onto to next stage
General Concept 1:
What is a logit model? 2 minute version
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A model that calculates the utility of each choice
from a set of discrete choices for a decision maker
based on characteristics of the choice and the
decision maker
 Suppose
we have a trip we know is 3 miles long, it’s
purpose is to eat a meal, it’s final location is the CBD,
the person who made the trip is age 68, the person’s
income is $28,000/year. What is the utility for this trip
for various travel modes?
 We calculate the utility of taking transit for example
based on the above information and the cost of transit,
the time on transit, etc
General Concept 1: Logit Models
Many
types: we use multinomial logit
and nested logit
Outcome is a simple closed form
probability (not the choice) The choice
must be randomly selected using a
monte carlo process.
Anything to add?
Questions?
General Concept 2:
Monte Carlo Simulation
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If model only assign probabilities to a choice, how do we
get a choice
Monte carlo simulation
Suppose you have three choices, one with probability 0.1,
one with probably 0.4 and one with probability 0.5.
Arbitarily, you assign choice one the range on the number
line from 0 to 0.1 to choice one, from 0.1 to 0.5 to choice
two and 0.5 to 1 to choice three.
Then you generate a pseudo-random number from 0 to 1.
If the number lands on the range assigned to the choice:
you pick that choice
For example, if you generate the number 0.6784536475,
you would select choice 3
General Concept 3: Tours and Trips
HOME
Outbound, Away From
Home Tour Half
WORK
Inbound, toward
home tour half
STORE
TOUR-BASED MODEL
TRIP-BASED MODEL
•1 home-based work tour
• 1 home-based work trip
•1 shopping stop
•1 non-home-based trip
•1 home-based non work trip
General Concept 4:
Focus Model Flow: “Four” Steps
STAGE 1: Make
Population
And Network
STAGE 2:
Run GISDK to
Mode Choice
FEEDBACK
STAGE 4: GISDK
Assignment
STAGE 3: C#
Logit Models to
Create Trips
General Concept 5:
Mechanics: Code Types used in Model
C# Code
Logit Model Running;
Model Manager
GISDK Code
Skimming,
Assignment, I-E/E-E
DIA Trips
SQL Server
Database
Queries
Data Storage
Java
For Population
Synthesizer
General Concept 6: Use of SQL Server
Households, Persons and Points in SQL
Server
Persons, Trips, and Tours in SQL Server
General Concept 7:
GISDK: Old
Model
Highway Network
Inputs
Transit
Network
Inputs
Socio-economic
Inputs
Network Processing
& Data Preparation
Area Type
Trip Generation
Highway
Transit
Skimming
Skimming
Trip Distribution
Parking Cost
Mode Choice
Time-of-Day
Highway
Assignment
Transit Assignment
General Concept 8:
Why are we doing this anyway?
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Data on ANY geography: all data is at a point level
Using Most Demographic Characteristics of People
Walking, biking, and transit
Vehicle Miles Traveled households in LoDo in 2035
Average Bike Miles per persons age 70+ years old in
2020
Number of Cars owned by college students attending
CU Boulder in 2015
Average Distance to Work by Restaurant Workers
Review of General Concepts
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1. Logit Models are models that make assign probabilities to
a set of choices for an individual from a list of discrete
choices.
2. The actual choice is made using a monte carlo process.
3. Travel in the model is made on a tour-level, and then a trip
level.
4. We can divide the model into four stages.
5. We use four types of code in the model: T-SQL, C#,
GISDK, and Java.
6. Much of the input and output data is stored in SQL Server.
7. We still have to run parts of our old GISDK code for path
building, skimming and assignment.
8. We are doing this because we can get much finer detail
and answer planning questions better using the model.
Thinking points before we dive into the
steps
How is the new model activity-based? How is it
disaggregate?
 How does the model actually do all this crazy stuff?
 How is the old model different than the new model?
 How does the model STILL simplify actual
human behavior?
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Focus Model Flow: 28 Steps
GISDK called from C#:
For DIA, I-E, E-E and Commercial Trips
GISDK called from C#:
GISDK Preprocess
Java:
3. Population Synthesizer
C#
4. PopSyn Output Processor
5. Size Sum Variable Calculator
1. DRCOG Multi-Period Highway Preprocess
2. DRCOG Multi-Period Transit Preprocess
3. DRCOG Transit Preprocess
4. Trip Generation
5. Highway and Transit Skimming
6. Trip Distribution
7. Mode Choice
FEEDBACK
C# Regular Trips
8. Regular Work Location Choice
9. Regular School Location Choice
10. Auto Availability
11. Aggregate Logsum Generation
12.Daily Activity Pattern
13. Exact Number of Tours
14.Work Tour Destination Type
15.Work-Based Subtour Generation
19 . Tour Main Mode Choice
20. Tour Time of Day Choice
21. Intermediate Stop Generation
22. Trip Time of Day Simulation
23. Trip Time Copier
24. Intermediate Stop Location
25. Trip Mode Choice
26. Trip Time of Day Choice
16. Tour Time of Day Simulation
17. Tour Primary Destination Choice
18. Tour Priority Assignment
27. Write Trips to TransCAD
GISDK called from C#:
28. Highway and Transit Assignment
User Interface: How the steps look
Focus Model Flow: Stage 1
STAGE 1: Make
Population
And Network
STAGE 2:
Run GISDK to
Mode Choice
FEEDBACK
STAGE 4: GISDK
Assignment
STAGE 3: C#
Logit Models to
Create Trips
STAGE 1: Make Population and
Network
Java: Population Synthesizer
 C# to process in database: Size Sum Variable
Calculator; PopSyn Output Processor
 GISDK called from C#: GISDK Preprocess
Creating networks for example
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Population Synthesizer
ACS or PUMS
Disaggregate Data
Questions?
Aggregate Data that
We Need to Match:
Economic Forecasts,
Land Use Forecasts
Disaggregate
Population With the
Right Portions Matching
the Economic and Land
Use Forecasts