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FOCUS MODEL OVERVIEWDenver Regional Council of Governments
June 24, 2011
This presentation
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
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
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 WORK
STORE
TOUR-BASED MODEL
•1 home-based work tour
•1 shopping stop
TRIP-BASED MODEL
• 1 home-based work trip
•1 non-home-based trip
•1 home-based non work trip
Outbound, Away From Home Tour Half
Inbound, toward home tour half
General Concept 4:Focus Model Flow: “Four” Steps
STAGE 1: Make
PopulationAnd Network
STAGE 2:Run GISDK to Mode Choice
STAGE 3: C# Logit
Models to Create Trips
STAGE 4: GISDK
Assignment
FEEDBACK
General Concept 5:Mechanics: Code Types used in Model
C# Code Logit Model Running;
Model Manager
GISDK CodeSkimming,
Assignment, I-E/E-E DIA Trips
SQL Server DatabaseQueries
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: OldModel Socio-economic
Inputs
Area Type
Parking Cost
Network Processing & Data Preparation
Highway
Skimming
Transit
Skimming
Trip Generation
Trip Distribution
Mode Choice
Highway
Assignment
Transit Assignment
Highway Network Inputs
Transit NetworkInputs
Time-of-Day
General Concept 8:Why are we doing this anyway?
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
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?
Focus Model Flow: 28 Steps
Outside The Speed Feedback Loop: Run Once-STAGE 1GISDK called from C#:GISDK PreprocessJava:3. Population SynthesizerC#4. PopSyn Output Processor5. Size Sum Variable Calculator
STAGE 2 GISDK called from C#:For DIA, I-E, E-E and Commercial Trips1. DRCOG Multi-Period Highway Preprocess 2. DRCOG Multi-Period Transit Preprocess3. DRCOG Transit Preprocess4. Trip Generation
5. Highway and Transit Skimming6. Trip Distribution7. Mode Choice
STAGE 3 C# Regular Trips8. Regular Work Location Choice 19 . Tour Main Mode Choice 9. Regular School Location Choice 20. Tour Time of Day Choice10. Auto Availability 21. Intermediate Stop Generation11. Aggregate Logsum Generation 22. Trip Time of Day Simulation12.Daily Activity Pattern 23. Trip Time Copier13. Exact Number of Tours 24. Intermediate Stop Location14.Work Tour Destination Type 25. Trip Mode Choice15.Work-Based Subtour Generation 26. Trip Time of Day Choice
16. Tour Time of Day Simulation 27. Write Trips to TransCAD17. Tour Primary Destination Choice18. Tour Priority Assignment
STAGE 4 GISDK called from C#:28. Highway and Transit Assignment
FEEDBACK
User Interface: How the steps look
Focus Model Flow: Stage 1STAGE
1: Make Populati
onAnd
Network
STAGE 3: C# Logit
Models to
Create Trips
STAGE 4:
GISDKAssignm
ent
FEEDBACK
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
Population Synthesizer
ACS or PUMS Disaggregate Data
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
Questions?