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What is the primary purpose of the Fratar Model in trip distribution?
What is the primary purpose of the Fratar Model in trip distribution?
Which assumption of the Fratar Model indicates that trip patterns remain mostly unchanged over time?
Which assumption of the Fratar Model indicates that trip patterns remain mostly unchanged over time?
In what scenario does the Fratar Model work best?
In what scenario does the Fratar Model work best?
What does the Fratar Model formula calculate?
What does the Fratar Model formula calculate?
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What is the Balanced Matrix assumption in the Fratar Model?
What is the Balanced Matrix assumption in the Fratar Model?
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What is the acceptable range for the growth factor in trip analysis?
What is the acceptable range for the growth factor in trip analysis?
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Which aspect is NOT considered in Direct Generation Models?
Which aspect is NOT considered in Direct Generation Models?
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Which factor does NOT influence mode choice?
Which factor does NOT influence mode choice?
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Mode choice models primarily aim to estimate the number of trips made by which of the following?
Mode choice models primarily aim to estimate the number of trips made by which of the following?
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In the context of mode choice, convenience primarily refers to what?
In the context of mode choice, convenience primarily refers to what?
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What type of models does NOT rely on trip generation or distribution steps?
What type of models does NOT rely on trip generation or distribution steps?
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Which of the following statements is true regarding the factors influencing mode choice?
Which of the following statements is true regarding the factors influencing mode choice?
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What is the main purpose of mode choice models?
What is the main purpose of mode choice models?
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What is the main focus of Direct Generation Models?
What is the main focus of Direct Generation Models?
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Which variable is NOT considered in Trip End Models?
Which variable is NOT considered in Trip End Models?
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What is one of the key elements evaluated in Trip Interchange Models?
What is one of the key elements evaluated in Trip Interchange Models?
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In the example of Direct Generation Models, how many total transit trips per day are determined for a zone with 5000 people?
In the example of Direct Generation Models, how many total transit trips per day are determined for a zone with 5000 people?
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What exponent value is used for work travel in the Trip Interchange Models example?
What exponent value is used for work travel in the Trip Interchange Models example?
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What does the QRS method primarily consider in estimating mode choice?
What does the QRS method primarily consider in estimating mode choice?
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What is indicated by the total number of productions in a zone in Trip End Models?
What is indicated by the total number of productions in a zone in Trip End Models?
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What percentage of residents is expected to use transit in the Trip End Models example if the number of households per auto is 1.80 and residential density is 15,000 persons/square mile?
What percentage of residents is expected to use transit in the Trip End Models example if the number of households per auto is 1.80 and residential density is 15,000 persons/square mile?
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What is the primary purpose of traffic assignment in transportation forecasting?
What is the primary purpose of traffic assignment in transportation forecasting?
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Which of the following is NOT required for effective trip assignment?
Which of the following is NOT required for effective trip assignment?
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What is the purpose of a diversion curve in traffic analysis?
What is the purpose of a diversion curve in traffic analysis?
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Which algorithm is associated with the decision rule for selecting routes in traffic assignment?
Which algorithm is associated with the decision rule for selecting routes in traffic assignment?
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In the trip forecasting process, traffic assignment follows which earlier phase?
In the trip forecasting process, traffic assignment follows which earlier phase?
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What method categorizes traffic according to relative travel time or cost?
What method categorizes traffic according to relative travel time or cost?
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Which traffic assignment method is characterized as a no-choice scenario for route selection?
Which traffic assignment method is characterized as a no-choice scenario for route selection?
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What aspect of modal utility does the logit model consider?
What aspect of modal utility does the logit model consider?
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What is the final goal of the incremental method in traffic assignment?
What is the final goal of the incremental method in traffic assignment?
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Which of the following represents a typical portion of trip exchanges assigned using the incremental method?
Which of the following represents a typical portion of trip exchanges assigned using the incremental method?
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After each increment in the incremental method, what is the next step?
After each increment in the incremental method, what is the next step?
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What does the function represent in the new travel time calculation?
What does the function represent in the new travel time calculation?
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Which step is NOT part of the incremental method process?
Which step is NOT part of the incremental method process?
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What is the primary theory behind the minimum path assignment method?
What is the primary theory behind the minimum path assignment method?
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Which of the following best describes a skim tree?
Which of the following best describes a skim tree?
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What is one major disadvantage of the all-or-nothing assignment method?
What is one major disadvantage of the all-or-nothing assignment method?
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In the process of determining minimum paths, what should be compared to find the best route?
In the process of determining minimum paths, what should be compared to find the best route?
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When evaluating the effectiveness of a path, what factor is considered in relation to link capacity?
When evaluating the effectiveness of a path, what factor is considered in relation to link capacity?
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What is the primary goal of the minimum path algorithm?
What is the primary goal of the minimum path algorithm?
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In the context of paths from node 1, which travel route to node 4 has the least total time?
In the context of paths from node 1, which travel route to node 4 has the least total time?
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Which statement best summarizes the all-or-nothing assignment advantages?
Which statement best summarizes the all-or-nothing assignment advantages?
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How does the minimum path assignment infer travel behavior of users?
How does the minimum path assignment infer travel behavior of users?
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Which of the following paths from node 3 to node 2 has the fastest travel time?
Which of the following paths from node 3 to node 2 has the fastest travel time?
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Study Notes
Trip Distribution - Fratar Model
- Also known as the Growth Factor Model
- Used in trip distribution to forecast travel demand between different zones
- Based on existing travel patterns
- Updates trip matrices by adjusting for future population, employment, or other travel demand factors
Assumptions of the Fratar Model
- Proportional Growth: The number of trips between zones increases proportionally to changes in population, employment, or other relevant factors.
- Fixed Trip Patterns: The overall pattern of trips between zones remains consistent over time.
- Balanced Matrix: The total trips originating from a zone equals the total trips arriving at that zone
- Limited Data Changes: Works best when there aren't significant structural changes to transportation or land use.
Fratar Model Formula
- The number of trips between two zones is the average of the trips from one point to the other (A to B and B to A).
- Formula: Tij = (tajGj) / ΣtirGr
- Where:
- Tij = trips between zone i and j
- tj = existing trips between zone i and j
- Gj = growth factor for zone j
- tir = existing trips originating from zone i
- Gr = growth factor for zone r
- Where:
Sample Problem (Data from Provided Images)
- A study of four zones (A, B, C, and D) using 5 year trip data
- Presents tables of present trips between zones
- Includes Present Trip Generation and Growth factors for each zone.
- Calculates future trip generation amounts based on growth factors.
- Shows calculations of estimated trips between each zone.
Mode Choice
- Mode choice is the aspect of transportation demand analyses that determines the amount of trips made by car versus transit.
- Mode choice models simulate traveler choices by replicating factors including traveler characteristics, transportation system features, and trip factors.
- Key elements that influence mode choice:
- Trip Purpose
- Travel Time
- Cost (fuel, fares, parking)
- Convenience (Accessibility, proximity to stops)
- Traveler characteristics (income, age, car ownership, preferences).
Types of Mode Choice Models
-
Direct Generation Models:
- Assumes that system attributes (time, cost, convenience) are not relevant.
- Mode shares are determined without considering detailed zone interaction.
- Simple and suitable for small-scale analysis.
-
Trip End Models:
- Consider the journey's origin and destination characteristics (land use, population density, employment).
- Mode choice is based on zone characteristics but not on detailed origin-destination interactions.
-
Trip Interchange Models (e.g., QRS method):
- Considers system level-of-service factors (travel time, cost, and travel convenience).
- Measures trip characteristics for travel mode choice like time, distance, cost.
-
Logit Models:
- Uses relative utility of each mode as a summation of each modal attribute.
- Expresses the choice of a mode as a probability distribution considering factors like disutilities and attributes.
Traffic Assignment
- Final step in the transportation forecasting process.
- Predicts actual routes and traffic volumes on highways and streets.
- Determines which routes travelers will take.
- Assigns trips to origin-destination (O-D) pairs to specific routes (transit or car).
- Calculates peak-hour traffic volume on each route.
- Identifying potential congestion based on routes and capacity.
Traffic Assignment Methods
- Diversion Curves: Similar to mode choice curves, showing traffic distribution based on relative travel time or cost between routes.
- Minimum Path Algorithm: Assigns all trips to the shortest paths between zones based on time. Represents possible routes in terms of a "skim tree"
- All-or-Nothing Assignment: Simplifies travel by assigning all trips along the shortest path between zones without considering traffic capacity.
- Capacity Restraint Assignment: Considers link capacity, thus recalculating travel times based on the loaded volume with each reassignment, ensuring balance is reached in successive assignments.
- Incremental Method: Assigns trips in increments to the shortest paths to adjust link times after each increment.
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Description
This quiz covers the Fratar Model, also known as the Growth Factor Model, used in trip distribution to forecast travel demand. It introduces key assumptions of the model, as well as its formula for calculating trips between zones. Ideal for understanding the dynamics of transportation planning and land use.
