Chapter 4 - modal split

Question 1

Factors Influencing the Choice of Mode

Answer 1

1. Characteristics of the trip maker
2. Characteristics of the journey
3. Characteristics of the transport facility

Question 2

What are some characteristics of the trip maker?

Answer 2

• car availability and/or ownership;
• possession of a driving licence;
• household structure (young couple, couple with children, retired, singles, etc.);
• income;

Question 3

What are some characteristics of the journey?

Answer 3

• the trip purpose
• time of the day,
• whether the trip is undertaken alone or with others

Question 4

What are some characteristics of the transport facility?

Answer 4

• components of travel time: in‐vehicle, waiting and walking times by each mode;
• components of monetary costs (fares, tolls, fuel and other operating costs);
• availability and cost of parking;
• reliability of travel time and regularity of service.
• comfort and convenience;
• safety, protection, security;
• the demands of the driving task;
• opportunities to undertake other activities during travel (use the phone, read, etc.)

Question 5

What is mode choice based on?

Answer 5

generalised cost of route

Question 6

3 types of modal split models

Answer 6

(1) Trip‐end (USA), (after generation)
(2) Trip‐interchange models
(EU) (after distribution)
(3) Individual choice models (discrete)
(nowadays used by everyone)

Question 7

Trip end model, describe and list advantages and disadvantages

Answer 7

AGGREGATED (zonal)
only takes into consideration attributes of the origin
•Assumes that public transport is
primarily a function of socio‐economic
variables
• In other words, virtually all public transport
users are assumed to be “captive” users
• The ‘variables’ used are the same as used
during trip generation
•Advantages:
• Relatively simple to apply and requires little
data
•Disadvantages:
• Is relatively insensitive to transport policy
changes (fuel e.g.)

Question 8

Trip interchange model, describe and list disadvantages

Answer 8

AGGREGATE (zonal)
takes into consideration attributes of origin and journey
• The models are predicted after trip distribution (thus after the trips have been assigned to destinations)
• Therefore, we can calculate the level of service between origin and destination with different modes and include the level‐of‐service in in modal split
• Example …
• We use diversion curves to predict the % public transport users
• Disadvantages:
• Diversion curves require a considerable amount of data
• Are difficult to update over time
• Are restricted to simple binary modal situations (in other word between two modes)

Question 9

Discrete (individual choice) describe

Answer 9

based on observed choices made by individual travellers or households.
• The models worked on the notion of utility maximisation
• Every person weighs alternatives and assigns a ranking to the alternatives in terms of their utility
• Every person is rational … will therefore choose the alternative with the highest utility

Question 10

What is the alternative variable constant?

Answer 10

The variable is the Alternative specific constant. It essentially represents the preferences that aren’t necessarily quantifiable regarding the mode in question (comfortable seats, warmth etc)