Chapter 4 - trip distribution Flashcards
Differentiate doubly and singly constrained
doubly constrained - total productions adds up to total attractions, closed matrix
singly constrained - increasing attractions but keeping origins the same, open matrix
Explain the concept of generalised cost
Not only direct travel cost, made up of many weighted factors
List some factors of generalised cost
- In-vehicle travel time
- walking time
- waiting time
- interchange time
- monetary charge
- terminal (parking) cost
- modal penalty (ASC)
Explain the gravity model
• derived from Newton’s law on gravitational interaction between two masses
• the attractive force between any two bodies is directly
related to the masses of the bodies and inversely related to the distance between them
• relationships between places (say homes and workplaces). It has long been posited that the interaction between two locations declines with increasing (distance, time, and cost) between them, but is positively associated with the amount of activity at each location.
Explain the deterrence function/distribution function
• This function is calculated (from existing data) and is the ‘mathematical expression’ of the generalized cost of transport
• Describes the relative willingness to make a trip as a function
of the generalised travel costs.
• represents the disincentive to travel as distance (time) or cost
increases.
Explain the term ‘distance decay’
Distance decay is a term which describes the effect of distance on cultural or spatial interactions. The distance decay effect states that the interaction between two locales declines as the distance between them increases.
• With the advent of faster travel, distance has less effect than it did in the past. Advances in communications technology, such as phones, radio and television broadcasts, and internet, have further decreased the effects of distance.
Explain trip distribution in layman’s terms
To determine the no.of trips from the (production zone i) to (destination j) zone for every i and
j
