2 Answer the following questions briefly but specifically a

2. Answer the following questions briefly, but specifically a. Mention and briefly discus two shortcomings of the growth factor model.

Solution

GROWTH FACTOR MODEL:

Growth factor model is a method which responds to only relative growth rates at origins and destinations and this is mainly suitable for short-term trend extrapolation. There are different methods in growth factor model namely

1.Uniform factor method

2. Average factor method

3. Detroit method

4. Furness method

5. Furness time-function iteration.

6. Fratar method.

SHORT COMINGS OF GROWTH FACTOR MODEL :

1. Depends heavily on the observed trip pattern

2. It cannot explain the unobserved trips

3. Do not consider changes in travel cost

4. Not suitable for policy studies like introduction of a mode.

5. New spatial developments for the study area cannot be accommodated.

6. The method depends heavily on the reliability of the data in the individual cells of the base year matrix.

7. There are instances when problems can occour with the iteration process.

EXAMPLES :

In Uniform growth factor model,

The assumption of a uniform growth rate for the entire study area is not correct as the growth factor varies across zones. Also the land use pattern changes with time, but not uniformly as assumed.

In average growth factor model,

The factors do not have real significance and large number of iterations are required.

In Fratar method,

It is tedious for even moderate sized problems and it does not take into account the effect of changes in accessibility of the study area.

So these are some of the shortcomings of the growth factor model.

Thankyou.