[sustran] Income and Trip-Making (was transport and asian econ. debacle)

[Christopher Zegras]

Paul Barter wrote:

>It is misleading to slip from talking about percentages of trips to taking
>about percentages of people.   Saying that 51 % of motorised TRIPS are by
>private modes (cars+ motorcycles) DOES NOT MEAN 51% of PEOPLE are using
>private modes.   The main reason for this is that people with private
>vehicles tend to make many more motorised trips per person than those with
>no private vehicles.  So a disproportionate number of the trips counted in
>modal split figures (such as the ones quoted by Bambang ) are trips that
>are made by people who own private vehicles (who tend to be the higher
>income people). Mode share figures are counting TRIPS not PEOPLE  - the
>percentage of people who actually have access to private vehiclce tends to
>be lower than the number of trips made by private transport.
>

Paul, 


Very good point.  

In Chile, the 1991 O-D survey shows the following:

Monthly Income          Walk	Car	Public Transport
(1991 Chilean Pesos)      (% of all trips, does not include mode "other")
 
<41,000	                32	3	59
41,000-72,500           24	5	64
72,500-110,400	        19	9	65
110,400-172,500	        15	17	61
172,500-262,000	        11.8	28	53
262,000-405,000	        9	45	37
405,000-1,000,000       6.5	57	25
>1,000,000	        2.9	71	17

The lowest two income groups, make up 43% of all tripmakers (48% of the
population), and a third of their trips are on foot, 2/3 by public transport
(Santiago has about 20% total walk trips per day, not including the less
than 400 m. trips).   The middle two income groups comprise 38% of
trip-makers (35% of the population).  The highest income groups (>262,000)
make up only 13% of all trip-makers (11% of the population).  (7% of
population did not respond to income question).

So, we see that not only do people with private motorized modes make more
motorized trips, but also tend to make more TOTAL Trips (which happen to be
motorized).  

What this data also shows, is that both walking and public transport display
-- in economists´ terms -- characteristics of an "inferior good", demand
declines as income increases.  Sustainable transport advocates need to
reverse this consumer perception....


>"Low income"  people who were 47.5 % of the sample:  took only 0.61
>motorised trips per day (0.20 private and 0.41 public) on average.  On the
>other hand, those with lower-middle, upper-middle, or high incomes
>(altogether 52.5 percent of the sample)  took 1.11 motorised trips per day
>on average (0.63 private and 0.48 public).  This implies that the richer
>52.5 % of the population took  67% of all motorised trips and the poorer
>47.5% of the population had only 33 % of all motorised trips.     (looking
>at vehicle owners versus non-vehicle owners would probably be even more
>striking).
>

Paul, it would be interesting to see the walk and nmt trips from this data,
was it taken?

Cheers, 

Chris

 Christopher Zegras       http://www.iiec.org                 /\   /^\
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