[sustran] Re: Transportation Modal Choice in Asian Cities

P. Christopher Zegras czegras at MIT.EDU
Sat Jun 25 00:35:35 JST 2005


Dear all,

I think that a comparable, international set of data on mode share across 
cities would be a valuable tool to help better gauge where 
differences/commonalities exist, where they come from, what lessons we can 
learn, etc.

But, we all know that the comparability issue is fairly challenging. Having 
been involved in a few efforts to come up with similar types of mode share 
'inventories,' I know that the problem of secondary, tertiary (and further 
on) sourcing is an issue, making it often quite difficult to track down the 
real source of information. This should not be taken lightly. For example, 
I recently found an instance where a Latin American government's public 
presentation of a city's mode share actually (inadvertently, I can only 
hope) switched the bus/auto share (relative to what the raw data and more 
detailed technical reports actually showed) - and I have since seen this 
incorrect figure cited elsewhere.

We know that the results are susceptible to: 1. definition of sampling 
frame (e.g., all persons, >5, adults, urban, suburban, metropolitan, etc. ) 
2. definition of trip (all 'outings' in the public realm, >200 m; motorized 
trips, etc.); 3. Sample size and related issues such as quality of the 
expansion/corrrection factors; 4. Day of the week; 5. Time of the year; 
among other factors.

That said, I think it would be of extremely high value if the international 
agencies, professional associations, etc. came up with a set of standards 
for conducting household (oh, and what about that poor cousin, freight...) 
origin-destination surveys and, importantly, REPORTING clearly those 
results (assumptions, etc. etc.) so that comparison might ultimately be 
possible. These standards already exist in many countries, but implementing 
them and ensuring transparency is fairly critical. At the very least, any 
development organization that finances data collection should ensure that 
those standards are met and, furthermore, ensure that the data produced is 
public (at least in aggregate form), with all influencing factors 
(partially enumerated above) clear.

Regards,

Chris



From: "V. Setty Pendakur" <pendakur at interchange.ubc.ca>
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Cc: Kyoto2020 at yahoogroups.com, Adb Eunkyung Kwon <ekwon at adb.org>,
         Peter Newman <newman at central.murdoch.edu.au>, chuizenga at adb.org,
         lfwright at usanet.jca.ne.jp, Jeff Kenworthy 
<kenworth at central.murdoch.edu.au>
To: "Asia and the Pacific sustainable transport"
         <sustran-discuss at list.jca.apc.org>
References: <016e01c5789d$c4b43470$6501a8c0 at jazz>
         <006d01c578c9$3ee546a0$7701a8c0 at WALTER>
Date: Fri, 24 Jun 2005 07:53:54 -0700
Reply-To: Asia and the Pacific sustainable transport
         <sustran-discuss at list.jca.apc.org>
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Subject: [sustran] Re: Transportation Modal Choice in Asian Cities
Message: 3

During the past 20 years, we have been saying at TRB, CODATU and WCTR that 
aggregating modal splits without making sure that they have a common base 
for the split, simply and blatantly distorts the data systems for policy 
formulation and implementation , with a bias favoring the MVs.  It is time 
that all of us, including the international funding agencies, recognize 
this bias.  If NMT data is not included in the modal splits, such data 
should be separated as specifically a data set not including NMT.  If 
possible, estimates can be made for NMT and such data can be 
adjusted.  However, combining, willy nilly, all data into one set will only 
repeat and reinforce the historic bias to favor the MVs.

Data sets should also be separated by chronological periods.  If you have 
several cities in Asia and the data set covers the period 1980-2005 all in 
one file, comparisons for policy making would be meaningless.  This applies 
to Africa also.

Whatever tabulations ADB wish to produce, we certainly don't need another 
data set with a lot implicit biases.

Best wishes.  Setty.

Dr. V. Setty Pendakur
Professor Emeritus, University of BC
Honorary Professor, National Academy of Sciences of the PRC
Chair, TRB-ABE90 & Director, ITDP
President
Pacific Policy and Planning Associates
702--1099 Marinaside Crescent
Vancouver, BC, Canada  V6Z 2Z3
Phone: 604-263-3576; Fax:604-263-6493
----- Original Message -----
From: <mailto:whook at itdp.org>Walter Hook
To: <mailto:eric.britton at ecoplan.org>eric.britton at ecoplan.org ; Asia and 
the Pacific sustainable transport
Cc: <mailto:newman at central.murdoch.edu.au>Peter Newman ; 
<mailto:chuizenga at adb.org>chuizenga at adb.org ; 
<mailto:Kyoto2020 at yahoogroups.com>Kyoto2020 at yahoogroups.com ; 
<mailto:kenworth at central.murdoch.edu.au>Jeff Kenworthy ; 
<mailto:lfwright at usanet.jca.ne.jp>lfwright at usanet.jca.ne.jp
Sent: Friday, June 24, 2005 7:30 AM
Subject: [sustran] Re: Transportation Modal Choice in Asian Cities

i agree we need to at least separate out the modal split data that has 
walking and nmt included and that which doesnt, as there is huge variation 
in the way walking trips are counted.

Walter Hook, Ph.D.
Executive Director
Institute for Transportation and Development Policy (ITDP)
127 West 26th Street, Suite 1003
New York, NY 10001
Ph:  (212) 629-8001
Fax: (212) 629-8033

Promoting environmentally sustainable and equitable transportation worldwide
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