Number Crunching in Transport

Friday, July 30, 2010

Walkability in Asian Cities - few Quotes and Statistics

Sudhir Gota

“In the age of carbon footprint we are forgetting human footprints”
I have collected few statistics and quotes on walkability. I am sure that these would derive a range of emotions from you – anger, surprise, despair, disgust, empathy etc….
Pedestrian facilities have been depreciating over the past decade. Cities which are naturally designed for walking are increasingly becoming motorized by vehicles. Travel time budgets are breaking new barriers with many people travelling for more than 2 hours a day and getting frustrated with the quality of transport. Everybody acknowledges that walkability is very important but however translating ideas to practice has been very slow.  Pedestrian improvement projects provide cheap solution to the problem of urban mobility. Using the same money as required for constructing 1 km metro, one can, on an average, construct 350 km of new quality sidewalks. 
If the footpaths had been expensive, things would have been different !!
Statistics from CAI-Asia study on Walkability in Asian cities
  1. 82% of people in asia are willing to walk maximum of only 100m to access pedestrian crossings.
  2. If the walking environment is not improved, 82% of people would shift to vehicles
  3. About 40% of people consider that they are most exposed to air pollution while walking
  4. More than 70% of people in Kathmandu and Jakarta consider their walkways as bad or of poor quality
  5. In Asia, the budget for pedestrian facilities is often in the range of 0.2 to 5% of transportation budget while it accommodates more than 30% of trips.
  6. On an average 28% of trips are within 3 km, 24% within 3 to 6 km in an asian city
  7. Using the same money as required for constructing 1 km metro, one can, on average, construct 350 km of new quality sidewalks
  8. In a city, commercial areas have the best walkability whereas the public transport terminals have the worst walkability

Source : Times of India

Statistics from other sources
  1. In Sri Lanka, at least 1/10th of space of all roads within urban areas provided exclusively for non-motorized transport such as for sidewalks for walking and bicycle lanes  (Action Plan for Traffic Management in Greater Colombo (2008))
  2. In Jakarta, people with disabilities must wear special signs that are visible to motorists - (Article 132 (3)) of Traffic and Road Transport Act of Indonesia
  3. 40% of the total Road Length of Delhi has no Sidewalks- RITES Transport Demand Forecast Study: May 2008
  4. Nearly half of fatal accidents in Delhi involve – pedestrians - Walkability Roundtable, Centre for Science and Environment, July 2009
  5. Nearly half of fatal accidents in Philippines and Bangladesh involve pedestrians - World Health Organization (WHO, 2009)
  6. Benefit-cost ratio of replacing the underground crossings with surface crossings is 7.6:1 – Transport for London
  7. 68% of countries in the world don’t have national or local level policies that promote walking and cycling  - World Health Organization (WHO, 2009)
  8. In Bangalore, three pedestrians are killed on roads every other day and more than 10,000 are hospitalized annually- Deccan herald
  9. Children under ten years old are the most vulnerable pedestrian group in Thailand - Asian Institute of Technology
  10. 50% of people don’t use skywalks since it involves climbing, descending and long detour - D Sanyal, Bangalore Transportation Summit
  11. In Hong Kong only 13.5% of households have access to private vehicles – 2002, Transport Department
  12. In Hong Kong, 49% of people don’t walk due to unsuitable weather – 2002, Transport Department
  13. In Fushun, 58% of the survey respondents either agreed or strongly agreed that cars do not slow down at marked midblock crossings - Wendy Tao
  14. In 2009, more than 70% of road fatalities in Mumbai were Pedestrians - Mumbai Traffic Police
Other quotes
  1. “Restore human legs as a means of travel. Pedestrians rely on food for fuel and need no special parking facilities.” -  Lewis Mumford quotes (American Writer, 1895-1990)
  2. Everywhere is walking distance if you have the time.  ~Steven Wright
  3. No city should be too large for a man to walk out of in a morning.  ~Cyril Connolly
  4. A pedestrian is someone who thought there were a couple of gallons left in the tank.  ~Author Unknown
  5. Thoughts come clearly while one walks.  ~Thomas Mann
  6. Walking:  the most ancient exercise and still the best modern exercise.  ~Carrie Latet
  7. Don't let people drive you crazy when you know it's in walking distance.  ~Author Unknown
  8. All truly great thoughts are conceived by walking. - Friedrich Nietzsche
  9. "It is solved by walking." - Latin Proverb
  10. "Every trip starts and ends on foot"  - ~Author Unknown
  11. improving walkability entails improvement not only in the physical infrastructure but equally in the minds of people - CAI-Asia (2010)
  12. Walking has important social benefits as well. More people walking on the streets is a signal that an area is safe and interesting. A prominent characteristic of vital urban neighborhoods is their vibrant pedestrian street life (Jacobs, 1961).
  13. Man is first and foremost a pedestrian  ~Author Unknown

Depreciation in Trips

Virtually all the cities are showing depreciation in percentage of people using walking as a means of transport. Some cities show dramatic reductions in-spite of traffic models inconsistency to measure walking trips.

Please find a video on walkability in Asian cities which my colleague developed for training participants of ADB transport forum. You may find this interesting..

Thursday, July 29, 2010

Impact of Expressways on Emissions

Sudhir Gota

Huge number of literature has been generated from around the world showing that an expressway which provides cheap mobility often induces more traffic and thus builds congestion in the network. But, not much research has been carried out on life cycle assessment of such expressways. Three corridors in India and one in VietNam were considered for investigation.  The projects were essentially two lanes to four lane conversion projects. The VietnNam corridor was a new expressway project.

The impact has been considered in two stages – short and long term.

a.       Short Term: It is incorrect to assume that higher speeds always reduce emissions

It's a myth that higher the speed, lower would be the emission.  On the contrary, the emission is lowest when speed is in the range of 40-60 kmph. Lower emissions not only mean better environment but also saving precious fuel. The impact of capacity expansion on corridors during the first 5 years after the improvement after neglecting the induced traffic is shown below.  

Description (Kilo tons CO2/Km)
Avg Speed (kmph)
1st Year
2nd Year
3rd Year
4th Year
5th Year
After Project
After Project
After Project
Ho Chi Minh -Long Thanh-Dau Giay
After Project
Impact of Road Capacity Expansion in Corridors during Five Years 
(excluding induced traffic impact)

It is clear that even during initial years the capacity expansion may not yield CO2 savings.  The savings are obtained only in the projects which has existing speed below 40kmph. Increasing the capacity of road which already facilitates speed between 40-60 kmph is iatrogenic. The spur in speed can have disastrous effects on emissions if it exceeds the 40-70 kmph range.

An increase in traffic speed reduces the cost thereby attracting more traffic. Researchers globally have found lane kilometer to have a statistically-significant relationship with VKT. This impact has been quantified in the range of 0.5 to 1. Considering the above criteria and by varying the levels of induced traffic, the emissions were quantified to evaluate the impacts of induced traffic. Using an induced traffic elasticity of 1, the analysis shows that emissions typical national highway in India are higher by over 58% as compared to a scenario which excludes induced traffic considerations.  Under varying scenarios of elasticity from 0.25 to 1, the quantified emissions may range from 17 to 58% when tested for 3 different corridors.

An analysis of a typical corridor shows that induced traffic would reduce the initial year savings and would increase the emissions over the project lifecycle.

c.       Air quality impacts are highly correlated to CO2 emissions

In case the project provides CO2 reductions there is a huge likelihood that the project may provide similar air quality benefits.

% Increase with induced traffic ( elasticity 1)

Surat Manor
Salem Namakkal

d.      Construction of expressways make individual travel more efficient

It’s true that expressways due to high induced traffic may increase the emissions when compared with no project scenario. It’s also true that expressways make the individual travel better.  Over the project lifetime, it was found that the improvement is in the range of 20-25%. However, more traffic on the road nullifies the benefit and increases the total emissions.

e.    Road maintenance can impact the emissions profile of vehicles

By increasing the roughness from 2m/km to 4, 6 and 9 m/km, the emissions (CO2 Tons/Km/Year) increase by 1.6, 3.3 and 5.8% respectively.  Thus by following good maintenance strategies, emissions can be reduced to a certain extent by keeping a check on emissions. More insights on impact of roughness can be found here.

f.      Construction Emissions should be considered in project analysis

Literature review and subsequent analysis indicated that the construction emissions are a significant fraction of total lifetime emissions. An analysis based on the quantity of construction materials used – cement, steel and bitumen indicates that the approximate emissions of a two lane to four lane improved highway is approximate 1100 tons/km. When all the quantities are considered including the emissions generated by machinery, the emissions range from 2100 to 2400 tons/km for high-speed roads  (four-lanes) based on traffic, topography and type of improvements suggested. The operations emissions calculated in the test corridors ranged from 1700 to 7000 tons/km indicating that for high speed roads, (at-grade four-lane highway) construction emissions can range from few months to maximum 2 years of operation emissions.

g.       Placeholders

The analysis of three corridors provided the following placeholders
  •      CO2 Footprint  = 1100  Tons/lane-km/Year
  •        CO2 Savings Indicator = -350 Tons/lane-km/Year ( - ve sign indicates increase in emissions when compared to BAU)
Please click here to read the entire report and access presentations. Comments can be mailed to sudhir(at)

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