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Monday, 5 May 2014

Mass transit. Which method is healthiest? Transportation and health part 5

On a per passenger per kilometer basis, how do forms of transit stack up against each other.  Put differently, in trying to minimize a personal fuel footprint, what chooses should we make when given options? Which is safer? More comfortable? More fun? 

Perhaps not the easiest questions to find an answers for but given that such questions may well influence people in the choice of transit that they prefer it is worth the exploration.  Piecing out the impact of personal transport from freight transportation is not easy.  Total fuel use also supports recreational, industrial, agricultural and other activities which are often included in attributions of fuel consumption for greenhouse gas emissions. Having flagged the caution, fasten your seatbelts for a bumpy but interesting ride. 

Canadian transportation sector information can be accessed at Natural resources Canada in a distinctly unfriendly user format.  Buried in the data are estimates of energy consumption per passenger kilometer (expressed as Megajoules per passenger kilometer. 

efficiency MJ/PKm
Efficiency compared to passenger vehicle (higher is better)
Proportion of total energy consumption
School - 0.43
Urban – 1.67
Intercity – 0.77
Light trucks

Wikipedia in quoting a US Energy Data Book would put intercity rail as the most efficient, at about 40% better than cars, with other forms of rail transit where stopping and starting are involved, slightly less efficient.  Air transit comes in 25% more efficient.   Urban buses at 18% less efficient (presumably due to lower ridership than full capacity).  Wikipedia energy efficiency.   The full energy data book can be found at US Energy Data Book 2011  Table 2.12 provides 2011 estimates with a well stated cautionary note on trying to develop comparisons.

Notable in the US figures is that energy efficiency for most forms of transport has improved considerably over the past few decades, averaging about 1% per year per passenger-km for cars, 1.3% for rail, and a whopping 3% per year for air transit.   The efficiency of transit buses is reported as having remained constant on a vehicle-km basis, but declined due to reduced ridership.  Canadian efficiency figures are harder to interpret but rightly appear to parallel US efficiency measures. 

The distinctly different pattern of efficiency combined with utilization between the countries is provided as a caution in making generalizable international comparisons.   Having said that, globally total greenhouse gas emissions are attributed as 74% on road, 12% in air, 10% marine, and 4% by rail.  These numbers are inclusive of freight and passenger transport. 

An older Australian report with dated material from 80s and 90s attempted to compare safety of various 
modalities, placing air, bus and rail at a fraction of the risk from travel in a car (respectively at about 1%, 15% and 20%).  Comparatively motorcycle travel was about 20 times more risky, bicycling at 8 times, and walking about 15 times.  Recent comparative information would be welcomed if someone is aware of a source  (contact drphealth@gmail.com ) .   The comparative risks would appear to carry some face value and better domestic data would be useful. 

May 15:  A follower directed DrPHealth to a CJPH article from November 2012 that attempted to compare Canadian rates and these provide some relative comparisons that confirm the relative safety of driving, cycling and walking.  

Fatalities per 100,000 population
Fatalities per 100 Million person-trips
Fatalities per 100 Million km
Injuries per 100 M person-trips
Injuries per 100 M km
Driver and Passengers

Nothing was located about the relative social value of various forms of mass passenger transport.  Comparisons of noise exposure for users are also lacking. Likewise are impacts on non-commuters in proximity to transportation channels. (there are studies of noise exposure near airports, sleep disruption near railways, air pollution exposure near roadways that collectively may inform the discussion on total impacts for non-commuters as a separate issue)

While inherently mass transit is passive to the user, as noted in the posting on public transit, there appears to be an inherent value in the exertion required to move to and from access to the transportation unit, and for those frequenting airports some would say a rigorous exertion, others might note that most car transport is associated with minimal out of vehicle exertion.  However in presenting a comparative analysis, the lack of comparability on issues that contribute to health and wellbeing is notable.  Lacking also is good information on the decision processes that normalize daily routines around specific forms of transit, or those factors that contribute to longer distance transit choices. 

For some the choice in which form of transportation to use may be limited.  For many the decision is based on existing routines.  Hence research on factors affecting decisions, comfort, ways to improve socialization and ways to increase activity while in transit can and should supplement work on energy efficiency and safety. One of the best examples is the Stockholm subway effort to increase users selecting the stairs over escalators.   Enjoy viewing at Piano stairs.    

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