The NY Times reports on an article re: pedestrian and cyclist safety from the Journal of Trauma and Acute Care Surgery.
-Gathering data from 1,400 people who have been injured is impressive.
-That pedestrians are most vulnerable in crosswalks is not surprising; it is where the pedestrians are–the whole “exposure” aspect.
-But now, we finally have a partial silver lining to the obesity epidemic in the US: excessive weight may prove a boon for pedestrians in a collision. Victims with an above-normal body mass index were found to have less severe injuries than their counterparts. “It is not implausible that a greater proportion of torso and extremity fat may protect against injury”
The Atlantic Cities has a diddy exposing some of the pollution ill-effects of cycling. But, the larger question is still left open. Even considering the air pollution burden from cycling–and perhaps even the safety risks owing to crashes–is it healthy? We need to look at the larger context. The prevailing evidence, I would argue, suggests that cycling is healthy–overall–because of the physical activity benefits.
Some of the most robust research, internationally, of the health benefits derived from switching car use to other modes is coming out of the Centre for Research in Environmental Epidemiology (CREAL) in Barcelona. They have looked at the impacts of Barcelona’s bike-sharing system in the past. Their latest work is more generally about the benefits of public transport and bike. Yes, they are working with future scenarios. Yes, there are lots of assumptions embedded. But the framework and the identification of key outcomes and specific measures is good to see.
Replacing car trips by increasing bike and public transport in the
greater Barcelona metropolitan area: A health impact assessment study
Volume 49, 15 November 2012, Pages 100–109
Rojas et al.
Estimate the health risks and benefits of mode shifts from car to cycling and public transport in the metropolitan area of Barcelona,Spain.
We conducted a health impact assessment (HIA), creating 8 different scenarios on the replacement of short and long car trips, by public transport or/and bike. The primary outcome measure was all-cause
mortality and change in life expectancy related to two different assessments: A) the exposure of travellers to physical activity, air pollution to particulate matter < 2.5 μm (PM2.5), and road traffic fatality; and B) the exposure of general population to PM2.5, modelling by Barcelona Air-Dispersion Model. The secondary outcome was a change in emissions of carbon dioxide.
The annual health impact of a shift of 40% of the car trips, starting and ending in Barcelona City, to cycling (n = 141,690) would be for the travellers who shift modes 1.15 additional deaths from air pollution, 0.17 additional deaths from road traffic fatality and 67.46 deaths avoided from physical activity resulting in a total of 66.12 deaths avoided. Fewer deaths would be avoided annually if half of the replaced trips were shifted to public transport (43.76 deaths). The annual health impact in the Barcelona City general population (n = 1,630,494) of the 40% reduction in car trips would be 10.03 deaths avoided due to the reduction of 0.64% in exposure to PM2.5. The deaths (including travellers and general population) avoided in Barcelona City therefore would be 76.15 annually. Further health benefits would
be obtained with a shift of 40% of the car trips from the Greater Barcelona Metropolitan which either start or end in Barcelona City to public transport (40.15 deaths avoided) or public transport and
cycling (98.50 deaths avoided).The carbon dioxide reduction for shifting from car to other modes of transport (bike and public transport) in Barcelona metropolitan area was estimated to be 203,251
t/CO2 emissions per year.
Interventions to reduce car use and increase cycling and the use of public transport in metropolitan areas, like Barcelona, can produce health benefits for travellers and for the general population of the
city. Also these interventions help to reduce green house gas emissions.
- We assess the health impacts of replacing car trips by bicycle or public transport.
- Replacement of the car trips reduces mortality in travellers who shift the mode.
- Replacement of the car trips also reduces mortality in residents of urban areas.
- Replacement of car trips can reduce the emissions of CO2.
The helmetless debate ensues, this time in the NYTimes.
Where should we come down on this matter? Here is what I want to know:
(1) Where helmetless behavior reigns strong, what is the average speed of the cyclist?
(2) Where helmetless behavior reigns strong, what is the average speed of the auto?
Nothing ever talks about these matters. I imagine both are substantially slower than in most US settings. Here’s a proposition: bring down the speeds of both and helmetless behavior might not be such a big deal.