From: Benjamin.Thielen
Sent: Monday, August 18, 2014 3:04 PM
To: FedsOnBikes
Subject: The Societal Costs and Benefits of Commuter Bicycling
Of possible interest.
Regards,
Ben Thielen
The Societal Costs and Benefits of Commuter Bicycling: Simulating the Effects of Specific
Policies Using System Dynamics Modeling
Alexandra Macmillan,1 Jennie Connor,2 Karen Witten,3 Robin Kearns,4 David Rees,5 and
Alistair Woodward1
http://ehp.niehs.nih.gov/wp-content/uploads/122/4/ehp.1307250.pdf
Background: Shifting to active modes of transport in the trip to work can achieve
substantial
co-benefits for health, social equity, and climate change mitigation. Previous integrated
modeling
of transport scenarios has assumed active transport mode share and has been unable to
incorporate
acknowledged system feedbacks.
Objectives: We compared the effects of policies to increase bicycle commuting in a
car-dominated
city and explored the role of participatory modeling to support transport planning in the
face
of complexity.
Methods: We used system dynamics modeling (SDM) to compare realistic policies,
incorporating
feedback effects, nonlinear relationships, and time delays between variables. We developed
a system
dynamics model of commuter bicycling through interviews and workshops with policy,
community,
and academic stakeholders. We incorporated best available evidence to simulate five policy
scenarios
over the next 40 years in Auckland, New Zealand. Injury, physical activity, fuel costs,
air pollution,
and carbon emissions outcomes were simulated.
Results: Using the simulation model, we demonstrated the kinds of policies that would
likely be
needed to change a historical pattern of decline in cycling into a pattern of growth that
would meet
policy goals. Our model projections suggest that transforming urban roads over the next 40
years,
using best practice physical separation on main roads and bicycle-friendly speed reduction
on local
streets, would yield benefits 10-25 times greater than costs.
Conclusions: To our knowledge, this is the first integrated simulation model of future
specific
bicycling policies. Our projections provide practical evidence that may be used by health
and
transport policy makers to optimize the benefits of transport bicycling while minimizing
negative
consequences in a cost-effective manner. The modeling process enhanced understanding by a
range
of stakeholders of cycling as a complex system. Participatory SDM can be a helpful method
for
integrating health and environmental outcomes in transport and urban planning.