Also see QALY
Chairman Degnan. Commissioners. I have previously discussed the benefits of widening the GWB paths, including enhancements to competitiveness, tourism, resiliency and sustainability. Today I will focus on public health, worth $200 million per year.
The U. S. Center for Disease Control has observed that low levels of physical activity contribute significantly to rising rates of morbidity (illness) dues to obesity, diabetes, heart disease and stroke and has called upon transportation providers to go beyond the efficient movement of goods and people towards policies that support health and reduce health care costs. 
The World Health Organization, which also recognizes this crisis, has developed a set of Health Economic Assessment Tools or “HEAT” to help planners identify promising opportunities that simultaneously meet both society’s transportation and public health objectives.
HEAT has been employed throughout Europe to quantify the reduction in mortality (deaths) resulting from the implementation of bike-walk infrastructure, and here in Boston to assess the impact of public transit service cuts and fare increases.    
I applied HEAT to two iterations of the GWB paths. In both cases, I limit the exercise to Saturday-Sunday bike travel (no weekdays or pedestrians) and for the warmest eight months of the year. Actual and projected numbers of users are derived from PA and NYC DOT traffic studies.
First the ADA-compliant South Path from 2002 through 2019:
- 3000 cyclists access the GWB 35 times per year to bike 50 miles. 
- That level of use prevents five deaths per year.
- Applying a Value of Statistical Life (“VSL”) of $9.1 million, the annual public health benefit is $40 million. 
Next, on AASHTO-compliant paths supporting 10% annual growth 2020 through 2035:
- 14,000 cyclists making the same trips saves 21 lives worth $195 million.
- Over 16 years, that’s 300 deaths averted and $3 billion in health benefits.
- Presuming $90 million to widen the paths, the discounted benefit-to-cost is 23:1. 
Cyclists’ Proposal: (2) 10′ paths for bicyclists. (2) 6.75′ paths for peds-runners on the upper level. 9′ high anti-suicide barrier. Rendering by Joseph Lertola.
The PA is poised to spend $50 million to install anti-suicide barriers but otherwise restore the GWB paths to their 1931 pedestrian configuration. This will cripple their usefulness as bikeways.
Understanding that such data is sensitive, but widened paths could save more lives than anti-suicide barriers.
Note: The HEAT model calculates the value of reduced mortality. It does not factor reduced morbidity – reducing levels of illness and disability the affect individuals’ quality of life. Nor does it take into account the health benefits to non-cyclists due to lower levels of GHG emissions resulting from the switch to active transportation. That adds even more value.
 A Health Impact Assessment of Proposed Public Transportation Service Cuts and Fare Increases in Boston, Massachusetts, International Journal of Environmental Research and Public Health, http://tinyurl.com/hrb7log
Note: Having led 50 rides per year for the last ten years, I’ve had opportunity to observe the riding habits of cyclists accessing the GWB. Also, the routes to and from the GWB can be quite hilly, which is not factored into the HEAT model. So I believe the use assumptions to be reasonable.
 HEAT Assessment Data for GWB 2002-2019 and 2020-2035: