Buildings and Cities
Bicycles are on the rise as cities attempt to untangle traffic and unclog skies, urban dwellers seek affordable transportation, and diseases of inactivity and billowing greenhouse gases become impossible to ignore. Infrastructure is essential for supporting safe, pleasant, and abundant bicycle use, and includes:
- Networks of well-lit, tree-lined bike lanes or paths—the more direct, level, and interconnected the better.
- Well-designed intersections, roundabouts, and points of access, where bicycles and cars meet.
- Access to public transport, secure bike parking, city bike-share programs, and workplace showers.
In the places where cycling thrives, programs and policies complement physical infrastructure. Educational initiatives target cyclists and motorists alike, for example, and stricter liability laws protect those on two wheels. Numbers from the world’s cycling capitals are compelling. In Denmark, 18 percent of local trips are done on two wheels, and in the Netherlands, 27 percent—with virtually zero emissions.
A virtuous cycle is clear: With more infrastructure come more riders. Perhaps counterintuitively, with more infrastructure and more riders, safety improves. And the more bicycles there are traversing a city, the more it reaps numerous returns on investment, including the health benefits of cleaner air and greater physical activity.
Susan B. Anthony [on] bicycling: Macy, Sue. Wheels of Change: How Women Rode the Bicycle to Freedom (With a Few Flat Tires Along the Way). Washington, D.C.: National Geographic Society, 2011.
Rob Penn [on] the bicycle: Penn, Robert. It’s All about the Bike: The Pursuit of Happiness on Two Wheels. New York: Bloomsbury, 2010.
elements that support…cycling: Hull, Angela, and Craig O’Holleran. “Bicycle Infrastructure: Can Good Design Encourage Cycling?” Urban, Planning and Transport Research, 2, no. 1 (2014): 369-406; Buehler, Ralph, and John Pucher. “Cycling to Work in 90 Large American Cities: New Evidence on the Role of Bike Paths and Lanes.” Transportation, 39, no. 2 (2012): 409–432; NACTO. Equitable Bike Share Means Building Better Places for People to Ride. New York: National Association of City Transportation Officials, 2016.
separated from car traffic: Baker, Linda. “How to Get More Bicyclists on the Road.” Scientific American, October 1, 2009.
[importance of] workplace showers: Buehler, Ralph. “Determinants of Bicycle Commuting in the Washington, DC Region: The role of Bicycle Parking, Cyclist Showers, and Free Car Parking at Work.” Transportation Research Part D: Transport and Environment, 17, no. 7 (2012): 525–531.
Dutch official…cycling tantamount to suicide: Jordan, Pete. In the City of Bikes: The Story of the Amsterdam Cyclist. New York: Harper Perennial, 2013.
In Amsterdam, bikes outnumber cars: Tagliabue, John. “The Dutch Prize Their Pedal Power, but a Sea of Bikes Swamps Their Capital.” New York Times. June 20, 2013.
Copenhagen…responsive traffic light system: Jaffe, Eric. “Of Course Copenhagen Is Giving Bicycles Traffic-Light Priority.” CityLab—from The Atlantic. February 19, 2016.
local trips…[Denmark and] the Netherlands: Folbre, Nancy. “The Bicycle Dividend.” New York Times. July 4, 2011.
United States…trips…by bike: Folbre, “Dividend.”
Bike commuting [growth]: Pallardy, Richard. “Urban Bicycling: Year in Review 2015.” Encyclopædia Britannica, 2016.
trips…less than two miles: Folbre, “Dividend.”
health benefits of cleaner air and…activity: Garrard, J, C. Rissel, and A. Bauman..”Health Benefits of Cycling.” In City Cycling, edited by J. Pucher and R. Buehler, 31-54. Cambridge, MA: MIT Press, 2012.
reduced risk of fatalities: Jacobsen and Rutter, “Health Benefits”; NACTO. Equitable Bike Share Means Building Better Places for People to Ride, New York: National Association of City Transportation Officials, 2016.
Europe’s new bike highways: Schwägerl, Christian. “Moving Beyond the Autobahn: Germany’s New Bike Highways.” Yale Environment 360. February 18, 2016.
Project Drawdown defines bike infrastructure as: the increased installation of bike paths to encourage more bike usage in urban environments. This solution replaces the use of motorized road vehicle infrastructure (i.e. more lanes for cars and buses).
In 2014, 3 to 5.5 percent of urban trips around the world were completed by bicycle, with some cities having well over 20 percent. In the European Union (EU), where over 7 percent of urban trips are completed by bicycle, the net economic benefits of bicycle infrastructure improvements have been estimated to be as high as €143.2 to €155.3 billion annually (Küster and Blondel, 2013). This accounts for reduced costs associated with health expenditures, congestion, fuel consumption, air pollution, and more. Research has shown that bicycle infrastructure has a significant effect on the mode of travel chosen in urban environments, most notably through the provision of separate cycling facilities along heavily traveled roads and intersections, and through traffic calming in residential neighborhoods.
This analysis investigates the greenhouse gas and financial impacts of an increase in urban bicycle ridership through expanded implementation of bike infrastructure.
Total Addressable Market 
The total addressable market for bike infrastructure is defined as the total projected passenger-kilometers traveled in urban environments from 2020-2050. Implementation was assumed to be in kilometers of lanes (bike or car/bus/other) installed, and we assumed a fixed usage of each lane-kilometer installed, with one bike lane-kilometer generating 5.2 million bike passenger-kilometers annually.
Adoption Scenarios 
There is limited data on existing global bicycle adoption in the literature. To determine the 2014 global adoption of 856 billion passenger-kilometers, data was used from a 2015 collaborative study on cycling by the Institute for Transport and Development Policy (ITDP) and University of California-Davis (UCD).
Impacts of increased adoption of bike infrastructure from 2020-2050 were generated based on three growth scenarios, which were assessed in comparison to a Reference Scenario where the solution’s market share was fixed at the current levels.
- Plausible Scenario: This case is aligned with the projected data from the global ITDP/UCD study, reflecting a reasonable high-adoption pathway.
- Drawdown Scenario: Here the projections from sources for each Drawdown region were used, and expanded upon with assumptions of 30 percent growth per ten-year period. This scenario was based on a total of 31 adoption estimates from 8 sources. Estimates were calculated for each region, summed to determine a global value, and then interpolated back to the estimated current adoption. 
- Optimum Scenario: Here, it was envisioned that all switches to bike use are only from internal combustion engine car users; hence, some adjustments to the inputs were made. Additionally, growth in adoption was assumed to 10 percent of the total addressable market in 2050—which at a global level is very high, although still lower than the current level in some developing cities. 
Emissions were calculated based on fuel use, but as we considered some electric modes in the first two scenarios (i.e. electric cars and buses), we also included some electricity emissions. Data for this came from the US Office of Energy Efficiency and Renewable Energy, the ITDP, and the Inter-Governmental Panel on Climate Change (IPCC) for emissions factors.
The first costs of bike infrastructure adoption were estimated from 29 different lane installation cost data points, collected from 17 sources. Operating costs were taken as the maintenance costs for road and bike lanes, and were much lower for bike lanes as the wear and tear from bikes is lower than that from cars and buses.
Bike infrastructure is considered a high-priority Drawdown solution, so its adoption was not limited in the integration process.
Should global ridership increase to 3.5 trillion passenger-kilometers, or 500,000 additional kilometers of bike lanes, by 2050 (as assumed in the Plausible Scenario), municipalities would avoid emissions of over 2.3 billion tons of carbon dioxide-equivalent, while providing construction savings of US$2 trillion and net operating saving of US$400 billion.  These financial savings compare the cost of constructing new roads and lanes for increased light-duty vehicle traffic to the cost of remodeling or renovating roads to accommodate and encourage bicycle ridership. In the Drawdown Scenario, 1 million additional lane-kilometers installed (i.e. 6 trillion passenger-kilometers of ridership) would result in 6.5 billion tons of carbon dioxide-equivalent emissions avoided, with the figures for the Optimum Scenario significantly higher at 11 billion tons of carbon dioxide-equivalent.
The ITDP/UCD study found that combined cycling (regular and e-bikes) could save $24 trillion between 2015 and 2050, and avoid 225 million tons of carbon dioxide-equivalent emissions in 2050. The total bike and e-bike impact in the Plausible Scenario is 150 million tons of emissions reductions in 2050, with total savings of $2.8 trillion from 2020-2050. These results are much more conservative, in part because we do not include car fuel, vehicle maintenance cost savings, and some other knock-on savings for the bike infrastructure solution.  Total bike and e-bike impact in the Drawdown Scenario is higher, at 471 million tons of emissions reductions in 2050, suggesting that the ITDP/UCD adoption probably lies between our Plausible and Drawdown Scenarios.
Additional benefits of cycling include improved health and lower health care expenses,  and an increase in the uptake of public transport by making more public transport stops accessible by bike. These benefits are of great value, and are not included in our analysis. The expansion of bike infrastructure and the rates of adoption are affected by many factors: besides the obvious ones like weather, type of bike lane, and geography of the city, other attributes of the city and its residents play important roles. All of these attributes are beyond the scope of this report. Nevertheless, our analysis shows that the benefits we can measure are large when there is significant expansion in bike infrastructure.
 For more on the Total Addressable Market for the Transport Sector, click the Sector Summary: Transport link below.
 For more on Project Drawdown’s three growth scenarios, click the Scenarios link below. For information on Transport Sector-specific scenarios, click the Sector Summary: Transport link.
 Current adoption is defined as the amount of functional demand supplied by the solution in the base year of study. This study uses 2014 as the base year due to the availability of global adoption data for all Project Drawdown solutions evaluated.
 For example, Curitiba (Brazil) and Guadalajara (Mexico) have around 20 percent cycling mode share each.
 For more on Project Drawdown’s Transport Sector integration model, click the Sector Summary: Transport link below.
 Unless otherwise noted, all monetary values are presented in US2014$.
 We only include costs that would be attributable to municipalities rather than the whole society, such as health costs which are challenging to estimate at the global level.
 This is so even after accounting for the increased risk of injury from collisions and accidents.