Pros and cons of adding a paved bike trail to Central Park

Brian G. Wolff, M.S., Ph.D., Conservation Biologist

Pros 1 & 2

1. A bicycle trail would provide bicyclists with a scenic, off-road experience. (Note P1)

2. A bicycle trail would provide bike riders with direct off-road access to the River Valley Trail. (Note P2)

Notes for Pros

(P1) It should be kept in mind when appraising this benefit that widening the existing trail to accommodate bikes will do much to destroy the scenic beauty of the Nine Mile Creek Corridor. Thus the objective of providing a scenic bikeway will be compromised from the onset.

(P2) It should be kept in mind when weighing this benefit that Lyndale Avenue provides access to the river valley trail system and is only a short distance to the east of the Nine Mile Creek Corridor. Creating a bicycle-only lane along Lyndale would bring bicyclists more directly to the river trails and the 35W bridge. Shortening the distance to the bridge would be beneficial because it provides access to existing trails on the Burnsville side of the river, and will therefore be a destination for many cyclists.


1. A bicycle trail will impede water infiltration and consequently foster the movement of pollutants into the creek, foster erosion, promote siltation, exacerbate flooding within the corridor and greater river valley, and rob the underlying aquifer of water. (Note C1)

2. A bicycle trail will displace natural vegetation, which normally removes eutrophying inorganic nutrients from melt and rainwater runoff. These nutrients will consequently enter the creek, river, and underlying aquifer. By eliminating natural vegetation, the trail will also eliminate wildlife food and cover. This will negatively impact native species, including species designated as threatened, endangered, or of special concern by the Minnesota Department of Natural Resources. (Notes C1 & C2)

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Image: Bloodroot photographed in the Nine Mile Creek Corridor. Showy bloodroot captures eutrophying nutrients and the attention of nature enthusiasts. Widening the existing trail for cyclists will reduce the abundance of native plants. By Brian Wolff.

Cons, continued

3. A bicycle trail, if blacktopped, will be a source of thermal pollution and exacerbate temperature fluctuations within the creek. Such fluctuations profoundly impact aquatic ecosystems by stressing and eliminating species, including keystone and other highly valued species (e.g., trout). (Notes C1 & C2)

4. A blacktopped bicycle trail will be a source of air pollution. In particular, the trail will release small particulates into the air. Such particulates are released in appreciable quantities and are known to have significant effects on public health. See Peeyush Khare et al. Asphalt-related emissions are a major missing nontraditional source of secondary organic aerosol precursors. Science Advances (6) 2020. DOI:10.1126/sciadv.abb9785. (Note C1)

Cons, continued

5. A bicycle trail will generate heat. Unlike surfaces covered by vegetation, which capture solar energy and chemically store it, blacktopped surfaces quickly release absorbed solar energy as heat. This heating will be sufficient to negatively impact those recreating in the Nine Mile Creek Corridor on summer days, and it will have deleterious effects on the biotic community. The loss of tree  cover that will result from widening the existing trail will exacerbate this concern.

6. Construction of a bicycle trail will promote global warming. Widening of the existing trail to accommodate cyclists will result in the removal of carbon-capturing vegetation, including large trees. Carbon-emitting fossil fuels will necessarily be used by landscaping equipment and trucks carrying construction materials. Greenhouse gas emissions during the production of construction materials, including base, asphalt, cement, and steel, will also be significant. (Note C1)

Cons, continued

7. Construction of a bicycle trail will necessitate disrupting and killing wildlife.

8. Widening the existing trail to accommodate cyclists will promote the spread of invasive and exotic species. (Notes C1, C2, & C3)

9. A shared-use bicycle trail will endanger trail users. Most serious bicyclists have learned from experience that the risks of colliding with dogs, children, and distracted pedestrians makes the use of shared trails dangerous. Research supports this assessment. For example, one shared-use study conducted in 2005 found that 6% of surveyed trail users had collided with another user or fallen while trying to avoid a collision. Several additional studies have demonstrated that off-road shared-use trails have incident and injury rates significantly higher than those associated with on-road cycling. See, for example, some of the research performed and cited by Altman-Hall. (Note C4)

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Image: Blackpoll warbler photographed in the  Nine Mile Creek Corridor. Conservation biologists have documented alarming population declines among Neotropical migrants, which are due principally to habitat loss. For these birds, it is important to protect migratory stopover feeding and resting sites as well as breeding habitat. By Brian Wolff.

Cons, continued

10. Cycling is incompatible with other, high-value uses. The Nine Mile Creek Corridor trail, as it exists today, draws children, dog walkers, bird watchers, photographers, and others who are interested in taking time to “smell the roses.” These individuals are commonly distracted and their eyes are often on the animals and flowers found along the creek. Fast-moving bicyclists would demand their attention and would, therefore, greatly detract from efforts to enjoy nature’s natural wonders.

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Image: Red fox photographed in the Nine Mile Creek watershed. Cyclists scare away wildlife and thereby prevent wildlife photographers from enjoying their interests. By Brian Wolff.

Cons, continued

11. Bicycle traffic would do direct harm to sentient organisms and inflict suffering on morally relevant “others.” It is not only common, but normal to see dead frogs, snakes, chipmunks, and other vertebrates on bicycle paths. In most instances, these animals are not immediately killed when run over. They die slowly. There is a tendency to underestimate the pain and suffering cyclists inflict because the victims of cycling commonly go unobserved. They drag themselves from the trail before dying or are carried away by scavengers.

Ethicists have progressively widened the sphere of moral relevancy to encompass women, minorities, the members of other religions, the poor, the mentally challenged, and those that do not conform to social norms. This process is ongoing and logic demands that it will not end until this simple fact is universally recognized: It’s not religion, wealth, gender, race, intelligence, social conformity, or species that makes an individual the proper subject of moral concern. It is sentience. If an individual can experience pain and suffer, its treatment is morally relevant and should not be discounted. (Note C5)

Cons, continued

12. Approval of a bicycle trail will signal a willingness on the part of city officials to undo the good done by environmentally conscious residents. The city cannot rip up the Nine Mile Creek Corridor and pave over roughly 100,000 square feet of earth without negating the efforts made by residents who have voluntarily conserved water, curtailed their use of fertilizers, and/or otherwise acted to protect the city’s biodiversity and water resources.

Consider one example. A property owner bordering Nine Mile Creek voluntarily agreed to have an infiltration pond constructed on a portion of his lot. What message will be sent to this property owner if a much larger area bordering the creek is blacktopped by the city? Certainly, it will be implied that Bloomington city officials do not greatly value his sacrifice.

Cons, continued

13. The construction of a bicycle trail would be inconsistent with previous promises made by city and state officials. Some of these promises have been explicitly stated, such as a 1970s promise to return trout to Nine Mile Creek, and the 1992 promise, by then Governor Arne Carlson, to make the Minnesota River fishable and swimmable in ten years. Other promises made are implicit in the actions pursued by city, state, and federal officials and codified by the Clean Air Act, Clean Water Act, Endangered Species Act, Wetland Conservation Act, and other regulatory measures. Environmental regulations, which impose restrictions and costs on the public, have received wide support from residents only because there is an implied promise to protect our environment and biological treasures. Anytime government involves itself in land development, does harm to our waterways, and erodes biodiversity in pursuit of non-vital public interests, it violates the public’s trust. Nine Mile Creek and the Minnesota River fail to meet minimum water quality standards and as long as this is the case, the promises to protect our natural resources should preclude city officials from supporting any and all nonessential projects destined to worsen existing conditions.

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Image: Trout fishermen and women are no longer seen along Nine Mile Creek because the trout that once inhabited the watershed have been extirpated. Streams are seldom destroyed by massive projects. They are incrementally degraded and biologically impoverished by thousands of small projects. By Brian Wolff.

Notes for Cons

(C1) It would be easy to dismiss the environmental impact of a bicycle trail through the Nine Mile Creek Corridor as inconsequential, given the amount of land in the watershed that has already been paved. Dismissal on such grounds would, however, demonstrate a failure to appreciate the dominant means by which ecosystems are destroyed, aquifers compromised, and biodiversity lost. Severe environmental damage is overwhelmingly attributable to the sacrifice of small bits and pieces, and only by stopping the creeping loss of green spaces can we hope to adequately protect our natural heritage.

(C2) It should be kept in mind that riparian and lotic organisms are over-represented on Minnesota’s lists of species deemed threatened, endangered, or of special concern. Projects that compromise riparian and lotic systems should thus receive exceptional scrutiny.

(C3) Unfortunately, it is not clear that this problem could get worse.

(C4) Sources

(C5) Like sexism and racism, speciesism is morally repugnant because it discounts the interests of “others” solely on the grounds of group affiliation and fails to recognize the source of our moral obligations, which is a shared capacity for suffering.


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