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Assessing the Benefits of Greenways

Updated: Jul 15, 2019

Stewart Greenway (Charlotte, NC)

While different segments of the public have staked out varying positions on the economic benefits and costs of living proximate to an off-road pedestrian/bicycle facility, much of the scholarly work published over the past 20 years has landed definitively on the side of clear benefits to the majority of property owners – and the closer the property owner to the greenway, generally the better. Nevertheless, the literature is less than clear on quantifying these benefits; the type and value of externalities (such as air quality benefits through emissions reductions) that should be counted in an assessment of greenways; and the reaction of the general public to the proposal of a new, adjacent greenway is still very mixed. This brief paper will explore some of the major themes of arguments both for and against the development of off-road greenway facilities, as well as some of the challenges of measuring indirect impacts particularly to health and job creation effects.

Benefits of Greenways

The most commonly cited benefits of greenways can be thought of as falling into two broad categories: direct and contingent effects. Most of the focus on this paper, as stated, aligns with contingent effects, but a brief overview of direct affects is presented in the following paragraph.

The direct benefits of greenways, namely those that are readily assessed in traditional input-output models favored by economists, are the expenditures created through the construction and (sometimes) maintenance of a greenway facility. An economic multiplier is typically applied to those expenditures to describe how they are expanded throughout different sectors of the economy such as retail purchases, construction materials, and distribution of those materials. Generally, the larger the expense of a project, the more these direct effects rise to the forefront in an analysis of benefits and costs. However, these impacts are readily assessed with existing tools that utilize available matrices of multipliers, typically in a software package. Before moving on, it is worth noting that conducting this type of input-output analysis, even with standardized software, is not a straightforward matter without training and a solid grasp of the proposed project’s expenditures, timing of construction, and sectors of the economy it might affect. Typically these models produce estimates of job-years created by the project as well as tax revenues in addition to their monetary benefits to businesses. Greenways also possess negative direct effects, particularly associated to their costs (both construction and maintenance), environmental, and loss of taxable property revenue if the greenway traverses private lands acquired through either fee-simple or conservation easement.

Contingent effects, like direct effects, may include both positive and negative elements, are potentially numerous and vary widely in the literature in terms of their magnitude and even their basic inclusion in analysis. All of them presuppose some contingent action occurring because the greenway is being constructed, maintained and/or used.

Improved property values for lands within easy walking distance to a greenway. These effects tend to be small compared to larger, external forces however, and can be easily swamped in larger market trends and events. Retail sales through the operation of the greenway, such as expenditures by residents on food, equipment, and (for out-of-town visitors especially) lodging.Health effects through an increased opportunity to access a new or improved exercise option that may encourage more people to seek recreation that, in turn, creates health benefits through lower rates of cancer, diabetes, heart disease and other risk factors associated to some degree with being overweight or obese. These effects extend to mental health, including mental acuity, school performance, and treatment for depression.  

Congestion reduction: more trips on greenways suggests fewer trips by cars, which in turn suggest less roadway congestion and less need for future capacity improvements. The congestion effects of greenways that generate more traffic or parking concerns due to an increased response by recreational users is seldom cited. Most of the remaining contingent effects are “chained” from one of the four effects listed above. The chained effects include reduced mobile source emissions (from reduced congestion), reduced health expenditures (from improved health effects related of trail users), and the creation or preservation of jobs (from increased retail sales or presenting a community that is attractive enough to lure or retain workers and employers, stereotypically in technology sectors). Environmental appreciation may also lead to environmental protection, preservation, and conservation actions that might not otherwise have occurred without a greenway providing access to natural settings, particularly in urbanized areas. Similarly, greenways can indirectly (or sometimes directly, through conservation easements) promote historic property preservation.

Most of the remaining contingent effects are “chained” from one of the four effects listed above. The chained effects include reduced mobile source emissions (from reduced congestion), reduced health expenditures (from improved health effects related of trail users), and the creation or preservation of jobs (from increased retail sales or presenting a community that is attractive enough to lure or retain workers and employers, stereotypically in technology sectors). Environmental appreciation may also lead to environmental protection, preservation, and conservation actions that might not otherwise have occurred without a greenway providing access to natural settings, particularly in urbanized areas. Similarly, greenways can indirectly (or sometimes directly, through conservation easements) promote historic property preservation.

Negative Consequences of GreenwaysBeyond public opposition – which can be more complex than it first appears. The negative impacts of greenways can also be grouped in either direct or contingent categories. Greenways negatively impact natural areas and stream riparian buffers by paving over or otherwise disturbing that natural topography, drainage, and foliage. Greenways require public and sometimes private funds that could have been used somewhere else for a different purpose, creating opportunity costs. They can and often do reduce tax revenues by taking land out of private ownership and converting it into either an easement (which usually will have a lower tax value or tax-exempt status for the duration of the conservation easement agreement) or land owned by local government.

Contingent effects are more controversial, but this type of effect is where most of the substance for both advocates of and opposition to greenways resides. The following is a brief encapsulation of the primary categories of the negative consequences arising from those effects that are contingent upon the upstream actions of users or other effects. Property Devaluation. Most of the research reviewed that has been conducted over the past two decades has presented the finding that properties proximate to greenways either have no change in value or a slight positive increase in value, particularly when the property has a direct connection to the greenway. As with property value increases, these effects tend to be challenging to prove or disprove.

Private Property Rights. Although it is rare and very undesirable for many reasons for a government to invoke eminent domain proceedings for the purposes of off-road greenway construction, it still does happen if there are one or two property owners that refuse to grant easements necessary to make the final linkage for a trail. The recent U.S. Supreme Court case (Marvin M. Brandt Revocable Trust et al. v. United States, Docket No. 12-1173) decided on March 10, 2014 has reinvigorated private property rights as they pertain to rail corridors, particularly in the aftermath of the more notorious Kelo v. New London case (2005). However, two things should be kept in mind by all the parties interested in the topic the Brandt case does not potentially affect railbanked railroad properties or those properties where the land is owned outright by the railroad company. Nevertheless, the real opposition is likely to come from a public sensitized to public takeovers of private lands even if there is no clear profit motivation, and elected officials who represent the public.

Increased Crime. Related to property devaluation in the minds of some potential greenway opponents, the research on criminal activities related to greenways is focused on either crimes occurring on the greenway itself, or increased numbers of burglaries or (more commonly) vandalism against adjacent properties. Although typically undertaken by greenway advocates, the research supports either minimal or no increase in crime against adjacent properties from the construction of greenway facilities. In cases where there have been publicized accounts of criminal activity occurring (e.g., recent incidents on the American Tobacco Trail in North Carolina), the areas where the crime is occurring are relatively high-crime areas away from the trail. Restricting the use of the greenway to daylight hours, controlling access points, being mindful of sight lines during design and maintenance, creating programs that foster a sense of ownership of the greenway among the nearby residents, familiarizing emergency response officers with easily identified mile-marker systems, and / or providing additional, trail-directed lighting seem to help limit negative effects from crime committed on the greenway in these communities. However, the increased use of greenways by law-abiding people is perhaps the best crime deterrent: a number of studies report a drop in crime after the construction of a greenway or lower crime rates on the greenway than in other parts of a community.

Difficulties Assessing Greenway BenefitsA number of challenges confront anyone that attempts to quantify the benefits of a particular greenway, or the benefits of greenways in general. The following discussion illustrates some of the limitations of past studies that are often cited in the literature, but are not intended as an indictment of the work, but simply note the challenges of working in this niche field of study. The authors of the work themselves often recognize one or more of these same weaknesses.

Lack of Range. The body of literature that exists dealing with the assessment of greenways (or bicycle facilities, or pedestrian facilities) has become considerable, but each study is often restricted to one or very few cases, often in a single market. This issue presents a problem for anyone trying to “port” the results from one case study to another: caution should be used in determining if the context of the case study(-ies) match those of the project under examination. The context of several important studies often include a setting that is probably quite favorable to the creation and acceptance of new greenways – Austin, Boulder, Seattle, and San Francisco, to name a few. These markets might be viewed as already on a path that includes a very “walkable” environment and demographic. While studies set in these areas nobly attempt to control for the contextual variability by taking into account various cross-correlating factors, the presence of hidden support for greenways like self-selecting biases of residents, may create an end-around of these efforts to control them.

Variability in Statistical Significance. Some of the literature has noted that there is wide variation in key variables that underpin benefit calculations – and even in calculations of cost as well. In part this is due to the first problem of not collecting enough data points from many different places, but it is easy to suspect that other, less tangible influences may also be at work. Weather, economic health, and perceptions of safety are a few of the influences that could easily be overlooked in trail use studies conducted at one point in time and in one place. One recent study worked on by the author (as well as Erin Convery, with Alta Planning+Design) in 2017 considered 29 greenway projects, using purchased CoStar microdata. Very little variation emerged that would support an advocate or bolster a protestor of such a project.

Data Acquisition and Realization. Obtaining data from greenway users is potentially a time consuming and expensive prospect. The primary citation for benefits from the Virginia Creeper Trail, for example, is a 2004 paper published for a Master’s Thesis; the candidate obtained 1,036 surveys to create the data set for his research. Few researchers have the time and resources to conduct such a study, and instead rely upon previous research, particularly if there is no trail in place from which to obtain user-derived information. However, even with directly collected data, there are issues with user’s perceptions of the value of their time (and that perception varies still further according to whether the trip is recreational or work-related), halo effects from previous questions or current conditions, or simple lack of memory.

When to Count Externalities. Often, the benefits of greenway studies hinge upon how much and what kind of externalities (here referred as contingent effects) are included in the study framework. The Office of Budget and Management recommends a 7% discount rate for future benefits, a figure used in recent TIGER grant applications for calculating net present value of future benefits of greenways (and other types of facilities). Even more disconcerting to hopeful grant applicants might be the lack of recognition of recreational trips and benefits in calculating benefits. This fact might appear puzzling given that FHWA – whose economics office evaluates the benefit-cost analyses submitted with each TIGER grant application – has never suggested adjusting downward automobile traffic volumes associated with recreational trips that impact the decision-making process associated with high-level bridges connecting to the Outer Banks, for example. However, even researchers without any guidelines or restrictions at various times and places have not used job creation, health-related, emissions reduction, and other contingent benefits in their studies of greenway proposals. The reasons for these omissions are probably varied, but a lack of knowledge of one or more topics, resource limitations, or simply being beyond the focus of the study at-hand are credible explanations. In some cases, external factors cited as a positive by one researcher may be viewed as a negative by another: property value increases (and increased tax rates) and increased recreational use (and increased traffic and parking problems) to name two. Conclusions

Given this degree of latitude in methods it shouldn’t come as a surprise when some researchers cite far lower levels of benefits of greenways than others. An excellent example is the paper that considered a recent (four years old) trail constructed as a rail-trail across three counties in Kansas with the purpose of comparing its performance with that of another, proposed trail that the author did not support. This researcher cited a net loss in revenues, even after accounting for the contingent effects of retail sales (minimal), job creation (none) and sales tax revenues (also minimal). However, this trail had only been open for four years and it was not mentioned how well-advertised or known it is in the general public; was located in a part of the country that likely doesn’t have a large population eagerly awaiting for the next greenway to open; and did not benefit from the (likely quite small) externalities of health benefits. The density of population or employment in close proximity to this trail was not discussed, nor was the demographic characteristics of the population that might have inclined or disinclined them to use the trail. Costs and revenues were not adjusted to current year dollars, although the short span of the data used would not reflect much change due to an inflation adjustment. The $10 per out-of-county user per day figure used in this study is comparatively low given that fuel purchases, food, and perhaps lodging for some percentage of the users are likely. There is also no mention of added revenues stemming from marathon, ultra-marathon or other events connected to the trail.

The point of considering both advocacy and opposition approaches to greenway studies is not to indicate whether a particular research effort is right or wrong, but to improve all of the research. The research into greenway benefits would benefit from considering several factors in future studies, most of which are commonplace in all sectors of social science or economic studies:Utilize OBM discount and inflation factors to bring all dollars into current year (NPV) values;Carefully consider the context of comparable cases cited as a source for inputs, including densities and demographic characteristics of populations in the vicinity of the corridor; • Utilize field data collection including interviews and locally-derived information on sales, taxation, and other key inputs whenever possible;Control for the context of the area being researched, particularly if using inferential statistical methods like multiple regression analysis; andChoose external factors as benefits (or costs) wisely: does using this external factor strengthen the robustness of the results, or does it potentially weaken it by bringing in a host of new assumptions?

The overwhelming body of evidence supports greenway construction and maintenance costs as being worthwhile from a benefit-cost standpoint over sufficient time to capture returns and adequately establish the value of the trail for potential out-of-town users. Most research either shows a slight property value benefit from being directly connected or in close proximity to a trail, or no significant impact at all. Realtors in many fast-growing real estate markets regularly tout the presence of a trail nearby, just as they would tout proximity to an airport, shopping center or downtown. The health benefits of greenways, contingent upon an increased number of people walking or biking (or just doing those things more often) are positive and real, but are hard to quantify when the research is on a trail that has not yet been constructed and is only in the planning stage. Similarly, the creation of jobs associated with a trail, which may include outfitters, retail food outlets, and short-term lodging, are challenging to quantify through comparable case studies but are a factor in those areas with established, well-marketed trails (e.g., the Virginia Creeper Trail, Lakefront Trail in Chicago, the Appalachian Trail, Mountains-to-Sea, etc.). Urban greenways typically provide an important enhancement to downtowns, riverfronts, or other areas that already have an established connection in the minds of the public. In these cases, the greenway represents part of a “walkable” environment that supports local businesses by enhancing pass-by traffic. Potential new businesses will certainly consider a walkable environment an asset, but there are likely other factors that will convince people to invest in the area as well that collectively contribute to an overall marketing image of a city. An example would be the embracing of bicycle facilities, greenways and urban trails that has been a hallmark of the Indianapolis, IN economic development strategy. Led by the eight-mile Cultural Trail that connects five of the six Indianapolis cultural districts, the Midwest city is creating an opportunity for recognition through biking and walking more frequently attributed to cycling and walking icons like Portland, OR. Even more highly publicized efforts in the largest metropolitan areas like Chicago and New York City are bringing the connection between livability, economics, and biking/walking accommodations into the forefront.

Originally published as, "Economic Arguments of Off-Road Pedestrian and Bicycle Facilities," J. Scott Lane, 5.20.2014; updated 2018)

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