Caveats & Limitations
Measurement instrument for planning and policy
The HDMT is a comprehensive evaluation metric to consider health needs in urban development plans and projects. Measurable indicators and development targets provide information about both the positive and negative ways in which health is impacted by a proposed development project and focuses attention on ways that development can improve population health. By providing measures and criteria for development, it allows those involved in policy- and decision-making to make more informed choices between trade-offs. As a result, the HDMT may provide an additional means to support greater transparency in development processes.
Voluntary not regulatory approach
The HDMT is not a new form of environmental regulation or a set of enforceable standards. The HDMT does not mandate the achievement of specific development targets. Similar to tools like LEED-ND, the HDMT is intended to encourage voluntary efforts to improve health-oriented development.
Developed for urban contexts through a local participatory process
The indicators and targets in the HDMT reflect the ENCHIA Community Council objectives and needs identified in their Healthy City Vision for San Francisco. In urban areas, the HDMT is appropriate for new developments in residential and mixed-use sites. A large part of this Tool may be relevant for evaluating land use development in other dense, socially and economically diverse cities. However, other locales may want to modify indicators and targets to reflect local needs.
Conflicts between objectives are made explicit
Good development will always represent an optimal balance between competing objectives. Therefore, a user of this HDMT should expect that for any given project, the HDMT will reveal particular advantages and disadvantages. The achievement of one or more targets alone does not signify good development and the non-achievement of one or more targets does not signal poor development. By providing information about both the positive and negative effects on health objectives, the HDMT helps to reveal trade-offs and aids those involved to make more informed choices with full-recognition of those trade-offs.
The HDMT does not provide a means to weigh conflicting priorities and goals, nor does it advocate for or discourage any specific means of evaluating these trade-offs. The optimal use of the HDMT will occur in an open and transparent decision-making process. While in some cases, a lack of data about a certain aspect of a project or plan will prohibit the evaluation of an indicator or target, the HDMT is meant to be used comprehensively, by using all objectives and indicators.
Several examples of the types of trade-offs one might expect in the evaluation of land use development projects are:
- Conflicts between established wetland buffers and local land use regulations.
- Mixed-use developments and higher densities are associated with higher noise levels.
- Abiding by LEED or Energy Star standards increases the cost of the housing production.
- Desegregating schools may conflict with promoting neighborhood-based education.
- Green space around schools may conflict with the ability of children to walk or bike to school if it necessitates schools being in urban neighborhoods.
- Development targets that decrease segregation and promote racial and economic integration can facilitate gentrification.
- Development impact fees or community benefits agreements may raise the cost of development which reduces developer desire or ability to pay for things like affordable housing or green building design.
- Development plans or projects designed to attract stable jobs with career ladders may work at a disadvantage to small businesses, since they will favor large firms which tend to have a hierarchy of success and enough resources to invest in employee retention and development.
- Development of green roofs may compete with the use of roofs for solar energy.
Can be applied at different scales
Every indicator or target in this HDMT may not be reasonably affected by projects at every scale. A plan level analysis might be able to affect many indicators. A small project may not be able to affect indicators to the same extent as a large project. There may be little value in the application of the HDMT to a small project with effects on few objectives.
Borrows from or adapts some existing standards
Some targets and indictors are borrowed from other indicators processes and criteria tools, such as the Healthy People 2010 objectives and the LEED-ND criteria. The Tool attempts to avoid duplicating regulatory building design standards in existing codes and voluntary criteria such as the LEED green building standards. Some development targets or indicators used in the HDMT may be the subject of regulations not related to the HDMT.
Limitations and recognized gaps
The HDMT does not provide indicators for all outcomes related to health. The focus of the HDMT is on environmental, social and economic level factors that affect health at the population level. The HDMT does not include traditional behavioral health indicators nor does the HDMT assess factors modifiable at the household level such as environmental tobacco smoke exposure. Many concepts in the HDMT present challenges to measurement. For example, while we use distance as a proxy for accessibility, distance does not represent aspects of accessibility such as time, cost, and quality.
Limitations of demographic analyses and forecasts
Demographic analyses and forecasts are frequently used to predict housing and job markets, school enrollments, consumer and transportation demands, etc which subsequently impacts resource allocation by public and private agencies and investors. It is important to note that demographic analyses and forecasts may be used to reinforce the status quo and therefore not address the needs of people who you may want to bring into a community or prevent from having to leave a community. Several examples help illustrate this point:
- A demographic and enrollment forecast of the San Francisco school district may show that a certain neighborhood is projected to have fewer and fewer children attending public schools over the next two decades. The school district may subsequently decide to phase out the school in that neighborhood and invest resources in other schools. By phasing out the school, future families with young children will be less likely to move to this neighborhood.
- An area cited for industrial use historically has low pedestrian and commercial activity. When the area is recited for residential or mixed use, all previous data would indicate that the area is not a pedestrian friendly environment. However, creative land use design may cultivate greater pedestrian access to commercial and residential spaces.
- Analyses indicating that 60% of customers currently use cars to access a store may be predicated on the fact that there are no safe pedestrian walkways to the store and/or there may be no public transportation stops near the store. Changing transportation and land use design in that region to promote pedestrian activity and access to public transportation, as well as disincentivize usage of private cars (i.e., by converting some parking spaces into green spaces), may therefore change the demographics of the store's clientele.
A learning document
Developing this Tool has been a collective learning process. The HDMT will continue to undergo peer review by national experts in the fields of public health, planning, environmental protection, and social indicators. New research findings and newly available technologies for measurement and assessment will be incorporated appropriately into the HDMT. The time and costs of applying the HDMT will be documented in its future development and as application occurs.