Effective Methods for Environmental Justice Assessment (2004) / Chapter Skim
Currently Skimming:
Pages 162-193
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 162... ...
In terms of environmental justice, the point of interest is the extent to which minority populations or lowincome populations would experience these benefits. To understand the distributive effects that would result from a potential transportation project, it is first necessary to examine the performance of the existing transportation service, including how this service varies between members of protected populations and others.
|
From page 163... ...
Public participation and dialogue with local officials can help in the selection of modes that need to be examined. A key element in environmental justice is to ensure that protected populations have mobility that is comparable to that of other populations; this often means that transportation modes other than the auto must be available.
|
From page 164... ...
However, they are limited in their ability to account for the attitudes, values, and constraints that determine travel patterns by the general population, much less specific groups such as minorities or those with low incomes. Activity-based approaches attempt to take into account the interdependences in trip decisions made by groups of individuals.
|
From page 165... ...
These trips are of particular significance when considering project impacts on low-income and some minority populations who may rely on networking more than others for purposes such as child care. By treating trip segments independently, trip-based models fail to reflect that trip decisions made by individuals often are interrelated.
|
From page 166... ...
It gives you the opportunity to assess environmental justice concerns based on the actual and forecasted performance of the road segments used most frequently by protected populations. Performance can be measured in terms of average vehicle speed.
|
From page 167... ...
Adapted transportation demand models Detailed Estimate travel demand (TD) between census tracts The project will impact travel demand patterns and protected population distribution is uniform within census tracts Medium/ High Standard travel demand modeling; census data analysis 3.
|
From page 168... ...
If the comparison reveals that travel times or V/C ratios related to protected populations are typically greater than for other groups, it may be concluded that low-income and minority groups are most likely carrying a disproportionate burden of transportation-related costs; and therefore an environmental justice problem may exist. Of course, if there is no significant difference, there is probably no environmental justice problem.
|
From page 169... ...
The third step is to identify the destination TAZs to which households of protected populations are routinely attracted, such as job and shopping centers, social service agencies and providers (including daycare centers) , and schools.1 The transportation demand model is first run with the data that characterize the current transportation system and the travel times on road links between origin and destination TAZs.
|
From page 170... ...
More advanced adaptation of transportation demand models This method is an advance on the previous one and disaggregates the applicable TAZs using census-block-group data instead of tract data. As before, the TAZs are redefined based on the presence of protected populations within zones before the model is used to determine travel times between analysis zones.
|
From page 171... ...
database.2 The HPMS database does not, however, routinely include data on urban and rural local roads, nor on rural minor collectors, as indicated in Figure 7-1. These categories of roads are important in assessing environmental justice concerns because low-income populations and minority populations are likely to use them, and their performance would have an impact on travel costs for these protected populations.
|
From page 172... ...
FHWA uses HERS to project needs for these highways KEY Arterials Arterials Urban roads Rural roads Collectors Collectors Local roads Local roads FHWA uses non-HERS methods to project needs for these highways Urban interstates Rural interstates Rural major collectors Rural local roads Rural minor collectors Rural other principal arterials Rural minor arterials Urban collectors Urban local roads Urban freeways and expressways Urban other principal arterials Urban minor arterials Figure 7-1. FHWA's road classification system Source: U.S.
|
From page 173... ...
Analysis. In the data analysis of urban and rural local roads and rural minor collectors, HERSST clumps together lower rural classified roads with rural major collectors and lower classified urban roads with urban minor collectors.
|
From page 174... ...
Furthermore, changes in average speed, which can be measured for each road segment, including those most frequently used by protected populations, are key to assessing whether an environmental justice concern exists. The model begins by assessing the current condition of the highway segments in the data sample.
|
From page 175... ...
Behavioral responses are captured by the statistics accumulator within the evaluation module, which provides descriptive and frequency statistics about vehicle miles traveled, number of trips by mode and time of day, number of stops by purpose, trip chains, vehicle occupancy, and travel times by trip purpose, among other classifications. Because this micro-simulation approach does not rely upon over-simplifying assumptions, it does not reduce the complexity and realism of the response and adaptation patterns of the travelers being modeled.
|
From page 176... ...
One significant advantage of this type of model is that it permits a dynamic, longitudinal analysis of travel behavior, as opposed to the static, cross-sectional analysis afforded by the traditional four-step demand models. This means not only that behavior is examined over a continuous time frame but also that impacts originating within and outside of the transportation system can all be evaluated together.
|
From page 177... ...
Realistically, it is highly unlikely that an agency would develop so ambitious a model solely for assessing environmental justice implications of a project. Rather, this type of model is most likely to be developed to meet an agency's general needs for travel demand analysis.
|
From page 178... ...
The data produced by each module, indicated in the bottom row, becomes the input for other modules. The population synthesizer creates a synthetic population of households and individuals that are distributed both geographically and demographically according to the input data related to the metropolitan area under study.
|
From page 179... ...
Furthermore, the matter of trip-chaining, which often is an important part of low-income people's travel itinerary, is dealt with explicitly by the model within the activity generation module -- a discrete choice-based model that generates trip chains along with activity locations using the data related to the synthesized householder's travel itinerary and domicile location. The operation of the traffic microsimulator module gives this model an important advantage over traditional demand models because it is capable of simulating multiple travelers per vehicle and multiple trips per traveler, both factors that are fairly common to low-income and minority travel routines.
|
From page 180... ...
Unlike conventional travel demand models, TRANSIMS is not merely concerned about peakhour activity, so travel diaries should cover an extended period of about a month to ensure that a reliable trend can be established. Information on whether individuals walk, use private vehicles or transit, or use any other mode of transportation is also gathered from the surveys.
|
From page 181... ...
. The latter capability underlines the importance of this model as a valuable tool in assessing environmental justice concerns in the foreseeable future.
|
From page 182... ...
187 • Nondrivers – People who cannot drive or do not have access to a motor vehicle. • Low-income persons – Drivers and nondrivers whose basic transportation needs are significantly constrained by financial limitations, especially out-of-pocket costs.
|
From page 183... ...
The following four general steps are suggested for analyses of the extent to which protected populations have a choice of transportation modes and services:
|
From page 184... ...
METHODS FOR STUDYING TRANSPORTATION CHOICE Table 7-4 summarizes the three methods we suggest for evaluating the extent to which transportation choice exists for protected populations. Method 7.
|
From page 185... ...
Modal quality assessment Screening Assess demand for various transportation modes Design phase when project will produce significant changes in availability of certain transportation modes Low Survey methods; graphs, charts, maps 8. User demand and evaluation surveys Screening Assess current level of use of various transportation modes Planning phase when project will produce significant changes in availability of certain transportation modes Low Survey methods; graphs, charts, maps 9.
|
From page 186... ...
If an area that is within the activity space of protected populations would be affected by a proposed transportation project, this method can be used to assess current capabilities and those if the project were undertaken. User surveys can be distributed to walkers and cyclists at a study site (e.g., survey forms can be
|
From page 187... ...
192 Table 7-5. Sample of factors to use in a modal quality analysis Issue Likely result As a result of this transportation project, traffic volumes are likely to: Increase Decrease Stay the same As a result of this transportation project, the number of pedestrian facilities surrounding the facility is likely to: Increase Decrease Not change As a result of this transportation project, the quality of pedestrian facilities (e.g., number of cracks or potholes)
|
From page 188... ...
. A crucial part of this analysis involves identifying specific problems that travelers encounter when walking and cycling, such as streets with inadequate sidewalks, roads with inadequate curb lane widths or shoulders, and dangerous railroad crossings.
|
From page 189... ...
When to use. In many circumstances, travel surveys can be improved to provide better information on travel demand for alternative modes, on travel requirements of transportationdisadvantaged groups, and on functional barriers to the use of alternative transportation.
|
From page 190... ...
in the area; • Survey data concerning the demand for transportation alternatives by the different groups (i.e., the types of modal attributes they find desirable and within their reach) ; • Survey data on the current quality of alternative modes and on the barriers that different user groups encounter, such as poor pedestrian conditions or inconvenient transit access; and • Analysis of survey data that can evaluate how a particular change in the transportation network would affect alternative modes and their use, especially by protected populations.
|
From page 191... ...
Smaller analysis zones were created, and various demographic and transportation system factors that affect nonmotorized travel behavior were incorporated into the model. This article should be useful to planners and modelers who might want to incorporate nonmotorized travel into a conventional traffic model.
|
From page 192... ...
1995. "Activity-Based Modeling System for Travel Demand Forecasting: Travel Model Improvement Program." Washington, DC: U.S.
|
From page 193... ...
198 Richardson, A
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.