Participatory Transportation Equity Mapping

Tong Zhang #1, Jiasong Zhu *, Peng Mu$, Shufang Liu@

#
State Key Laboratory for Information Engineering in Surveying, Mapping and Remote Sensing
Wuhan University, China 430079
1
geogrid@gmail.com
*
Department of Traffic Engineering, Faculty of Civil Engineering, Shenzhen University
Shenzhen, China 518060
$
Wuhan Gaoao Network Technology Co., Ltd. Wuhan, China 430080
@
Department of Geography, University of South Carolina, Columbia, SC, U.S. 29208

Abstract—Transportation equity maps are essential for People-based accessibility measures may complement to
allocating limited public resources to achieve social equity. place-based accessibility measures as complexities can be
Transportation equity mapping uses accessibility as a primary captured by disaggregate measurement of individual’s
indicator to measure inequity in a region. Traditional place-
based accessibility measures can not offer fine-grained
accessibility [4]. Many factors can affect access such as age
information to describe socio-economic characteristics and travelgender, employment status and socio-economic status, both of
patterns individually. People-base accessibility measurements which vary by individuals. People living in the same
are capable of revealing inequity more accurately. Participatory neighborhood may have different travel patterns with various
GIS can enable every citizen to make contributions to equity transportation modes. Additionally, people tend to be
mapping and express particular concerns about transportation concerned about a limited number of places they regularly
inequality. This paper introduces a new approach to adopt web- visit rather than all areas. These places of interests have to be
based participatory GIS techniques for transportation equity collected at individual level. The computation of travel cost
mapping. A preliminary research prototype is presented to assumes people travel at the same speed without considering
demonstrate the feasibility and effectiveness of the participatory
equity mapping approach.
traffic situations.
While high resolution geographic data and demographic
I. INTRODUCTION data are available, fine-grained human activity data are
extremely difficult to collect at large-scale, for example, a city
An equitable transportation system must deliver reliable
with 100,000 residents. To reduce data collection cost, web-
and affordable services to disadvantaged people.
based activity diary survey tools have been developed and
Transportation equity is a key aspect in transportation
used to support activity-based modeling [5]. We can then
planning since the allocation of public resources must address
adopt the idea of web-based survey to design and develop
the needs for those groups that have been discriminated
participatory transportation equity mapping systems.
against (or underserved) by current transportation systems.
Participatory equity mapping is fundamentally a Public
The equity principle has been reflected in many civil rights
Participation GISystems (PPGIS). PPGIS is a platform for
legislations as well as transportation laws. Legislations and
regular citizens to participate in spatial decision making.
regulations require that transportation planning activities must
PPGIS try to empower those marginalized groups and citizens
take into account equity issues in metropolitan transportation
with GIS technologies in the context of public involvement in
plans and transportation improvement programs. Equity
community-based decision making [6]. This paper proposes a
mapping is an intuitive visual form to represent transportation
new participatory approach for transportation equity mapping.
resource distribution across the space. Equity maps are
Web-based PPGIS tools can be used to harvest high resolution
powerful tools not only for planners in guiding their planning
geo-referenced activity data. The accuracy and reliability for
activities [1], but also for advocates to voice discriminatory
equity mapping is thus assured. The approach is partially
facts for socially and economically disadvantaged populations.
implemented in a preliminary transportation equity mapping
Equity mapping is essentially access mapping. Varying
prototype in which the advantages of high resolution activity-
levels of access, when visualized, reveal people’s abilities to
based accessibility are demonstrated.
reach desired locations to perform specific errands. Since
accessibility is the core of equity mapping, research can be II. TRANSPORTATION EQUITY AND EQUITY MAPPING
directed to accessibility measurement and representation. In
addition to traditional accessibility measurement metrics Major issues for transportation equity evaluation include
development, numerous studies have been conducted on the the lack of widely accepted definition and standard analysis
topic of measuring accessibility by means of geographic procedures of equity, the difficulty to select appropriate
information systems (GISystems) [2][3]. However, aggregate accessibility measures, high cost of data collection, the
accessibility has been criticized due to its weakness of challenge to achieve consensus among stakeholders, and the
problem of efficient equity computation and visualization. The
overlooking space and time constraints at individual level.
_____________________________ interdisciplinary nature of equity research results in disparities
978-1-4244-4158-7/09/$25.00 ©2009 IEEE


in equity evaluation practices. The analysis and evaluation of further reveal the relationship between equity, access and
equity must first clarify the underpinning conception of equity. associated socio-economic characteristics. This may help
Planners should identify in what context to pursuit equitable decision makers to achieve deep understanding of underlying
distribution of public resources. Equity among individuals is a reasons of inequality.
choice as every citizen is supposed to be treated equal in terms Advanced analysis usually is performed by means of
of public benefit distribution. Space-based equity is applicable specifically developed models or statistical tools.
when equitable distribution among space is achieved. Need- Traditionally, the most popular practice was to adopt a
based equity [7] seems to be more appropriate since loosely-coupled approach that links GISystems with
disadvantaged populations should be compensated with extra statistical/analysis models via data exchange. Talen [1] used
resources. Similarly, population groups that explicitly voice ArcView and SpaceStat to investigate assess inequality for
demands may claim for demand-based equity. park planning. She contends that equity mapping is essentially
Access is a primary indicator to measure spatial equity. an interactive exploratory data analysis process. Multivariate
However, in contrast to mobility, accessibility is a relatively spatial analysis can derive hidden correlations between equity
vague and complex concept. The selection of suitable measurement and various characteristics of populations and
measurement metrics appears to be a critical problem. facilities (attractiveness). The entire workflow is
Corresponding to various accessibility measures, in particular, fundamentally iterative and interactive. Planners, upon
people-based and space-time measurement requires extensive interpretation and evaluation of equity maps, can return to
data to perform effective analysis. High-level aggregate change access measures to produce more effective equity
accessibility analysis is inadequate to describe heterogeneity visualization.
of transportation preferences and socio-economic status within A few accessibility analysis studies have adopted integrated
a neighborhood, or even a household and to capture the GIS tools that integrate both visualization and analysis into a
sensitivity of measures given detailed data. The tasks to stand-alone system. Liu and Zhu [3] demonstrate their
collect high spatial and temporal resolution data, including “ACCESS” tool for accessibility analysis. Therefore, data
infrastructure data, census data and activity data, if at exploration, access measure selection, access measurement
disaggregate levels, would be extremely demanding. As the computation, and accessibility interpretation and analysis can
conception of equity is diverse, different population groups or be conducted in a united user interface without troublesome
stakeholders may perceive equity from different perspectives. data exchange. Obviously, data are critical for both
As a result, the evaluation, the representation, and the approaches. In particular, the collection of low-level geo-
interpretation of spatial equity may not be able to reach referenced census data and activity data are extremely time-
consensus easily. consuming. If using people-based space-time access measures,
Finally, if exploring equity issues into disaggregate levels, planners must either conduct a comprehensive travel survey or
planners confront intensive computation challenges due to the collect old survey data before any mapping and analysis can
vast amount of data and the complexity of accessibility be done. Travel survey data have the issue of incomplete
models. Both the data and model complexity produces representation and low coverage. Besides, most survey data, if
understanding barriers for effective visualization for planners collected long time ago, could not reflect current situation.
and regular citizens who lack professional GIS training. It is Also, individuals should be granted freedom to choose their
challenging to strike a balance between information desired access measures, visualization and analysis tools. The
complexity and visualization effectiveness in accessibility rising issues here call for more extensive public participation
mapping and equity analysis. In response to these issues, we in access and equity mapping.
call for more public involvement and more active discourse,
negotiation and collaboration to reduce data collection efforts, III. PARTICIPATORY TRANSPORTATION EQUITY MAPPING
to promote mutual understanding among stakeholders, and to Traditionally, GIS-based equity mapping goes through
encourage interactive data exploration and visualization. multiple steps: data collection, data preparation, access
Research on accessibility measurement has proliferated measure metric selection, access measurement computation,
during the past several decades. Maps and GISystems have and visualization. Typically, planners are in charge of the
been widely used to present accessibility analysis results. entire process. User information such as socio-economic
However, the embrace of Geovisualization in equity planning characteristics, opinion and preference is only presented in the
is relatively new and primitive [1]. At least two categories of data collection step. Planners that operate on the data are
data must be collected to enable equity mapping: GIS usually ignorant of local fine-grained traffic and census
fundamental data (road networks, public service locations and information.
attributes), and census data (population characteristics). The
computation of space-time measures needs activity and space- A. A New Approach
time constraint data. Equity maps have two roles to play in We propose a participatory transportation equity
transportation planning: representation and explanation. In mapping approach in which regular citizens will play a
addition, equity mapping can go beyond simple visualization major role in producing equity maps for their own
of equity patterns over space, time and people. By means of community and contribute to access analysis for the
exploratory data analysis techniques, equity mapping can whole region by aggregating individual accessibility.


The new approach adopts PPGIS techniques and community or within similar socio-economic groups) thus
encourages virtually anyone who can access the Internet they can utilize maps as visual evident for direct and fast
to participate in equity mapping. People can use discourse.
interactive maps to input personal and household travel B. A Technical Framework
information such as employment types, commute routes, Obviously, a participatory transportation equity mapping
time and expenditures, income, travel habits, travel (PTEM) system must be web-based to allow for Internet
modes and major travel origins and destinations. Using access and participation. A variety of participatory tools can
intuitive graphic user interfaces, participants can directly be deployed on the Internet at different participation levels (or
provide the most update travel survey data. More on a participation ladder) [8]. Both planners and public
importantly, travel origins, destinations or even travel participants should be provided with various mapping,
routes can be marked on the maps. Based on PPGIS, analysis, and planning tools to enable extensive public
participants can also visualize their space/time involvement and effective collaboration between planners and
constraints on the map. participants. According to Figure 2, the entire technical
framework can be roughly divided into two components: one
for planners and one for public participants. Public
participants primarily generate personalized people-based
equity maps while planners produce regional place-based
equity maps. Both of them can access planning, Exploratory
Spatial Data Analysis (ESDA), access measure and mapping
tools. At the core of the entire system are the interactive maps
that are the basis of all tools and other components such as
online forum, online registration, and map-based survey tools.

Fig. 1. Participatory equity mapping workflow

Figure 1 shows a participatory equity mapping workflow.

Participants can provide up-to-date activity, census and
attractiveness data. They can even report GIS fundamental
data problems such as errors and incompleteness. Public Fig. 2. A technical framework for participatory transportation equity mapping
participants, upon the completeness of data input, can produce Participatory equity mapping workflow
personalized equity maps. Then they can utilize integrated
access analysis tools to conduct exploratory data analysis and
evaluation. When more and more participants contribute to Using mapping tools, participants can sketch out their
data collection, aggregate accessibility maps for blocks, travel habits in a visual form. Regular travel routes, critical
communities, or even a city, a region can be created. We can attractive places, common travel origins and destinations,
build two types of aggregate regional place-based accessibility along with associated attributes such as activity durations,
maps: one is totally relying on the aggregation of actual frequency, and time allocation, can be obtained intuitively.
participatory data; the other regards available participants as Access measures, upon user’s request, can be selected to
samples from the whole population and compute estimated calculate either people-based or place-based access values for
aggregate accessibility maps based on census data. Regional specific people or areas. ESDA tools, including coordinated
accessibility maps then can be evaluated and analyzed by multiple views, interactive choropleth maps for social-
planners who can also explore into individual accessibility economic and other characteristics, interactive statistical
maps for more information. While regional accessibility maps graphs, can significantly facilitate the exploration of inequity
can be used for transportation planning purposes, personalized among population groups and areas. Planning tools can enable
accessibility maps can be useful for local residents as well. both participants and planners to create a what-if scenario in
For example, when a new resident moves in, she/he can which new transportation facilities are added or old facilities
follow the same process to create her/his own personal are removed from current transportation infrastructure. Then
accessibility maps and examine travel habits of neighborhood new equity maps would be created to examine the effects of
residents. Certainly, participants can evaluate regional place- proposed planning activities.
based accessibility maps to identify any inequity and similar Normally, a participant needs to register before her/his
transportation-disadvantaged residents (either living in same involvement. Registration will ask for some basic personal
questions such as home and work locations, household, travel


modes. These questions can be answered on interactive maps.
Map-based survey then can be conducted to solicit in-depth
information of travel habits and socio-economic status. Online
forum support both synchronous and asynchronous Fig. 4. Drawing tools
communications to support sharing views and information
among participants. They can use forums to identify other As we have argued, personalized equity maps are
participants with similar transportation disadvantaged issues influenced by many factors such as attractiveness, differences
or similar views. They can organize to voice their concerns, within household and between individuals, conception about
needs and demands. Planners can work as travel cost. By means of the PTEM tool, everyone can directly
coordinators/facilitators to promote and direct efficient public input and visualize her/his own transportation access for
discussion. From registration, survey, online discussion, various activities. Integrated forums can enable direct and fast
through mapping, analysis, to planning, it can become a ladder discourse for citizens. Compared to place-based access maps
for public participation in equity analysis. (Fig. 5), users can customized personalized access maps and
visualize their access capabilities in road networks. Figure 6
IV. PROTOTYPE
presents potential accessible roads from a hypothetical home
Based on the technical framework proposed in the last at the time interval of two minutes.
section, we devise an implementation solution to develop an
applicable plan for a web-based participatory transportation
equity mapping system. Since public participants and planners
(there may be other users) require different functions,
interfaces, and privileges to manipulate data and information,
plus privacy issues, security is a serious concern for
participatory equity mapping. User with specific roles may
access specific functions via specifically customized
interfaces. Role-based access control and single sign-on Fig. 5. Place-based access map
authentication mechanisms can ensure that only authorized
users can access sensitive data and tools. Google Map API,
due to its simplicity is selected as the basic mapping template.
Based on Google Maps, we can develop interactive drawing,
editing, exploratory analysis, choropleth mapping, and
labeling tools to support personalized mapping, planning and
collaboration using JavaScript and shp2text tool. An open
source online forum system, JForum, can be adopted to enable
online map-based registration, survey and discussion when
integrated with Google Maps and JavaScript. Fig. 6. People-based access map

Individual people-based access maps can capture

heterogeneity in travel patterns as users can modify their
destinations, their preferences, and their activity constraints to
create dynamic access maps. They are simply working as a
map-based travel survey. Although aggregated (people-based)
equity maps can still reveal some spatial equity patterns (e.g.
Fig. 5 shows that areas north to the San Diego zoo is the most
accessible area in San Diego County), they tend to ignore
individual needs while individual equity maps can help reveal
Fig. 3. The PTEM prototype the inequity more accurately. Participatory approach can
enable citizens to voice their needs and concerns fast and
Figure 3 shows the interface of a web-based participatory effectively. Our PTEM system can also incorporate ESDA
equity mapping tool. We combine Google Maps APIs with tools to perform interactive spatial data analysis of related
JForum to deliver flexible user participation and interaction socio-economic characteristics to support better public
functions for equity mapping. Users can register to use participation.
interactive mapping and discourse tools to create personalized
V. CONCLUSION
equity maps. Figure 4 shows a few common mapping tools
allowing quick and easy drawing of point, lines, polygons and This paper introduces a new approach to construct
circles. Users can also add annotations to new objects they transportation equity maps using PPGIS techniques.
create. Participatory equity mapping enables regular citizens to voice


their needs through interactive maps. PPGIS provides an
easily accessible platform for public participant to exchange
views and concerns. Additionally, map-based public
participation can encourage and stimulate dialogues and
discussion by visual languages. The regression of the
participation ladder can be implemented in a web-based
participatory transportation equity mapping using widely
accessible technologies and tools. Future research may
address above-mentioned usability, privacy, and bias issues.
To conclude, we contend that equity maps for the people
should be made by the people.

ACKNOWLEDGMENT
This research was jointly supported by National Natural
Science Foundation of China (No. 40830530, No. 60872132),
and the Open Research Fund of State Key Laboratory of
Information Engineering in Surveying, Mapping and Remote
Sensing, Wuhan University (No. 09P01).

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