I. SummaryThis report summarizes the presentations and discussions at a Peer Exchange held through the FHWA/FTA Transportation Planning Capacity Building (TPCB) Program. The peer exchange was organized by the American Association of State Highway and Transportation Officials (AASHTO) Standing Committee on Planning (SCOP) Census Data Workgroup chaired by Jonette Kreideweis (Minnesota DOT). Attendees were from AASHTO, state departments of transportation, metropolitan planning organizations and councils of government, universities, Census Bureau, the United States Department of Transportation, and the private sector. Following the keynote addresses, issue-specific sessions were held in which multiple presenters gave short presentations and all participants joined in discussion. Twenty—one presentations are posted at ftp://ftp.camsys.com/clientsupport/CTPPdata/Daytona_peer/ II. BackgroundTransportation planners and analysts are making or contemplating a transition from using data from the decennial Census "long form" to the new American Community Survey (ACS). The Census Bureau released the first round of data from the 2005 ACS in the fall of 2006. In October 2006, the AASHTO SCOP Census Data Workgroup secured support for continuing the Census Transportation Planning Products (CTPP) concept using a consolidated purchase. The Peer Exchange presented an opportunity to share emerging practices and discuss issues and challenges in applying and integrating ACS data into transportation planning activities. States, MPOs and universities are independently beginning to use the ACS data and develop analytic tools using the ACS The Peer Exchange provided a platform for sharing information, documenting practices and issues, discussing plans for the future CTPP, and exploring how to help inform the larger transportation planning community. III. Key Findings from the Peer ExchangeThere is a Strong Demand for Transportation Data Products from ACS The CTPP 2000 is widely used in the transportation planning community and beyond. Distinguishing characteristics are that the sample size is large (relative to local surveys), response rates are high due to the requirements to participate in the census, and it is one of the best sources for trip distribution data (data on the origins and destination of work trips). The national availability of the CTPP 2000 enables professionals to become familiar with it and use it in various locations. As a nationally collected data source it has the benefit of having high credibility and professional oversight in its development and supporting resource and training materials. To date, once the States and MPOs paid for CTPP, there have not been additional fees charge to other users. This has enabled local planners to avoid the time and cost of new primary data collection. There is Strong Support for Transportation Data Products from ACS For the reasons cited above, there is strong interest in having a CTPP product from (or using) the ACS. While the sample size will be different there remains a desire to have this standardized national resource to support transportation planning. States, MPOs and universities are independently beginning to use the ACS data and develop analytic tools that rely on ACS. The Peer Exchange provided a platform for sharing information, documenting practices and issues, discussing plans for the future data products. Uncertainty has Surrounded Transportation Data Products from ACS Several factors have collectively resulted in a great deal of uncertainty in the planning community regarding the ACS and the prospect of transportation data tabulated from it. These uncertainties have been exacerbated by larger uncertainties regarding several federal level data collection initiatives. Funding for the ACS has regularly been uncertain clouding expectations. In addition, funding for the next National Household Travel Survey (NHTS) has been uncertain. Thus, practitioners have been faced with a confusing and unsettling picture regarding the availability of transportation planning data from federal sources and the ability to validate, fuse, merge, or substitute various data resources as details on their timing, quality and features evolve. Understanding the American Community Survey The planning profession is in the early stages of understanding the nature of the potential applications of the ACS. Some of the uncertainty is simply due to busy professionals not yet being aware while other uncertainty stems from limited disclosure or dissemination of important aspects of the planned future data products. Other issues involve the release and usability of the data. To date, the only data released has been for areas with 65,000 residents or more. This has left many areas with partial data and planners left 'waiting" for the rest of the data. Remaining questions include:
ACS as a Source of Zone-to-Zone Flow Data One of the unique characteristics of the CTPP 2000 was its value for understanding local work trip distribution. This application has no readily available alternative data source. Trip distribution is relatively stable over time thus enabling older CTPP data to retain value. Flow data is fundamental to calibrating regional models so has relevance to roadway and transit modes for major regional and corridor planning. Sample sizes for local survey are too small to substitute for this purpose. The smaller ACS sample and data suppression raise concerns about the availability of flow data for smaller geographies. The zone to zone flow tables, preferably by mode, provide the greatest challenge for survey data in terms of ensuring adequate sample size. One potential alternative worth examination for small area home-to-work flow data is the Longitudinal Employer-Household Dynamics (LEHD) On-The-Map data produced being developed by the U.S. Census Bureau and funded by the US Department of Labor. This project synthesizes "home-to-work" flows using federal and State administrative records. The potential for fusing LEHD On-The-Map data with ACS data that includes travel mode and time and other household characteristics could be used to develop a richer understanding of trip distribution. This might enable analysts to better understand and model home to work distributions thus reducing the need for location specific zone flow data on a recurring basis. ACS and Transit Transit is fundamentally different than the auto mode. It is typically involves a walk access/egress mode and thus significantly benefits from small scale geographies for planning data. Also, since transit use is modest, it requires a very larger general population sample to produce a sufficient number of transit passenger responses. These traits influence the transit applications of ACS, as well as the applications for bike and walk modes. As small area ACS data becomes available there may be more use by transit planners. Transit continues to benefit from the role of ACS data in regional and corridor model validation/calibration for major investment studies and ACS may be of future value in updating zonal socio-demographic characteristics that can support service planning. The ACS also supports general policy research and planning that can impact transit. The annual updating of the data can benefit transit particularly in dynamic fast growth/change areas. The ACS use of the "usual mode" versus "actual mode" requires caution when using the ACS transit mode data. Administrative Issues Through the course of the exchange a variety of questions arose regarding numerous aspects of the ACS and future CTPP data products. The diverse conference participation list exemplified one of the challenges of producing, refining, disseminating ACS data products and research. Building the CTPP around the ACS is a collaborative initiative with a broad base of participants that exemplifies the value of these products; however, this array of participants also clouds the responsibilities and creates uncertainty regarding roles and responsibilities. This, combined with other uncertainties referenced previously, has left most users with a very modest level of understanding of what products, training, research, and other resources will be available to support their application of ACS and any CTPP data products. Absent a clear institutional or legislative mandate, initiatives of concerned individuals and institutions in a somewhat ad hoc fashion have been responsible for the very important progress to date. While this partnership arrangement may be a necessary feature going forward, efforts to define roles and responsibilities and to communicate what is being done will be of great value to the user community as we continue through this transitional period. Communications strategies, outreach mechanisms, training priorities, scheduling release dates, opportunities for input, redefining geography, and developing consensus on data formats are all issues that will benefit from collaborative input but will also benefit from coordinated communications amongst entities. This situation clearly highlights the need for an ongoing partnership commitment from the states, MPOs, regions, US DOT and AASHTO. This partnership should serve as the forum for coordination of actions and decisions and as a means of assuring communications between the partners. Evolution of ACS and Integration with Other Data Sources Increased computing power, growing use of micro simulation, a growing interest in the transportation land use interface, interest in bike pedestrian and transit competitiveness, and the prospects for funding and impact assessment at the small zone or parcel level of detail all support the evolution to more micro scale planning and analysis. As these trends continue there will be increasing interest in utilizing the ACS in conjunction with other data sources to provide the small area data necessary to support transportation planning. Additional research and applications experiences will need to be developed and shared with planning community. Resources to support the ongoing evolution of ACS applications will extend its value and support the planning community. Training/Capacity Building with ACS While mentioned previously, it is critical to emphasize the importance of the ongoing need for resources to support training on ACS use. To leverage available resources, web-based products may be useful to complement hands-on training and technical support. Coupled with training and capacity building, the user community has enjoyed the benefits of "on-demand" technical support with CTPP 2000. Given the evolving nature of the ACS and a potentially steep learning curve for the user community, this aspect can not be lost. Many times when planners are looking for help with the data they are trying to respond to a time sensitive issue, where critical policy decisions will be made with or with out the adequate data. How quickly, professionally, and with substantive information the analyst can respond can make a difference. Framing and Communicating ACS results The ACS has a range of applications from input to broad national policy deliberations to its application for small area technical modeling. Each of these applications places different demands on the data and requires the users to consider different tactics to ensure valid and meaningful application. It's important that users understand different applications have different requirements in terms of accuracy and precision. The user should exercise caution in application of the data and can benefit from relying on multiple data sources, multiple analysis methods and integration of finding with strong theoretical and anecdotal linkages to the topical issue being addressed. Next Steps in Securing Transportation Data Products from ACS AASHTO is now in the process establishing a CTPP Review Board to guide the development of transportation data products from ACS. To ameliorate the administrative challenges of coordinating this multi-stakeholder initiative will require establishment of a consensus work program including specification of necessary tasks (including technical tasks, coordination, research, communications, training, etc.), prioritization, identification of critical dates and deadlines, assignment of responsibility, establishment of communications protocols, and staffing for execution. This work plan can then serve as the basis for subsequent interactions between the stakeholders in this important initiative. ACS is Part of the Knowledge Foundation for Sound Planning and Policy Analysis While there are many opportunities to enhance and improve the ACS products and their applications, this data source remains critical to transportation planning. The costs for this data are increasingly modest in contrast to infrastructure costs that have risen dramatically. The need for well informed decisions is even more critical in an era of tight resources. While there are shortcomings of the ACS, as the old saying goes, "One should not let the pursuit of perfection stand in the way of progress." IV. Day One: Keynote AddressesRon McCready introduced the agenda, and welcomed the participants. He thanked Jonette Kreideweis (MN DOT) for organizing the peer exchange, and for her advocacy of transportation data issues. Ron mentioned that the CTPP Consolidated Purchase for potential CTPP like products from ACS is a focus area for AASHTO. Ron distributed "draft" pre-publication copies of NCHRP 08-48 "ACS Guidebook" A. Challenges and Opportunities in Using ACS Data Dr. MacDonald provided an overview of both the challenges and opportunities that the ACS presents for transportation planners, stressing throughout the need to educate and inform the public and decision makers. She said that the ACS represents a major reengineering of information infrastructure, and as such offers many opportunities along with challenges.
Challenges:
Some concepts have changed fundamentally from the decennial Census. Data users will be tempted to use year-to-year releases to track trends, but it is important to understand that those estimates come with associated standard errors. One area of particular concern is the additional attention needed to handle media enquiries. ACS data could easily end-up being used spuriously when the underlying concepts are not understood. It is important to be ready to explain to decision makers that apples-to-apples comparisons will not be possible for some time. It is important to compare like to like when working with jurisdictions of different sizes - a large metropolitan area may have smaller standard errors associated with the data than a smaller sized area. Opportunities:
The ACS offers opportunities for improvement, if it is used carefully. Dr. MacDonald offered the following advice:
B. Al's Top Ten Tidbits from Commuting in America 3 and the ACS Mr. Pisarski posed a series of questions related to commuting to the audience regarding the "Top Ten Trends" identified in Commuting in America 3. He presented the metrics used to identify these trends. 10. Single-occupancy vehicle growth in share slows
9. Variable carpool & transit trends Between 1990 and 2000, the Northeast saw declines in carpooling and transit use, while the West saw increases.
8. African-American vehicle ownership surges
7. Immigrant role 6. Older workers
5. Extreme commutes
4. The "donut" metro
3. Continuing growth in working at home
2. Leaving home before 6am
1. Workers leaving home county to work
Most of the questions raised point to the need for continuing availability of data for national policy development. ACS data on commuting are going to be vital in order to continue answering these questions.
C. How Good It's Going To Be Mr. Ismart focused on the value of Census data and the CTPP in transportation planning and presented three examples from his own experience. He noted that for any project, he begins by searching for existing data, as the most expensive part of any planning project is the data collection. Avoiding primary data collection results in faster, less expensive projects. If Census data were not available, the projects presented would have been prohibitively expensive. He summed up by saying that despite the issues presented by Dr. MacDonald, the long form (Census or ACS) data are one of the most useful sources for urban transportation planning. Lewiston-Auburn Model Washington DC planning analysis New Hampshire statewide model and corridor study
Other applications
Principles to remember
D. Some Observations and Perspectives on Using ACS Data Dr. Polzin discussed the status of transportation data and provided advice on working with policymakers. Importance of Data Dr. Polzin emphasized the difference between data applications for modeling and for policy analysis by comparing them to criminal law and civil law. The former is more stringent and tests against the standard of removing all reasonable doubt, while the latter requires only a preponderance of evidence. Some projects that do not require much capital investment, but redeployment of existing resources (example: changing signal timing, neighborhood calming) require data that are "ball park" estimates, while the data required for defending a costly Capital Improvement Project (example: New Starts programs) will need much more precise data. In order to advance the state of the practice, planners must be assured of consistently available datasets and adequate resources for analysis and dissemination. Timely data is critical in an area such as Miami-Dade County, which is experiencing volatility in its population. There was net population growth, largely stemming from in-immigration, but at the same time a large number of existing residents moved out. There are pressures at work which both increase the demand for detail and precision; at the same time, there are pressures against this level of detail and precision, mostly due to confidentiality and privacy concerns.
Dr. Polzin pointed out discrepancies in popular perceptions of common transportation facts:
Transit observations
Communicating with policy makers
Making the case:
Discussion Questions for Keynote Speakers
V. Census Data Issues, Challenges and Successes—Case StudiesA. Population Estimates Chuck Purvis, Metropolitan Transportation Commission Mr. Purvis recommended papers from the July 2006 COPAFS Conference on Population Estimates: Meeting User Needs, (available online at http://members.aol.com/copafs/EstimatesIndex.html). He noted that many state demographers are trying to take a multi-pronged approach to using the "best of everything" from all of the sources out there today and suggested that attendees talk to their state demographer about what can be done to ensure the best population estimates possible. Greg Harper, U.S. Census Bureau At the county level, ACS results are controlled to Census estimates; this is not the case at the subcounty (eg: State-Place) level. At the place level, there are differences between ACS estimates, population estimates from CB, and local estimates. Many analysts have expressed concerns about the population estimate numbers. Mr. Harper pointed out that states can challenge these estimates. The challenge procedure is outlined at http://www.census.gov/popest/archives/challenges.html While estimates are not used for allocating Federal transportation funds, they are used for the Department of Housing and Urban Development's Community Development Block Grant program and many other Federal programs. Discussion
B. Demographic Indicators and Trends—Income, Race, Poverty Sharon Ju, Houston—Galveston Area Council (HGAC) Comments
Kristen Rohanna, San Diego Association of Governments (SANDAG) She attempted at several possible explanations for the discrepancy.
Resolutions: For the county and city of San Diego, SANDAG will apply the ACS rate of change for 2000-2005. For the other cities in the region, SANDAG will continue using its previous methodology and "start fresh" in 2010. Ms. Rohanna concluded by pointing to the usefulness of current data from ACS, even if they are inconsistent, quoting Jeff Tayman from the previous peer exchange in Irvine, CA that "Consistent lies are better than inconsistent truths." In the second example, SANDAG planners wanted to develop ACS based Quality of Life Indicators in a regional comprehensive plan baseline report. The indicators focused on household variables since group quarters were not included. Ms. Rohanna's dilemma was how to interpret these trends for non-statisticians, since the planners want to know, "did some variable go up or did it go down"? However, when using ACS data, it is critical to test whether or not results are statistically significant and provide the interpretive text. She also recommends presenting a simplified text along with the table or charts, so results will be read and understood. Xuan Liu, Southeast Michigan Council of Governments (SEMCOG)
Mr. Liu spoke forecasting household characteristics for the Detroit region. SEMCOG used micro simulation (UrbanSim) and a three step process. Step one is developing regional trends for controlling small area analysis and forecast, step two is synthesizing individual households, and step three is developing and running models. SEMCOG did not use 2005 ACS data. However, they compared ACS results to the modeling results to see the differences. As a result of this effort, SEMCOG analysts were able to forecast locations of population, households and jobs at various geographic levels for planning, land development, and evaluating policy consequences. Mr. Liu hopes to use the ACS for this process in the future. Participants were intrigued by thematic maps that exaggerated geography based on density of occurrence. For example, the following map presents exaggerating geographies with high concentrations of persons in poverty for 2000. Discussion
C. Workers and Employment Data
Nanda Srinivasan, Cambridge Systematics Inc. None of the primary sources give the same results due to differences in coverage, definitions, seasonality, and absenteeism. However, there is some overlap at an aggregate level. Mr. Srinivasan focused on two Federal sources of data: the CTPP JTW Flows, and the Longitudinal-Employer Household Dynamics (LEHD). Some examples from local research show that although LEHD is a promising source, there have been some systematic issues with the data. Local agencies must review LEHD data, particularly, locations of workers for state or federal agencies, before deciding to use it for planning applications.
Mr. Srinivasan pointed users to some ready-made profiles developed by the CTPP Technical Group. These profiles (posted at http://ctpp.transportation.org/) compare 1990, 2000, and 2005 data side-by-side, along with margins of error (MOEs) and significance tests. There are also some ready-made spreadsheets developed by the NY State Data Center that incorporate these formulas. Another resource for LEHD data is the LED on the map, an online mapping tool for LEHD data. Nathan Erlbaum, New York State Department of Transportation Mr. Erlbaum compared employment changes between 1990 and 2000 from different sources for New York State. Results varied widely, depending on the source. Differences in results between CTPP 2000, ES202 and Global Insight data at the county level are hard to explain, and comparisons between Global Insight and CTPP 2000 at the census place level are even more difficult to explain. These differences are also seen in the aggregate data and data across the industrial categories. One cause could be definitional issues: workers and industries are defined differently by different sources. The question on "who is a worker", jobs, establishment employment elicits different responses from different surveys: different counts of workers are obtained from Census, ACS, and the NHTS, simply by asking the work for pay or profit question in a different location on the survey form. In the NHTS this resulted in 1.5 million more workers. The NHTS found people who do not have jobs who get paid, and in other surveys, people who are "retired" report going "to work" but do not get paid. This difference between the transportation view and the respondent view of what it means to be a worker can be significant. Perhaps of greater concern is the accuracy of the industry coding. In some data sets it is clear that they are derived from the Standard Industry Classification and later translated to North American Industry Classification System creating another inconsistency of definition. He pointed out several data sources for local analysis, and said that given the differences across the various data sources, choosing the right source to address specific questions especially policy questions is very important. Of greater import is in understanding why they are different. He noted that most executive staff are not interested in the details. Mr. Erlbaum observed that the data analyst's role is to understand the problem they are working on and the audience for whom this information is needed. Then, one can give them appropriate information from the appropriate source. Mr. Erlbaum felt that the lack of work place surveys is a major data gap nationwide. He also felt that worker/establishment type data might benefit from different geographic tabulation geography than traditional TAZ used in travel demand models. Many discussants, who were predominately modelers however, felt that the TAZ, by definition, should be structured to separate areas of high residence, and high employment. TAZs should be created so as to reflect underlying land-use, and should separate out areas of residence from areas of predominantly commercial activity. Creating mixed use TAZs would cause several problems to existing travel models because the travel models have a need to minimize intra-zonal trips. Mr. Erlbaum felt that travel demand models were only one application of worker/employment data and meeting the needs of modelers might not be the best solution. Discussion
In the end, one has to be an educated "consumer" when using employment data. Each source of employment data is used for a different purpose and is structured slightly differently. D. Journey to work - travel time, mode split, flows, and model development Reporting Commute Time to Work: Metro Atlanta's Coweta County Experience Lessons learned:
The group discussed the need for the Census Bureau to do more internal quality control before releasing data.
Florida Transportation Modeling—Using CTPP and ACS Data In Florida, urban and regional modeling is decentralized to the FDOT districts and the MPOs. This is coordinated at the state level by Ms. Shen. FDOT uses a wide variety of methods to make the best of what data is available. Locally, CTPP 2000 was used for transit ridership modeling, for model validation, to address Environmental Justice issues, and for many other purposes. Ms. Shen noted that TAZ definition changes caused some areas to not be able to take advantage of CTPP and that timely data is needed to coincide with long-range transportation plan update cycles. For Florida, the ACS may offer opportunities to allow for inclusion of more demographic variables in travel demand models. Ms. Shen discussed Florida's expectations for an ACS-based CTPP product, including timing, user education, and updating the Florida Standard Urban Transportation Model Structure (FSUTMS) Standards:
Discussion
Virginia Transportation Planning—Using CTPP and ACS Data In the past, the CTPP has been primarily used in the large urban areas comprising the eastern part of the state, e.g., Northern Virginia, Richmond/Tri-Cities, and Hampton Roads. In travel demand modeling, the CTPP has been used to calibrate or validate Home Based Work (HBW) trips for the models in Northern Virginia, Richmond/Tri-Cities, Hampton Roads, and the statewide model. In the future, NHTS add-on data will be used to develop HBW trip purposes in the urban area models, but the CTPP and ACS will likely continue to be used by the statewide model. Additionally, the Virginia State Legislature recently created a new Multimodal Office, which among its other responsibilities, is charged with developing multimodal transportation performance measures to be used in statewide analysis. The Multimodal Office established a task force, which is developing the desired list performance measures and data sources that are available for this analysis. Initially travel demand models were used to support this effort, but there were too many differences between the different models to perform a statewide comparison. As a result, the task force looked into using other data sources including the CTPP, ACS, and NHTS. Efforts are underway to perform statewide comparisons of urban areas using CTPP and ACS data.
ACS Data Issues, Challenges and Model Development at the ARC ARC maintains both a classic four-step transportation demand model and an activity-based/tour-based model. ARC's Population Synthesizer (ARC PopSyn) uses Census data and ARC's land use model to create a synthetic population to feed the travel demand model. The travel demand model then predicts travel for this population. 2000 is the base year and validation is achieved by back-casting to 1990. There are some differences in how the base year and the forecast year are handled:
With the introduction of the ACS, the ARC will have to revisit the geography of the program, manipulate the standard tables, re-engineer the PopSyn, modify the forecast year, and revisit the validation. Inconsistencies in the 2000 Census PUMS data dictionary and the ACS PUMS data dictionary cause some coding issues. The ultimate goal is to create an ACS version of the population synthesizer and get to a point where data can be drawn from either the 2000 PUMS or the ACS PUMS. ARC hopes to eventually begin using ACS data for the controls, the seed distribution, and for the PUMS households that are drawn into the synthetic population. If the variable definitions themselves are different (ie, not just name differences) two versions of the PopSyn might be created. Discussion
E. Transit applications and New Start analysis Using the CTPP for Transit Applications & New Starts Analysis: Part I Federal Transit Administration New Starts analysis is an investment grade level decision. The models undergo rigorous scrutiny. To make the case for decision makers, FTA puts together a briefing sheet. Trip distribution is a major issue in transit planning because it defines potential corridors for transit investments. Work trips constitute 80 percent of benefits in New Starts programs. Validating work trips, especially during AM peak, is essential to replicate existing conditions. CTPP data help to validate these flows. The Census has much higher sample sizes than typical household surveys or on-board surveys and CTPP flows are available to the transit agency at "no additional" cost. On-board surveys are useful but the survey instruments commonly used need improvement. CTPP data are used in validating travel markets, in the Aggregate Rail Ridership Forecasting (ARRF) models, and in comparing employment data to land use. Travel patterns do not change as rapidly for transit, so data quality is of more interest than timeliness. CBD-orientation maps are used to display concentrated work-trip destinations - the CTPP flow data is compared to results from the model. The target level of geography for most of these validations is the block group or the TAZ, aggregated to corridors of interest. It would be helpful to have ACS data at the same level as for CTPP 2000.
Discussion
Aggregate Rail Ridership Forecasting Model (ARRF Model) One of the primary tasks of the FTA Office of Planning is to review New Starts and Small Starts applications. All models used are examined and compared with data from existing sources. Aggregate Rail Ridership Forecast (ARRF) is a sketch planning tool developed by FTA to support quality control testing of forecasts for new proposals. The inputs to AARF are GIS shape files for the rail line, underlying Census geography, and CTPP Part 3 flow data, income data at the home end (Part 1), and employment density data from CTPP, Part 2. The tool is used to provide a 'reality check' for areas which do not have fixed guideway transit currently. Rail ridership is estimated for different segments and different markets. Light rail and commuter rail ridership is analyzed separately using different thresholds. FTA encourages project sponsors to use the AARF model and compare with their model output. Mr. Islam can provide a copy of the model to interested parties (nazrul.islam@dot.gov).
Discussion: Transit Applications Using LED On-The-Map Data Mr. LaMothe reported that transit ridership has been increasing in the Twin Cities region. The region is expected to grow considerably over the next 25 years. Version 2 of LED On-The-Map is being rolled out. Minnesota was a pilot state for LED and Metro has been using it for service planning since August 2005. 44 states are participating for version 2. Because CTPP data are based on Census 2000, they cannot capture short term impacts of gas prices, suburbanization, etc. but are still used for long term planning. Metro Transit uses the LED for service planning, facility planning, system planning, and marketing. Examples include evaluating park-and-ride proposals, performing corridor studies, and identifying target areas for direct mail marketing on new routes. Metro has been using the data behind the tool. Limitations of the online tool for transit include the inability to buffer by a quarter-mile and to integrate other regional datasets. The data are used in Metro's GIS with an Access database. Mr. LaMothe is continually finding new applications for the LED for short-term and day to day planning. Local consultants, cities, and counties are being trained in using the data behind the online tool.
Discussion
F. Dealing with geography: challenges and opportunities Ms. Ju provided a brief overview of the various geographies in use at HGAC. Because TAZ size varies greatly from area to area, HGAC is considering using a gridcell for the TAZ in the future to be compatible with UrbanSim. There are currently 3,000 TAZs in the H-GAC area and there are plans to expand them to 5,000. The issue is for Census data and other data sources to keep up with developments in travel modeling. Guidelines for bringing data down to small geographies are needed. Some consultants have previously split larger geographies by area size alone, which is not necessarily a good idea.
ACS Data Release Schedule Mr. Christopher presented the release schedule for ACS data and highlighted potential changes in Census geographies and in data release rules. The three-year product will be available for areas with population of 20,000 or more. CTPP's first 3-year product will have to be based on Census 2000 geography such as place or PUMAs. New TAZs developed in 2008-2009 should be integrated into the first five-year release. While the three-year product will likely have actual flows, the five-year product may well have synthetic flows for cross-tabulations involving mode and income. The Census Bureau released a Federal Register notice on April 6, 2007 on the Participant Statistical Areas Program (PSAP). The FR outlines current plans to define tracts and block groups. Comments are due by July 5, 2007. The CB is contemplating changing the average size of a block group to an average of 1,200 residents, up from 300-600. Also, a housing unit count may used to set block group thresholds for the first time. This change is necessitated by the smaller sample size in ACS, and may allow for getting data at the block group level. Block groups may be becoming as big as or bigger than TAZs with this new definition. For CTPP, the CTPP Technical Group is considering development of three types of TAZs -
Discussions are in place with the Census Bureau on developing a TAZ geography program using a customized version of the PSAP software. The goal is for the Census Bureau to release draft tracts and block groups in 2009. The TAZs will be developed slightly behind the tract and block group definitions so that MPOs could address nesting their TAZ geographies with Census geography, if desired. MPO planning area boundaries are larger than urbanized areas as they are to include areas likely to become urbanized in the next twenty years. Mr. Christopher would like to incorporate these boundaries into TIGER. If these boundaries were added to TIGER, they could be used as a tabulation unit. A final issue for MPOs to note is the new Disclosure rules for ACS (See below).
Discussion
G. New CTPP Consolidated Purchase Ms. Oakley and Mr. McCready updated the group on the status of the CTPP consolidated purchase. Invoices are starting to go out to the states for the project. An oversight panel is being convened. AASHTO's Standing Committee on Planning (SCOP) Census Data Workgroup will be the primary motivator, and will oversee the effort. The AASHTO Board of Directors will provide fiduciary oversight. Ms. Oakley noted that CTPP should about more than just doing the tabulations. Rather, it should include a suite of programs which establish the capacity and capability among MPOs and states to "help themselves" and to provide the tools to advance the state of the practice in planning. There has been a great deal of emphasis on performance-based approaches and asset management and these have lead to an increased understanding of the importance of data. The consolidated purchase is an opportunity to develop and institutionalize the program. There is also a possibility of extending the success of this program to other opportunities in planning and modeling data beyond the Census. SCOP may try to strategize about how a broader program might be developed. Ron McCready noted that the existing relationship with TRB is a strong asset. Through the consolidated purchase, the NCHRP regular research projects and quick-response research through NCHRP Project 8-36, and other avenues, AASHTO is in a position to carry out research to complement CTPP effort. A topic for future discussion is that there may be a way to better share the costs with those outside of the pooled fund community and to take that revenue and put it back into the project.
Discussion
CTPP training
Data and Delivery
Research
VI. Summary RemarksSteve Polzin, University of South Florida Center for Urban Transportation ResearchDr. Polzin hoped that the appreciation for data is growing. He noted that Walmart reports weekly sales and revenues from across all its locations worldwide by Sunday evening, while the transportation community often is forced to make decisions on capital improvements based on very limited data that is years old. Pedestrian, bike, transit have inherently different data needs than the motor vehicle. Flow data is the most critical constraint in terms of data quality. There are still administrative issues to resolve - communications, training, release dates, opportunities for input, redefining geography, developing consensus on data formats etc. These are all solvable problems. However, the element of research is an issue that often gets ignored. Big picture issues include the continuity of funding for ongoing research and technical transfer. Traditionally there has been a lack of continuity of support and technical training because of the 10 year cycle in decennial Census. It is not always clear who has which of these responsibilities, although, he favored national "centralized" technical support and training. The tendency towards precision and accuracy is increasing. We need more and better communications, training, and information dissemination. There are opportunities to involve the private sector, especially big data houses and modeling groups. Finally, meeting once a year may not be enough to resolve all these issues, we may need to develop a continuing dialog via webinars or other means.
VII. For More InformationThe CTPP website, located at http://www.fhwa.dot.gov/ctpp/, provides CTPP products, updated information on CTPP, and links to other online resources for transportation planners. Other ways to get CTPP help are to call 202-366-5000 or email ctpp@dot.gov.
VIII. Attendees
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