County-to-County Worker Flow Map Journeys To and From Hampden MA

County Sub-Divisions

Journeys To and From HAMPDEN MA (Threshold = 50) County # County A State County B Journeys from A to B Journeys from A to B % of Total Journeys from B to A Journeys from B to A %of Total 3 HARTFOR D CT CT HAMPDEN MA 4, %17, % 13 TOLLAND CT CT HAMPDEN MA 1, %1, % 13 MA 165, %165, % 15 HAMPSHIR E MA MA HAMPDEN MA 21, %9, % 27 WORCEST ER MA MA HAMPDEN MA 2, %3, % 11 FRANKLIN MA MA HAMPDEN MA 1, % % 3 BERKSHIR E MA MA HAMPDEN MA % % 17 MIDDLESE X MA MA HAMPDEN MA % % Villanova University Department of Civil and Environmental Engineering

ABSTRACT The Census Bureau is planning to replace the Census Long Form that is distributed during the decennial census to 1/6 households with the American Community Survey, a continuous survey intended to sample the same number of households over a five- year period. The USDOT and other agencies are concerned that the sampling errors may outweigh the benefits of more frequent data. By looking at the microdata collected during an ACS “test” in Springfield, MA, this project is looking at seasonality and other data issues related to the transportation variables. Acknowledgements:  This research is funded by Federal Highway Administration (Elaine Murakami, Census Transportation Planning Package) Villanova University Department of Civil and Environmental Engineering

American Community Survey  Replacement of the census long form (CLF)  CLF reached 17% of households; ACS will try to reach 3% of all HH per year  Annual release of data for areas over 65,000  Three year release for areas over 20,000  Five year release for other areas  Currently, 34 three-year test sites  Mail-back survey; no marketing with some phone and in person follow-up to non-respondents  Concerns over low response rates from minorities and low incomes Villanova University Department of Civil and Environmental Engineering

Desirable Transportation Data  Similar to current census long form  Direct transportation data  Travel time to work and place of work  Means of transportation to work  Departure time from home for work Seasonality Concerns  Travel times, mode choices, departure times may change by season  Some areas have changing populations Villanova University Department of Civil and Environmental Engineering

Continuous Advantages  Data isn’t twelve years old  You can argue that larger areas (with larger data and planning needs) will get acceptable data every year or three years (still with two-year lag, possibly)  Seasonal data: capture more bike and walk trips; capture different times leaving for work Villanova University Department of Civil and Environmental Engineering

Continuous Disadvantages  DISCLOSURE—getting enough data for transportation uses  Aggregation of five year data  Error may propagate over five years  One planning agency uses data; another using data may lead to different baselines  Worries about continuous congressional funding  Unexpected costs per completed interview may lead to longer data accumulation periods or only voluntary data Villanova University Department of Civil and Environmental Engineering

1999 and 2000 ACS data from Springfield, MA Villanova University Department of Civil and Environmental Engineering

Rough “Look” at the Data (I)  Approximately people per year (6000 households)—5%  50% in Springfield, 50% in Hampden County  Approximately 6300/6400 work (45%)?  Journey to work data for 97% of these (some work at home)  Live in 14 census-defined “places”. Work in 114. Villanova University Department of Civil and Environmental Engineering

Rough “Look” at the Data (II)  Enough to give us some causes for concern  Aggregate all Februarys? Aggregate all “winter”? Is winter, Dec, Jan, Feb or Jan, Feb, March?  Are year to year differences “real” or caused by sample errors? Month to month differences?  Date issues: 27-32% of surveys are initially started 1-3 months before they are received and journey to work Qs are towards the end of the questionnaire  Rough differences in number of observations year to year from the same census tracts  Are census-provided “person-weights” helpful? Villanova University Department of Civil and Environmental Engineering

“Closer Look” Example [B us riders to place “123” (~75% of transit trips)]  1999: 53 morning peak worker riders (2-8 observations per month)  Unweighted and weighted travel time varies from minutes (after deleting obvious outliers)  2000: 38 morning peak worker riders (1-8 observations per month)  Unweighted travel time varies from mins  Weighted travel time varies from  No discernable seasonal patterns or year-to- year comparisons Villanova University Department of Civil and Environmental Engineering

Conclusions  Month to Month differences in some transportation variables  Sampling differences across geographies and people suggest by aggregation Future  Statistical tests: ANOVA, Bonferroni, paired t-tests, etc.  Hopefully other researchers are addressing the “how to aggregate ACS data” issues  NCHRP study 08-48: Using American Community Survey Data for Transportation Planning—a guidebook will result