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Seasonality of Transportation Data

Figure 9

The journey to work departure times separated by income quartiles are found in Figures 9a through 9d. Respondents with the lowest incomes left for work later than respondents in the second, third and high income quartiles. Respondents in the second quartile left for work both above and below the monthly mean departure time values. Respondents in the third and fourth quartiles left for work earlier than the mean in most cases.

FIGURE 9a - Low Income Departure Times to Work

The journey to work departure times separated by income quartiles are found in Figures 9a through 9d. Respondents with the lowest incomes left for work later than respondents in the second, third and high income quartiles. Respondents in the second quartile left for work both above and below the monthly mean departure time values. Respondents in the third and fourth quartiles left for work earlier than the mean in most cases.

FIGURE 9b - Second Quartile Departure Times to Work

The journey to work departure times separated by income quartiles are found in Figures 9a through 9d. Respondents with the lowest incomes left for work later than respondents in the second, third and high income quartiles. Respondents in the second quartile left for work both above and below the monthly mean departure time values. Respondents in the third and fourth quartiles left for work earlier than the mean in most cases.

FIGURE 9c - Third Quartile Departure Times to Work

The journey to work departure times separated by income quartiles are found in Figures 9a through 9d. Respondents with the lowest incomes left for work later than respondents in the second, third and high income quartiles. Respondents in the second quartile left for work both above and below the monthly mean departure time values. Respondents in the third and fourth quartiles left for work earlier than the mean in most cases.

FIGURE 9d - High Income Departure Times to Work

Figure 9e showing weighted three-year average departure times for each quartile compared to the overall departure time mean demonstrates that there is more variability in the data corresponding to smaller numbers of respondents.

FIGURE 9e - Average Departure Times to Work Based on Income

Figure 9f is analogous to Figure 8f and shows the trends by quartile over the 36 month period of data collection. Again, the month to month variation is striking with few similarities between adjacent points. For the most part the data fluctuates with adjacent points varying by almost thirty minutes in the low income case, for example. Twenty minute variations occur in adjacent months in the third quartile case.

FIGURE 9f - Departure Time to Work Each Month Based on Income in Hampden County, MA

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