TRANSCAD教程5：DEMAND FORECASTING: TRIP DISTRIBUTION

  ent, the trip matrices must be converted to Origin-Destination format. A simple process for doing so averages the original and transposed trip matrices, an approach which is valid for 24-hour matrices where most trips are paired with an equivalent trip in the reverse direction. An appropriate time-specific trip table must be extracted for formal assignment since network capacities (as with volumes) are temporal measures. Conversion of the P/A matrices to O/D format must reflect observed time-of-day patterns. For example, the majority of HBW trips have an origin at the production (residential) end and a destination at the attraction (employment) end in the AM-peak.[Page]

Using the base year Miasma Beach Origin-Destination Survey, the percentages of trips by time-of-day were computed and are displayed in Table 6a and 6b. Table 6b is used by transcad to extract appropriate O/D matrices from the 24-hour trip matrices and simultaneously convert person-trips to vehicle-trips.

Spring 2004: Miasma Beach is only concerned with PM-peak period (defined as 5 to 6 PM).

      Table 6a. Temporal Distribution of Trips by Purpose

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                         -- HBW --      -- HBO --      -- NHB --

     Analysis Period     PA     AP      PA     AP      PA     AP

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1-hr AM-peak (7-8 am)   0.15   0.00    0.03   0.01    0.02   0.02

1-hr PM-peak (5-6 pm)   0.01   0.10    0.03   0.05    0.04   0.04



Full AM-peak (7-9 am)   0.30   0.00    0.06   0.02    0.04   0.04

Full PM-peak (4-7 pm)   0.03   0.30    0.09   0.15    0.12   0.12

Off-peak (other)        0.17   0.20    0.33   0.33    0.34   0.34

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      Note: See Table 6b 
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