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97 ture characteristics. If the restaurant component is expected to cle trips and use mode split and vehicle occupancy to generate be only a minor portion of the overall retail component of the person trips. If the analyst wishes to work in assumed ITE con- MXD (e.g., a traditional shopping center), assume the site has ditions (no adjustments for mode split or vehicle occupancy), no restaurant component. then it is workable to perform all calculations in this step (skip- Enter the development units by land use in sub Table 1-A ping Steps 3B and 3C) and all subsequent steps in vehicle trips. of Table 103 and the corresponding sub table in the P.M. peak In this case, input mode split as 100% vehicle occupancy is period Worksheet 2 (not shown). ITE land use codes are 1.00; these will cause the inherent ITE values to be reflected found in the ITE Trip Generation report (2). The "quantity" through the process. is the number of development units. "Units" are the applica- ble development units such as dwelling units or gross sq ft of building floor area. Undefined shopping center space should Step 3A: Estimate Trip Generation all be classified as just that--shopping center (ITE land use Enter vehicle trips in the two right columns of Table 103, classification Code 820 or similar applicable classification). sub Table 1-A for the A.M. peak hour and in corresponding No guesses should be made as to how it may break out into sub Table 1-P on Worksheet 2 for the P.M. peak hour. For cinema, restaurant, and so forth, unless that has already been each land use within the MXD, estimate single-use trip gen- determined in the development plan. eration individually. Then, sum the individual estimates into the six aggregated classifications: office, retail, restaurant, res- Step 2B: Determine Proximity idential, cinema, and hotel. Do not combine development units into the six classifications and then use one single-use Determine the walking distance between each pair of inter- trip generation rate or equation to estimate trip generation acting land uses within the MXD. This component of the esti- for the aggregated land use. If specific land uses are not mation procedure requires particular consistency in applica- known at the time of analysis, use a more general category-- tion. If there is only one building of each land use classification for example, at zoning, no specific retail categories may be (e.g., one apartment building and one office building), enter known, so "shopping center" may be the best approximation. the distance between the entrances of each building. If there is The nationally accepted method of estimating site trip gen- a group of buildings or businesses of one land use category in eration is to use ITE Trip Generation report (2) trip genera- an area, the distance used should be the weighted (by trip gen- tion rates, equations, and data and apply them as described in eration) average of distances between each pair of buildings of the ITE Trip Generation Handbook (1). However, local agen- the interacting land uses. cies may have special local rates they prefer to use. Locally For each pair of interacting land uses, determine the actual determined rates accepted by the reviewing agency can also walking distance along the most direct and reasonable path. Do be used. The choice of trip generation rates/equations should not use the airline (i.e., shortest direct) distance. For the A.M. be discussed with the review agency prior to preparing the street peak hour, there are no proximity adjustments, so the estimates. distances are not entered into sub Table 3-A of Table 103; how- Analysts should keep track of the directional split (inbound/ ever, proximity distances are to be entered into sub Table 3-P outbound) of the generated trips for each land use. Directional of Worksheet 2 for the P.M. street peak-hour analyses. trips are essential to the proper balancing of internal travel demand within the MXD (described in Step 4). If beginning directly with person trips, see the last paragraph of Step 3C. Step 3: Calculate Single-Use Trip Generation for the Site Components Step 3B: Enter Vehicle Occupancy In this step, trip generation is estimated for each land use within the MXD. The procedure accounts for (1) trip- Enter vehicle occupancy for the trips generated by each generating characteristics of the specific land uses (described land use in Table 103, sub Table 2-A for the A.M. peak hour in Step 3A) and (2) vehicle occupancy (described in Step 3B). and corresponding sub Table 2-P of Worksheet 2 for the P.M. Mode split is not applied here because it is assumed that peak hour. The vehicle occupancy can be different for enter- the ITE trip generation data, which was almost all collected in ing and exiting vehicles. The vehicle occupancy rate should suburban areas, is almost totally by motor vehicle. There is be based on local data if possible. It is acceptable to use an typically no or very limited transit and walking for trips to overall average vehicle occupancy rate based on a survey of and from development sites. a similar mixed-use site or to use land use specific vehicle The recommended approach is to work in person trips occupancy rates based on surveys of nearby similar land uses. rather than in vehicle trips, but the analyst can begin from vehi- Metropolitan planning organization (MPO) data could also