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104 CHAPTER 4 Conclusions, Recommendations, and Suggested Research This chapter pulls together the conclusions, recommenda- The ITE method covers only trips among the three most fre- tions, and lessons learned during this project. Statements made quent components of MXDs--office, retail, and residential. herein are intended to help practitioners use the results of this Data are available for the weekday P.M. peak hour, for midday, project either to estimate internal capture for MXDs or to add and for what is called "daily," but which is drawn from data to the database and perhaps further refine the methodology collected between noon and 6:30 P.M. The ITE method has and tools provided. nothing for the A.M. peak hour. The policy percentages men- tioned above are applied to each analysis period used. There is some limited use of invalid applications for internal Existing Practice capture estimation. The two found most frequently were use of shared parking reduction percentages and metropolitan area Internal capture for MXDs is of most interest to those travel forecast model intrazonal trip percentages. Shared park- who either prepare or review TIAs for such developments, ing reductions apply only to parking accumulations in a park- but transportation planners and developer consultants are ing facility serving multiple uses; the percentage reduction also interested in internal capture and the resulting external applies only to parking accumulation, not trip generation. trip generation. Some additional uses include planning for Intrazonal trips apply to complete traffic analysis zones used TODs and preparing environmental impact statements or in regional travel forecast models. Zones may range from a assessments. block to a square mile. Intrazonal trips are for the complete ITE provides a recommended practice for estimating inter- zone and are not applicable to portions of a zone. Estimates nal capture and associated external trip generation for what are also accurate only to a regional level, not a development it calls "multi-use developments." As described, those devel- site level. Neither method should be used for estimating inter- opments have characteristics similar to the common defini- nal capture for MXDs. tion used for MXDs. The research team accepted the two Six land uses are the most frequent components of MXDs-- terms as used as being essentially equal. The ITE method doc- office, retail, restaurant, residential, cinema, and hotel. Most umented in their Trip Generation Handbook (1) is the most major MXDs have all of these. Most other MXDs have at least widely used technical method. four. MXDs come in all sizes and layouts: some are vertically The other widely used approach is a policy-determined integrated and developed in one block, some are spread over flat percentage reduction in external trips. Such percentages are several or many blocks with land uses well mixed or concen- established by local planning, zoning, or transportation engi- trated in interconnected single-use areas. Six MXDs analyzed neering officials for use in TIAs prepared to support applica- in this project ranged in size from 7 and 300 acres. All were tions for zoning, subdivision, site plan approval, or access single developments from one master plan developed either to permits. The percentages are usually arbitrarily selected for use integrate fully all land uses or otherwise to promote interaction throughout the jurisdiction. These percentages are most typi- between onsite land uses. There are other larger MXD types of cally in the range of 10%, but were found to range from less developments such as SACs and even new towns or very large than 5% to as much as 25%. Most percentages are conservative self-contained urban sections. These last two types were not compared with internal capture data found in past research covered in this project because it was felt that they act differ- and this project. Other approaches found included tables of ently than does the MXD of 300 acres or less and because they applicable rates and a formula to modify ITE estimates. are far less frequently found in most states of the country.