Norman W. Garrick Forms of Trip Generation Models Three Forms of Trip Generation Models are featured in the text 1.Regression Models A regression model is used to estimate the trip rate based on characteristics of the zone 2.Trip-Rate Analysis Trip rate is estimated on characteristics of the trip generators with in the zone. Production rates are determined using the characteristics of the residential land uses and attraction rates using the characteristics of the nonresidential land uses 3.Cross-classification Models This is a variation of the trip-rate analysis from above. The difference is that the trip generation models (for the residential land uses) are disaggregate models

Norman W. Garrick Form of the Cross-Classification Model Trip rate for households with 4 persons and 1 vehicle is equal to 5.05 trips per day This model has two independent variables - persons/hh and vehicles/hh

Norman W. Garrick Estimated No. of HH for Cross-Classification Model Estimated number of households with 4 persons and 1 vehicle is 300

Norman W. Garrick Trip Ends from Cross-Classification Models Estimated number of trips from households with 4 persons and 1 vehicle is (5.05*300) = 1515

Norman W. Garrick Trip Rate Analysis Trip-Rate Analysis Trip rate is estimated on characteristics of the trip generators with in the zone. Production rates are determined using the characteristics of the residential land uses and attraction rates using the characteristics of the nonresidential land uses Example from Text, Page 355, Table The characteristics of the trip generator is given in 1000 SQ. FT. And the trip generation rate for each generator is given as TRIPS PER 1000 SQ. FT. For example Residential: Total Sq. Ft. = sq. ft., Trip Gen. Rate = 2.4 trips/1000 sq.ft TOTAL NO. of TRIP from residential land use = 2744*2.4 = 6586 Trips

Norman W. Garrick ITE Trip Generation Manual

Norman W. Garrick ITE Trip Generation Manual Low Rise Apartment, Weekday

Norman W. Garrick ITE Trip Generation Manual Low Rise Apartment, Weekday 19 data points!

Norman W. Garrick ITE Trip Generation Manual Limitations The data contained in Trip Generation are, by definition, from single-use developments where virtually all access is by private automobile and all parking is accommodated on site. For new developments with characteristics that reduce automobile use--located close to transit, containing a mix of uses, or charging for parking--the use of unadjusted average ITE trip-generation rates will in many cases drastically overestimate the amount of traffic generated. A corner store with no parking across from a subway station in a dense, transit- oriented development is often forecast to have the same impact as a 7-Eleven on a suburban highway. Ref: Playing the numbers game: when it comes to TODs, trip-generation figures can make all the difference by Millard-Ball, Adam, Siegman, Patrick

Norman W. Garrick ITE Trip Generation Manual Dangers of Overbuilding "The traffic engineering profession is just waking up to the fact that one can overbuild infrastructure so it no longer serves the community," continues Walters ( a California-based principal at Fehr & Peers Associates ). "When one tries to design facilities to cater to the maximum demand that may occur, one can end up with too much. "It's true of parking," Walters says. "It's also true of streets," where oversizing can lead to more lanes, wider lanes, and longer signal phases than are strictly warranted. This not only adds to development costs but reduces the amount of space available for trees and other amenities, and creates physical barriers in the community. Ref: Playing the numbers game: when it comes to TODs, trip-generation figures can make all the difference by Millard-Ball, Adam, Siegman, Patrick

Norman W. Garrick Storrs Center

Norman W. Garrick Storrs Center Google Earth The Site

Norman W. Garrick Storrs Center Google Earth The Site Constraints Wetlands Forest Reserve

Norman W. Garrick Storrs Center Google Earth The Site Built Area

Norman W. Garrick Storrs Center

Norman W. Garrick Storrs Center Model

Norman W. Garrick Storrs Center Model Village Road

Norman W. Garrick Storrs Center Google Earth

Norman W. Garrick Storrs Center 195 Problem

Norman W. Garrick Storrs Center Importance of the Network

Norman W. Garrick Using TG Manual without Correction Estimated number of trip ends = 24,600 ITE Trip Generation Manual Proposed size of project

Norman W. Garrick Using TG Manual with Correction for Mixed Use Estimated number of trip ends = 15,900 It is very important to remember that this total includes walking, biking and transit trips Not just car trips