2013 Session: 646

• Implications of Trip Generation Rate Changes over Time
  Abstract: An investigation of two North Carolina case studies assesses the impacts of changes in trip generation rates over time. The first case study considers a regional travel demand model and the second a traditional trip based travel demand model for a small urban area. The evaluation includes three different sets of trip generation rates for the regional model and four trip rate sets for the small urban area. The trip rate sets describe rate changes from five different household travel surveys, three from Baltimore, Maryland administered in 1977, 1993, and 2001; and the other two from the Research Triangle region of North Carolina administered in 1995 and 2006. The change in total trip rates ranged from ten to twenty percent depending on the years compared, a statistically significant change considering the t-statistic at a 95% confidence level. Trip generation, system level, and project performance measures quantify the effects of the rate changes on the model results. The results of this investigation show that trip rates that do not remain stable over time can have implications for system level and project level planning, resulting in unexpected changes in vehicle miles traveled and associated emissions, transit ridership, traffic forecasts, and local travel.
  Authors: Huntsinger, Leta F.; Rouphail, Nagui M.; Stone, John R.
  Authors: Huntsinger, Leta F.; Rouphail, Nagui M.; Stone, John R.
  Year: 2013
  Document Type: Paper
  Subject: Planning and Forecasting
  Session: 646
  Paper Number: 13-0455
  Practice-Ready: Yes
• Evolution of ITE Trip Generation Handbook: Proposal for Collecting Multimodal, Multicontext Establishment-Level Data
  Abstract: This paper outlines a new perspective on data collection to inform site-level trip generation studies with amendments to ITE’s Trip Generation Handbook in mind. The data collection proposed here is informed from the authors’ experiences in a study that aimed to adjust trip generation rates for urban context. In this study, a consistent and reliable method for adjusting ITE’s trip generation rates to account for increased non-automobile travel in different urban contexts was developed. Based upon these experiences, the design presented here proposes more emphasis on collecting information on person counts and how those person trips are distributed across various modes, including walking, cycling and transit. This paper advocates a move away from the vehicle-based counts used historically in these studies, to a focus on how new development impacts all transportation system users.
  Authors: Clifton, Kelly J.; Currans, Kristina Marie; Muhs, Christopher
  Authors: Clifton, Kelly J.; Currans, Kristina Marie; Muhs, Christopher
  Year: 2013
  Document Type: Paper
  Subject: Planning and Forecasting
  Session: 646
  Paper Number: 13-4318
  Practice-Ready: Yes
• A Destination Choice Model for Commercial Vehicle Movements in the Metropolitan Area
  Abstract: This paper describes the development of a destination choice model for modeling commercial vehicle movements in the metropolitan area. This proposed model has two major differences from other regional commercial vehicle models in the US, which include: 1) this model is stratified by commercial vehicle type and trip purpose jointly, instead of being stratified by vehicle type only, and 2) this model employs the discrete choice modeling technique, instead of using a traditional gravity model. With this technique, non-impedance variables were able to be tested for inclusion in the utility function of the model. It was found that, second only to travel time, inter-county crossing and inter-area-type dummy variables, especially the latter, are statistically significant and can add additional explanatory power to the model. The model estimation results also indicate the model fits the data well with likelihood ratio index (rho-squared) values ranging from 0.24 to 0.32. This research effort demonstrates that a destination choice model stratified by both vehicle types and trip purposes can be successfully developed and employed for modeling commercial vehicle trip distribution.
  Authors: Mei, Bing
  Authors: Mei, Bing
  Year: 2013
  Document Type: Paper
  Subject: Planning and Forecasting
  Session: 646
  Paper Number: 13-4692
  Practice-Ready: Yes
• Too Many Trips? Problems with Trip Generation in Theory and Practice
  Abstract: Trip Generation is the standard reference for assessing the impacts of new development on traffic congestion and the environment in the U.S. However, a comparison to household surveys suggests that Trip Generation overestimates trips by 56% – likely because its data represent a biased sample of development in the U.S. Moreover, the data in Trip Generation are ill-suited to analysis of regional traffic impacts, imposition of development impact fees and studies of greenhouse gas emissions, because they do not account for substitution effects. Most trips to new developments are not new, but involve households reshuffling trips from other destinations. These twin problems – theoretical and practical – help reinforce the dominance of the private auto, and are likely to lead to excessive roadway infrastructure that is unnecessary in practice.
  Authors: Millard-Ball, Adam
  Authors: Millard-Ball, Adam
  Year: 2013
  Document Type: Paper
  Subject: Planning and Forecasting
  Session: 646
  Paper Number: 13-0532
  Practice-Ready: Yes
• Mixed-Use Development Trip Generation Model
  Abstract: The Mixed-Use Development Trip Generation model provides a mechanism for estimating vehicle, walking, and transit trips for a mixed-use development (MXD). The model applies trip modifications to standard single-use trip generation estimates developed by the Institute of Transportation Engineers (ITE). MXDs with diverse internal activities have been shown to capture internal trips at a rate higher than conventional suburban developments; therefore, the MXD Trip Generation model accounts for the internal capture of MXD sites by reducing the external trips produced and estimating the number of walking and transit trips that would typically be conducted by automobile. In addition, MXDs located in central areas have been shown to generate shorter vehicle trips, which has been accounted for in the model as internal and external vehicle miles traveled (VMT) are estimated based on published travel characteristics of MXDs.The MXD Trip Generation model provides a straightforward method of testing transportation-related metrics of MXDs. The model uses ratios from a leading research-based MXD model to reduce ITE vehicle trip estimates and presents a summary of results that show the effects on VMT, internal capture, and mode split as a result of enhanced activity density and diversity of land uses within the MXD. The MXD trip reductions are based on the methodology described in Ewing et al. (2011), which analyzed datasets for 239 MXDs in six large and diverse metropolitan regions. Benefits of locally-calibrated vehicle ownership characteristics are also included in the mode split of the trip estimates of the MXD Trip Generation model.
  Authors: Gulden, Jeff; Goates, JP; Ewing, Reid
  Authors: Gulden, Jeff; Goates, JP; Ewing, Reid
  Year: 2013
  Document Type: Paper
  Subject: Planning and Forecasting
  Session: 646
  Paper Number: 13-4080
  Practice-Ready: Yes
• Implications of Trip Generation Rate Changes over Time
  Authors: Huntsinger, Leta
  Authors: Huntsinger, Leta
  Year: 2013
  Document Type: Presentation
  Subject: AICP Certification Maintenance Session; Planning and Forecasting
  Session: 646
  Paper Number: 13-0455
• Too Many Trips? Problems with Trip Generation in Theory and Practice
  Authors: Millard-Ball, Adam
  Authors: Millard-Ball, Adam
  Year: 2013
  Document Type: Presentation
  Subject: AICP Certification Maintenance Session; Planning and Forecasting
  Session: 646
  Paper Number: 13-0532
• Mixed-Use Development Trip Generation Model
  Authors: Gulden, Jeff
  Authors: Gulden, Jeff
  Year: 2013
  Document Type: Presentation
  Subject: AICP Certification Maintenance Session; Planning and Forecasting
  Session: 646
  Paper Number: 13-4080
• A Destination Choice Model for Commercial Vehicle Movements in the Metropolitan Area
  Authors: Mei, Bing
  Authors: Mei, Bing
  Year: 2013
  Document Type: Presentation
  Subject: AICP Certification Maintenance Session; Planning and Forecasting
  Session: 646
  Paper Number: 13-4692
• Evolution of ITE Trip Generation Handbook: Proposal for Collecting Multimodal, Multicontext Establishment-Level Data
  Authors: Clifton, Kelly
  Authors: Clifton, Kelly
  Year: 2013
  Document Type: Presentation
  Subject: AICP Certification Maintenance Session; Planning and Forecasting
  Session: 646
  Paper Number: 13-4318