Miguel Jaller

Freight Generation, Freight Trip Generation, and Perils of Using Constant Trip Rates

Several findings call into question current practices. The chief conclusion is that the accuracy of freight generation (FG) and freight trip generation (FTG) models depends on the consistency between the models structure and actual FG-FTG patterns, the degree of internal heterogeneity of the economic and land use aggregation used to estimate the model, and the appropriateness of the spatial aggregation procedure used to obtain the desired FG-FTG estimates. Relative to model structure, the paper establishes strong reasons to treat FG and FTG as separate concepts, because the latter is the output of logistic decisions, whereas the former is determined by the economics of production and consumption. The connection between business size variables–for example, employment–and FG is relatively strong because they are economic input factors, whereas the one with FTG is weaker because inventory and transportation costs come into play. Thus it is generally not correct to assume proportionality between FTG and business size or to assume that using constant FTG rates could be problematic. For instance, only 18% of the industry sectors in New York City exhibit constant FTG rates per employee. For economic and land use aggregation, the finer the level of detail the better, as independent variables have a better chance to explain FG-FTG. In the case of spatial aggregation, the correct aggregation procedure depends on the underlying disaggregate model. For a FG-FTG model to work well, both economic and land use and spatial aggregations must be appropriate.

Material Convergence: Important and Understudied Disaster Phenomenon

AbstractThis paper reports the research conducted on material convergence, which is one of the most important and, ironically, one of the most understudied disaster phenomena. This spontaneous flow of supplies, equipment, and general donations to the impacted area brings much-needed relief and major complications to the operations. The paper reviews empirical evidence from disaster literature and complements it with lessons learned from fieldwork to identify the problems created by the nonpriority component of the material convergence. The paper ends with policy suggestions regarding the use of appropriate material convergence management and control strategies.

Parking in the City: Challenges for Freight Traffic

This paper provides insight into the magnitude of the freight parking problem in large urban areas and the effectiveness of alternative solution strategies. The paper estimates the demand for parking through the use of freight trip generation estimates and estimates the supply of parking on the basis of curb space. The paper discusses strategies for the management of freight parking demand developed by governmental agencies and other organizations. In addition, the paper proposes an approximate methodology to quantify freight parking demand and on-street parking availability. Parking demand is expressed as a function of the freight trip generation of individual establishments, and parking availability is estimated to be a function of curb space dimensions and commercial vehicle characteristics. Empirical findings are provided. New York City is used as a case study. From the analyses and results, the paper provides a set of policy recommendations to help mitigate the identified issues.

Estimated Generation of Freight Trips Based on Land Use

The effects of land use and business size (quantified as number of employees) on freight trip generation were analyzed. Standard trip generation rates, ordinary least squares, and multiple classification analysis were applied to a New York City data set. Three land use classification codes—the City of New York zoning resolution (NYCZR), the Land-Based Classification Standards (LBCS), and the Institute of Transportation Engineers (ITE) manual—were used. The authors developed models for NYCZR and function and activity of LBCS and used the ITE manuals trip rates. Root mean square error analysis was used to compare the performance of these models. It was found that models for NYCZR and LBCS land use classification codes provide better alternatives to ITE trip rates because they give more accurate estimates of freight trip attraction, cover a wider range of land use classifications, and are exclusively for freight trip attraction.

Transferability of Freight Trip Generation Models

The main objectives of this paper are to assess and define ways to enhance the transferability of freight trip generation (FTG) models. After the key premises that should guide the development of FTG models have been presented, the paper assesses transferability in two ways. The first is through analyses of how well representative FTG models are able to estimate the actual FTG for a number of external validation cases. The second is through FTG econometric models that assess the statistical significance of binary variables that represent specific geographic locations. In addition, the paper introduces and assesses the accuracy of a synthetic correction procedure that is intended to improve the transfer-ability and quality of the estimates provided by the FTG rates available in the literature. The results show that the models developed as part of the National Cooperative Freight Research Programs Project 25, Freight Trip Generation and Land Use, have better prediction capabilities than the models included in other compilations. In addition, the synthetic correction procedures improve transferability, and no locational effects are present in the test data.

Comprehensive Freight Demand Data Collection Framework for Large Urban Areas

The chapter analyses characteristics and unique features of the freight system, data requirements of different modeling techniques, and the roles of various data collection procedures. The analyses produce a set of findings of relevance to the design of comprehensive freight data collection frameworks for mid-size and large urban areas. Building on these findings, the chapter identifies a modular data collection framework that would enable transportation agencies to mix and match data collection efforts depending on their needs and constraints.

Freight Generation and Freight Trip Generation Models

This chapter provides an overview of freight generation (FG) and freight trip generation (FTG) modeling for urban areas. To this effect, the authors discuss the literature, propose a logistical interpretation of FG and FTG, summarize the key factors for effective FG and FTG modeling, and describes the FTG models developed for New York City. The chapter concludes with statements of conclusions.

Improving Freight System Performance in Metropolitan Areas: A Planning Guide

This report provides a regional public planning guide that identifies potential strategies and practical solutions for public and private stakeholders to improve freight movement system performance in diverse metropolitan areas. The Guide is intended to serve as a comprehensive reference for all portions of a metropolitan area, from the urban core to more suburban and exurban areas (urban fringe). The Guide includes an Initiative Selector tool to aid in the selection of possible alternatives for various problems, and Freight Trip Generation (FTG) software that planners can use to identify main locations where freight is an issue based on freight trips produced and attracted. Links to access the Initiative Selector and FTG software appear in this report. The report is divided into three sections: Section 1: Urban Freight Transportation Decision-Making Process; Section 2: Overview of Public-Sector Initiatives; and Section 3: Case Studies.

Fostering the Use of Unassisted Off-Hour Deliveries: Operational and Low-Noise Truck Technologies

The main objective of this paper is to provide an overview of the technologies available for use in unassisted off-hour deliveries (i.e., deliveries made outside of regular business hours without the presence of receiving staff). The focus is on technologies that monitor and provide access, on some level, to the establishment and those that lessen or eliminate the noise created by delivery trucks and equipment. This paper also touches on the costs and benefits to companies that use unassisted off-hour deliveries and, ultimately, the question of who should cover the costs of the technologies. This issue is tied to the discussion of policy implications and how the public sector can help increase the adoption of these delivery programs.

Freight Trip Generation and Land Use

This report provides a comprehensive discussion of how the freight system, and specifically freight trip generation and land use, relate. The report consolidates available freight trip generation models in an electronic database to assist practitioners interested in using these models; identifies the most appropriate approaches to develop and apply freight trip generation models; and estimates establishment-level freight trip generation models in a number of case studies. The case studies confirm the superiority of economic classification systems over standard land use classification systems as the foundation for estimating freight trip generation.