Modal Mix Research Articles

Operational effects of right turn on red in New Jersey : W.L. Mullowney and T.D. Davis, New Jersey Department of Transportation, Trenton, NJ, April 1984, FHWA/NJ-84/010

Connected and autonomous vehicles are expected to gradually enter the transport modal mix sooner or later. Academic discussions of their expected impacts are well underway, often with conflicting or wide-ranging results. In this chapter, the existing literature is reviewed and summarized, with a focus on the traffic flow efficiency impacts. The expected impacts of autonomous vehicles on the roadway capacity are found not to be unanimous, partly because this seems to depend on the specific modeling conditions. Therefore, common factors that determine whether capacity is expected to increase or decrease are discovered from existing studies, along with determining the factors that influence other traffic flow efficiency-related impacts, such as traffic stability and congestion. An analysis is also performed on the vehicular requirements for autonomous vehicles to serve the mobility demand, and change in vehicle kilometers traveled (VKT) that may happen. Based on the reviewed studies, 19 factors that influence traffic flow efficiency implications of autonomous vehicles are identified and grouped into four categories, namely (i) vehicle characteristics, (ii) travel behavior, (iii) network characteristics, and (iv) policies. The chapter ends with a discussion on policy recommendations in tune with the factors identified. The discussion shows that the policy makers should enact laws to ensure connectivity between AVs to experience significant benefits, integrate CAVs with public transport to avoid mode shifts, incentivize ridesharing to reduce network load, develop suitable parking management policies to avoid empty relocations and introduce congestion pricing to curb induced demand.

A dynamic urban growth model for strategic transport planning

This paper presents an exploratory model of the population redistribution process in metropolitan areas with transport pricing as the main driving determinant. A set of 10 differential equations developed from logistic growth theory describe the dispersal of population from an urban area into two encompassing concentric zones. These outward flows give rise to changes in the commuting flows by mode as well as changes in the modal mix of journey to work trips within the urban area. The model is calibrated for Greater London and the South‐East Standard Region of England between 1961 and 1976, and various possible pricing scenarios are tested to examine the population trajectories up to 1991. The results illustrate the feasibility of dynamic process‐descriptive models in urban analysis, but also suggests an integrated programme of research and model‐building as part of this development.

An Interactive Strategic Model of Transport Costs and Metropolitan Population Dynamics

This paper presents an exploratory model of the population redistribution process in metropolitan areas. A set of ten differential equations developed from logistic growth theory describes the dispersal of population from an urban area into two encompassing concentric zones. These outward flows give rise to changes in the commuting flows by mode as well as changes in the modal mix of journey-to-work trips within the urban area. The model is calibrated for Greater London and the South-East Standard Region of England between 1961 and 1976, and various possible pricing scenarios are tested to examine the population trajectories up to 1991. The results illustrate the feasibility of dynamic process-descriptive models in urban analysis, but also suggest an integrated programme of research and model-building as part of this development.

Mode choice, transport structure and urban land use

A theoretical model of the urban land market is solved to examine the impact of bimodal passenger transportation on equilibrium residential land use. In this model travel to the central business district occurs on a dense system of radial roads or bus routes and a competing system or radial expressways or mass transit lines fed by a subsidiary system of densely spread access streets. Under rational behavior assumptions for households, it is shown that various basic urban forms can result depending on the relative generalized cost characteristics of the competing dense and sparse radial networks. The basic urban forms yield fundamental shapes, differing as to the relative geometry and position of the market areas for the two modes. The standard Alonso-Muth model of unimodal travel and circular urban form is found to result as a special case in several of these cases. American urbanized areas of various sizes and modal mix provide plausible examples for each of the basic forms. The paper concludes with a discussion of the model's implications as a framework for examining optimum urban transport structure and the proliferation of transport routes as a function of urban size.

Energy-Intensiveness of Transportation

Historical, present, and possible future patterns of energy consumption in the transportation sector are examined for intercity freight and passenger traffic and for urban passenger traffic. The energy-efficiencies among the various transport modes are quite variable. Airplanes are relatively inefficient; cars and trucks are slightly more efficient; and railroads, waterways, pipelines, mass transit, and buses are quite efficient. The energy implications of changes in modal mix for freight and passenger transport are explored using two hypothetical futures.

“Blueprint for Survival”

A blueprint for survival through curtailment of demand is outlined using a transportation model system. Techniques available for reducing total energy demand in transportation include decreasing population size, increasing the price of gasoline, changing the "modal mix", or relative availability of different types of transportation systems, changing the spatial design of society to increase population density, increasing the interposition of places of work, living, shopping, and leisure by encouraging high-rise construction, and more efficient interaction between transportation systems and the structure and dynamics of society. Sensitivity analysis of energy consumption in transportation systems to different conservation strategies was examined using a statistical model that explains data and reflects plausible interactions.