Highway Capacity Manual改訂の動向--テイラ-教授の講演より

Historically, most demographic data for states and substate areas were collected from the long version of the decennial census questionnaire. A “snapshot” of the characteristics of the population on the April 1 census date was available once every 10 years. The long form of the decennial census has been replaced by the American Community Survey (ACS) that has been conducted on an ongoing basis for the entire country since 2005. Instead of a snapshot in which all of the data are gathered at one time, the ACS aggregates data collected over time, making the results more difficult to interpret. However, the ACS data are updated annually.

A practical guide to the American Community Survey (3-year estimates)

Transportation research. part c, emerging technologies

Transportation Networks. Optimality. Cost Functions. Deterministic User Equilibrium Assignment. Stochastic User Equilibrium Assignment. Trip Table Estimation. Network Reliability. Network Design. Conclusions. References. Index.

Transportation network analysis

This paper develops a novel linear programming formulation for autonomous intersection control (LPAIC) accounting for traffic dynamics within a connected vehicle environment. Firstly, a lane based bi-level optimization model is introduced to propagate traffic flows in the network, accounting for dynamic departure time, dynamic route choice, and autonomous intersection control in the context of system optimum network model. Then the bi-level optimization model is transformed to the linear programming formulation by relaxing the nonlinear constraints with a set of linear inequalities. One special feature of the LPAIC formulation is that the entries of the constraint matrix has only {−1, 0, 1} values. Moreover, it is proved that the constraint matrix is totally unimodular, the optimal solution exists and contains only integer values. It is also shown that the traffic flows from different lanes pass through the conflict points of the intersection safely and there are no holding flows in the solution. Three numerical case studies are conducted to demonstrate the properties and effectiveness of the LPAIC formulation to solve autonomous intersection control.

A linear programming formulation for autonomous intersection control within a dynamic traffic assignment and connected vehicle environment

Bus transportation is considered as one of the most convenient and cheapest modes of public transportation in Indian cities. Due to their cost-effectiveness and wide reachability, they help a significant portion of the human population in cities to reach their destinations every day. Although from a transportation point of view they have numerous advantages over other modes of public transportation, they also pose a serious threat of contagious diseases spreading throughout the city. The presence of numerous local spatial constraints makes the process and extent of epidemic spreading extremely difficult to predict. Also, majority of the studies have focused on the contagion processes on scale-free network topologies whereas, spatially-constrained real-world networks such as, bus networks exhibit a wide-spectrum of network topology. Therefore, we aim in this study to understand this complex dynamical process of epidemic outbreak and information diffusion on the bus networks for six different Indian cities using SI and SIR models. This will allow us to identify epidemic thresholds for these networks which will help us in controlling outbreaks by developing node-based immunization techniques.

Contagion processes on urban bus networks in Indian cities

• Method to disentangle the effect of unfamiliarity from that of informed perceptions of service quality in Likert scale responses. • Application to the analysis of bus transit usage in Bengaluru, India. • Ignoring travelers’ unfamiliarity with a transit system can distort the analysis of the effect of their perceptions of service quality on transit usage. • Travel surveys will benefit from including a “don’t know” option as a response to Likert scale questions on service quality perceptions. This study presents an integrated model to shed light on the factors influencing individuals’ likelihood and frequency of usage of bus transit in Bengaluru, India, with a focus on the role of individuals’ subjective perceptions of service quality. Typically, subjective perceptions of transit service characteristics such as comfort, cleanliness, reliability, and safety are measured using Likert rating scale questions in travel surveys. A shortcoming with many such surveys is that the Likert rating scale questions do not include a “don’t know” response category for the respondents to express their unfamiliarity and lack of opinion on the transit service. For this reason, some respondents who are not familiar with and do not have an opinion about the transit system are likely to choose the neutral response to Likert scale questions. At the same time, travelers who are familiar with and/or informed about the transit system may also choose the neutral response to state their opinion neutrality. As a result, some travelers’ unfamiliarity with (and lack of opinion about) transit services may be confounded with the informed perceptions of those who are familiar with transit. This is because those who are unfamiliar with the transit system are less likely to use it and more likely to state neutral responses than those who are familiar with the system. Ignoring such influence of travelers’ unfamiliarity can potentially distort the ordinal scale of Likert variables, result in biased parameter estimates and distorted implications about the influence of perceptions on transit usage. To address this concern, this study uses a generalized heterogeneous data model (GHDM) that allows a joint econometric analysis of the influence of individuals’ perceptions of transit service quality on their likelihood of transit use and frequency of use and at the same time disentangle unfamiliarity from informed perceptions. The empirical results shed light on: (a) the role of individuals’ demographic variables and subjective perceptions on their use and frequency of use of the bus transit system in Bengaluru, (b) the importance of separating unfamiliarity from informed opinions on transit service quality, (c) the need to include an option for respondents to reveal their unfamiliarity in Likert rating scale survey questions on perceptions, and (d) demographic segment-specific strategies for attracting new riders and enhancing ridership of current users of the bus transit system in Bengaluru. 

An analysis of individuals’ usage of bus transit in Bengaluru, India: Disentangling the influence of unfamiliarity with transit from that of subjective perceptions of service quality

Heterogeneous traffic as observed in several south Asian countries is characterized by complex interactions of widely varying vehicle types that do not follow lanes and with smaller vehicles filling any gaps available. This paper discusses on four main components of macroscopic simulation of traffic flow in the Indian traffic context. One of the prime component, namely the traffic flow model, is discussed in detail with respect to the continuum modelling approach.

Numerical Study with Field Data for Macroscopic Continuum Modelling of Indian Traffic

The primary focus of this study is to understand the current port operating condition and recommend short term measures to improve traffic condition in the port of Chennai. The cause of congestion is identified based on the data collected and observation made at port gates as well as at terminal gates in Chennai port. A simulation model for the existing road layout is developed in micro-simulation software VISSIM and is calibrated to reflect the prevailing condition inside the port. The data such as truck origin/destination, hourly inflow and outflow of trucks, speed, and stopping time at checking booths are used as input. Routing data is used to direct traffic to specific terminal or dock within the port. Several alternative scenarios are developed and simulated to get results of the key performance indicators. A comparative and detailed analysis of these indicators is used to evaluate recommendations to reduce congestion inside the port.

/pdf/simulation-of-truck-congestion-in-chennai-port-5caz987vt9.pdf

Simulation of truck congestion in Chennai port

Urban freight trip generation is an important component of urban transportation planning. However, it does not receive the same degree of importance as passenger trip generation in studies done in India. In this context a focused study on freight trip generation will throw light on its importance. While there are studies in India available on trip generation rates for passenger travel there are no numbers to quote for freight trips. The main purpose of this paper is to study freight demand through the estimation of freight trip generation models developed with disaggregated survey data at the establishment level. The survey gave significant insight into the freight trip generation characteristics in Chennai city. From the data collected it is seen that on an average about 3 freight trips are made to an establishment and 6 trips leave an establishment every day. Predominantly bikes and small pick-up vans are used for carrying goods in the city. The authors compare their study to a similar study conducted recently in New York City. Overall, establishments in Chennai attract more trips than in New York City. This is in contrast to what is observed in the passenger trip rates where Indian cities have lesser value compared to western countries.

Gitakrishnan Ramadurai

Papers

Contagion processes on urban bus networks in Indian cities

An analysis of individuals’ usage of bus transit in Bengaluru, India: Disentangling the influence of unfamiliarity with transit from that of subjective perceptions of service quality

Numerical Study with Field Data for Macroscopic Continuum Modelling of Indian Traffic

Simulation of truck congestion in Chennai port

Freight Trip Generation Models for Chennai, India