Erratum

"Erratum on the article ‘A bi-level framework for pricing of high-occupancy toll lanes’." Transport, 29(4), p. 46

Proactive detection of high collision concentration locations on highways

In previous research (Chung et al., 2009), the potential of the continuous risk profile (CRP) to proactively detect the systematic deterioration of freeway safety levels was presented. In this paper, this potential is investigated further, and an algorithm is proposed for proactively detecting sites where the collision rate is not sufficiently high to be classified as a high collision concentration location but where a systematic deterioration of safety level is observed. The approach proposed compares the weighted CRP across different years and uses the cumulative sum (CUSUM) algorithm to detect the sites where changes in collision rate are observed. The CRPs of the detected sites are then compared for reproducibility. When high reproducibility is observed, a growth factor is used for sequential hypothesis testing to determine if the collision profiles are increasing over time. Findings from applying the proposed method using empirical data are documented in the paper together with a detailed description of the method

HOV Lane Configurations and Safety Performance of California Freeways – An Investigation of Differential Distributions and Statistical Analysis

From a recent study of safety evaluation of HOV-equipped freeways, it was found that limited-access HOV lanes appear to have a safety performance disadvantage when measured by collision distribution or collision rates for the HOV lane alone and for the HOV and left lanes combined. This paper describes the work performed to verify the statistical significance of related findings. Several statistical tests were used: empirical cumulative density function (CDF), Kolmogorov-Smirnov Tests, and comparison of means based on Poisson Distributed Samples. The conclusion that continuous-access HOV lanes perform better than limited-access ones by several safety metrics is confirmed by the three separate approaches. In addition, the historical data for the HOV segments and the general-purpose lanes are extracted and compared, which offers supporting evidence for similar conclusions. The work described in this paper offers a methodology of statistical verification and can provide support to assist policy-making in selecting HOV configurations

A Dynamic Congestion Pricing Strategy for High-Occupancy Toll Lanes

High Occupancy Toll (HOT) lanes are emerging as a solution to address the underutilization of High Occupancy Vehicle (HOV) lanes and also means of generating revenue for state department of transportation. This paper proposes a method for dynamically determining the HOT toll price in response to the changes in traffic condition and documents procedures for estimating parameters needed for the proposed pricing strategies: revenue maximization and delay minimization. The proposed strategies have been applied to 14-miles of freeway segment in the San Francisco Bay Area, and the findings show that utilizing all the available HOV lane capacity (i.e. difference between HOV lane capacity and HOV demand) to serve the HOT demand does not result in maximizing the total revenue. There exists optimal level of HOV lane capacity that can be allowed for the use of HOT vehicle to maximize the revenue.Engineering

HOV Lane Configurations and Safety Performance of California Freeways – An Investigation of Differential Distributions and Statistical Analysis

From a recent study of safety evaluation of HOV-equipped freeways, it was found that limited-access HOV lanes appear to have a safety performance disadvantage when measured by collision distribution or collision rates for the HOV lane alone and for the HOV and left lanes combined. This paper describes the work performed to verify the statistical significance of related findings. Several statistical tests were used: empirical cumulative density function (CDF), Kolmogorov-Smirnov Tests, and comparison of means based on Poisson Distributed Samples. The conclusion that continuous-access HOV lanes perform better than limited-access ones by several safety metrics is confirmed by the three separate approaches. In addition, the historical data for the HOV segments and the general-purpose lanes are extracted and compared, which offers supporting evidence for similar conclusions. The work described in this paper offers a methodology of statistical verification and can provide support to assist policy-making in selecting HOV configurations

Develop safety surrogate measure for evaluating motor carrier companies and drivers

The risk of accidents of commercial vehicles is higher than that of ordinary vehicles. Traffic fatalities per registered vehicles are 3.8 times higher than in commercial vehicles than ordinary vehicles in 2016. Because of the high severity of accidents, there should be a lot of effort to reduce accidents and manage traffic safety of motor carrier companies. So far, safety assessments for commercial vehicles have been evaluated according to the frequency and the severity of accidents. This approach has several problems. First, the accident can not be preemptively prevented because it is based on the post evaluation of the accident. Second, it is difficult to provide consulting or action guidelines because it is impossible to determine what factors caused traffic accidents. With the recent development of data collection technology, not only traffic accident information, but also the various characteristics of motor carrier companies and drivers such as vehicle driving record, dangerous driving behavior, law violation information are collected. Therefore, this study aims to develop a new safety surrogate measure based on various characteristics of motor carrier companies and drivers

Rebound Effect or Induced Demand? Analyzing the Compound Dual Effects on VMT in the U.S.

This research explored the dual influence of fuel efficiency and roadway capacity on vehicle distance traveled. The empirical study was conducted by applying a generalized least square (GLS) analysis to the U.S. state-level panel data of fuel efficiency, roadway lane-miles, and vehicle miles traveled (VMT) for over three decades (1980–2010). The analysis confirmed the co-existence of rebound effect and induced demand on driving distances over the decades—improved fuel efficiency and expanded roadway capacity caused additional vehicle distance traveled, partially offsetting the benefits of the measures taken. Furthermore, the results showed that the magnitude of each effect would be unjustifiably overestimated if this dual influence was not taken into consideration