conference paper

Integrating a smith predictor into ramp metering control of freeways

Proceedings of the 96th annual meeting of the transportation research board

Publication Date

January 1, 2017

Author(s)

Felipe De Souza, Wenlong Jin

Abstract

Ramp metering on freeways is one, among many others, application in which a proportional-integral (PI)-Controller has been successfully used to keep the system at a desired state. However, the design becomes challenging if the system presents a dead time restricting the stability region and affecting performance. The cause of the dead time is the distance between the on-ramp and the lane drop. A change in the control action affects the system after the time taken to vehicles travel this distance. There are a vast literature in the control theory addressing the effects of dead time and techniques to overcome it, but it is not to ramp metering control. In this study, a dynamic model of the system is presented along with ALINEA, an established Ramp Metering control algorithm based on a PI-Controller. The authors show that by incorporating a Smith Predictor into ALINEA, the stability region becomes larger, insensitive to the dead time, and can be found analytically. Numerical experiments confirm the analysis and that the proposed controller still presents a larger stability region even when there are modeling errors, allowing a faster response to disturbance.

Suggested Citation

Felipe Augusto de Souza and Wenlong Jin (2017) “Integrating a smith predictor into ramp metering control of freeways”, in Proceedings of the 96th annual meeting of the transportation research board, p. 20p.

research report

An analysis of the characteristics and congestion impacts of truck-involved freeway accidents

Publication Date

December 1, 1988

Associated Project

AN ANALYSIS OF THE CHARACTERISTICS AND CONGESTION IMPACTS OF TRUCK INVOLVED FREEWAY ACCIDENTS

Author(s)

Will Recker, Thomas Golob, Chang-Wei Hsueh, Paula Nohalty

Final Report

FHWA/CA/UCI-ITS-RR-88-2

Areas of Expertise

Infrastructure Delivery, Operations, & Resilience

View research report

Suggested Citation

Wilfred W. Recker, Thomas F. Golob, Chang-Wei Hsueh and Paula D. Nohalty (1988) An analysis of the characteristics and congestion impacts of truck-involved freeway accidents. Final Report FHWA/CA/UCI-ITS-RR-88-2. ITS-Irvine. Available at: https://catalog.hathitrust.org/Record/005512489.

Related Publications

working paper | Dec 1988

An Analysis of the Characteristics and Congestion Impacts of Truck-Involved Freeway Accidents

published journal article

A neural network-based methodology for pavement crack detection and classification

Transportation Research Part C: Emerging Technologies

Publication Date

December 1, 1993

Author(s)

Mohamed Kaseko, Stephen Ritchie

View published journal article

Suggested Citation

Mohamed S. Kaseko and Stephen G. Ritchie (1993) “A neural network-based methodology for pavement crack detection and classification”, Transportation Research Part C: Emerging Technologies, 1(4), pp. 275–291. Available at: 10.1016/0968-090x(93)90002-w.

conference paper

Land use and vehicle miles of travel in the climate change debate: Getting smarter than your average bear

Proceedings of the land policy conference of the lincoln institute of land policy, cambridge, massachusetts

Publication Date

May 1, 2010

Author(s)

Marlon Boarnet, Doug Houston, Gavin Ferguson, Steven Spears

Suggested Citation

M.G. Boarnet, D. Houston, G. Ferguson and S. Spears (2010) “Land use and vehicle miles of travel in the climate change debate: Getting smarter than your average bear”, in Proceedings of the land policy conference of the lincoln institute of land policy, cambridge, massachusetts.

published journal article

JTRF volume 56 no. 3, fall 2017On-Demand, app-based ride services: A studyof emerging ground transportation ModesServing Los Angeles international airport (LAX)

J Transp Res Forum

Publication Date

September 1, 2017

Author(s)

Karina Hermawan, Amelia Regan

View published journal article

Suggested Citation

Karina Hermawan and Amelia C. Regan (2017) “JTRF volume 56 no. 3, fall 2017On-Demand, app-based ride services: A studyof emerging ground transportation ModesServing Los Angeles international airport (LAX)”, J Transp Res Forum, 56(3). Available at: 10.5399/osu/jtrf.56.3.4462.

working paper

Estimating the Potential Cost Savings of Transit Service Contracting

Publication Date

December 1, 1986

Author(s)

Genevieve (Gen) Giuliano, Roger Teal

Working Paper

UCI- ITS-WP-86-9

Areas of Expertise

Public Transit, Shared Mobility, & Active Transportation Transportation Economics, Funding, & Finance

View working paper

Abstract

The continued financial problems of the public transportation industry have motivated a search for more cost-effective ways of delivering transit services. Service contracting–the contracting of public transit services to private providers–has emerged as one of the most promising alternatives. Existing evidence suggests that service contracting could reduce public agency cost by 10 to 50 percent. If service contracting were implemented throughout the public transit industry, services currently provided by public agencies would be shifted to private provision. However, little is known about how such service shifts would affect transit service costs, and whether significant cost savings would occur. This paper presents an assessment of the cost savings potential of transit agency service contracting. A cost model based on the concept of avoidable cost is used in a series of case studies to generate estimates of potential cost savings resulting from contracting various quantities of transit service. Research results showed average cost savings of 23 percent for the contracted service. These savings are equivalent to about 4 percent of the transit agency’s total operating cost. Cost savings depend on a number of factors, but are roughly associated with the size of the transit agency. Cost savings for small agencies are insignificant and can be negative, while savings for agencies larger than 250 vehicles typically range between 5 and 7 percent of total operating cost when 20 percent of existing service is contracted.

Suggested Citation

Genevieve Giuliano and Roger F. Teal (1986) Estimating the Potential Cost Savings of Transit Service Contracting. Working Paper UCI- ITS-WP-86-9. Institute of Transportation Studies, Irvine. Available at: https://escholarship.org/uc/item/70k9f185.

published journal article

Generalized bathtub model of network trip flows

Transportation Research Part B: Methodological

Publication Date

June 1, 2020

Author(s)

Wenlong Jin

View published journal article

Abstract

Vickrey (1991, 2020) proposed a bathtub model for the evolution of trip flows served by privately operated vehicles inside a road network based on three premises: (i) treatment of the road network as a single bathtub; (ii) the speed-density relation at the network level, also known as the network fundamental diagram of vehicular traffic, and (iii) the time-independent negative exponential distribution of trip distances. However, the distributions of trip distances are generally time-dependent in the real world, and Vickrey’s model leads to unreasonable results for other types of trip distance distributions. Thus there is a need to develop a bathtub model with more general trip distance distribution patterns. In this study, we present a unified framework for modeling network trip flows with general distributions of trip distances, including negative exponential, constant, and regularly sorting trip distances studied in the literature. In addition to tracking the number of active trips as in Vickrey’s model, this model also tracks the evolution of the distribution of active trips’ remaining distances. We derive four equivalent differential formulations from the network fundamental diagram and the conservation law of trips for the number of active trips with remaining distances not smaller than any value. Then we define and discuss the properties of stationary and gridlock states, derive the integral form of the bathtub model with the characteristic method, and present two numerical methods to solve the bathtub model based on the differential and integral forms respectively. We further study equivalent formulations and solutions for two special types of distributions of trip distances: time-independent negative exponential or deterministic. In particular, we present six equivalent conditions for Vickrey’s bathtub model to be applicable.

Suggested Citation

Wen-Long Jin (2020) “Generalized bathtub model of network trip flows”, Transportation Research Part B: Methodological, 136, pp. 138–157. Available at: 10.1016/j.trb.2020.04.002.

working paper

Optimal Sensor Requirements

Publication Date

August 1, 2009

Author(s)

Lianyu Chu, Henry Liu

Areas of Expertise

Infrastructure Delivery, Operations, & Resilience Intelligent Transportation Systems, Emerging Technologies, & Big Data

View working paper

Abstract

PATH Task ORder 6328 addresses the optimal deployment of traffic detectors on freeway to ensure that adequate information is collected at the lowest possible cost. The project team produced a study framework and tools that can be applied locally to test the sensitivity of traffic data quality to detectors location and spacing, and ultimately recommend a deployment plan.

Various types of traffic detectors, including loop detectors, radars, toll tag readers and video cameras are deployed on highways. They provide the data needed to run traffic management applications such as ramp metering control, bottleneck identification, and travel times estimation. However, few studies have systematically analyzed the data requirements of these applications in terms of detector spacing and location. In other words, the trade-offs between the cost of the detectors and their benefits for traffic estimation accuracy are not well known. As a result, most highway detectors are installed using ad hoc guidelines or on a case-by-base basis, rather than through the application of measurable objectives. This in turn makes it difficult for practitioners to justify equipment and maintenance expenditures, often slowing deployment.

The product of this research is two-fold. First, we developed a framework to study the sensitivity of traffic information to sensor location and spacing and reached general conclusions. Second, the team created practical tools to assist practitioners at the local level with optimal sensor deployment. These tools include recommendations for rural areas and an Excel-based model for urban areas.

conference paper

Selective vehicle routing problems under uncertainty without recourse

Proceedings of the INFORMS annual meeting, phoenix, AZ

Publication Date

October 1, 2012

Author(s)

Mahdieh Allahviranloo, Joseph Chow, Will Recker

Suggested Citation

M Allahviranloo, J Chow and W.W. Recker (2012) “Selective vehicle routing problems under uncertainty without recourse”, in Proceedings of the INFORMS annual meeting, phoenix, AZ.

book/book chapter

A Review of the Ridership Prediction Models for the California High Speed Rail

Publication Date

June 1, 2020

Author(s)

Samer Madanat, David Brownstone, M. Hansen

Suggested Citation

Samer Madanat, D. Brownstone and M. Hansen (2020) “A Review of the Ridership Prediction Models for the California High Speed Rail”, in A Review of the Ridership Prediction Models for the California High Speed Rail. CA HSR Authority and the State Senate Transportation and Housing Committee.