Portland, OR, United States
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Li J.-Q.,University of California at Berkeley | Wu G.,University of California at Riverside | Zou N.,Kittelson and Associates Inc.
Transportation Research Part D: Transport and Environment | Year: 2011

This paper investigates the environmental impacts of signal timing on vehicle emissions at a pre-timed signalized intersection. We use a two-stage approach: the first consists of developing optimization models that examine the trade-off between vehicle delays and the number of stops; and, based on the outcomes of the first stage, the second of estimating vehicle emissions using microscopic emission estimation models. A dynamic programming algorithm is developed to solve the optimization problems appearing in the first stage. A vehicle specific power approach is used to estimate the vehicle emissions near the intersection based on the results from the first stage. © 2011 Elsevier Ltd.


Sun X.,Nanjing Institute of City and Transport Planning | Urbanik T.,Kittelson and Associates Inc. | Han L.D.,University of Tennessee at Knoxville
Applied Mechanics and Materials | Year: 2013

This paper presents a neurofuzzy signal control system to improve the efficiency at closely-spaced signalized intersections. Building on the conventional actuated-coordinated control system, the neurofuzzy controller establishes a "secondary coordination" between the upstream coordinated phase and the downstream non-coordinated phase based on real-time traffic demand. Under the neurofuzzy signal control, the traffic from the upstream intersection can arrive and join the queue at the downstream left turn lane and be served, and therefore reduce the possibility of being delayed at the downstream intersection. The membership functions in the fuzzy controller are calibrated to further the performance. The simulation results indicate that the neurofuzzy signal control consistently outperformed to the conventional actuated-coordinated controller, in terms of reduction in system-wide average delay and average number of stops per vehicle, under a wide range of traffic volumes, especially under higher demand conditions. © (2013) Trans Tech Publications, Switzerland.


Ferguson E.M.,Kittelson and Associates Inc. | Duthie J.,University of Texas at Austin | Travis Waller S.,University of New South Wales
Computer-Aided Civil and Infrastructure Engineering | Year: 2012

Traditionally, transportation road networks are designed for minimal congestion. Unfortunately, such approaches do not guarantee minimal vehicle emissions. To fill this apparent gap in network design research, an emissions network design problem and solution method is proposed in this article for the purposes of comparing to the traditional network design results. Three air pollutants are considered on two road networks. The model is formulated as a bi-level optimization problem and a solution is approximated using a genetic algorithm. The influence of demand uncertainty is also incorporated into the model. Designing for minimal congestion tends to increase emissions of criteria air pollutants. However, not adding capacity to a road network also increases emissions of pollutants. Therefore, an optimization problem and solution method, such as the emissions network design problem and solution method presented here, is useful for identifying capacity additions that reduce vehicle emissions. It is also useful for understanding the tradeoffs between designing a network for minimal congestion versus minimal vehicle emissions. © 2011 Computer-Aided Civil and Infrastructure Engineering.


Ferguson E.M.,Kittelson and Associates Inc. | Duthie J.,University of Texas at Austin | Unnikrishnan A.,West Virginia University | Waller S.T.,Research Center for Integrated Transport Innovation r 110
Transportation Research Part A: Policy and Practice | Year: 2012

This paper and the proposed formulation contribute to an apparent gap in transit research design by integrating equity considerations into the transit frequency-setting problem. The proposed approach provides a means to design transit service such that equitable access to basic amenities (e.g., employment, supermarkets, medical services) is provided for low-income populations or disadvantaged populations. The overarching purpose is to improve access via transit to basic amenities to: (1) reduce the disproportionate burden faced by transit dependent populations; and (2) create a more feasible transportation option for low-income households as an opportunity to increase financial security by reducing dependence on personal autos. The formulation is applied to data from a mid-sized US metropolitan area. The example application illustrates the formulation successfully increases access to employment opportunities for residents in areas with high percentages of low-income persons, as well as demonstrates the importance of considering uncertainty in the locations of populations and employment. © 2011.


Bonneson J.A.,Texas A&M University | Pratt M.P.,Texas A&M University | Vandehey M.A.,Kittelson and Associates Inc.
Transportation Research Record | Year: 2010

This paper describes the development of a procedure for predicting the arrival flow profile for an intersection approach. This profile describes the variation in flow rate during the average signal cycle as it would be measured at a specified point downstream of a signalized intersection. Research indicates that platoon decay (due to midsegment driveway access and egress) tends to have a more significant impact on the arrival flow profile than platoon dispersion. Platoon dispersion reflects drivers' desire to increase their headway, while platoon decay reflects vehicles departing the platoon at midsegment access points. The procedure is recommended for inclusion in the Urban Street Segments chapter of the forthcoming 2010 Highway Capacity Manual.


Hauer E.,University of Toronto | Bonneson J.,Kittelson and Associates Inc. | Council F.,University of North Carolina at Chapel Hill | Srinivasan R.,University of North Carolina at Chapel Hill | Zegeer C.,University of North Carolina at Chapel Hill
Transportation Research Record | Year: 2012

Crash modification factors (CMFs) are listed in the Highway Safety Manual and other authoritative publications. This information does not allow the reader to distinguish between the predictions of safety effect that can be made confidently and are likely to lead to correct decisions and those that can easily be wrong. Nor can it be known how transferable past research results are to decisions about future actions to be implemented under different circumstances. The conceptual framework described in this paper aims to provide guidance for research about CMFs and for meta-analyses. The central claim is that CMFs are random variables and are not universal constants that apply everywhere at all times. The smaller the standard deviation of a CMF, the more confident the related decision making can be. Therefore, the aim of research into CMFs is to reduce their standard deviations. Ways to do so efficiently are indicated. The requisite theory and equations are provided.


Pochowski A.,Georgia Institute of Technology | Myers E.J.,Kittelson and Associates Inc.
Transportation Research Record | Year: 2010

As the modern roundabout continues to grow in popularity in the United States, more states are considering or implementing statewide roundabout programs. To assist states in implementing statewide roundabout programs, a review of four such programs was conducted in Kansas, Maryland, New York, and Wisconsin. The review was completed through an examination of published state roundabout guides and interviews. Results from the review indicate that agency buy-in, public perception, and establishment of a statewide roundabout policy all play crucial roles in the success or failure of a statewide round-about program. It is recommended, therefore, that agencies focus on these areas to ensure success in establishing a roundabout program statewide.


Roess R.P.,New York University | Vandehey M.A.,Kittelson and Associates Inc. | Kittelson W.,Kittelson and Associates Inc.
Transportation Research Record | Year: 2010

The concept of level of service (LOS) was introduced in the 1965 edition of the Highway Capacity Manual (HCM). It provided for the familiar letter-grade system for characterizing the quality of operations on a variety of traffic facilities from intersections to freeways. The LOS concept will remain primarily unchanged in the next edition of the HCM, expected in 2010. It will, however, introduce material directly related to user perceptions for the first time, and discussions surrounding LOS have raised interesting issues that may result in more extensive changes in the future. This paper attempts to address some of these issues in the context of the history of the LOS concept and its use in the planning, design, and analysis of traffic facilities. Among the major issues that should be thoroughly examined in the future is whether the concept is needed with the rapidly advancing state-of-the-art, which produces many quantifiable measures of service quality. The application of LOS to corridors, networks, and multimodal systems needs to be addressed, as it will differ from previous applications to points and uniform segments. Incorporating the results of research concerning user perceptions into the LOS framework has also raised interesting issues as the 2010 HCM has been developed. With the forthcoming 2010 HCM as a starting point, this paper explores current issues and makes suggestions as to how to address them while moving toward the as yet undefined edition that will follow the 2010 HCM.


Quayle S.M.,Kittelson and Associates Inc. | Koonce P.,Kittelson and Associates Inc. | Depencier D.,Kittelson and Associates Inc. | Bullock D.M.,Purdue University
Transportation Research Record | Year: 2010

This study reports on the use of media access control (MAC) readers hrough the Bluetooth protocol by means of off-the-shelf equipment to measure arterial travel performance (segment travel time, average running speed, and origin-destination). First, the MAC reader technology was deployed at the same time that travel time runs by the traditional floating-car method were used to evaluate the general reliability and accuracy of the MAC technology. Second, the MAC reader technology was used to track before-and-after changes to signal timing along the corridor to measure the effectiveness of the adjustments, proving its real-world applicability while requiring far fewer resources than raditional data collection means. A comparison of the Bluetooth MAC address data with traditional Global Positioning System floating-car studies suggests that the larger data set from the Bluetooth data more effectively captures performance characteristics of the arterial. The research was conducted on a 2.5-mi suburban signalized arterial in Portland, Oregon, over 27 days. The paper concludes by discussing the system architecture for a permanent real-time deployment and other areas for future research. The real-time MAC reader information provides substantial opportunity to add new control and performance monitoring capability to other intelligent transportation system components, such as ramp metering, transit signal priority systems, and adaptive signal control.


McGill G.,00 Airport Road SE | Quayle S.,Kittelson and Associates Inc.
21st World Congress on Intelligent Transport Systems, ITSWC 2014: Reinventing Transportation in Our Connected World | Year: 2014

ODOT through their ITS innovative grant program recently funded five new adaptive traffic signal control systems (ASCT), which aimed to isolate the incremental impact of the ASCT treatments. The detailed evaluation used ITS high-resolution, automated data collection equipment (e.g. Bluetooth travel time/speed readers, controller logs and detailed video) to avoid biasing the results. The highest value was discovered on corridors at or near capacity and during event conditions, where ASCT allowed cycle lengths to flex up to account for peak demands. All ASCT systems increased cycle lengths, but overall movement average delay at intersections stayed mostly consistent. Travel time changes were observed of +5% to -20%, which was lower than vendor claims.

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