John Collura

Resiliency of Transportation Network of Santo Domingo, Dominican Republic

Every day dependence on transportation grows as local, regional, national, and international independence increases. Resilient transportation systems are needed to secure the highest possible level of service during disruptive events, including natural disasters and those caused by humans. To prepare for these events, decision makers need guidance to determine what investments are likely to improve the resiliency of their networks, which are often hampered by limited resources. To date, such guidance has been primarily qualitative. This paper presents a methodology to quantify resiliency, under preevent conditions, by use of a fuzzy inference approach. This methodology expands on previous work by the authors and others, by refining the definitions of key variables, adjusting model interactions, and increasing transparency between metrics. The paper includes a case study in which the methodology is applied to a disruptive event in Santo Domingo, Dominican Republic. The case study illustrates the methodologys ability to (a) evaluate the extent to which the Dominican Republics transportation network is prepared for a disruptive event, (b) help select investments that have the potential to increase the resiliency of the network, and (c) provide outputs that will support a variety of current economic analysis strategies, allow comparison of different investment scenarios, and facilitate decision making. The paper concludes with a sensitivity analysis that shows the effects of alternative investments on the network.

Transition Strategies to Exit Preemption Control: State-of-the-Practice Assessment

Preempting the normal control of a traffic signal has the potential to affect the safety and efficiency of the vehicle requesting priority and the generalpurpose traffic at the intersection. These impacts may also influence traffic flow at other intersections along a roadway or within the corridor. A state-of-the-practice assessment is provided of different transition strategies used to exit a preemption control plan and return to the coordinated operation of a signal timing plan. The reallocation of green time that results from preempting a traffic signal has the potential to affect the flow of traffic negatively. A methodology that integrates the operation of a traffic signal controller with a microscopic traffic simulation model will accurately replicate the stochastic characteristics of travel and quantify the impacts of preemption control. The time required to exit a preemption control plan will vary on the basis of the exit transition strategy selected, when this plan terminates, and where the normal signal timing plan would have been if it had not been preempted. The preemption control exit transition strategies available to practitioners are typically restricted to the options supported by different types of traffic controllers or firmware products. The five most commonly available exit transition strategies are reviewed, and additional research needed to advance the state of the practice and the state of the art in using preemption control exit transition strategies is also identified.

Do Advance Yield Markings Increase Safe Driver Behaviors at Unsignalized, Marked Midblock Crosswalks? Driving Simulator Study

In the United States, 78% of pedestrian crashes occur at noninter-section crossings. As a result, unsignalized, marked midblock crosswalks are prime targets for remediation. Many of these crashes occur under sight-limited conditions in which the view of critical information by the driver or pedestrian is obstructed by a vehicle stopped in an adjacent travel or parking lane on the near side of the crosswalk. Study of such a situation on the open road is much too risky, but study of the situation in a driving simulator is not. This paper describes the development of scenarios with sight limitations to compare potential vehicle–pedestrian conflicts on a driving simulator under conditions with two different types of pavement markings. Under the first condition, advance yield markings and symbol signs (prompts) that indicated “yield here to pedestrians” were used to warn drivers of pedestrians at marked, midblock crosswalks. Under the second condition, standard crosswalk treatments and prompts were used to warn drivers of these hazards. Actual crashes as well as the drivers’ point of gaze were measured to determine if the drivers approaching a marked midblock crosswalk looked for pedestrians in the crosswalk more frequently and sooner in high-risk scenarios when advance yield markings and prompts were present than when standard markings and prompts were used. Fewer crashes were found to occur with advance yield markings. Drivers were also found to look for pedestrians much more frequently and much sooner with advance yield markings. The advantages and limitations of the use of driving simulation to study problems such as these are discussed.

Evaluation of Resiliency of Transportation Networks After Disasters

The resiliency of infrastructure, particularly as related to transportation networks, is essential to any society. This resiliency is especially vital in the aftermath of disasters. Recent events around the globe, including Hurricane Katrina and significant seismic events in Haiti, Chile, and Japan, have increased the awareness and the importance of resiliency. Transportation systems are key to response and recovery. These systems must withstand stress, maintain baseline service levels, and be stout enough in physical design and operational concept to provide restoration to the system. Analysis of a transportation networks resiliency before a disruptive event will help decision makers identify specific weaknesses within the network so that investments and improvement projects are prioritized appropriately. Previous research in quantification of network resiliency was expanded into a proposed methodology, through which understanding and applying concepts of network resiliency could preclude many devastating effects of destabilizing events and preserve the quality of life and economic stability.

Simulation Models for Assessment of the Impacts of Strategies for Highway Work Zones: Eight Case Studies Along Interstate Highways and State Routes in New England

As the National Highway System reaches the end of its serviceable life, transportation agencies increasingly need to focus on the preservation, rehabilitation, and maintenance of these roads. In light of significant increases in work zone activity, transportation officials and contractors are challenged to find ways to reduce the negative impacts on driver mobility. The key to addressing this challenge is to recognize potential impacts well in advance. One major tool used for this purpose is computer simulation. Many simulation models exist, some designed specifically for work zone analysis, including QUEWZ, QuickZone, CORSIM, and CA4PRS. This purpose of this paper is to present case studies that illustrate and evaluate these models for ease of use, data requirements, and ability to simulate and assess work zone strategies, shedding light on the relative reliability and accuracy of these simulation models as well as their user-friendliness and data requirements. This paper compares simulation results with actual work zone conditions in eight locations across New England. The results of this evaluation will be of interest to state and local transportation engineers responsible for planning and designing work zone strategies. This research has shown that some simulation models provide a low-risk, low-cost environment in which to test and analyze a variety of work zone alternatives. For example, QUEWZ and QuickZone were able to provide reasonable order of magnitude queue length estimates on Interstate highways that were comparable with observations made in the field. In addition, such estimates required few data, including hourly volume and roadway geometry information.

Methodology to Assess Traffic Signal Transition Strategies for Exit Preemption Control

Enabling vehicles to preempt the normal operation of traffic signals has the potential to improve the safety and efficiency of both the requesting vehicle and all other vehicles. Little is known about which strategy is the most effective to exit from preemption control and transition back to the normal traffic signal timing plan. This research evaluates the commonly available transition strategies: best-way, long, short, and hold strategies. The major contribution of this research is to enhance the methodology to evaluate the impacts of using these alternative transition strategies with the software-in-the-loop simulation tool. The research concludes that a statistically significant interaction exists between traffic volume levels and traffic signal transition strategies; this eliminates the ability to determine the isolated effects of either the transition strategies on average travel delay and average travel time or the effects of changes in traffic volume levels on average travel delay and average travel time. Conclusions, however, could be drawn on the performance of different transition strategies for specific traffic volume levels. The research also concludes that for the base traffic volume and a 40% increase in traffic volume, the most effective transition strategies are the best-way and long or hold alternatives. The best way was the most effective transition strategy for a 20% increase in traffic volume. The least effective strategy is the short transition strategy for both the base and 40% increase in traffic volume and the long and short for a 20% increase in traffic volume. Further research needs to be conducted to assess the performance of different transition strategies in returning to coordinated operation under higher levels of traffic volume with varying cycle lengths and different signal timing plans and when different roadway geometric configurations are present.

A DSS framework for advanced traffic signal control system investment planning

This paper presents ongoing research on the initial development of a decision support system (DSS) framework for integrated emergency vehicle preemption and transit priority system investment planning. A conceptual intelligent DSS framework offers a holistic framework to perform analytical assessments of integrated emergency vehicle preemption and transit priority systems. Three analytical tools are presented for incorporation into future DSS design: the first addresses the potential impact of transit travel time reduction on transit operating costs; the second addresses the potential impact of reduced emergency vehicle crashes at signalized intersections on fire and rescue operating costs; and the third integrates fuzzy sets concepts and multiattribute decisionmaking methods to rank order transit signal priority strategy alternatives at the intersection level.

DEVELOPING A DECISION SUPPORT SYSTEM FOR EVALUATING AN INVESTMENT IN FARE COLLECTION SYSTEMS IN TRANSIT

This article presents the initial development of a decision support system (DSS) to assess cost impacts of upgrading or replacing a transit ticketing and fare collection (TFC) system. Assessment of these costs, typically, requires extensive calculations and involves estimation of unknown parameters such as future ridership growth rate, equipment utilization rate, and interest rate on debt financing. This DDSD is developed with wo categories of policy- and decision-makers in mind - transit agency managers and transit industry researchers.

Effect of advance yield markings and symbolic signs on vehicle-pedestrian conflicts: field evaluation

The Commonwealth of Massachusetts has made walkable communities a priority. Pedestrian safety is key to the success of this objective. Pedestrians are at especially high risk when traversing unsignalized, marked crosswalks located either midblock or at T-intersections, especially when a vehicle adjacent to the driver is blocking the view of a crossing pedestrian. Several treatments have been proposed to reduce crashes at such crosswalks in such situations. Two experiments were conducted in the town of Greenfield, Massachusetts, to assess the effectiveness of advance yield markings on drivers’ scanning for pedestrians and to study their yielding behavior. Advance yield markings consist of a line of white triangles 20 to 50 ft in advance of the crosswalk together with a sign indicating that drivers should yield at the markings. The first experiment was an observational one involving a staged pedestrian attempting to use the crosswalk, and the second experiment was an in-vehicle field study conducted on an open road course in Green-field. Results demonstrated that advance yield markings coupled with the vacating of parking spots immediately adjacent to the crosswalk to clear the line of sight of approaching vehicles improved yielding compliance. In addition, when advance yield markings and warning signs were present, drivers approaching the crosswalk were more likely to scan areas to the sides of the roadway at crosswalks in anticipation of a pedestrians entering the crosswalk.

Planning and Deploying Transit Signal Priority in Small and Medium-Sized Cities: Burlington, Vermont, Case Study

Innovations in traffic signal systems have generated a great deal of interest in the provision of preferential traffic signal strategies and treatments for transit buses and other vehicles at signalized intersections in cities of all sizes. The primary objective of this paper is three fold: 1) to synthesize the literature of the lessons learned associated with planning and deploying transit signal priority (TSP) strategies in small and medium-sized cities; 2) to demonstrate the application of a micro-simulation model, VISSIM, to assess transit priority impacts in small and medium-sized communities where the required VISSIM input data are often limited; and 3) to present guidelines to aid traffic engineers and transit planners who are considering TSP strategies in small and medium-sized cities. An underlying aim of this paper is to recognize the differences in transit priority planning and deployment in small and medium-sized cities as compared to major metropolitan areas.