Browsing by Author "Queiroz, Cesar"
Now showing 1 - 5 of 5
Results Per Page
Sort Options
- Addressing Uncertainties of Performance Modelling with Stochastic Information Packages – Incorporating Uncertainty in Performance and Budget ForecastsKadar, Peter; Martin, Tim; Baran, Michelle; Sen, Ranita (2015-05-19)A large volume of data is collected world-wide to feed pavement management systems (PMS). The data is typically condensed to characterize pavement sections or smaller sub-networks by using statistical measures mostly averages. In this process valuable information is lost, thus increasing the likelihood of providing inaccurate or in some cases misleading answers. The pitfalls of using averages can be avoided by utilizing the full data set and treating each data set as an entity or stochastic information packet (SIP). Modeling with SIPs means that the input as well the output of the modeling is a distribution as opposed to the singular outcome of deterministic models. The resulting distribution allows determination of the probability of the outcome besides its predicted value. Budget and condition forecasts therefore may include not only the future condition and budget requirements, but their reliability and consequently the level of associated risks. Managing agencies and contractors may choose the budget scenario best reflecting their level of risk acceptance or tolerance. Modeling with SIPs builds on deterministic models by expanding their outcomes into full distributions. Working with arrays (SIPs) requires using a novel approach that is described and illustrated in the paper.
- Empirical Studies on Traffic Flow in Inclement WeatherHranac, Robert; Sterzin, Emily; Krechmer, Daniel; Rakha, Hesham A.; Farzaneh, Mohamadreza (United States. Federal Highway Administration, 2006-10)Weather causes a variety of impacts on the transportation system. While severe winter storms, hurricanes, or flooding can result in major stoppages or evacuations of transportation systems and cost millions of dollars, day-to-day weather events such as rain, fog, snow, and freezing rain can have a serious impact on the mobility and safety of the transportation system users. These weather events can result in increased fuel consumption, delay, number of accidents, and significantly impact the performance of the transportation system. The overall goal of the research work undertaken in this study was to develop a better understanding of the impacts of weather on traffic flow. The research was intended to accomplish the following specific objectives: (1)Study the impact of precipitation on macroscopic traffic flow parameters over a full range of traffic states; 2) Study the impact of precipitation on macroscopic traffic flow parameters using consistent, continuous weather variables; 3) Study the impact of precipitation on macroscopic traffic flow parameters on a wide range of facilities; 4) Study regional differences in reaction to precipitation; and 5) Study macroscopic impacts of reduced visibility. The work documented in this report was conducted in two parts: 1) literature review and development of a data collection and analysis plan, and 2) analysis and interpretation of the results. The recommended plan combined the use of macroscopic traffic data archives with archived weather data in order to meet the research goals that include achieving better understanding of the impacts of weather on macroscopic traffic flow. The results of the research conducted for this study were helpful in identifying weather impacts of traffic flow in the three cities studied, Minneapolis-St. Paul, Baltimore and Seattle. No impacts were found on traffic stream jam density, but both rain and snow did impact traffic free-flow speed, speed-at-capacity and capacity and parameters varied with precipitation intensity. The results of these analyses are documented in the report. This report concludes with some recommendations of future research related to weather and traffic flow. Several ideas are presented including enhancing the macroscopic analysis used in this study. Additional work is proposed related to human factors and microscopic traffic modeling.
- Feasibility of Using In-Vehicle Video Data to Explore How to Modify Driver Behavior That Causes Nonrecurring Congestion: SHRP 2Rakha, Hesham A.; Du, Jianhe; Park, Sangjun; Guo, Feng; Doerzaph, Zachary R.; Viita, Derek; Golembiewski, Gary A.; Katz, Bryan J.; Kehoe, Nicholas; Rigdon, H. (National Research Council (U.S.). Transportation Research Board, 2011)Nonrecurring congestion is traffic congestion due to nonrecurring causes, such as crashes, disabled vehicles, work zones, adverse weather events, and planned special events. According to data from the Federal Highway Administration (FHWA), approximately half of all congestion is caused by temporary disruptions that remove part of the roadway from use, or "nonrecurring" congestion. These nonrecurring events dramatically reduce the available capacity and reliability of the entire transportation system. The objective of this project is to determine the feasibility of using in-vehicle video data to make inferences about driver behavior that would allow investigation of the relationship between observable driver behavior and nonrecurring congestion to improve travel time reliability. The data processing flow proposed in this report can be summarized as (1) collect data, (2) identify driver behavior, (3) identify correctable driver behavior, and (4) model travel time reliability, as shown in Figure ES.1.
- A Financial Model to Estimate Annual Payments Required under Performance Based ContractsMladenovic, Goran; Queiroz, Cesar (2015-06-04)Over the last couple of decades there has been an increased interest by road agencies to adopt performance based contracts (PBC) for road maintenance as a means to increase the efficiency of maintenance operations. PBC is a type of contract in which payments for the management and maintenance of road assets are explicitly linked to the contractor successfully meeting or exceeding certain clearly defined minimum performance indicators. This paper presents the development of a user-friendly tool for estimating the annual payments by the government that will be required by potential contractors to undertake a PBC project. The model is expected to be useful to both the public and the private sectors. For example, a road agency planning to launch a PBC program will need to make an estimate of the annual payments that the agency will have to make to the private contractors. Conversely, private contractors interested in competing for the PBC program will have to make an estimate of the annual payments to include in their bids. The applicability of the tool is demonstrated through a numerical example of a potential road PBC project. The model can also be applied to other types of transport infrastructure, such as a railway or waterway. The model can be used to carry out sensitivity analyses. For example, the user can change the value of an input parameter (e.g., construction cost) and obtain the resulting impact on the project financial internal rate of return, or other key model output.
- Light Vehicle-Heavy Vehicle Interactions: A Preliminary Assessment Using Critical Incident AnalysisHanowski, Richard J.; Keisler, Aysha S.; Wierwille, Walter W. (United States. Federal Motor Carrier Safety Administration, 2004-05)Two recently completed on-road, in situ data collection efforts provided a large data set in which to conduct an examination of near-crashes and crashes (critical incidents) that occurred between light vehicles (LV) and heavy vehicles (HV). Video and other sensor data collected during the two studies were used to characterize critical incidents that were recorded between LV and HV drivers. Across both studies, 210 LV-HV critical incidents were recorded. Of these, 78 percent were initiated by the light vehicle driver. Aggressive driving, on the part of the LV driver, was found to be the primary contributing factor for LV driver initiated incidents. For HV driver initiated incidents, the primary contributing factor was poor driving technique. The results suggest that efforts at addressing LV-HV interaction incidents should focus on aggressive light vehicle drivers. Additionally, it is recommended that HV drivers might benefit from improved driver training that includes instruction on defensive driving.