2013 Session: 375

• Control Strategy for Rural Variable Speed Limit Corridor
  Abstract: Speed and speed variance among the vehicles are important factors related to safety, especially during the severe weather conditions. A variable speed limit (VSL) system was implemented in 2009 by the Wyoming Department of Transportation (WYDOT) to change the posted, enforceable speed limits in an effort to improve safety. During the initial years of implementation, decisions regarding the posted speed limit were made by maintenance, highway patrol and traffic management center personnel. This paper discusses the development of a methodology to support speed posting decisions based on the real time observed vehicle speeds and weather variables. The results from this methodology indicate that there could be a significant increase in speed compliance and reduced speed variation with the implementation of an automated control strategy over the current manual protocol.
  Authors: Sabawat, Vijay; Young, Rhonda Kae
  Authors: Sabawat, Vijay; Young, Rhonda Kae
  Year: 2013
  Document Type: Paper
  Subject: Maintenance and Preservation; Operations and Traffic Management
  Session: 375
  Paper Number: 13-0874
• Effect of Winter Weather and Road Surface Conditions on Macroscopic Traffic Parameters
  Abstract: This paper presents an empirical study focusing on identifying the main factors that affect the capacity and free-flow-speed (FFS) of urban freeways under inclement winter weather conditions. The weather and road surface condition factors examined include air temperature, wind speed, hourly snow intensity, visibility, snow on ground, and road surface condition describing the road slipperiness caused mainly by snow events. Data on traffic operations, the associated weather and road conditions observed at two freeway locations over the 2010-2012 winter seasons were used in an extensive statistical analysis. Linear regression models were calibrated for both capacity and FFS reductions as related to various weather and road condition variables. It was found that visibility and road surface conditions have a statistically significant effect on both capacity and FFS. Snow intensity was found to be significant only when the visibility factor was excluded, suggesting the presence of confounding of these two factors on capacity and FFS. The modeling results were compared with those recommended by the Highway Capacity Manual 2010, showing that in many cases, HCM could underestimate or overestimate the effects of winter weather conditions and that the proposed models provide more reasonable estimate at a higher level of granularity.
  Authors: Kwon, Tae-Jung; Fu, Liping; Jiang, Chaozhe
  Authors: Kwon, Tae-Jung; Fu, Liping; Jiang, Chaozhe
  Year: 2013
  Document Type: Paper
  Subject: Maintenance and Preservation; Operations and Traffic Management
  Session: 375
  Paper Number: 13-1763
• Modeling Temperature Distribution in Soil Profile: Impacts of Moisture Transport, Snow Cover, and Soil Freezing
  Abstract: Prediction of soil temperature is important to simulation of pavement, railway and bridge with significant earth contact. A one-dimensional numerical model for heat and moisture transfer in partially frozen soils has been developed and validated. In addition to modeling conduction heat transfer, model variations that include moisture transport, snow accumulation and melting and soil freezing and thawing are investigated. This model was evaluated against measured data at depths of 0.5 and 1.0 m for two locations in the northern United States of America. The results show that the model is capable of providing good simulations of the evolution of temperature all over the year. Comparisons of simulation results with five combinations of modeled phenomena to experimental data demonstrate that both snow cover and freezing and thawing of soil are of important when modeling temperature for soil. However, temperature was not substantially affected by the moisture transport.
  Authors: Xu, Hui-ning; Yiqiu, Tan
  Authors: Xu, Hui-ning; Yiqiu, Tan
  Year: 2013
  Document Type: Paper
  Subject: Maintenance and Preservation; Operations and Traffic Management
  Session: 375
  Paper Number: 13-1924
• Modeling Temperature Distribution in Soil Profile: Impacts of Moisture Transport, Snow Cover, and Soil Freezing
  Authors: Xu, Hui-ning
  Authors: Xu, Hui-ning
  Year: 2013
  Document Type: Presentation
  Subject: Maintenance and Preservation; Operations and Traffic Management
  Session: 375
  Paper Number: 13-1924
• Control Strategy for Rural Variable Speed Limit Corridor
  Authors: Sabawat, Vijay
  Authors: Sabawat, Vijay
  Year: 2013
  Document Type: Presentation
  Subject: Maintenance and Preservation; Operations and Traffic Management
  Session: 375
  Paper Number: 13-0874
• Effect of Winter Weather and Road Surface Conditions on Macroscopic Traffic Parameters
  Authors: Kwon, Tae-Jung
  Authors: Kwon, Tae-Jung
  Year: 2013
  Document Type: Presentation
  Subject: Maintenance and Preservation; Operations and Traffic Management
  Session: 375
  Paper Number: 13-1763
• Devising and Demonstrating Extreme Weather Risk Indicator for Transportation Systems
  Authors: Leviakangas, Pekka
  Authors: Leviakangas, Pekka
  Year: 2013
  Document Type: Presentation
  Subject: Maintenance and Preservation; Operations and Traffic Management
  Session: 375
  Paper Number: 13-1549
• Devising and Demonstrating Extreme Weather Risk Indicator for Transportation Systems
  Abstract:

  This paper describes a novel risk indicator for extreme weather risks for transportation system. The risk indicator is applied to European transportation system indicating and ranking the risks for the member states of EU-27. The paper starts with definitions of hazards, vulnerability and risk, based on relevant literature, and then operationalizes the risk, hazard and vulnerability with the help of EU-27 data. Finally, it discusses the risk extreme weather risk indicator (EWRI), evaluating its applicability and limitations. The risk indicator is a relative indicator, meaning that it should be viewed and treated as a ranking system. The devised indicator is able to assist national/state and international/federal level decision makers in the prioritization of extreme weather risks within their jurisdiction. The overall approach of EWRI is based on mainstream risk and vulnerability assessment research, following for most part the existing conceptual models. The novelty of EWRI lies in its application area (transportation) and wide use of both empirical and statistical data. EWRI was used to assess the hazards, vulnerabilities and risks of extreme weather for the EU-27, but there is nothing that hinders its application either as such or in a modified form in other contexts.

  Authors: Leviakangas, Pekka
  Authors: Leviakangas, Pekka
  Year: 2013
  Document Type: Paper
  Subject: Maintenance and Preservation; Operations and Traffic Management
  Session: 375
  Paper Number: 13-1549
  Practice-Ready: Yes