2013 Session: 253

• Probabilistic Design of Freeway Entrance Speed Change Lanes Considering Acceleration and Gap Acceptance Behavior
  Abstract: An adequate length of entrance speed change lanes (SCL) is required for vehicles’ acceleration and gap searching purposes so that they can merge onto the freeway comfortably. The current design guides use a deterministic approach for the design of SCL length based only on the acceleration behavior of SCL vehicles. This study introduces a probabilistic approach for the design of SCL length considering both acceleration and gap acceptance behavior of drivers during the merging process. A microscopic simulation is used, coupled with Monte Carlo simulation technique, to develop a probabilistic model to evaluate the probability of forced merge by SCL vehicles, termed as the probability of non-compliance (PNC). Different reliability measures can be developed based on the distribution of PNC values for all simulated SCL vehicles at a specific site. Several such measures were estimated for seven study sites and were shown to have high potential to indicate the safety performance at entrance SCL sites. As an example application of the developed model, the mean PNC was estimated to the recommended SCL lengths in North American design guides for a specific freeway design speed but different values of controlling curve design speed and traffic volume on the freeway right lane. The results indicate that the mean PNC may change with the change of either the design speed of the ramp controlling curve or the traffic volume on the freeway right lane.
  Authors: Fatema, Tazeen; Hassan, Yasser
  Authors: Fatema, Tazeen; Hassan, Yasser
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 253
  Paper Number: 13-0819
• Variables Influencing Speed Distribution on Urban Arterials and Collectors
  Abstract: Speeds are affected by several variables such as driver characteristics, vehicle performance, road geometrics, environmental conditions and driving regulations. A knowledge of the relationship between speed and such variables allows conscious speed management on existing and planned roads, with the aim of compelling drivers to select a speed consistent with the posted speed limit. This relationship is of great interest to those who wish to achieve roadway functionality and improve overall safety.Focusing on this objective, some contributions concerning urban roads are already available in literature with the caveat that they can be applied only to specific road types and recently built-up areas. Moreover, they refer mainly to the 85th percentile of speed. Lastly, they can only be applied in locations which are homogeneous in terms of geometry, environment, driving regulations and vehicle type.The research aims to establish the correlation between roadway features and operating speed by elaborating new models for the urban environment. The paper presents the results of an investigation carried out on Italian urban arterials and collectors within the municipality of Torino (Italy). The fact that this area is characterized by dissimilar geometric features facilitated the inclusion and study of a fully representative range of variables. Models were calibrated by combining the complete dataset and disaggregating it for the different road typologies. The results showed that, when consideration was given to all the selected variables, certain variables were found to be ever present and statistically significant across all models.
  Authors: Bassani, Marco; Dalmazzo, Davide; Marinelli, Giuseppe
  Authors: Bassani, Marco; Dalmazzo, Davide; Marinelli, Giuseppe
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 253
  Paper Number: 13-1138
• Speed-Reduction Treatment Analysis at High- to Low-Speed Transition Zones for Rural Highways
  Abstract: This paper presents the results of a study to develop improved design guidance for high-speed to low-speed transition zones on rural highways. The primary steps of the research included a literature review and state-of-practice review on speed reduction treatments utilized in transition zones (both domestically and internationally) and observational field studies of several transition zone treatments implemented in the United States. Several important or fundamental findings from the observation field studies are:•Roundabouts and transverse pavement markings increase the rate of compliance of vehicles traveling at or below the speed limit at the end of a transition zone by 15 and 20 percent, respectively, compared to no treatment.•Roundabouts increase the rate of compliance of vehicles traveling within 5 mph of the speed limit at the end of a transition zone by 11 percent, compared to no treatment.•The findings support previous research indicating the need to provide additional measures through the community to maintain a speed reduction downstream of the transition zone through the community.This paper also addresses some of the issues to be considered in the design of high- to low- speed transition zones, including:•Definitions and site characteristics to define the geographical limits or boundaries of the transition zone study area.•A methodology for assessing whether a high- to low-speed transition zone has speed-limit compliance or safety issues to support the need for, and the selection of, an appropriate treatment to address the issue(s).•Guiding principles and design concepts to be considered in the design of a transition zone.
  Authors: Gilmore, David K.; Bauer, Karin M.; Torbic, Darren John; Kinzel, Christopher S.; Frazier, Robert J.
  Authors: Gilmore, David K.; Bauer, Karin M.; Torbic, Darren John; Kinzel, Christopher S.; Frazier, Robert J.
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 253
  Paper Number: 13-4092
  Practice-Ready: Yes
• Evaluation of Safety Performance of Passing-Relief Lanes
  Abstract: This paper documents the evaluation of the safety performance of passing relief lanes using data from the State of Michigan. The study was based on volume and crash history data for 7 sites where passing lanes were implemented within the study period and for 100 reference sites (without passing lanes) and 231 passing lanes sites that existed throughout the study period. The analysis involved an empirical Bayes before-after evaluation and a comparative, cross-sectional evaluation of safety performance of locations with and without passing lanes. The methodologies were also applied to adjacent non-treated sites one mile upstream and downstream of the passing relief lane segment to examine possible migration or spillover effects. Based on the results, Crash Modification Factors (CMFs) were established for passing lanes in Michigan. These CMFs, which indicated significant safety benefits of passing relief lanes, may be considered for use in locations in other jurisdictions, given that there is precious little information in this regard. The results from the cross-sectional and before-and-after evaluations were generally consistent.
  Authors: Persaud, Bhagwant; Lyon, Craig; Bagdade, Jeffrey; Ceifetz, Andrew Hershel
  Authors: Persaud, Bhagwant; Lyon, Craig; Bagdade, Jeffrey; Ceifetz, Andrew Hershel
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 253
  Paper Number: 13-4106
  Practice-Ready: Yes
• Probabilistic Design of Freeway Entrance Speed Change Lanes Considering Acceleration and Gap Acceptance Behavior
  Authors: Hassan, Yasser
  Authors: Hassan, Yasser
  Year: 2013
  Document Type: Presentation
  Subject: Operations and Traffic Management
  Session: 253
  Paper Number: 13-0819
• Variables Influencing Speed Distribution on Urban Arterials and Collectors
  Authors: Bassani, Marco
  Authors: Bassani, Marco
  Year: 2013
  Document Type: Presentation
  Subject: Operations and Traffic Management
  Session: 253
  Paper Number: 13-1138
• Evaluation of Safety Performance of Passing-Relief Lanes
  Authors: Persaud, Bhagwant
  Authors: Persaud, Bhagwant
  Year: 2013
  Document Type: Presentation
  Subject: Operations and Traffic Management
  Session: 253
  Paper Number: 13-4106
• Speed-Reduction Treatment Analysis at High- to Low-Speed Transition Zones for Rural Highways
  Authors: Gilmore, David
  Authors: Gilmore, David
  Year: 2013
  Document Type: Presentation
  Subject: Operations and Traffic Management
  Session: 253
  Paper Number: 13-4092
• Presiding Officer
  Authors: Dimaiuta, Michael
  Authors: Dimaiuta, Michael
  Year: 2013
  Document Type: Presentation
  Subject: Operations and Traffic Management
  Session: 253
  Paper Number: Z13-253