2013 Session: 438

• Safety and Operational Benefits of Variable Speed Limit Under Different Traffic Conditions and Driver Compliance Levels
  Abstract: Control of traffic by Variable Speed Limit (VSL) has been researched for a long time but there is lack of consensus on the safety and operational benefits of VSL and on the impact of driver compliance. The objective of this paper is to provide quantitative evaluations of these benefits and show the importance of driver compliance to VSL which ultimately narrows down the lack of consensus. Combination of VISSIM and Surrogate Safety Assessment Model (SSAM) was used in the study. SSAM analyzes the trajectories of simulated vehicles and detect possible conflicts along their journey. To support the safety analysis of this study, an attempt was done to correlate the simulated vehicle conflicts with historic crashes. Three scenarios of traffic conditions were considered, namely: 1) heavily congested, 2) lightly congested, and 3) non-congested. Each scenario is further examined under four driver compliance levels, including: 1) low compliance, 2) medium compliance, 3) high compliance, and 4) very high compliance. The results confirmed that VSL has safety and operational benefits on motorway traffic. VSL has the highest safety benefits during highly congested traffic conditions followed by lightly congested and least during non-congested conditions. Moreover, the system has the highest operational benefits during lightly congested traffic conditions, little during non-congested and no benefit during heavily congested conditions. It was also found that the safety benefits of VSL are not at the expenses of increase in travel time. However, these benefits showed significant variations depending on the level of compliance to the system. The study concludes that the success of VSL is highly dependent on the level of driver compliance.
  Authors: Habtemichael, Filmon; Picado-Santos, Luis Guilherme
  Authors: Habtemichael, Filmon; Picado-Santos, Luis Guilherme
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management; Safety and Human Factors
  Session: 438
  Paper Number: 13-0138
• Safety Implications of Truck and Car Speed Limits for Two-Lane Highway Operations
  Abstract: The safety implications of car-truck speed limits have not been adequately researched, and this has been especially true for two-lane highways. On two-lane highways speed controls can have a significant effect on rear-end and head-on vehicle interactions. This paper uses simulation to assess the effect on safety of different speed control strategies applied to two-lane highway operations. Two different types of speed control strategies are considered: uniform speed limit (USL) and car-truck differential, which is introduced in two different ways: discretionary differential car and truck posted speed limits (DSL) and mandated truck speed limiters (MSL). Safety implications are considered using three overtaking-related indicators: Number of vehicles overtaking (NOT), 2) Percentage time spent in “desire to overtake mode” (PTDO), and 3) Average Time-to-Collision (TTC) with the on-coming vehicle prior to returning back to the original lane. Vehicle interactions affecting safety are estimated through the application of a calibrated microscopic traffic simulation model to a 6Km straight segment of two-lane highway with zero and -3% grade.Differential speed strategies (DSL and MSL) were observed to have a slight increase in the total number and rate of overtaking maneuver in comparison to the uniform control strategy (USL). DSL strategies significantly increased the number and rate of car-truck overtakes over the range of volumes considered in the simulation, suggesting a negative effect on safety. At the same time the number of car-car overtakes were reduced suggesting a positive effect on safety. No considerable effects were observed concerning differential speed control strategies and average TTC and PTDO for the studied cases. The number of overtakes were found to be higher on the level segment than the downgrade segment for the control strategy; although, not very significant for MSL. Car-Car and Car-Truck overtakes appeared to be consistently higher in level section than the grade section; however, this was opposite where the MSL strategy was considered.
  Authors: Ghods, Amir H.; Saccomanno, Frank
  Authors: Ghods, Amir H.; Saccomanno, Frank
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management; Safety and Human Factors
  Session: 438
  Paper Number: 13-2329
• Community Perceptions and Beliefs Regarding Low-Level Speeding and Suggested Solutions
  Abstract: Speeding is the single largest behavioural contributor to road traffic deaths and injuries in Australia and the developed world, and the management of speed is critical to the success of the safe systems approach. Analyses of the contribution of various levels of speeding to the road toll are reviewed, demonstrating that low level speeding (within 10km/h of the speed limit) is a major contributor to death and injury. However, speeding, especially low level speeding, remains socially acceptable and commonly practiced by most Australians and is broadly accepted and practiced by drivers throughout the world. This paper reviews evidence of attitudes and beliefs which engender low level speeding from surveys and social media, to suggest policy revisions which may help address this behaviour and its social acceptability, including low tolerances on speed enforcement, escalating penalties for repeat offending as occurs with drink-driving, and penalties more aligned with real risks compared with other risky behaviours. These policies not only directly address low level speeding through deterrence, but also send messages which counter currently held unhelpful beliefs. Additional messages on the accuracy of speedometers and speed detection devices, and the costs of low level speeding to the community, may also be helpful.
  Authors: Job, Raymond Franklin Soames; Sakashita, Chika; Mooren, Lori Elyse; Grzebieta, Raphael H.
  Authors: Job, Raymond Franklin Soames; Sakashita, Chika; Mooren, Lori Elyse; Grzebieta, Raphael H.
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management; Safety and Human Factors
  Session: 438
  Paper Number: 13-5247
• Impact of Dynamic Speed Display Sign on Speed Limit Compliance on Multiple Roadway Classes
  Abstract: This study investigates the effect of dynamic speed display signs (DSDSs) on drivers’ speed-related behavior. A survey questionnaire regarding drivers’ attitudes to a DSDS on different road classes was distributed to supplement a wide-range speed data collection upstream and downstream of the DSDS locations on multiple road classes with different speed limits: 25, 35, and 45 mph. Conventional statistical analysis, regression model, and Bayesian network were applied to assess the DSDS’s effectiveness with reducing speed and to develop a speed compliance model. To investigate the short-term and long-term effects of the DSDS and the effective distance, speed data was collected in different periods after the installation and further downstream of DSDS locations. The effect of road class, school zone, DSDS size, DSDS operation duration, distance from DSDS, and other ambient conditions on drivers’ speed compliance are explored and discussed.
  Authors: Ardeshiri, Anam; Jeihani, Mansoureh
  Authors: Ardeshiri, Anam; Jeihani, Mansoureh
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management; Safety and Human Factors
  Session: 438
  Paper Number: 13-5306
• Safety Implications of Truck and Car Speed Limits for Two-Lane Highway Operations
  Authors: Ghods, Amir H.
  Authors: Ghods, Amir H.
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Operations and Traffic Management; Safety and Human Factors
  Session: 438
  Paper Number: 13-2329
• Toward Multimodal Speed Data Collection in Urban Areas
  Authors: Auberlet, Jean-Michel
  Authors: Auberlet, Jean-Michel
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Operations and Traffic Management; Safety and Human Factors
  Session: 438
  Paper Number: P13-5572
• Modeling Highway Travel Time with Markov Chains
  Authors: Oliveira Neto, Francisco
  Authors: Oliveira Neto, Francisco
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Operations and Traffic Management; Safety and Human Factors
  Session: 438
  Paper Number: P13-5573
• Determining Vehicle Operating Speed and Lateral Position Along Horizontal Curves Using Linear Mixed-Effects Models
  Authors: Fitzsimmons, Eric
  Authors: Fitzsimmons, Eric
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Operations and Traffic Management; Safety and Human Factors
  Session: 438
  Paper Number: P13-5562
• Exploring Real-Time Applications of License Plate Recognition Technology for Tracking Commercial Vehicles
  Authors: Oliveira Neto, Francisco
  Authors: Oliveira Neto, Francisco
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Operations and Traffic Management; Safety and Human Factors
  Session: 438
  Paper Number: P13-5563
• 2012 Maryland State Highway Mobility Report
  Authors: Farokhi Sadabadi, Kaveh
  Keywords: poster presentation; poster design; poster template
  Authors: Farokhi Sadabadi, Kaveh
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Operations and Traffic Management; Safety and Human Factors
  Session: 438
  Paper Number: P13-5564
• Nationally Representative Speeds: How Hard Can It Be?
  Authors: De Leonardis, Doreen
  Authors: De Leonardis, Doreen
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Operations and Traffic Management; Safety and Human Factors
  Session: 438
  Paper Number: P13-5566
• Quality Control of Pneumatic Speed Measurements
  Authors: Bar-Gera, Hillel
  Authors: Bar-Gera, Hillel
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Operations and Traffic Management; Safety and Human Factors
  Session: 438
  Paper Number: P13-5571