Hatem Abou-Senna

This paper focuses on Dynamic Message Signs (DMS) as crucial traffic control devices, providing real-time traffic information to drivers. With a view to better communication, some state transportation agencies have started using nontraditional messages on DMS to influence driver visual attention, but there is a lack of scientific evidence supporting their effectiveness. The study aims to investigate how message type (traditional vs. creative) impacts driver visual attention, considering individual differences and contextual factors such as age, gender, time of day, and traffic density. The statistical analyses revealed that drivers notice traditional signs faster but look at creative signs longer, regardless of sign word number. Age and gender also play a role in visual attention, with older participants taking slightly longer to notice DMS, while middle-aged individuals tend to examine traditional messages longer than younger participants observing creative signs. Furthermore, driving conditions have an impact on visual attention, with night driving resulting in longer noticing times and shorter dwell times compared to daytime driving. In low-density traffic conditions, drivers have longer gaze durations on signs, while the time-to-notice remains consistent across traffic densities. Interestingly, drivers notice traditional messages faster in low-density traffic but spend less time looking at them compared to creative messages in high-density traffic. Notably, the most common sign that was correctly recalled was a creative sign, supporting the notion that they were particularly attention-grabbing with lasting cognitive effects. Our findings suggest that creative DMS, regardless of word length, are potent in drawing driver’s attention compared to traditional signs.

Electric buses (EBs) are increasingly adopted for their environmental and operational benefits, yet their real-world efficiency is influenced by climate, route characteristics, and auxiliary energy demands. While most existing research identifies winter as the most energy-intensive season due to cabin heating and reduced battery performance, this study presents a contrasting perspective based on a three-year longitudinal analysis of the LYMMO fleet in Orlando, Florida—a subtropical U.S. region. The findings reveal that summer is the most energy-intensive season, primarily due to sustained HVAC usage driven by high ambient temperatures—a seasonal pattern rarely reported in the current literature and a key regional contribution. Additionally, idling time exceeds driving time across all seasons, with HVAC usage during idling emerging as the dominant contributor to total energy consumption. To mitigate these inefficiencies, a proxy-based HVAC energy estimation method and an optimization model were developed, incorporating ambient temperature and peak passenger load. This approach achieved up to 24% energy savings without compromising thermal comfort. Results validated through non-parametric statistical testing support operational strategies such as idling reduction, HVAC control, and seasonally adaptive scheduling, offering practical pathways to improve EB efficiency in warm-weather transit systems.

A permissive left turn is one of the most dangerous movements a driver can make because the driver travels across opposing traffic lanes. In recent years, flashing yellow arrow (FYA) signals have been proven to help drivers make safer left turns. The four-section signal display with FYA permissive left-turn indication creates an opportunity to enhance the left-turn phase with a variable mode that can change on demand. A challenge to using this system is knowing the best times of day to apply the FYA indication. The authors developed an exclusive hardware platform: first, to provide a generic device compatible with the different controller types used by different jurisdictions and, second, to automate selection of the FYA left-turn modes based on available gaps in the opposing traffic at intersections acquired in real time from existing sensors in the field. Phase IV provided conclusive field testing and evaluation of the decision support system (DSS), by switching between red and FYA modes in a rational manner consistent with driver expectations and left-turning gap acceptance thresholds. It was also concluded that coordinated signals with long cycle lengths, 3 min and longer, help provide adequate gaps even in heavy traffic patterns since most of the vehicle arrivals are in platoons and at the beginning of the cycle. The analysis showed that the utilization factor for the DSS recommendations for all the intersections ranged between 65% and 75% during peak conditions on weekdays and between 90% and 95% during off-peak conditions and weekends. The total delay in the before study for all the intersections amounted to 737 vehicle-hours and in the after-study was 440 vehicle-hours of delay. An overall reduction of about 40% in delay which confirms the operational benefit of the dynamic FYA DSS. The developed platform is applicable at any four-section head configuration to maximize safety and efficiency of the intersections.

Express lanes (ELs) are an increasingly accepted traffic management tool for congestion relief and traffic efficiency. White, yellow, and orange vertical delineators are typically used for lane separation and channelization applications. However, upcoming changes to sections of the Manual on Uniform Traffic Control Devices that would affect the current use of the orange retroreflective delineators will have a statewide impact on current and future ELs. The availability of a wide array of delineator colors and the potential range of application purposes brings into question this blanket requirement. The ineffective use of color in roadway design could lead to an increase in driving errors/response time, driver fatigue, loss of situational awareness, and increased workload. Driver perception and reaction time is shown to be affected by visual factors, such as color, luminance, distractions, and speed. The objective of this study is to determine the impact of color usage and other environmental and demographic factors on driver perception. A fractional factorial experiment was designed to study the EL delineator color selection using a driving simulator and an eye-tracking device. The potential factors included time of day (night versus day), visibility (high versus low), traffic density (high versus low), and road surface type (concrete versus asphalt). Some 176 subjects were selected to participate in the experiment. It was found that, in general, white was the quickest to be noticed, while black took the longest time to perceive. Furthermore, it was found that delineators were generally more noticeable under night-time conditions, likely because of the standard use of retroreflective striping on delineators.

Distracted driving poses one of the most difficult challenges to ensuring a safe and efficient transportation system. Modern communications have delivered greater convenience. However, this has come at the cost of attention spans. Safety has been thoroughly explored from the perspective of distracted driving. However, impacts on traffic operations have received minimal research attention. A few studies have provided a theoretical mechanism on how intersection operations can be affected, but fail to quantify the real-life impacts on traffic operations. This research aims to quantify how distracted driving affects vehicle discharge headways at signalized intersections for through lanes. Thousands of observations were collected from four intersections in Orange County, Florida, covering a variety of land uses, intersection configurations, and periods of high demand. The results demonstrated that approximately a quarter of all drivers were distracted. Drivers were less distracted in commercial zones and more attentive to signal changes compared to school and residential areas. Cell phone usage had the primary effect on headways among distraction types with a 20% increase, which resulted in reducing the intersection capacity by 16.5%. The statistical model demonstrated that the overall effect of distraction on the discharge headway is significant. The base headway increased by 0.93 s, which resulted in reducing the intersection capacity by 45.5%. The results also revealed that the 10th vehicle position in the queue had a detrimental effect on the headway and the overall intersection capacity. The green phase gaps out because of the amount of time needed to reach the stop bar.

The increase in the left‐turn demand is the main cause of congestion at conventional intersections, and the traditional countermeasures are inadequate to solve this congestion due to the high changes in demand. This paper looks at the justifying threshold to redesign a signalized intersection from a conventional intersection (CI) to a continuous flow intersection (CFI) and create performance guidelines for decision‐makers and professionals deciding to consider the alternative. A performance comparison between the CI and CFI was conducted to define the main parameters affecting the operational performance. To accomplish the paper’s objective, candidate locations that have already implemented the CFI were identified, and the location with sufficient data for analysis was selected. After the consideration of different evaluation tools, microsimulation (VISSIM 8) was utilized to model the before and after conditions of the location. Using the field data, signal optimization and driving behavior parameter sensitivity analysis were performed to calibrate the models to replicate real‐life conditions. Afterwards, an experiment was designed to examine the different factors that affect the efficiency of each design. The experiment involved 72 different configurations of CFI and CI with 5 different volume levels and used two measures of effectiveness, average vehicle delay, and capacity to assess the results. The results were used to develop guidelines that will help the decision‐makers to decide which design should be considered, which will result in developing a decision support system that will accelerate finding which design is superior to others.

The right-turn flashing yellow arrow (FYA) signal display is still considered a new signal practice in the United States. The Manual on Uniform Traffic Control Devices (MUTCD; 2009) allocates a signal phasing section for the right-turn FYA, which requires a four-section configuration. It supports multiple phase indications that guide the motorists through permissive, protected, or permissive or protected phases. However, there are no right-turn FYA or protected permissive right turn (PPRT) guidelines in place with a focus on operational efficiency. In this paper, we investigated two permissive right-turn FYA phases in various traffic conditions and signal timing plans. The first permissive right-turn FYA phase is the right turn on impeding through (RTOIT) taking place during cross-street through movement. The second permissive right-turn FYA phase occurs during opposing left-turn movement and is thus called right turn on impeding left (RTOIL). We aimed to develop warrants leading to the efficient implementation of permissive right-turn FYA phases based on a microsimulation analysis. The response, the average maximum right-turn throughput (MRTT) per cycle, was categorized into three categorical variables represented as the nonefficient (NE), low efficient (LE), and efficient (E) categories depending on the number of executed right turns per cycle. A multinomial logit model was developed to establish a decision support system that predicts the efficiency attributes of the permissive RTOIT and RTOIL FYA phases that can help traffic management center operators in planning and operational-level applications.