Speed Signs Research Articles

Development of a Traffic Speed Limit Sign Detection System Based on Yolov4 Network

Recent developments in artificial intelligence technologies have accelerated the transition to smart systems in the automotive industry. By anticipating driving conditions, these technologies enable the prevention of driver-related errors and accidents as well as the provision of crucial information to the driver. In this study, an artificial intelligence-based system is designed to provide information to drivers about speed signs on the road in order to support traffic safety. In this system, Yolov4 model is used to achieve high speed and accuracy levels. After the model training, the model was validated and the test results were found to be 98%.

Detection of Traffic Signs using feature based on of Speed Up Robust method

Variations in perspective, illumination, occlusion, motion blur, and weatherworn degeneration of signs could all be crucial in identifying road signs. The goal of this project is to evaluate the image processing technique's performance in detecting and recognizing road signs, as well as determine the optimum threshold value range for doing so. The Speed Up Robust Features (SURF) detector was tested in the current project to detect and recognize road signs through Bagdad’s streets under various speeds and threshold values. The importance of the threshold’s value was highlighted here to occupy an accurate detection and hence recognize road sign at final. The optimum threshold value for best detection resulted usually in the range (20-25) for all speed signs. The latter recorded its highest precision value at five threshold value while the highest precision value (i.e. 0.5) resulted for speed sign 40 followed by 60 and 80-speed signs

Enhancement of Vehicle Eco-Driving Applicability through Road Infrastructure Design and Exploitation

Energy moderation of the road transportation sector is required to limit climate change and to preserve resources. This work is focused on the moderation of vehicle consumption by optimizing the speed policy along an itinerary while taking into account vehicle dynamics, driver visibility and the road’s longitudinal profile. First, a criterion is proposed in order to detect speed policies that are impeding drivers’ eco-driving ability. Then, an energy evaluation is carried out and an optimization is proposed. A numerical application is performed on a speed limiting point with 20 usage cases and 5 longitudinal slope values. In the hypothesis of a longitudinal slope of zero, energy savings of 27.7 liter per day could be realized by a speed sign displacement of only 153.6 m. Potential energy savings can increase to up to 308.4 L per day for a −4% slope case, or up to 70.5 L per day for an ordinary −2% slope, with a sign displacement of only 391.5 m. This results in a total of 771,975 L of fuel savings over a 30 year infrastructure life cycle period. Therefore a methodology has been developed to help road managers optimize their speed policies with the aim of moderating vehicle consumption.

Freeway Crash Prediction Models with Variable Speed Limit/Variable Advisory Speed

Variable speed limit (VSL) and variable advisory speed (VAS) signs are efficient, cost-effective and among the state-of-the-art active traffic management (ATM) strategies. They adopt the idea of dynamically changing posted speed limits to improve highway safety performance and operation by harmonizing traffic speed. VSL/VAS system involves changing speed limits according to real-time traffic events and weather conditions. Hence, traditional average annual daily traffic (AADT) based crash prediction models may not capture the temporal effect of traffic characteristics due to the high level of aggregation. To address this issue, short-term safety performance functions (SPFs) with aggregation levels of average annual weekday hourly traffic (AAWDHT) and average annual weekday peak traffic (AAWDPT) along with AADT-based SPFs were developed using high-resolution traffic detector and VSL/VAS operational data. In this study, the Poisson log-normal model performed well at each level of aggregation and thus is recommended for developing short-term SPFs. In line with previous studies, traffic volume and standard deviation of speed were found to be positively associated with crash frequency in all the estimated models. In addition, it was found that implementation of VSL/VAS significantly reduced crash frequency by 15.97% and 26.14% for the AAWDHT and AAWDPT models, respectively. The safety improvement was captured in the short-term models in a more distinguished way than in the highly aggregated AADT-based model. The findings of this study pave the way for practitioners and policymakers to evaluate and select important parameters for VSL/VAS strategy implementation on freeways.

Which visual cues do drivers use to anticipate and slow down in freeway curve approach? An eye-tracking, think-aloud on-road study

Although much research is done on speed and gaze behaviour inside curves, there is little understanding of which cues drivers use to anticipate and slow down while approaching curves. Therefore, an on road experiment was conducted in which 31 participants drove through six freeway curves in their own car. During the experiment, look-ahead fixations and speed were recorded using an eye-tracker and a GPS tracker, respectively. In addition to these measurements, the participants verbalised their reasons for changing speed. The distribution of fixations over various areas of interest was investigated around the start of deceleration before each curve and around the start of each curve. Verbalisation data were analysed to infer the number and types of reasons for changing speed and when these were mentioned together with mentions of deceleration before a curve. The results showed that before starting to decelerate, the participants fixated mostly on the Focus of Expansion and edges parallel to the curve trajectory, whereas most fixations on warning or speed signs were recorded mostly after participants started to decelerate. These findings suggest that drivers use information from the Focus of Expansion, be it a change in optical flow or the presence of a kink in the alignment, as the main cue to start decelerating. Parallel edges are also important cues, whereas warning and speed signs are primarily used to confirm that a speed change is needed.

Propagating direction in the two species Lotka-Volterra competition-diffusion system

The sign of the traveling wave speed in the two species Lotka-Volterra competition-diffusion system under strong competition provides important information about the competitive advantage of the species. To study the sign problem, we propose a mini-max characterization of the coefficients in the reaction terms when the wave speed is zero. Applying our characterization, some explicit conditions under which the speed sign can be determined are obtained.

Automating the updated grade severity rating system (GSRS) using the Visual Basic.net programming language

Truck crashes on steep downgrades due to excessive brake heating, resulting from brake applications to control speeding, are a continuing cause of concern for the Wyoming Department of Transportation (WYDOT). In 2016, WYDOT funded a project to update the existing Grade Severity Rating System. Furthermore, in 2020, WYDOT commissioned a research project to automate the updated version of the mathematical model through an interactive, intuitive, aesthetically appealing and user-friendly Visual Basic.net objected-oriented software to simplify the computation of the maximum safe descent speed on these downgrades based on the truck weight. The software provides functionality for both the continuous Slope and separate downgrade methods. The primary beneficiaries of this software will be the highway agencies who will be able to estimate the maximum safe speed of descent for trucks with various weight categories and hence produce Weight Specific Speed (WSS) signs for each downgrade or a multigrade section.

Quantifying the Foregone Benefits of Intelligent Speed Assist Due to the Limited Availability of Speed Signs across Three Australian States.

By being able to communicate the speed limit to drivers using speed sign recognition cameras, Intelligent Speed Assist (ISA) is expected to bring significant road safety gains through increased speed compliance. In the absence of complete digital speed maps and due to limited cellular connectivity throughout Australia, this study estimated the forgone savings of ISA in the event that speed signs are solely relied upon for optimal advisory ISA function. First, speed-related fatalities and serious injuries (FSI) in the Australian states of Victoria, South Australia, and Queensland (2013–2018) were identified, and published effectiveness estimates of ISA were applied to determine the potential benefits of ISA. Subsequently, taking into account speed sign presence across the three states, the forgone savings of ISA were estimated as FSI that would not be prevented due to absent speed signage. Annually, 27–35% of speed-related FSI in each state are unlikely to be prevented by ISA because speed sign infrastructure is absent, equating to economic losses of between AUD 62 and 153 million. Despite a number of assumptions being made regarding ISA fitment and driver acceptance of the technology, conservative estimates suggest that the benefits of speed signs placed consistently across road classes and remoteness levels would far outweigh the costs expected from the absence of speed signs. The development and utilisation of a methodology for estimating the foregone benefits of ISA due to suboptimal road infrastructure constitutes a novel contribution to research. This work provides a means of identifying where infrastructure investments should be targeted to capitalise on benefits offered by advanced driver assist technologies.

The lack of correlation between symptoms and signs in patients with meibomian gland dysfunction: a secondary analysis of the multicenter, randomized controlled trial

BackgroundThis study was performed to investigate the association between symptoms and signs in patients with meibomian gland dysfunction (MGD).MethodsData were obtained from 122 MGD patients who were recruited for intense pulsed light therapy from November 2017 to April 2018 and the severity of their symptoms and signs at baseline were observed and recorded. Spearman correlation analyses were performed to analyze the relationships between SPEED score and signs. Subjects were divided into different subgroups based on possible influencing factors, and the differences in symptoms and signs were compared between different subgroups. Then influencing factors were controlled by regression analysis to explore the relationship between symptoms and signs and the strong factors affecting symptoms and signs.ResultsAnalysis of baseline data showed that SPEED scores were not correlated with TBUT, CFSS, MGYSS or any index of eyelid margin abnormality (p > 0.05). In addition, abnormalities of lid margins, including hyperemia, thickening, rounding, hyperkeratinization, and telangiectasia around orifices, were more likely to occur in older patients, menopausal patients, and patients living in northern China. Multiple linear regression analysis indicated that there was still no correlation between symptoms and signs (p > 0.05) after adjusting for influencing factors. Further analysis suggested that each influencing factor has different effects on symptoms and signs, among which menopause affects the SPEED score (R = -4.112, p = 0.025), and age and region have significant effects on eyelid margin abnormalities.ConclusionsIn conclusion, the results demonstrated a poor correlation between symptoms and signs in MGD patients. Age, hormone, and a dry environment may influence the disease, which suggests that the severity of the disease needs to be comprehensively assessed.

Evaluating Driver Response to a Dynamic Speed Feedback Sign at Rural Highway Curves

Research was performed to assess the effectiveness of a dynamic speed feedback sign (DSFS) as a speed reduction countermeasure when installed at horizontal curves on rural highways. It was of particular interest to assess whether the DSFS effectiveness varied based on curve advisory speed and to identify the optimal DSFS placement location with respect to the curve. A series of field evaluations were performed at five horizontal curves located along two-lane rural state highways in northern Michigan possessing posted speed limits of 65 mph and curve advisory speeds varying between 25 and 60 mph. The DSFSs were installed and evaluated at two different locations at each curve: 1. at the curve advance warning/advisory speed sign and 2. at the point of curvature. Vehicle speeds were tracked along the approach to each curve using handheld LIDAR guns. The results indicate that the DSFS was generally more effective at reducing motorists’ speeds when installed near the advance curve warning sign. Furthermore, the DSFS was more effective at locations with sharper curvature (i.e., lower advisory speeds). Continued use of DSFSs as a speed reduction countermeasure on rural horizontal curves is recommended, particularly at locations with a significant differential (e.g., at least 25 mph) between the upstream speed limit and the curve advisory speed. The DSFS should be positioned near the advance curve warning/advisory speed sign to provide adequate time for drivers to react and decelerate before reaching the curve.

The need for independent safety investigation and regulation of road infrastructure

Morgan’s article (Morgan, 2022) raises an important topic and makes valuable points. In complex systems, crashes result from a combination of factors. Often, not all are recognised, a phenomenon known as What-You-Look-For-Is-What-You-Find (Lundberg et al., 2009). While driving over 40,000km around Australia, nonsensical or dangerous signage has been observed. For example, a 100km/h speed sign was posted when leaving a town, and that road terminated less than 100m later at a T-junction with a highway. Another example is the use of roadwork signs with no road workers, no pavement narrowing, or no roadworks at all. As Morgan (2022) indicates, poor signage contributes to crashes.

Automatic Speed Control System in Speed Zone Areas Using OpenCV

Road accidents near school or hospital zones are all too common in today’s environment. We see a lot of people driving at high speeds under the influence of alcohol or for thrill causing road accidents. So, vehicle speed control must be taken into consideration to avoid casualties due to over speeding. The purpose of this system is to control the speed of the vehicle by recognizing speed sign boards on the roadside with the help of Rasberry Pi board and image processing. The camera is positioned at the front of the vehicle to capture the images of sign boards to process them. The captured images are then compared with the stored images using Python open CV to control the vehicle’s speed in the speed restricted areas. The objective of this project is to reduce the accidents caused due to over speeding.

Safety Evaluation of Freeway Exit Ramps with Advisory Speed Reductions

Posted speed limits inform drivers of the legal maximum allowable speed. In contrast, advisory speeds provide recommendations to drivers based on highway design, operating characteristics, and conditions. Various studies have investigated the safety impacts of speed limit changes, particularly on high-speed rural highways. One area of particular concern on such roadways is the approach to exit ramps that require substantive speed reductions, such as loop ramps. To date, there has been limited research examining the safety impact of the differential between the mainline speed limit and the lower exit ramp advisory speeds. This study aims to evaluate this relationship through the estimate of a series of safety performance functions. Random effects negative binomial regression models were estimated using data from 187 exit ramps where advisory speed signs are present throughout Michigan. The analyses were conducted based on a five-year period from 2014 to 2019, excluding 2017 data because of speed limit increases. In addition to speed differentials, various roadway characteristics such as deceleration lane length and curve radius were also evaluated. Results indicate that crashes increased as the difference between mainline and ramp speed increased. Crashes were also shown to decrease on ramps where the upstream deceleration lane length was greater than the minimum recommendation as per current design guidance.

Bistable wave-speed for monotone semiflows with applications

The sign of bistable wave speed indicates the propagation direction of bistable wavefronts. This paper deals with the propagation dynamics of bistable traveling waves for abstract monotone semiflows. We first prove that the bistable wave speed is unique and bounded by spreading speeds of two mono-stable subsystems. We then establish speed-sign determinacy by way of comparison principles. Based on these results, for both irreducible and reducible cases we derive general conditions for determining the speed sign. Finally, the obtained theory is applied to three kinds of evolution systems.

Incorporating Horizontal Curves and Roadway Geometry into the Automated Updated Grade Severity Rating System

Highway agencies all around the country, including the Wyoming Department of Transportation (WYDOT), have deep concerns about truck crashes resulting from brake temperatures exceeding the critical brake temperature as they descend steep downgrades. Through a series of research initiatives starting in the 1980s, WYDOT has developed a Grade Severity Rating System (GSRS) to estimate the maximum safe speed for trucks during downgrade descent. In 2020, the updated mathematical model was automated through an interactive, intuitive, aesthetically appealing, and user-friendly objected-oriented Visual Basic.net software. Additional research on the GSRS model was commissioned by WYDOT to account for large truck vehicle stability—specifically, rollovers and skidding/side slip during grade descent. These scenarios become relevant in the presence of horizontal curves. Consequently, this latest mathematical model has been automated to simplify the computation of maximum safe descent speed on the downgrades combined with curves, all based on the truck weight. As in the previous version of the software, it provides functionality for both the continuous slope and the separate downgrade method. The primary beneficiaries of the software will be highway agencies who will be able to estimate the maximum safe speed of descent for trucks descending downgrades with horizontal curves at various weight categories and therefore produce Weight Specific Speed (WSS) signs for each downgrade or multi-grade section.

Speed sign of traveling waves to a competitive Lotka-Volterra recursive system with bistable nonlinearity

<p style='text-indent:20px;'>Traveling wave propagation is a significant phenomenon observed in population biology. Due to the occurrence of nonlocal effect in recursive systems, a deep understanding of the wavefront in the propagation direction (speed sign) is challenging. In this paper we study the sign of wave speed for bistable traveling waves to a two-species competitive system that biologically models the dynamics of two species in competition for a common resource. By a proper choice of the kernel functions, we transfer our model into a coupled localized differential system and shed a new light on how to determine the wave speed sign. Sufficient conditions with symmetry are obtained on the propagation directions of the wavefronts. This symmetry is further verified in the final analysis and numerical simulations are provided to illustrate our theoretical results.</p>

Driver’s visual perception as a function of age. Using a driving simulator to explore driver’s eye movements in vertical signs

This research aims to evaluate the impact of age on the driver’s attention and perception of road signs, using a driving simulator. The sample focused on drivers aged between 20 and 60 years, since this age range accounts for the largest number of qualified drivers - almost 75% of the total. As drivers gain more experience on the road, the more likely they are to drive safely and therefore, less likely to crash. However, many young and adult drivers become overconfident in their ability to drive and mistakenly believe they are driving safely. The sample studied was analyzed according to the following age groups: Group I, “young” drivers and Group II, “adult” drivers. The collected data included that from the eye tracking system (SmartEye) and questionnaires applied after the experiment. The test scenario replicated a 10 km stretch of a Brazilian highway were the gaze tracking data allowed the measurement of the following variables: observation time, maximum fixation time of signals and the number of signs observed. Both groups had excellent performances in the Simulator’s Post-Drive Questionnaire, with an average correct rate of 94% for Group I and 89% for Group II. Regarding the data provided by eye-tracking system, Group II proved to be more attentive in perceiving speed signs, although in general, they needed to observe the speed sign for longer to be able to perceive it.

Development of a Methodology for Estimating the Availability of ADAS-Dependent Road Infrastructure

Advanced driver assist systems are being promoted with the expectation that enhanced driver support will mitigate road trauma. While these technologies are optimised for certain road and traffic conditions, not all roads across Australasia are equipped with ADAS-supportive infrastructure. This study developed a desk-top methodology for using road classes (disaggregated by remoteness levels) to estimate the presence of quality roads, road delineation and speed signage in Victoria, Australia. Aerial imagery and mapping data were used to assess a number of random locations based on a developed protocol. The methodology demonstrated that in Victoria, major and arterial roads across all remoteness levels had high-quality sealed surfaces but 42% of all remote roads were unsealed. Delineation (crucial for lane support systems) were absent across 73% of sub-arterial roads independent of remoteness, and absent across 96% of sub-arterial roads in regional and remote areas. Speed sign availability across remote and regional areas was sparse, with only 65% of all roads assessed having signage. Results are reflective of Victoria’s road funding model and consistent with on-road audits conducted by other researchers. This methodology enables the proportion ADAS-ready roads to be estimated so the benefits of ADAS technologies can be quantified and investments into ADAS-supportive infrastructure be readily allocated.

The Road Speed Sign Board Recognition, Steering Angle and Speed Control Methodology based on Double Vision Sensors and Deep Learning

The Road Speed Sign Board Recognition, Steering Angle and Speed Control Methodology based on Double Vision Sensors and Deep Learning

Evaluation of Integrated Variable Speed Limit and Lane Change Control for Highway Traffic Flow

A sudden lane drop on a freeway with high volume of vehicles can cause severe traffic congestion and safety issues. Forced lane changes near the bottleneck reduce the traffic mobility on all lanes and trigger the capacity drop phenomenon. Numerous studies have explored the effect of Variable Speed Limit (VSL) and Lane Change (LC) control on solving the bottleneck congestion, but only a few have taken the measurement or model uncertainties into considerations. In this paper, we design an integrated VSL and LC controller based on a modified multi-section Cell Transmission Model (CTM) to alleviate the freeway bottleneck congestion and reject uncertainties. The location of the most upstream speed sign is treated as a parameter and optimized using simulation data. We first evaluate the proposed controller without uncertainty to demonstrate its effectiveness in improving traffic flow. Then we incorporate the uncertainties in measurements and model parameters to examine the robustness of the control. The proposed combined VSL and LC controllers are demonstrated to be robust with respect to uncertainties. The bounds of allowable uncertainties are more sensitive when uncertainties lead to a reduction of speed limit commands than an increase.