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Concept: Traffic light


Since their appearance at the end of the 19th century, traffic lights have been the primary mode of granting access to road intersections. Today, this centuries-old technology is challenged by advances in intelligent transportation, which are opening the way to new solutions built upon slot-based systems similar to those commonly used in aerial traffic: what we call Slot-based Intersections (SIs). Despite simulation-based evidence of the potential benefits of SIs, a comprehensive, analytical framework to compare their relative performance with traffic lights is still lacking. Here, we develop such a framework. We approach the problem in a novel way, by generalizing classical queuing theory. Having defined safety conditions, we characterize capacity and delay of SIs. In the 2-road crossing configuration, we provide a capacity-optimal SI management system. For arbitrary intersection configurations, near-optimal solutions are developed. Results theoretically show that transitioning from a traffic light system to SI has the potential of doubling capacity and significantly reducing delays. This suggests a reduction of non-linear dynamics induced by intersection bottlenecks, with positive impact on the road network. Such findings can provide transportation engineers and planners with crucial insights as they prepare to manage the transition towards a more intelligent transportation infrastructure in cities.

Concepts: Transport, Road, Street, Traffic, Infrastructure, Traffic light, 19th century, Pedestrian crossing


ACCESSIBLE SUMMARY: This paper discusses how an acute inpatient unit has implemented the ‘Productive Ward’ initiative, and utilized three of the Productive Ward Modules - Ward Round, Admissions and Planned Discharge, and Patient Status At a Glance - to promote better communication and working between inpatient nursing and medical teams, Home Treatment Team and Community Mental Health Team (CMHT), as they endeavour to ensure timely discharge for patients. Using the Patient Status At a Glance board to make information on patient status clear and immediate, nursing staff have begun utilizing the Zoning system for managing and targeting nursing resources - a red, amber and green traffic light system, which identifies and categorizes patient risk on a daily basis. Ward staff have initiated a daily ‘Rapid Review’ of patients, a tightly focused meeting, involving the ward nursing staff, the Inpatient Medical Team, the Home Treatment Team and the CMHT to discuss allocation of Care Co-ordinators, and to identify accommodation issues and other potential blocks to timely discharge. The Productive Ward is an initiative whereby nursing staff are empowered to bring about changes in the workplace to streamline systems and release time to care for patients. It is an evidence-based approach, which brings about improved clinical and safety outcomes. This paper discusses how three of the Productive Ward Modules - Ward Round, Admissions and Planned Discharge, and Patient Status At a Glance - have meshed to promote better communication and working between inpatient nursing and medical teams, Home Treatment Team and Community Mental Health Team, and to endeavour to ensure timely discharge for patients.

Concepts: Health care provider, Health, Patient, Physician, Illness, Patience, Nursing, Traffic light


Colour coded front-of-pack nutrition labelling (‘traffic light labelling’) has been recommended for use in the UK since 2006. The voluntary scheme is used by all the major retailers and some manufacturers. It is not clear how consumers use these labels to make a single decision about the relative healthiness of foods. Our research questions were: Which of the four nutrients on UK traffic light labels (total fat, saturated fat, sugar and salt) has the most influence on decisions? Do green lights or red lights have a greater influence? Are there age and gender differences in how people use the colour and nutrient information?

Concepts: Nutrition, Nutrient, Vitamin, Food, Green, Saturated fat, Label, Traffic light


The green and red lights of a traffic signal can be viewed as the up and down states of an Ising spin. Moreover, traffic signals in a city interact with each other, if they are controlled in a decentralised way. In this paper, a simple model of such interacting signals on a finite-size two-dimensional lattice is shown to have Ising-like dynamics that undergoes a ferromagnetic phase transition. Probabilistic behaviour of the model is realised by chaotic billiard dynamics that arises from coupled non-chaotic elements. This purely deterministic model is expected to serve as a starting point for considering statistical mechanics of traffic signals.

Concepts: Fundamental physics concepts, Physics, Paramagnetism, Ferromagnetism, Phase transition, Green, Traffic light, Ising model


The implementation of a standardized front-of-pack-labelling (FoPL) scheme would likely be a useful tool for many consumers trying to improve the healthfulness of their diets. Our objective was to examine what the traffic light labelling scheme would look like if implemented in the US. Data were extracted from Label Insight’s Open Access branded food database in 2017. Nutrient levels and the proportion of products classified as “Red” (High), “Amber” (Medium) or “Green” (Low) in total fat, saturated fat, total sugar and sodium for food and beverage items were examined. The proportion of products in each category that had each possible combination of traffic light colors, and met the aggregate score for “healthy” was examined. Out of 175,198 products, >50% of all US packaged foods received a “Red” rating for total sugar and sodium. “Confectionery” had the highest mean total sugar (51.9 g/100 g) and “Meat and meat alternatives” the highest mean sodium (781 mg/100 g). The most common traffic light label combination was “Red” for total fat, saturated fat and sodium and “Green” for sugar. Only 30.1% of products were considered “healthy”. A wide variety (n = 80) of traffic light color combinations were observed. A color coded traffic light scheme appears to be an option for implementation across the US packaged food supply to support consumers in making healthier food choices.

Concepts: Health, Nutrition, Food, Color, Green, Saturated fat, Traffic light, Color code


The assumed minimum walking speed at pedestrian crossings is 1.2 m/s. In this prospective cohort study, usual walking speed was measured over a 4 m course in 926 community-dwelling, ambulatory patients with stable COPD. Mean (SD) walking speed was 0.91 (0.24) m/s with only 10.7% walking at a speed equal or greater than 1.2 m/s. In order for 95% of this cohort to safely negotiate a pedestrian cross, traffic lights would have to assume a minimum walking speed of 0.50 m/s (2.4 times longer than current times). The current assumed normal walking speed for pedestrian crossings is inappropriate for patients with COPD.The studies were registered on and these data relate to the pre-results stage: NCT01649193, NCT01515709 and NCT01507415.

Concepts: Clinical trial, Walking, Road, Traffic, Locomotion, Traffic light, Pedestrian, Pedestrian crossing


In 2010, British Columbia (BC) introduced new traffic laws designed to deter impaired driving, speeding, and distracted driving. These laws generated significant media attention and were associated with reductions in fatal crashes and in ambulance calls and hospital admissions for road trauma.

Concepts: Canada, Road, Traffic, Driving, Freeway, Traffic law, Traffic light, British Columbia


This work applies evolutionary computation and machine learning methods to study the transportation system of Quito from a design optimization perspective. It couples an evolutionary algorithm with a microscopic transport simulator and uses the outcome of the optimization process to deepen our understanding of the problem and gain knowledge about the system. The work focuses on the optimization of a large number of traffic lights deployed on a wide area of the city and studies their impact on travel time, emissions and fuel consumption. An evolutionary algorithm with specialized mutation operators is proposed to search effectively in large decision spaces, evolving small populations for a short number of generations. The effects of the operators combined with a varying mutation schedule are studied, and an analysis of the parameters of the algorithm is also included. In addition, hierarchical clustering is performed on the best solutions found in several runs of the algorithm. An analysis of signal clusters and their geolocation, estimation of fuel consumption, spatial analysis of emissions, and an analysis of signal coordination provide an overall picture of the systemic effects of the optimization process.

Concepts: Algorithm, Evolution, Artificial intelligence, Machine learning, Learning, Traffic, Traffic light, Evolutionary algorithm


The symptomatology of autism spectrum disorder (ASD) can make driving risky, but little is known about the on-road driving behaviour of individuals with ASD. This study assessed and compared the on-road driving performance of drivers with and without ASD, and explored how the symptomatology of ASD hinders or facilitates on-road driving performance. Sixteen drivers with ASD and 21 typically-developed drivers participated in the study. Drivers with ASD underperformed in vehicle manoeuvring, especially at left-turns, right-turns and pedestrian crossings. However, drivers with ASD outperformed the TD group in aspects related to rule-following such as using the indicator at roundabouts and checking for cross-traffic when approaching intersections. Drivers with ASD in the current study presented with a range of capabilities and weaknesses during driving.

Concepts: Autism, Pervasive developmental disorder, Asperger syndrome, Autism spectrum, PDD-NOS, The Current, Traffic light, Traffic calming


Research in the laboratory as well as in naturalistic driving studies has shown that texting while driving seems to be the most dangerous driver distraction. However, there is still some discussion about the extent to which drivers adapt their behavior to the traffic situation. Accordingly, they might use their phones only in easy driving situations but refrain from doing so when driving becomes more demanding. For Germany, no reliable data on these topics could be found although overall smartphone use has also increased exponentially in this country. As observational studies have proven to be an effective means to gather these data, such a study was done observing 11,837 drivers in three big German cities (Braunschweig, Hannover, Berlin) during daytime. An alarmingly high rate of texting while driving was found (4.5%) as compared to other international studies. This was even more frequent than the use of handheld (2.2%) and hands-free (1.7%) phones combined. Thus, there seems to be a special problem in Germany with texting which should be further examined as this activity is highly distracting. Finally, there was some indication that drivers adapt their secondary task activities to the requirements of the driving task (e.g. somewhat less texting when moving than when stationary at a red traffic light). However, these adaptations were not very strong. Thus, drivers seem to underestimate the dangers due to distraction. This could be a starting point for countermeasures which increase this awareness of danger.

Concepts: Scientific method, Germany, Activity, Human behavior, Mobile phone, Traffic, Traffic light, BlackBerry