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.
The aim of this study was to analyze the association between the characteristics of the built and social and environmental microscale and walking and bicycling for transportation in adults in Curitiba, Paraná State, Brazil. A cross-sectional study was performed in 2009 with a household survey that included 1,419 adults. Objective evaluation of environment was performed on the resident’s street segments, using an instrument for systematic observation consisting of six dimensions: “land use”, “public transportation”, “streetscape”, “conditions and aesthetics”, “places for walking and bicycling”, and “social environment”. The score for each dimension was obtained as the sum of positive items related to physical activity. The items for “public transportation” (≥ 1 items) and “places for walking and bicycling on the streets” (≥ 3 items) were dichotomized, while the scores for the other items were classified in tertiles. Walking and bicycling for transportation were assessed with the International Physical Activity Questionnaire (IPAQ). The data were analyzed using multilevel Poisson regression. Medium “streetscape” score was inversely associated with walking ≥ 150min/week (PR = 0.60; 95%CI: 0.40-0.91; VPC = 12%) and bicycling (PR = 0.54; 95%CI: 0.29-0.99; VPC = 60%). In conclusion, only “streetscape” was associated with walking and bicycling for transportation in adults.
The evolution of infrastructure networks such as roads and streets are of utmost importance to understand the evolution of urban systems. However, datasets describing these spatial objects are rare and sparse. The database presented here represents the road network at the french national level described in the historical map of Cassini in the 18th century. The digitization of this historical map is based on a collaborative methodology that we describe in detail. This dataset can be used for a variety of interdisciplinary studies, covering multiple spatial resolutions and ranging from history, geography, urban economics to network science.
Urban transportation systems are vulnerable to congestion, accidents, weather, special events, and other costly delays. Whereas typical policy responses prioritize reduction of delays under normal conditions to improve the efficiency of urban road systems, analytic support for investments that improve resilience (defined as system recovery from additional disruptions) is still scarce. In this effort, we represent paved roads as a transportation network by mapping intersections to nodes and road segments between the intersections to links. We built road networks for 40 of the urban areas defined by the U.S. Census Bureau. We developed and calibrated a model to evaluate traffic delays using link loads. The loads may be regarded as traffic-based centrality measures, estimating the number of individuals using corresponding road segments. Efficiency was estimated as the average annual delay per peak-period auto commuter, and modeled results were found to be close to observed data, with the notable exception of New York City. Resilience was estimated as the change in efficiency resulting from roadway disruptions and was found to vary between cities, with increased delays due to a 5% random loss of road linkages ranging from 9.5% in Los Angeles to 56.0% in San Francisco. The results demonstrate that many urban road systems that operate inefficiently under normal conditions are nevertheless resilient to disruption, whereas some more efficient cities are more fragile. The implication is that resilience, not just efficiency, should be considered explicitly in roadway project selection and justify investment opportunities related to disaster and other disruptions.
Noise annoyance (NA) might lead to behavioral patterns not captured by noise levels, which could reduce physical activity (PA) either directly or through impaired sleep and constitute a noise pathway towards cardiometabolic diseases. We investigated the association of long-term transportation NA and its main sources (aircraft, road, and railway) at home with PA levels. We assessed 3842 participants (aged 37-81) that attended the three examinations (SAP 1, 2, and 3 in years 1991, 2001 and 2011, respectively) of the population-based Swiss cohort on Air Pollution and Lung and Heart Diseases in Adults (SAPALDIA). Participants reported general 24-h transportation NA (in all examinations) and source-specific NA at night (only SAP 3) on an ICBEN-type 11-point scale. We assessed moderate, vigorous, and total PA from a short-questionnaire (SAP 3). The main outcome was moderate PA (active/inactive: cut-off≥150min/week). We used logistic regression including random effects by area and adjusting for age, sex, socioeconomic status, and lifestyles (main model) and evaluated potential effect modifiers. We analyzed associations with PA at SAP 3 a) cross-sectionally: for source-specific and transportation NA in the last year (SAP 3), and b) longitudinally: for 10-y transportation NA (mean of SAP 1+2), adjusting for prior PA (SAP 2) and changes in NA (SAP 3-2). Reported NA (score≥5) was 16.4%, 7.5%, 3%, and 1.1% for 1-year transportation, road, aircraft, and railway at SAP 3, respectively. NA was greater in the past, reaching 28.5% for 10-y transportation NA (SAP 1+2). The 10-y transportation NA was associated with a 3.2% (95% CI: 6%-0.2%) decrease in moderate PA per 1-NA rating point and was related to road and aircraft NA at night in cross-sectional analyses. The longitudinal association was stronger for women, reported daytime sleepiness or chronic diseases and it was not explained by objectively modeled levels of road traffic noise at SAP 3. In conclusion, long-term NA (related to psychological noise appraisal) reduced PA and could represent another noise pathway towards cardiometabolic diseases.
Road networks are characterised by several structural and geometrical properties. The topological structure determines partially the hierarchical arrangement of roads, but since these are networks that are spatially constrained, geometrical properties play a fundamental role in determining the network’s behaviour, characterising the influence of each of the street segments on the system. In this work, we apply percolation theory to the UK’s road network using the relative angle between street segments as the occupation probability. The appearance of the spanning cluster is marked by a phase transition, indicating that the system behaves in a critical way. Computing Shannon’s entropy of the cluster sizes, different stages of the percolation process can be discerned, and these indicate that roads integrate to the giant cluster in a hierarchical manner. This is used to construct a hierarchical index that serves to classify roads in terms of their importance. The obtained classification is in very good correspondence with the official designations of roads. This methodology hence provides a framework to consistently extract the main skeleton of an urban system and to further classify each road in terms of its hierarchical importance within the system.
An experimental investigation into the effects of traffic noise on distributions of birds: avoiding the phantom road
- Proceedings. Biological sciences / The Royal Society
- Published almost 7 years ago
Many authors have suggested that the negative effects of roads on animals are largely owing to traffic noise. Although suggestive, most past studies of the effects of road noise on wildlife were conducted in the presence of the other confounding effects of roads, such as visual disturbance, collisions and chemical pollution among others. We present, to our knowledge, the first study to experimentally apply traffic noise to a roadless area at a landscape scale-thus avoiding the other confounding aspects of roads present in past studies. We replicated the sound of a roadway at intervals-alternating 4 days of noise on with 4 days off-during the autumn migratory period using a 0.5 km array of speakers within an established stopover site in southern Idaho. We conducted daily bird surveys along our ‘Phantom Road’ and in a nearby control site. We document over a one-quarter decline in bird abundance and almost complete avoidance by some species between noise-on and noise-off periods along the phantom road and no such effects at control sites-suggesting that traffic noise is a major driver of effects of roads on populations of animals.
To examine the effect of Florida’s adoption of Statute 335.065-a law requiring the routine accommodation of nonmotorized road users (i.e., a “Complete Streets” policy)-on pedestrian fatalities and to identify factors influencing its implementation.
Land use regression (LUR) models have been widely used to provide long-term air pollution exposure assessment in epidemiological studies. However, models have rarely offered variables that account for the dispersion environment close to source (e.g. street canyons, position and dimensions of buildings, road width). This study used newly-available data on building heights and geometry to enhance the representation of land use and the dispersion field in LUR. Models were developed for PM10, NOX and NO2 for 2008-2011 for London, UK. A separate set of models using ‘traditional’ land use and traffic indicators (e.g. distance from road, area of housing within circular buffers) were also developed and their performance compared with ‘enhanced’ models. Models were evaluated using leave-one-out (n-1) (LOOCV) and grouped (n-25%) cross-validation (GCV). LOOCV R(2) values were 0.71, 0.50, 0.66 and 0.73, 0.79, 0.78 for traditional and enhanced PM10, NOX and NO2 models, respectively. GCV R(2) values were 0.71, 0.53, 0.64 and 0.68, 0.77, 0.77 for traditional and enhanced PM10, NOX and NO2 models, respectively. Data on building volume within the area common to a 20 m road buffer within a 25 m circular buffer substantially improved the performance (R(2) > 13%) of NOX and NO2 LUR models.
Despite similarities to the US in terms of transportation, land use, and culture, Australia kills 5.3 people per 100,000 population on the roads each year, as compared to the US rate of 12.4. Similar trends hold when accounting for distance driven and the number of registered cars. This paper seeks to understand what is behind the road safety disparities between these two countries. The results suggest that a number of inter-related factors seem to play a role in the better road safety outcomes of Australia as compared to the US. This includes Australia’s strategies related to seat belt usage and impaired driving as well as their efforts to help curb vehicle speeds and reduce exposure. Design-related differences include a much greater reliance on roundabouts and narrower street cross-sections as well as guidelines that encourage self-enforcing roads. Policy-related differences include stronger and more extensive enforcement programs, restrictive licensing programs, and higher driving costs. Combined with a more urban population and multimodal infrastructure, Australia tends to discourage driving mileage and exposure while encouraging safer modes of transportation such as transit, at least more so than in most of the US. Australia also enacted their version of Vision Zero - called the Safe System Approach - more than a decade before similar policies began cropping up in US cities. While it is difficult to attribute recent road safety successes to any specific policy, Australia continues to expand their lead on the US in terms of safety outcomes and is a road safety example worthy of consideration.