Spatial modeling of bicycle activity at signalized intersections Jillian Strauss, Luis F Miranda-M

JTLU vol. 6 no. 2 pp. 47-58 (2013)This paper presents a methodology to investigate the link between bicycle activity and built environment, road and transit network characteristics, and bicycle facilities while also accounting for spatial autocorrelation between intersections. The methodology includes the normalization of manual cyclist counts to average seasonal daily volumes (ASDV), taking into account temporal variations and using hourly, daily, and monthly expansion factors obtained from automatic bicycle count data. To correct for weather conditions, two approaches were used. In the first approach, a relative weather ridership model was generated using the automatic bicycle count and weather data. In the second approach, weather variables were introduced directly into the model. For each approach, the effects of built environment, road and transit characteristics, and bicycle facilities on cyclist volumes were determined. It was found that employment, schools, metro stations, bus stops, parks, land mix, mean income, bicycle facility type (bicycle lanes and cycle tracks), length of bicycle facilities, average street length, and presence of parking entrances were associated with bicycle activity. From these, it was found that the main factors associated with bicycle activity were land-use mix, cycle track presence, and employment density. For instance, intersections with cycle tracks have on average 61 percent more cyclists than intersections without. An increase of 10 percent in land-use mix or employment density would cause an increase of 8 percent or 5.3 percent, respectively, in bicycle flows. The methods and results proposed in this research are helpful for planning bicycle facilities and analyzing cyclist safety. Limitations and future work are discussed at the end of this paper

Spatio-Temporal Analysis of Car Distance, Greenhouse Gases and the Effect of Built Environment: a Latent Class Regression Analysis

This work examines the temporal-spatial variations of daily automobile distance traveled and greenhouse gas emissions (GHGs) and their association with built environment attributes and household socio-demographics. A GHGs household inventory is determined using link-level average speeds for a large and representative sample of households in three origin-destination surveys (1998, 2003 and 2008) in Montreal, Canada. For the emission inventories, different sources of data are combined including link-level average speeds in the network, vehicle occupancy levels and fuel consumption characteristics of the vehicle fleet. Built environment indicators over time such as population density, land use mix and transit accessibility are generated for each household in each of the three waves. A latent class (LC) regression modeling framework is then implemented to investigate the association of built environment and socio-demographics with GHGs and automobile distance traveled. Among other results, it is found that population density, transit accessibility and land-use mix have small but statistically significant negative impact on GHGs and car usage. Despite that this is in accordance with past studies, the estimated elasticities are greater than those reported in the literature for North American cities. Moreover, different household subpopulations are identified in which the effect of built environment varies significantly. Also, a reduction of the average GHGs at the household level is observed over time. According to our estimates, households produced 15% and 10% more GHGs in 1998 and 2003 respectively, compared to 2008. This reduction is associated to the improvement of the fuel economy of vehicle fleet and the decrease of motor-vehicle usage. A strong link is also observed between socio-demographics and the two travel outcomes. While number of workers is positively associated with car distance and GHGs, low and medium income households pollute less than high-income households

Diseño de la metodología para determinar caudales característicos mensuales multianuales en una cuenca rural no instrumentada a través del programa HEC-HMS

Trabajo de gradoEl trabajo de grado tiene como objetivo determinar los caudales característicos mensuales multianuales en una cuenca no instrumentada a través del programa HEC-HMS. La cuenca objeto de estudio corresponde al caño Dumacita, afluente directo del río Cusiana ubicada en el municipio de Maní, en el departamento del Casanare. Para desarrollar el análisis de caudales característicos se trabajará con información meteorológica proporcionada por el Instituto de Hidrología, Meteorología y Estudios Ambientales – IDEAM e información morfométrica, tipo de suelos y coberturas de la tierra de la microcuenca, provenientes del Estudio de impacto ambiental fase de explotación Campo Puntero, elaborado por la empresa Auditoria Ambiental S.A.S. durante el año 2014, donde se pudo establecer de manera satisfactoria la estimación del régimen de caudales característicos del caño Dumacita.EspecializaciónEspecialista en Recursos Hídrico

Safety benefits of automated speed advisory systems at signalized intersections

ABSTRACT: Human-driving behavior at signalized intersections may lack efficiency because drivers try to reach their desired speed without the upcoming traffic-signal information. This causes idling time, sharp accelerations, hard braking, traffic congestion, emissions, and energy consumption. Connected vehicles, for example those equipped with a speed advisory system (SAS), can provide prior information to drivers for optimizing their driving behavior while approaching signalized intersections. However, the current literature focuses only on the fuel consumption, emissions, and travel-delay reduction impacts of SASs. This paper evaluates the safety impact of SAS vehicles using the proposed approach that simulates mixed-traffic situations between SAS and human-driven vehicles (HDVs). HDVs in the model follow real vehicle trajectories based on car-following conditions. The study investigates various scenarios including the impact of the different ranks of SAS vehicles in the vehicle group, the lane-changing possibility, and market penetration rates (MPRs). The results suggest that SAS vehicles can reduce rear-end collision risks from 25% MPR. The minimum time to collision increases by 1.2 s and the deceleration rate to avoid crash declines by 0.3 on average for 100% MPR relative to 0%. The study demonstrated that this safety benefit is also strongly related to the rank of SAS vehicles within a vehicle group. In addition, the conflict locations in the approaching lane gradually move away from the intersection up to where the communication range starts as the MPR increases, which would reduce abrupt vehicle speed changes near pedestrian crosswalks

Using microscopic video data measures for driver behavior analysis during adverse winter weather: opportunities and challenges

ABSTRACT: This paper presents a driver behavior analysis using microscopic video data measures including vehicle speed, lane-changing ratio, and time to collision. An analytical framework was developed to evaluate the effect of adverse winter weather conditions on highway driving behavior based on automated (computer) and manual methods. The research was conducted through two case studies. The first case study was conducted to evaluate the feasibility of applying an automated approach to extracting driver behavior data based on 15 video recordings obtained in the winter 2013 at three different locations on the Don Valley Parkway in Toronto, Canada. A comparison was made between the automated approach and manual approach, and issues in collecting data using the automated approach under winter conditions were identified. The second case study was based on high quality data collected in the winter 2014, at a location on Highway 25 in Montreal, Canada. The results demonstrate the effectiveness of the automated analytical framework in analyzing driver behavior, as well as evaluating the impact of adverse winter weather conditions on driver behavior. This approach could be applied to evaluate winter maintenance strategies and crash risk on highways during adverse winter weather conditions

Proyecto de alcantarillado en la isla "Las casitas" Archipiélago de Jambelí, provincia de El Oro

One of the most relevant problems is the lack of basic services such as the Sanitary Sewer network, so the construction of this would prevent the collapse of the Septic Tanks, which would significantly reduce the contamination of groundwater, preventing the population from contracting diseases. , and thus improve the standard of living of the Community.   The Sewer System will necessarily have a Wastewater Treatment Plant; in order to cause the least impact to the ecosystem since it is very sensitive for its particular characteristics.Uno de los problemas más relevantes es la inexistencia de servicios básicos como la red de Alcantarillado Sanitario por lo que la construcción de éste, evitaría el colapso de las Fosas Sépticas lo que disminuiría notablemente la contaminación del agua subterránea, evitando que la población no contraiga enfermedades, y así mejorar el nivel de vida de la Comunidad. El Sistema de Alcantarillado, necesariamente contará con una Planta de Tratamiento de Aguas Residuales; con el fin de causar el menor impacto al ecosistema ya que es muy sensible por sus características particulares

Measuring and visualizing space–time congestion patterns in an urban road network using large-scale smartphone-collected GPS data

Congestion is a dynamic phenomenon with elements of space and time, making it a promising application of probe vehicles. The purpose of this paper is to measure and visualize the magnitude and variability of congestion on the network scale using smartphone GPS travel data. The sample of data collected in Quebec City contained over 4000 drivers and 21,000 trips. The congestion index (CI) was calculated at the link level for each hour of the peak period and congestion was visualized at aggregate and disaggregate levels. Results showed that each peak period can be viewed as having an onset period and dissipation period lasting one hour. Congestion in the evening is greater and more dispersed than in the morning. Motorways, arterials, and collectors contribute most to peak period congestion, while residential links contribute little. Further analysis of the CI data is required for practical implementation in network planning or congestion remediation

IAA : Información y actualidad astronómica (9)

Sumario : Investigación: Las colas de polvo de los cometas.-- Agua en el Universo.-- Ventana Abierta: Sobre la enseñanza de la ciencia en la educación secundaria.-- Charlas con… Max Pettini.-- Actualidad Científica: La luz y los colores de las nebulosas planetarias.-- Magnetares.-- Actividades IAA.-- Agenda.Esta revista se publica con la ayuda de la Acción Especial DIF 2001-4284-E del Programa Nacional de Difusión de la Ciencia y la Tecnología, del Ministerio de Ciencia y Tecnología.Peer reviewe

Analysing cyclist behaviour at cycling facility discontinuities using video data

RÉSUMÉ: The primary purpose of any transportation network is to provide connectivity between the origin and travel destination. However, given the vehicle oriented structure of the road network in many countries, there are connectivity issues in the cycling network, which has been implemented later. Discontinuities are physical interruptions in the cycling network where cyclists are faced with unexpected situations such as the end of a cycling facility or the change from one facility type to another that are perceived as inconvenient and less safe. The microscopic behaviour of cyclists and the risks they face at these points of discontinuity has not been extensively investigated in the literature. This study aims to evaluate the challenges faced by cyclists at discontinuities by observing cyclist behaviour at these locations and comparing them to control sites using automated video analysis techniques. Our methodology allows the extraction of valuable microscopic data for evaluation of cyclist behaviour at any location. The methodology is applied to a case study of four sites in Montreal, Canada. Using a set of discontinuity measures proposed in a previous work and applied to Montreal’s cycling network, video data was collected from a pole-mounted camera at locations with discontinuity and control sites. After extracting road user trajectories from the video data, a trajectory clustering algorithm was applied to find cyclists’ motion patterns and the various maneuver strategies adopted by cyclists. Speeds and acceleration statistics are extracted and compared between different motion patterns and between discontinuity and control sites. Results show that cyclists undertake a larger number of maneuvers at points of discontinuity compared to their control sites, and that both cyclist accelerations and speeds exhibit larger variations at discontinuities compared to larger and more stable speeds at control sites