Aspects Regarding Priority Settings in Unsignalized Intersections and the Influence on the Level of Service

At unsignalized intersections, both on the major street and on the minor street, there may be short turning lanes alongside the through lanes following downstream from one single lane. This combined system is termed a shared-short lane (SSL). Up to now it has only been possible to calculate the capacity of these lanes at the stop line and the capacity of the diverging point, where the turning lane diverges from the through lane. For the total average delay of the involved individual movements, there is no applicable estimation procedure. As a special case, the shared lane (SL), which is used by several movements without a separate turning lane, must also be reconsidered. This paper presents a new model for the estimation of average delays of SSL with SL as a special case at unsignalized intersections. The model is based on the analogy to standard queuing systems. The results depend on the length of the short lane. The model is validated by simulation. The results demonstrate that the outcome of the models in current highway capacity manuals may be misleading, with the risk of inaccurately classifying the level of service of an intersection. Therefore, there is an urgent need to complete the relevant procedures in highway capacity manuals by more realistic estimation procedures for the total delay at an SSL or an SL. The methods in this paper—even if they are rather complex—are recommended to be incorporated into future versions of highway capacity manuals using some simplifications.

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Why Field Measurements Differ from Model Estimates: Analysis Framework for Capacity and Level-of-Service Analysis of Unsignalized Intersections

Transportation Research Record Journal of the Transportation Research Board ◽

10.3141/1852-05 ◽

2003 ◽

Vol 1852 (1) ◽

pp. 32-39 ◽

Cited By ~ 4

Author(s):

Michael Kyte ◽

Michael Dixon ◽

Purushotham Murali Basavaraju

Keyword(s):

Field Measurements ◽

Level Of Service ◽

End User ◽

Microscopic Simulation ◽

Highway Capacity ◽

Highway Capacity Manual ◽

Unsignalized Intersections ◽

User Expectations ◽

Using Data ◽

Moderate User

Several questions are considered relating to the variability between field measurements and model forecasts, with a focus on the need to moderate user expectations about this variability. Considered first are the degree of variability observed in field measurements of delay and the stochastic effects in delay estimates produced by microscopic simulation. Examined next are the structure of the models of two-way stop-controlled (TWSC) intersection capacity and delay and how this structure might cause differences between field measurements and model estimates. How much the end user can moderate these differences using backcalculations, observation, and calibration and a “correct” perspective for the end user regarding these differences and variability are also discussed. These questions are considered using data collected as part of the NCHRP project used to develop the TWSC intersection capacity and level-of-service procedures contained in the Highway Capacity Manual models.

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DETERMINAÇÃO DA CAPACIDADE E NÍVEL DE SERVIÇO EM INTERSEÇÕES RODOVIÁRIAS ATRAVÉS DE SIMULAÇÃO

TRANSPORTES ◽

10.14295/transportes.v5i2.280 ◽

1997 ◽

Vol 5 (2) ◽

Author(s):

Sergio Henrique Demarchi ◽

José Reynaldo Setti

Keyword(s):

Weight Ratio ◽

Level Of Service ◽

Heavy Vehicle ◽

Analysis Method ◽

Average Delay ◽

Unsignalized Intersections ◽

De Se ◽

Intersection Analysis ◽

The Impact

Este trabalho descreve o uso de um simulador na analise do impacto de veículos pesados na capacidade e no nível de serviço de interseções rodoviárias não semaforizadas. O impacto na capacidade é medido através da determinação de fatores de equivalência veicular, enquanto que a avaliação do nível de serviço da interseção baseia-se nos tempos médios de espera dos veículos durante as manobras de cruzamento. Os resultados obtidos mostram que os veículos que causam maior impacto na operação das interseções são os caminhões articulados, devido ao seu comprimento, e os caminhões médios, devido a sua menor relação potência/peso. Os fatores de equivalência obtidos são, em geral, maiores que equivalentes veiculares adotados pelo HCM de 1994, mostrando a necessidade de se desenvolver um método para analise de interseções não semaforizadas mais adequado as condições nacionais.ABSTRACTThis paper describes the use of a simulator to analyze heavy vehicle impacts on capacity and level of service of rural unsignalized intersections. The impact on capacity is measured d by the do termination of equivalence factors and the level of service a assessment is based on average delay crossing times. The results indicate that the two vehicle classes responsible for the greatest intact are articulated trucks (due to their length) and medium-sized trucks, because of their poor power-to-weight ratio. The equivalence factors obtained are greater than those shown in the 1994 HCM, demonstrating the need for development of an unsignalized intersection analysis method more adequate to the Brazilian operational and vehicle conditions.

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Method to Determine Pedestrians Level of Service for Unsignalized Intersections

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.253-255.1936 ◽

2012 ◽

Vol 253-255 ◽

pp. 1936-1943 ◽

Cited By ~ 2

Author(s):

Yang Bian ◽

Lu Jian ◽

Lin Zhao

Keyword(s):

Urban Areas ◽

Chinese Population ◽

Pearson Correlation ◽

Level Of Service ◽

Unsignalized Intersections ◽

Factors Influencing ◽

Operational Characteristics ◽

Traffic Conflicts ◽

Pearson Correlation Analysis ◽

Broad Cross Section

This paper aims at developing a Level of Service (LOS) model for unsignalized intersection crosswalks for pedestrians from the perspective of the pedestrian’s perception of comfort and safety in unsignalized intersection environment. Firstly, the potential primary factors influencing pedestrian LOS at crosswalk were summarized from three respects: traffic conflicts, crossing facilities and delay. Secondly, data for the model were collected, including 459 participants’ real-time sense of comfort and safety when they crossing the 11 selected intersection crosswalks and the design and operational characteristics of the selected intersections. The selected crosswalks were typical of those prevalent in the urban areas of China, and the participants of questionnaire survey covered a broad cross section of Chinese population of pedestrians. Based on the survey data, Pearson Correlation analysis and step-wise regression analysis were carried out to develop pedestrian LOS model for unsignalized intersections. A reliable, statistically calibrated pedestrian LOS model for unsignalized intersections was developed, suitable for application in the vast majority of Chinese urban areas. The study revealed that the factors significantly influencing pedestrian LOS at unsignalized intersections included: left turning bicycles from side streets, through bicycles from side streets, right turning bicycles from side streets, left turning bicycles approaching from the street parallel to the crosswalk, through bicycles from the approach opposite to the crosswalk, right turning bicycles from the street parallel to the crosswalk, through bicycles from the approach opposite to the crosswalk and the presence of the median.

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Capacity and Level of Service at Unsignalized Intersections

10.17226/6339 ◽

1996 ◽

Author(s):

Keyword(s):

Level Of Service ◽

Unsignalized Intersections

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Analysis of Traffic Operations at All-Way Stop-Controlled Intersections by Simulation

Transportation Research Record Journal of the Transportation Research Board ◽

10.1177/0361198196155500109 ◽

1996 ◽

Vol 1555 (1) ◽

pp. 65-73 ◽

Cited By ~ 2

Author(s):

Michael Kyte ◽

Wayne Kittelson ◽

Tian Zong Zhong ◽

Bruce Robinson ◽

Mark Vandehey

Keyword(s):

Simulation Model ◽

Field Data ◽

The United States ◽

Level Of Service ◽

Traffic Operations ◽

Unsignalized Intersections ◽

Common Intersection ◽

Significant Research ◽

Vehicle Delay ◽

The Common

All-way stop-controlled (AWSC) intersections are one of the common intersection types in the United States. Although significant research has been completed on signalized intersections and two-way stop-controlled intersections, a limited number of studies have been made of traffic operations at AWSC intersections. In addition, although a general analytical procedure now exists for AWSC intersections, it is not capable of handling the wide variety of conditions typically faced by the practicing traffic engineer. Further, it may not be computationally possible for an analytical model to handle the large number of vehicle interaction combinations that exist at AWSC intersections. This study presents a new AWSC simulation model and some of the results from that simulation. The model was tested against the field data collected during NCHRP Project 3-46, Capacity and Level of Service at Unsignalized Intersections. The model can be used to predict vehicle delay, queue length, and saturation headways, which have shown good correlation with the field data. The simulation model predicted the same level of service for about 66 percent of the cases tested, and for 100 percent of the cases the model predicted level of service within one level difference.

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