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Author: Srinivasa Srivatsav Kandala
Publisher:
ISBN:
Category : Traffic congestion
Languages : en
Pages : 109
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Book Description
Traffic congestion is a major externality in modern transportation systems with negative economic, environmental and social impacts. Freeway bottlenecks are one of the key elements besides the demand for travel by automobiles that determine the extent of congestion. The primary objective of this research is to provide a better understanding of factors for variations in bottleneck discharge rates. Specifically this research seeks to (i) develop a methodology comparable to the rigorous methods to identify bottlenecks and measure capacity drop and its temporal (day to day) variations in a region, (ii) understand the variations in discharge rate of a freeway weaving bottleneck with a HOV lane and (iii) understand the relationship between lane flow distribution and discharge rate on a weaving bottleneck resulted from a lane drop and a busy off-ramp. In this research, a methodology has been developed to de-noise raw data using Discrete Wavelet Transforms (DWT). The de-noised data is then used to precisely identify bottleneck activation and deactivation times, and measure pre-congestion and congestion flows using Continuous Wavelet Transforms (CWT). To this end a methodology which could be used efficiently to identify and analyze freeway bottlenecks in a region in a consistent, reproducible manner was developed. Using this methodology, 23 bottlenecks have been identified in the Phoenix metropolitan region, some of which result in long queues and large delays during rush-hour periods. A study of variations in discharge rate of a freeway weaving bottleneck with a HOV lane showed that the bottleneck discharge rate diminished by 3-25% upon queue formations, however, the discharge rate recovered shortly thereafter upon high-occupancy-vehicle (HOV) lane activation and HOV lane flow distribution (LFD) has a significant effect on the bottleneck discharge rate: the higher the HOV LFD, the lower the bottleneck discharge rate. The effect of lane flow distribution and its relationship with bottleneck discharge rate on a weaving bottleneck formed by a lane drop and a busy off-ramp was studied. The results showed that the bottleneck discharge rate and lane flow distribution are linearly related and higher utilization of the median lane results in higher bottleneck discharge rate.
Author: Srinivasa Srivatsav Kandala
Publisher:
ISBN:
Category : Traffic congestion
Languages : en
Pages : 109
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Book Description
Traffic congestion is a major externality in modern transportation systems with negative economic, environmental and social impacts. Freeway bottlenecks are one of the key elements besides the demand for travel by automobiles that determine the extent of congestion. The primary objective of this research is to provide a better understanding of factors for variations in bottleneck discharge rates. Specifically this research seeks to (i) develop a methodology comparable to the rigorous methods to identify bottlenecks and measure capacity drop and its temporal (day to day) variations in a region, (ii) understand the variations in discharge rate of a freeway weaving bottleneck with a HOV lane and (iii) understand the relationship between lane flow distribution and discharge rate on a weaving bottleneck resulted from a lane drop and a busy off-ramp. In this research, a methodology has been developed to de-noise raw data using Discrete Wavelet Transforms (DWT). The de-noised data is then used to precisely identify bottleneck activation and deactivation times, and measure pre-congestion and congestion flows using Continuous Wavelet Transforms (CWT). To this end a methodology which could be used efficiently to identify and analyze freeway bottlenecks in a region in a consistent, reproducible manner was developed. Using this methodology, 23 bottlenecks have been identified in the Phoenix metropolitan region, some of which result in long queues and large delays during rush-hour periods. A study of variations in discharge rate of a freeway weaving bottleneck with a HOV lane showed that the bottleneck discharge rate diminished by 3-25% upon queue formations, however, the discharge rate recovered shortly thereafter upon high-occupancy-vehicle (HOV) lane activation and HOV lane flow distribution (LFD) has a significant effect on the bottleneck discharge rate: the higher the HOV LFD, the lower the bottleneck discharge rate. The effect of lane flow distribution and its relationship with bottleneck discharge rate on a weaving bottleneck formed by a lane drop and a busy off-ramp was studied. The results showed that the bottleneck discharge rate and lane flow distribution are linearly related and higher utilization of the median lane results in higher bottleneck discharge rate.
Author: Ishtiak Ahmed
Publisher:
ISBN:
Category :
Languages : en
Pages : 119
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Author: Shantanu Das
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
A modified approach to treat traffic flow parameters (flow, density and speed) has been introduced in this paper. A queuing analysis has been conducted on traffic flow data on Interstate 94 in the Minneapolis-St. Paul metro area. A methodology has been developed to calibrate loop detector count data. Corrected flow data has been subjected to analysis using queuing analysis to compute densities and speeds on freeway sections. Statistical analysis identifies 'active bottleneck' locations on freeways and sections where bottlenecks occur because of disturbances caused by downstream bottlenecks propagating backwards in the form of shockwaves. A sample of six days on Interstate 94 was considered for the analysis. Our analysis reveals that the same section cannot always be characterized as a 'bottleneck' location; at some times it is active and at others, it is subject to downstream bottlenecks. Traffic flow characteristics change and that leads to changing situations on each freeway section.
Author: Qi Gong
Publisher:
ISBN:
Category :
Languages : en
Pages : 120
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Author: Lei Zhang
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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The capacity of a freeway segment should be measured only when it is an active bottleneck. The properties of flows at active freeway bottlenecks have a bearing on both the definition of capacity and the procedure of capacity analysis. Past studies have examined the flow features at bottlenecks on several freeways in Toronto, Canada, and San Diego, California. This study examined 27 active bottlenecks in the Twin Cities metro area in Minnesota for a 7-week period. The analysis focuses on the properties of prequeue transition flows (PQFs) and queue discharge flows (QDFs) averaged across various time intervals (30-s, daily average, and long-run average). It is found that the proportion by which flows drop after upstream queues form at all studied bottlenecks ranges from 2% to 11%. The 30-s QDFs display high variation and should not be assumed to be constant. The daily average QDFs at each studied bottleneck follow a normal distribution based on two normality tests and visual inspection of the normal probability plot. Results also suggest that the long-run average QDFs [mean of 2,016 passenger cars per lane per hour (pcplph)] and PQFs (mean of 2,124 pcplph) are both normally distributed. The implication of these empirical findings on capacity estimation is also discussed.
Author: Joon ho Lee
Publisher:
ISBN:
Category :
Languages : en
Pages : 178
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Author: Patrick John Athol
Publisher:
ISBN:
Category : Express highways
Languages : en
Pages : 378
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Author: Carol H. Walters
Publisher:
ISBN:
Category : Air quality management
Languages : en
Pages : 58
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Book Description
Freeway bottlenecks cause deterioration in freeway operation. These overcapacity sections of freeway are responsible for increased fuel consumption, increased emissions, and increased delay to motorists. The Texas Department of Transportation has funded and implemented many freeway bottleneck improvement projects around the state to reduce these problems. These projects provide significant benefits in terms of increasing speeds and reducing delays; however, little information exists on quantifying energy and air quality benefits from implementation of bottleneck removal projects. This research investigated the relationships between traffic operating characteristics and environmental factors such as fuel consumption, hydrocarbon emissions, carbon monoxide emissions, and nitrogen oxide emissions. A methodology was developed to analyze existing before and after data from traffic improvement projects that have been implemented. The change in fuel consumption was quantified and guidelines were developed to help predict energy benefits from implementing future freeway bottleneck improvements. The total reduction in fuel usage ranged from 0.0% to 5.2% for the examples studied, with an average of 2.2%. However, the attempt to quantify the air quality benefits was less successful and further research, now underway on a national level, will be required. Current methodology is based on an average speed, and this fails to account for the stop and go nature of driving within congestion upstream of a bottleneck. Under such conditions it has been demonstrated that greater emissions occur, but this has not yet been reliably quantified.
Author: Shantanu Kumar Das
Publisher:
ISBN:
Category :
Languages : en
Pages : 138
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Book Description
Author: H. C. Chin
Publisher:
ISBN:
Category :
Languages : en
Pages : 7
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