[PDF] Validation Of Arterial Travel Time Estimation Models Using Field Data And Simulation eBook

Author :
Publisher :
Page : 44 pages
File Size : 16,14 MB
Release : 2004
Category : Air quality management
ISBN :

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The air quality conformity analysis process requires the estimation of speeds for a horizon year on a link-by-link basis where only a few future roadway characteristics, such as forecast volume and capacity, are known. Accordingly, the Virginia Department of Transportation (VDOT) has at its disposal a variety of techniques, known as "speed post processors" that estimate average travel speeds on each roadway link based on projected volumes from urban travel demand models. Using field data collected at 15 sites in Richmond and Charlottesville, the accuracy of three post-processing techniques was determined by comparing predicted average travel speed and measured average travel speed. On average, the mean absolute errors for the post processors were relatively similar, ranging between 8 and 12 mph. The post processors overpredicted speeds on some links and underpredicted speeds on others; the average of these positive and negative errors for the post processors was between 2 and 6 mph. Based on MOBILE6 simulation runs with Richmond area data, the differences in speed predictions from the speed post processors would have led to at most a 2.5 percent difference in estimated emissions of volatile organic compounds. All three post processors would have underestimated Richmond area emissions of nitrogen oxides by less than 2 percent. Although differences in national fleet data and Richmond fleet data hamper a direct comparison, additional MOBILE6 simulation results with national data suggest these Richmond results are indicative of the sensitivity of MOBILE6 emissions to changes in estimated vehicle speed. For a class of nine suburban arterial roadways, this study showed that the error associated with any of the post processors could be reduced through judicious altering of the default capacity. This reduction was effected relatively easily by modifying the group capacity rather than computing a capacity for each link. Therefore, although any of the three post processors can be used, this study recommends, in the short term, sampling a few links for each roadway category to determine the appropriate capacity for the category, following an approach similar to that presented in this study. For arterial facilities in particular, this study showed what has been anecdotally known in practice: average travel speeds are affected not just by volume but also by other factors such as signal timing. For this study, this proved to be both a curse and a blessing. On the one hand, the twin facts that the speed post processors are volume dependent and that volume explained only a small amount of the variation in travel speed meant that field results did not show the sensitivity to volume expressed in the literature. On the other hand, because average travel speeds tended to stay within a moderate range, this study showed how better calibration with simple post processors can lead to predictions that are within 5 mph of observed data.

Author : Dwayne Anthony Henclewood
Publisher :
Page : pages
File Size : 11,31 MB
Release : 2012
Category : Traffic congestion
ISBN :

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Traffic congestion is a one hundred billion dollar problem in the US. The cost of congestion has been trending upward over the last few decades, but has experienced slight decreases in recent years partly due to the impact of congestion reduction strategies. The impact of these strategies is however largely experienced on freeways and not arterials. This discrepancy in impact is partially linked to the lack of real-time, arterial traffic information. Toward this end, this research effort seeks to address the lack of arterial traffic information. :To address this dearth of information, this effort developed a methodology to provide accurate estimates of arterial performance measures to transportation facility managers and travelers in real-time. This methodology employs transmitted point sensor data to drive an online, microscopic traffic simulation model. The feasibility of this methodology was examined through a series of experiments that were built upon the successes of the previous, while addressing the necessary limitations. The results from each experiment were encouraging. They successfully demonstrated the method's likely feasibility, and the accuracy with which field estimates of performance measures may be obtained. In addition, the method's results support the viability of a "real-world" implementation of the method. An advanced calibration process was also developed as a means of improving the method's accuracy. This process will in turn serve to inform future calibration efforts as the need for more robust and accurate traffic simulation models are needed. :The success of this method provides a template for real-time traffic simulation modeling which is capable of adequately addressing the lack of available arterial traffic information. In providing such information, it is hoped that transportation facility managers and travelers will make more informed decisions regarding more efficient management and usage of the nation's transportation network.

Author :
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Page : pages
File Size : 30,29 MB
Release : 2005
Category :
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The primary objective of this research was to estimate travel time on a signalized arterial highway corridor using empirical data. Two different methods or techniques were explored; (a) a simulation model NETSIM, which is a comprehensive microscopic traffic simulation model for surface streets; and (b) an analytical approach for estimating average green times of vehicle-actuated signals using bunched exponential model. Field data were collected on an arterial highway (OH-48) located in Lebanon, Ohio. The travel time affected by traffic signals, co-ordination of the signal system, volume or rate of flow of traffic, and geometry of the arterial corridor was considered. NETSIM was used to simulate traffic flow conditions and estimate arterial travel time for the same time period. The NETSIM output of average travel time was compared against the actual travel time recorded on the field. The results of NETSIM study were found to be satisfactory and acceptable for the existing signalized arterial highway conditions. However, further work is required to test the simulation model for greater variability in field observed travel time. Additionally in this paper, a set of formulations to estimate average green times of vehicle-actuated signals employing bunched exponential model were verified for field conditions. Using these formulations, an analytical method for estimating arterial travel time has been demonstrated.

Author : Der-Horng Lee
Publisher : Edward Elgar Publishing
Page : 420 pages
File Size : 40,73 MB
Release : 2004-01-01
Category : Transportation
ISBN : 9781845420536

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'This collection in honor of David Boyce contains genuinely interesting and quality papers that reflect the diversity of interests of the honoree. David Boyce has made a number of significant contributions at the interface of transportation and regional science. He has been a pioneer of injecting rigor and consistency into spatial analysis. The papers here both reflect the ethos of this copious body of analysis and take it further in extensions and applications. It will prove to be an enduring source of ideas and insight.' - Kenneth Button, George Mason University, US

Author : H. Michael Zhang
Publisher :
Page : 96 pages
File Size : 10,37 MB
Release : 1998
Category : Travel time (Traffic engineering)
ISBN :

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This report describes efforts towards developing an arterial travel time model using data from inductive loop detectors and traffic controllers. The model consists of two parts. including the speed estimated from the volume and occupancy measured by detectors and the speed estimated based on critical volume/capacity ratio.