en-us Tue, 5 Jun 2012 00:25:14 UTC Inmagic DB/Text WebPublisher http://114.111.144.247/ics-wpd/exec/icswppro.dll?AC=QUERY&TN=inroads&QY=find+RC+=+1205AR289E Mon, 14 May 2012 14:00:00 UTCMopeds, experiencing faster growth of use than bicycles, have been swarming urban streets in China in recent years. The mixture of mopeds and bicycles in the same road space has led to great change in the composition and the traffic flow characteristics of nonmotorized traffic. It is impractical to measure the nonmotorized traffic flow by simply aggregating the vehicle counts of mopeds and bicycles because of their distinct temporal-spatial traffic features. This paper proposes a methodology to measure the normalized volume of a nonmotorized traffic mix of mopeds and bicycles. A bicycle equivalent (BE) concept is introduced to measure the moped in equivalent bicycle units and then to normalize the traffic flow mix. Two BE analysis methods that express the relationship between speeds, densities, and occupied spaces for mopeds and bicycles have been developed. A case study estimates the BE from these methods by using field data collected at a midblock section of an arterial in Shanghai. Statistical analysis of observed data shows that the estimated equivalent unit of moped to bicycle is variable under different traffic conditions. Specifically, the equivalent value of moped to bicycle is less than one under lower-density conditions. The value is, however, more than one under higher-density conditions. These findings are valuable to support the measurement of a nonmotorized traffic mix of mopeds and bicycles. http://114.111.144.247/ics-wpd/exec/icswppro.dll?AC=QUERY&TN=inroads&QY=find+RC+=+1205AR290E Mon, 14 May 2012 14:00:00 UTCAccurate estimation of traffic in intelligent transportation system applications, such as the advanced traveler information system and the advanced traffic management system, requires fixed location-based measurements, vehicle-based measurements, or both. Using both data sources is too expensive for most government agencies, especially in developing countries such as India, and also leads to issues related to installation and maintenance, especially on urban roads. The main drawback of vehicle-based measurements is the potential lack of participation because of privacy concerns; lack of participation would limit data collection to a sample of the population, primarily on public transport vehicles. The study aims to overcome such difficulties by using only location-based flow data for the estimation of spatial parameters, such as density and travel time. These parameters are difficult to measure or estimate on an urban arterial, especially under heterogeneous traffic conditions, because of lack of lane discipline and because of complex interactions among different vehicle types. The Lighthill-Whitham-Richards macroscopic traffic flow model discretized in both space and time was employed in the estimation scheme. The resulting partial differential equations were solved numerically with the finite difference formulation of forward-time backward-space. Both linear and exponential speed-density relationships were considered and incorporated into the macroscopic model. Linear and cubic spline interpolations of input flow values were compared. The estimated density was corroborated with the density obtained from input-output analysis. Estimated travel times were compared with manually observed travel times and travel times obtained from probe vehicles fitted with Global Positioning System devices. http://114.111.144.247/ics-wpd/exec/icswppro.dll?AC=QUERY&TN=inroads&QY=find+RC+=+1205AR293E Mon, 14 May 2012 14:00:00 UTCGeometrical features of intersections, such as T-intersections and four-leg intersections, can give rise to several conflict points at those intersections. Without proper control at such conflict points, accidents can occur. In Thailand, the application of intelligent transportation system (ITS) technology for improvement of traffic flow and road safety is still in its infancy. This paper describes one of the pioneering uses of ITS technology to mitigate congestion and reduce accidents at intersections. The intersections under study are located in suburban Bangkok, Thailand, where major accidents have occurred as a result of red light running and speeding. Through the use of accident analysis modeling and ITS technology, it is possible to improve traffic flow and reduce the number of crashes. ITS technology, including an image-sensing concept for adaptive synchronization (green wave), was used to detect headway, spacing, number of speeding vehicles, angle of lane changing, and number of vehicles changing lanes. In particular, the image-sensing concept of traffic classified counting was used to calculate and evaluate signal phasing and cycle times for adaptive synchronization. In this operation, two closed-circuit television cameras and electronic equipment installed at each intersection were used to track vehicles passing through virtual loops, similar to the way in which induction loops in pavement detect vehicles. A variable message sign was used to flash a warning to errant drivers. After the implementation of this locally developed ITS technology, traffic flow improved significantly and the number of accidents caused by red light running and speeding decreased drastically. http://114.111.144.247/ics-wpd/exec/icswppro.dll?AC=QUERY&TN=inroads&QY=find+RC+=+1205AR233E Mon, 14 May 2012 14:00:00 UTCThis paper describes a data collection methodology to address insufficient data sources for estimation of urban container truck traffic (drayage) volumes. The methodology is sensitive to the characteristics of drayage and offers a systematic approach for acquiring container truck traffic data for constructing models to estimate drayage volumes. The methodology consists of (a) acquiring urban truck traffic estimates and national and provincial- or state-level container traffic databases, (b) characterizing shippers and carriers through field investigations and surveys, and (c) designing a container truck data collection program. Short-term manual truck classification intersection turning movement counts were conducted to obtain body style and axle configuration data for articulated trucks. Temporal expansion factors were developed and applied to short-term count data to produce average daily container truck traffic volume estimates and reveal temporal, physical, and spatial distribution differences between container trucks and other articulated trucks. The paper provides a rationale for selecting count station locations and their temporal characteristics, choosing the number of counts and their duration, determining the types of data to collect, and identifying container generators. The methodology is generally applicable to North American inland port cities. The data feed a model that is intended to assist transportation engineers in understanding urban drayage operations and quantifying the exposure of these trucks. http://114.111.144.247/ics-wpd/exec/icswppro.dll?AC=QUERY&TN=inroads&QY=find+RC+=+1205AR259E Mon, 14 May 2012 14:00:00 UTCBicycle volume data are useful for practitioners and researchers to understand safety, travel behavior, and development impacts. Several simple models of bicycle intersection volumes were developed for Alameda County, California. The models were based on 2-h bicycle counts performed at a sample of 81 intersections in the spring of 2008 and 2009. Study sites represented areas with a wide range of population density, employment density, proximity to commercial property, neighborhood income, and street network characteristics. The explanatory variables considered for the models included intersection site, land use, transportation system, and socioeconomic characteristics of the areas surrounding each intersection. The models showed that bicycle volumes tended to be higher at intersections surrounded by more commercial retail properties within 1/10 mi, closer to a major university, with a marked bicycle facility on at least one leg of the intersection, surrounded by less hilly terrain within 1/2 mi, or surrounded by a more connected roadway network. The models also showed several important differences between weekday and weekend intersection volumes. The positive association between bicycle volume and proximity to retail properties or a large university was greater on weekdays than on weekends, whereas bicycle facilities had a stronger positive association and hilly terrain had a weaker negative association with bicycle volume on weekends than on weekdays. The study found that further testing and refinement was necessary before accurate count predictions could be made in Alameda County or other communities. http://114.111.144.247/ics-wpd/exec/icswppro.dll?AC=QUERY&TN=inroads&QY=find+RC+=+1205AR286E Mon, 14 May 2012 14:00:00 UTCTo alleviate traffic congestion on Malaysia's highways and roads, the Integrated Transport Information System (ITIS) was established in Klang Valley, Malaysia, to collect and disseminate updated traffic information. One important aspect of this system is the use of various traffic information tools [Internet, radio, and variable message signs (VMS)] in disseminating traffic information pretrip and en route. To investigate the effectiveness of ITIS, this paper assesses the level of awareness and use of ITIS in the Klang Valley region. Using a revealed preference survey and adopting a discrete choice modeling approach, researchers found that the level of awareness (58 per cent for VMS, 22 per cent for radio pretrip, 48 per cent for radio en route, and 12 per cent for Internet) and use (29 per cent change departure time and 22 per cent divert) of ITIS were low in the region. Driver demographics had little impact on the awareness and use of ITIS, whereas trip characteristics played an important role. Drivers in the Klang Valley region had limited trust in the accuracy of data provided by ITIS and did not perceive such data to be useful in reducing their travel time. These findings demonstrate the need for strategies to improve awareness of ITIS and to increase its credibility. http://114.111.144.247/ics-wpd/exec/icswppro.dll?AC=QUERY&TN=inroads&QY=find+RC+=+1205AR014E Mon, 14 May 2012 14:00:00 UTC http://114.111.144.247/ics-wpd/exec/icswppro.dll?AC=QUERY&TN=inroads&QY=find+RC+=+1205AR020E Mon, 14 May 2012 14:00:00 UTC http://114.111.144.247/ics-wpd/exec/icswppro.dll?AC=QUERY&TN=inroads&QY=find+RC+=+1205AR028E Mon, 14 May 2012 14:00:00 UTC http://114.111.144.247/ics-wpd/exec/icswppro.dll?AC=QUERY&TN=inroads&QY=find+RC+=+1205AR038E Mon, 14 May 2012 14:00:00 UTC http://114.111.144.247/ics-wpd/exec/icswppro.dll?AC=QUERY&TN=inroads&QY=find+RC+=+1205AR040E Mon, 14 May 2012 14:00:00 UTC http://114.111.144.247/ics-wpd/exec/icswppro.dll?AC=QUERY&TN=inroads&QY=find+RC+=+1205AR043E Mon, 14 May 2012 14:00:00 UTC http://114.111.144.247/ics-wpd/exec/icswppro.dll?AC=QUERY&TN=inroads&QY=find+RC+=+1205AR044E Mon, 14 May 2012 14:00:00 UTC http://114.111.144.247/ics-wpd/exec/icswppro.dll?AC=QUERY&TN=inroads&QY=find+RC+=+1205AR046E Mon, 14 May 2012 14:00:00 UTC http://114.111.144.247/ics-wpd/exec/icswppro.dll?AC=QUERY&TN=inroads&QY=find+RC+=+1205AR051E Mon, 14 May 2012 14:00:00 UTC http://114.111.144.247/ics-wpd/exec/icswppro.dll?AC=QUERY&TN=inroads&QY=find+RC+=+1205AR052E Mon, 14 May 2012 14:00:00 UTC http://114.111.144.247/ics-wpd/exec/icswppro.dll?AC=QUERY&TN=inroads&QY=find+RC+=+1205AR068E Mon, 14 May 2012 14:00:00 UTC http://114.111.144.247/ics-wpd/exec/icswppro.dll?AC=QUERY&TN=inroads&QY=find+RC+=+1205AR069E Mon, 14 May 2012 14:00:00 UTC http://114.111.144.247/ics-wpd/exec/icswppro.dll?AC=QUERY&TN=inroads&QY=find+RC+=+1205AR072E Mon, 14 May 2012 14:00:00 UTC http://114.111.144.247/ics-wpd/exec/icswppro.dll?AC=QUERY&TN=inroads&QY=find+RC+=+1205AR078E Mon, 14 May 2012 14:00:00 UTCPedestrian traffic flow does not always consist of individuals with uniform characteristics. Disparity in walking speed as a result of ageing is becoming more evident in populations of developed countries such as Australia. Unlike vehicular traffic where diversity is tackled by using passenger car equivalent (PCE) factors, pedestrian traffic analysis has no similar concept. This paper introduces the standard pedestrian equivalent (SPE) factor to normalise mixed pedestrian flow. A micro-simulation approach was employed to generate flow relationships with and without older adults in the commuter flow. The walking speed distributions of older adults in Brisbane, Australia, were used as input, and commuter characteristics were derived from design-guide values in order to highlight the effect of increased proportions of older adults on design values. The findings showed that a shift in pedestrian level of service (LOS) was observed as a result of introducing older adults. Additionally, increasing the proportion of older adults yielded lower SPE factors, suggesting that the overall negative effect decreases as the proportion increases. SPE values were higher for narrow walkways than for wider walkways as a result of more blocking and less overtaking. The concept introduced can be adapted to develop factors for design and analysis of constrained walkways catering to older adults. http://114.111.144.247/ics-wpd/exec/icswppro.dll?AC=QUERY&TN=inroads&QY=find+RC+=+1205AR082E Mon, 14 May 2012 14:00:00 UTC http://114.111.144.247/ics-wpd/exec/icswppro.dll?AC=QUERY&TN=inroads&QY=find+RC+=+1205AR084E Mon, 14 May 2012 14:00:00 UTC http://114.111.144.247/ics-wpd/exec/icswppro.dll?AC=QUERY&TN=inroads&QY=find+RC+=+1205AR102E Mon, 14 May 2012 14:00:00 UTC http://114.111.144.247/ics-wpd/exec/icswppro.dll?AC=QUERY&TN=inroads&QY=find+RC+=+1205AR122E Mon, 14 May 2012 14:00:00 UTC http://114.111.144.247/ics-wpd/exec/icswppro.dll?AC=QUERY&TN=inroads&QY=find+RC+=+1205AR171E Mon, 14 May 2012 14:00:00 UTCThis paper presents a methodology for real-time estimation of exit movement specific average travel time on urban routes by integrating real-time cumulative plots, probe vehicles and historical cumulative plots. Two different approaches, Component based and Extreme based are discussed for route travel time estimation. The methodology is tested using simulation and validated with real data (from Luzern, Switzerland) that demonstrates its potential for accurate estimation. Both approaches provide similar results. The Component based approach is more reliable with a greater chance of obtaining a probe vehicle in each interval, though additional data from each component is required. The Extreme based approach is simple, and only requires data from upstream and downstream of the route, but the chances of obtaining a probe that traverses the entire route might be low. The performance of the methodology is also compared with a method solely based on probe (Probe-Only). The proposed methodology requires only a small number of probes for accurate estimation, whereas Probe-Only requires a significantly larger number of probes. http://114.111.144.247/ics-wpd/exec/icswppro.dll?AC=QUERY&TN=inroads&QY=find+RC+=+1205AR177E Mon, 14 May 2012 14:00:00 UTCThe case for transit priority can be substantially enhanced if direct passenger travel time benefits are supplemented by secondary benefits including mode shift from auto drivers and operating fleet resource savings due to running time improvements. Although these effects have been theorised in previous research no quantitative evidential basis has been established. The paper aims to fill this gap and expand on previous theoretical models using actual evidence of transit priority impacts. It is part of a wider international research project aiming to develop new methodologies to plan and optimise the design of transit priority schemes. Evidence of mode shift effects suggests that transit priority can generate mode shift from auto drivers at levels of travel time savings much lower than suggested in previous theoretical models. A strong statistical link between the percentage of travel time savings resulting from transit priority and reductions in auto driving was established. Evidence of transit fleet savings resulting from priority schemes shows that they can occur at much lower levels of travel time savings than previous suggested as long as transit route lengths and headways are reasonably short. The analysis suggested that savings in fleet resources will continue beyond the thresholds suggested in theoretical models. The paper suggests a revised theoretical model of the secondary benefits of transit priority which reveals benefits are cumulative and generally higher than previously suggested. Areas for future research are suggested. http://114.111.144.247/ics-wpd/exec/icswppro.dll?AC=QUERY&TN=inroads&QY=find+RC+=+1205AR180E Mon, 14 May 2012 14:00:00 UTCHeavy vehicles and cars have different manoeuvrability and acceleration characteristics. Heavy vehicles thus influence a traffic stream in a different manner to passenger vehicles and cause different levels of traffic instability. The increasing number and proportion of heavy vehicles on the road may result in quite different traffic flow characteristics. Over the last half a century many studies have modelled car drivers’ car following behaviour. However, the existence of heavy vehicles in the traffic stream has not received the same attention. This paper investigates the different car following behaviour of drivers in heterogeneous traffic conditions. It explicitly considers the existence of heavy vehicles in general traffic and their interaction with other vehicles. Four types of passenger car and heavy vehicle combinations were considered. These were car-car, car-heavy vehicle, heavy vehicle-car, and heavy vehicle-heavy vehicle. A real world data set from a freeway in USA was used to show the different car following behaviour of drivers for each combination. This study analyses the space and time headways, driver’s reaction times and vehicle accelerations. It also introduces different Weidemann car following thresholds for each car following combination. It was found that the presence of heavy vehicles causes larger space and time headways, longer reaction time and more robust car following behaviour. It also shows that the car following thresholds are different for each combination. The findings of this paper indicate that further research is required to develop a car following model that incorporates these behavioural differences. http://114.111.144.247/ics-wpd/exec/icswppro.dll?AC=QUERY&TN=inroads&QY=find+RC+=+1205AR189E Mon, 14 May 2012 14:00:00 UTCLong traffic queues on off-ramps can significantly compromise motorway safety and throughput. Obtaining accurate queue information is crucial for developing or improving traffic control strategies to better manage long queues and also to prevent potential queue spillover. However, it is challenging to estimate traffic queues with locally installed inductive loop detectors. This paper deals with the queue estimation problem by interpreting queuing dynamics and the corresponding time-occupancy distribution over signalised off-ramps. A novel real-time queue estimation algorithm which uses two detectors is presented and discussed. The results derived from microscopic traffic simulation have validated the effectiveness and revealed that: 1) the proposed algorithm can accurately estimate long and intermediate traffic queues; 2) relatively simple detector input is required, i.e. time-occupancy measurements; and, 3) the estimation philosophy is independent with signal timing changes, which provides potentials to cooperate with advanced signal control strategies. Some issues for field implementation are also discussed. http://114.111.144.247/ics-wpd/exec/icswppro.dll?AC=QUERY&TN=inroads&QY=find+RC+=+1205AR195E Mon, 14 May 2012 14:00:00 UTCThis paper presents a novel method for adaptive traffic signal control. The method is denoted as the vehicle-to-infrastructure communication based adaptive control (VICAC). The VICAC uses real-time data from wireless communication (dedicated short-range communication, DSRC) to estimate travel time for individual vehicles, with the objective in minimising travel time throughout the controlled network. The VICAC controller may also send speed adjustment messages to approaching vehicles, which is intended to reduce unnecessary stops, thus improving fuel economy and reducing emission. As part of the proposed method, a model for estimating vehicle travel-time with real-time state information is presented. The control algorithm is based on approximate dynamic programming, and the signal control process is aperiodic. Microscopic traffic simulation is used to evaluate the performance of the proposed method against benchmark methods. The results show that enhanced awareness of the traffic state using wireless data substantially improves performance of a simple junction and only hints at what may be possible in traffic management. http://114.111.144.247/ics-wpd/exec/icswppro.dll?AC=QUERY&TN=inroads&QY=find+RC+=+1205AR198E Mon, 14 May 2012 14:00:00 UTCThis paper focuses on a generic sensor placement model for vision based traffic monitoring. A significant problem with using such sensors is the difficulty in detection due to the occlusion between vehicles. Thus, the efficiency of traffic monitoring can be directly affected by sensor placement. To simulate various traffic flows, models are developed for various aspects of moving traffic. Included in these models are Gaussian mixture distributions for vehicle dimensions, and the distribution for gap length between vehicles. The models are used to predict the vehicle detection error in a traffic flow as perceived from various sensor locations, while utilising vehicle headlight detection methods. Validation of the model has shown that the accuracy is consistent with performance from a vehicle detection framework with approximately 3 per cent variance on average. http://114.111.144.247/ics-wpd/exec/icswppro.dll?AC=QUERY&TN=inroads&QY=find+RC+=+1205AR199E Mon, 14 May 2012 14:00:00 UTCIn microscopic traffic simulators, the interaction between vehicles is considered. The dynamics of the system then becomes an emergent property of the interaction between its components. Such interactions include lane-changing, car-following behaviours and intersection management. Although, in some cases, such simulators produce realistic prediction, they do not allow for an important aspect of the dynamics, that is, the driver-vehicle interaction. This paper introduces a physically sound vehicle-driver model for realistic microscopic simulation. By building a nanoscopic traffic simulation model that uses steering angle and throttle position as parameters, the model aims to overcome unrealistic acceleration and deceleration values, as found in various microscopic simulation tools. A physics engine calculates the driving force of the vehicle, and the preliminary results presented here, show that, through a realistic driver-vehicle-environment simulator, it becomes possible to model realistic driver and vehicle behaviours in a traffic simulation. http://114.111.144.247/ics-wpd/exec/icswppro.dll?AC=QUERY&TN=inroads&QY=find+RC+=+1205AR203E Mon, 14 May 2012 14:00:00 UTCThe focus of this research is to develop minimum cost dynamic routing policies that can identify connecting paths between nodes in a Stochastic-State Network. In this particular context, the stochastic element of the network is the network structure, i.e., the set of links that exist under each realization of the network state. It is furthermore assumed that information about the true network state can only be gathered endogenously through the routing decisions themselves. As such, the objective becomes to find a dynamic policy that accounts for information gathered in-route that minimizes the cost of finding a viable path between a given origin and destination. This paper presents an exact solution method, based on a Markovian Decision Process, and then develops a heuristic based on an aggregating function of the network. http://114.111.144.247/ics-wpd/exec/icswppro.dll?AC=QUERY&TN=inroads&QY=find+RC+=+1205AR213E Mon, 14 May 2012 14:00:00 UTCThe aim of the wider study was to understand whether crash data supported common assumptions about the safety performance for left-turn treatments such as exclusive lanes, shared lanes or slip lanes (various design types) in relation to pedestrian versus vehicle crashes. In particular, this study sought to assist in a review of whether the current practice of including left-turn slip lanes wherever feasible in new or upgraded signalised intersections should be continued, modified in certain circumstances, or abandoned. This paper presents the key findings from the crash statistics review component of the wider study supplemented by selected extracts from the wider study relating to the current road rules, left-turn treatment implementation guidelines and detailed reviews of every single crash involving a pedestrian at slip lanes. It then extends to examining design issues for slip lanes and signal controlling of turns. http://114.111.144.247/ics-wpd/exec/icswppro.dll?AC=QUERY&TN=inroads&QY=find+RC+=+1205AR314E Mon, 14 May 2012 14:00:00 UTCThe main objective of this study was to estimate the speed impact of occasional hazard (playground) warning (OHPW) signs along residential streets. Three types of data were collected at each of three study sites approximately one month before and one week to one month after the installation of a pair of OHPW signs. Vehicle speed data were collected with a pneumatic tube device. Manual observations were recorded, and focused on the magnitude and location of the on-street parking and park and/or playground activities occurring at the study sites. Linear regression analysis was used to estimate the change in mean vehicle speed associated with the presence of the OHPW signs, while controlling for the effects due to activity levels on the streets and the playgrounds. At one site the OHPW sign had no discernible effect on mean vehicle speeds, while at the other two sites mean vehicle speeds decreased by 1.5 mph and 0.9 mph following installation of the OHPW signs. http://114.111.144.247/ics-wpd/exec/icswppro.dll?AC=QUERY&TN=inroads&QY=find+RC+=+1205AR315E Mon, 14 May 2012 14:00:00 UTCThis research produced several important tools that are essential in managing and operating freeway corridors. First, a computer-based off-line process was developed to automatically estimate a set of traffic measures for a given freeway corridor using the historical detector data. Secondly, a prototype on-line estimation procedure was designed to calculate selected traffic measures in real time to assist operators in identifying abnormal traffic patterns. Third, the IRIS-in-loop simulation system was developed by linking IRIS, the freeway control system developed by MnDOT, to a microscopic simulation software through a data communication module, so that new operational strategies can be directly coded into IRIS and evaluated under the realistic simulation environment. Finally, two new freeway operational strategies, variable speed limit control and a density-based adaptive ramp metering strategy, were developed and evaluated with the IRIS-in-Loop simulation system. http://114.111.144.247/ics-wpd/exec/icswppro.dll?AC=QUERY&TN=inroads&QY=find+RC+=+1205AR316E Mon, 14 May 2012 14:00:00 UTCThe classification problem of distinguishing bicycles from pedestrians for traffic counting applications is the objective of this research project. The scenes that are typically involved are bicycle trails, bridges, and bicycle lanes. These locations have heavy traffic of mainly pedestrians and bicyclists. A vision-based system overcomes many of the shortcomings of existing technologies such as loop counters, buried pressure pads, infra-red counters, etc. These methods do not have distinctive profiles for bicycles and pedestrians. Also most of these technologies require expert installation and maintenance. Cameras are inexpensive and abundant and are relatively easy to use, but they tend to be useful as a counting system only when accompanied by powerful algorithms that analyze the images. This report employs state-of-the-art algorithms for performing object classification to solve the problem of distinguishing bicyclists from pedestrians. It details the challenges that are involved in this particular problem, and it proposes solutions to address these challenges. It explores common approaches of global image analysis aided by motion information and compares the results with local image analysis in which we attempt to distinguish the individual parts of the composite object. It compares the classification accuracies of both approaches on real data and present detailed discussion on practical deployment factors.