Travel Time Delay Research Articles

Economic Evaluation of Trends in Travel Time Reliability in Road Transport

This study aimed to demonstrate that travel time reliability and road network robustness from the user's perspective could be measured with the use of detailed traffic data and according to a definition proposed by international experts. These measurements can be used to describe and explain the trend of travel time reliability and to describe the trend of extreme travel time delays (or nonrecurrent congestion). In the Netherlands, the trend of travel time unreliability increased until 2008 but was followed by a decline in subsequent years until 2011. Socio-economic factors, such as population growth and employment, appeared to be the underlying factors for the increase in travel time unreliability. Serving as a counterbalance were various transport policy measures, such as the addition of lanes, traffic management, and speed limitation and control, which were implemented primarily during the years 2009 to 2012. Finally, the study demonstrated how the volume of travel time reliability could be used as a component for the cost–benefit analyses of adding infrastructure and for calculating the social costs of travel time unreliability for users of the main trunk road network.

Significance of Sensor Location in Real-time Traffic State Estimation

Short-term congestion caused due to traffic incidents or other road environment factors significantly reduces traffic flow capacity of a link which forms a major part of travel time delays. Accurate and reliable estimate of real-time traffic state is essential for optimizing network performance during unpredictable events. Inaccurate estimate of current traffic state produces unreliable travel-time estimations which lead to ineffective traffic management strategies during traffic incident.This study highlights the accuracy and reliability of traffic state estimate when a traffic flow prediction model is not provided with information about duration and impact of the incident on traffic flow capacity of the link. Cell Transmission Model (CTM) is used for prediction of traffic state and measurements from the sensor are combined in Extended Kalman Filter (EKF) to minimize square of error between predicted and measured traffic state. A simple link is used to highlight the difference between actual traffic state and estimated traffic state using a naive prediction model for real-time traffic state estimation. Analysis of simulation results shows that estimate of traffic state is reliable and accurate for cells upstream of the measurement sensor when incident occurred downstream of measurement sensor. Whereas when incident location is upstream of measurement sensor, the estimated traffic state for downstream cells of measurement sensor is more close to actual traffic condition.

Model based Traffic Control in Indian Conditions

Congestion and associated traffic safety are the major challenges for transportation systems all over the world in recent years. Congestion occurs when traffic demand exceeds the operational capacity of the roadway. Better management of infrastructure is required in improving the operational capacity. Traffic signals are one of the most popular traffic control strategies that have been adopted for managing the demand and to reduce congestion; but if not properly designed will lead to excessive delay and increase in travel time. Therefore, signals need to be designed based on theory of traffic flow that requires a good understanding of the traffic system. The present study proposes a macroscopic model based control scheme for Indian traffic conditions. Traffic density and speed are used as the state variables to characterize the system and the developed control scheme regulates the density inside the section.

Punctuality-based departure time scheduling under stochastic bottleneck capacity: formulation and equilibrium

This paper proposes a departure time scheduling model for a single bottleneck that is subjected to degradable capacity. Instead of considering travel cost due to uncertainty (either in form of schedule delay or travel time variance) as an additional cost term to be traded with congestion delay and other out-of-pocket costs, it is supposed that travellers deal with uncertainty by adjusting their departure times in order to achieve a certain desirable level of punctuality in accordance to their behavioural preference and trip characteristic. This paper develops the formulation in solving for the scheduling equilibrium, with a detailed exposition on how the expected travel time and schedule delays can be computed. Moreover, this paper discusses the existence of equilibrium of the proposed scheduling equilibrium. In the deterministic bottleneck model and subsequent works that extend to the case of stochastic bottleneck, it is often assumed that the start time of congestion (first appearance of queue) is fixed; in this paper, it is demonstrated that the congestion start time is in fact dependent on the random bottleneck capacity. Lastly, some interesting properties regarding the equilibrium departure profile are discussed and compared with the deterministic bottleneck results.

Analysis of Micro-cars' Influence on Traffic Network Using a Microscopic Simulator

The environmental effects and network performance of mixed traffic, consisting of micro-cars and conventional cars, on a small network are investigated using microscopic simulations. After calibrating the simulation model, the effects of three assumptions concerning micro-car speeds are investigated using the model. First, the parameters needed for network performance evaluation are determined iteratively. The power required to meet total travel demand is then computed to predict emissions. A higher ratio of micro-cars in the traffic reduces emissions, as does a lower micro-car speed. To investigate travel efficiency, the main parameters used are average speed, total travel time and total delay time. The results suggest that a higher ratio of micro-cars has a positive effect on the network when their speed is the same as or a slightly lower than that of conventional cars, while a higher ratio of micro-cars has a negative effect when their speed is close to the average traffic speed of the base model. To obtain a suitable balance between desired environmental effects and road network performance, we recommend that the desired speed of micro-cars be set to 40–45 km/h on a small urban traffic network.

교통량 측정 : CCTV를 이용한 주행 차량 조사법

본 논문에서는 교통망의 서비스 수준을 측정하는 주요 척도인 통행 시간과 지체 시간에 대하여 알아본다. 그리고 통행 시간의 측정 방법 중 하나인 CCTV를 활용한 주행 차량 조사법을 이용하여 교통량을 측정한다. 신호등 간격이 넓어서 연속적인 교통류 특성을 갖는 곳에서 측정을 하도록 한다. 또한 반대편의 교통류가 충분히 식별 가능한 구간이어야 하고, 구간의 끝부분에서는 유턴이 가능해야 한다. 이 방법은 CCTV를 이용하므로 측정차량의 운전수만 있으면 된다. 또한 시간, 거리, 교통량을 기록할 수 있는 장비도 필요 없다. 이런 일을 할 수 있는 소프트웨어 장비를 갖추고 있기 때문이다. 교통량 외에 평균 통행 시간, 공간 평균 속도, 교통 밀도 등도 구할 수 있다. In this paper, we watch out key measure of the level of transportation service about travel time and delay time. And we measured vehicle traffic by moving vehicle method using CCTV which is one of the travel time measure. We should be measured in place of continuous traffic flow characteristics with wide traffic light interval. In addition, traffic flow on the other side of the interval must be sufficiently identifiable and at the end of this section must be possible U-turn. This method it requires only the driver of the vehicle because of the CCTV measure. In addition, We cannot require time, distance, and traffic equipment that can be recorded. Because equipped with the software to do that. In addition to traffic, average travel time, average space speed, traffic density are also available.

Door-to-door travel times in RP departure time choice models: An approximation method using GPS data

A common way to determine values of travel time and schedule delay is to estimate departure time choice models, using stated preference (SP) or revealed preference (RP) data. The latter are used less frequently, mainly because of the difficulties to collect the data required for the model estimation. One main requirement is knowledge of the (expected) travel times for both chosen and unchosen departure time alternatives. As the availability of such data is limited, most RP-based scheduling models only take into account travel times on trip segments rather than door-to-door travel times, or use very rough measures of door-to-door travel times. We show that ignoring the temporal and spatial variation of travel times, and, in particular, the correlation of travel times across links may lead to biased estimates of the value of time (VOT). To approximate door-to-door travel times for which no complete measurement is possible, we develop a method that relates travel times on links with continuous speed measurements to travel times on links where relatively infrequent GPS-based speed measurements are available. We use geographically weighted regression to estimate the location-specific relation between the speeds on these two types of links, which is then used for travel time prediction at different locations, days, and times of the day. This method is not only useful for the approximation of door-to-door travel times in departure time choice models, but is generally relevant for predicting travel times in situations where continuous speed measurements can be enriched with GPS data.

Evaluating the Effects of Different Control Strategies on Traffic Operations at Isolated Merge Bottlenecks

The primary objective of this study was to develop variable speed limit (VSL) and ramp metering (RM) strategies that particularly focused on preventing the capacity drop and increasing the discharge flow rate at freeway merge bottlenecks, and to evaluate the effects of the proposed control strategies on traffic operations. A cell transmission model was developed to evaluate the effects of the proposed control strategies on traffic operations. The CTM was adjusted and calibrated using real- world traffic data to accurately capture the capacity drop phenomenon. With space-time diagrams and traffic characteristic diagrams, the occurrence mechanism of traffic congestion at the bottleneck under different control strategies was compared. The simulation results showed that total travel time and vehicle delay were reduced under the proposed control strategies. It was found that the VSL control and RM control were effective in improving traffic operations at freeway isolated merge bottlenecks. In addition, the RM control outperformed the VSL control in reducing traffic congestion when the on-ramp flow rate was low.

Distributed travel time savings of a multiscale transportation access management program

Access management in transportation planning can save travel time, reduce crashes, and increase route capacities. The planning literature suggests a need for performance metrics and a decision-aiding framework to guide access management programs across large corridor networks and diverse time horizons. This paper describes a quantitative framework to support access management programs, applying multicriteria analysis and cost-benefit analysis with parameter uncertainties. The metrics used to assess relative priorities at existing access points include the following: travel time delay index, traffic exposure, value of time, and costs of typical access management activities. Uncertain parameters that influence the estimates of the potential benefits and costs are identified and treated via a numerical interval analysis. The framework is demonstrated at several geographic scales and locations including 7,000 km of highway arterials of a 110,000 square-kilometer region and several sub-regions. The results assist decision makers to identify route segments that should be addressed sooner by eliciting additional information, reserving right-of-way, closing access points, planning new alignments, facilitating development proffers, etc. The approach is transferable to other topics involving resource allocation for preservation and improvement of multiscale infrastructure systems.

Precipitable Water from GPS Zenith Delays Using North American Regional Reanalysis Meteorology

Abstract Precipitable water or integrated water vapor can be obtained from zenith travel-time delays from global positioning system (GPS) signals if the atmospheric pressure and temperature at the GPS site is known. There have been more than 10 000 GPS receivers deployed as part of geophysics research programs around the world; but, unfortunately, most of these receivers do not have collocated barometers. This paper describes a new technique to use North American Regional Reanalysis pressure, temperature, and geopotential height data to calculate station pressures and surface temperature at the GPS sites. This enables precipitable water to be calculated at those sites using archived zenith delays. The technique has been evaluated by calculating altimeter readings at aviation routine weather report (METAR) sites and comparing them with reported altimeter readings. Additionally, the precipitable water values calculated using this method have been found to agree with SuomiNet GPS precipitable water, with RMS differences of 2 mm or less, and are also generally in agreement with radiosonde measurements of precipitable water. Applications of this technique are shown and are explored for different synoptic situations, including atmospheric-river-type baroclinic storms and the North American monsoon.

GPS Precipitable Water as a Diagnostic of the North American Monsoon in California and Nevada

Abstract Precipitable water derived from archived global positioning system (GPS) zenith travel-time delays is used to describe the seasonal and interannual variation of the North American monsoon in California and Nevada. A 3-hourly dataset of precipitable water from 2003 to 2009, for over 500 sites in California and Nevada using temperature and pressure interpolated from the North American Regional Reanalysis (NARR), is constructed to study the temporal and spatial extent of the North American monsoon in the desert regions of California and Nevada. The statistical distribution of precipitable water values is shown to delineate the region that is most often affected by the monsoonal influence. A normalized precipitable water index is employed to indicate when the monsoon starts and stops and to investigate spatial variability. The GPS network provides much higher spatial resolution than other meteorological networks using surface-based methods, such as dewpoint criteria and rainfall, and is seen to contain comparable ability in capturing temporal variations. This dataset reveals the northwestward propagation of the monsoon onset both synoptically and seasonally. The GPS observations indicate that in the mean the decay of the monsoon is less well defined than the onset. Seven-year reanalysis 700-mb geopotential height composites for the monsoon onset and 3 days prior indicate that the onset of the monsoon is associated with a shift in the synoptic pattern characterized by upper-level high pressure building from the east and offshore troughing retreating to the northwest.

지반의 비균질성이 탄성파 전파 특성에 미치는 영향에 대한 추계론적 수치해석 연구

ABSTRACT: Various elastic wave-based site investigation methods have been used to characterize subsurface ground because the dynamic properties can be correlated with various geotechnical parameters. Although the inherent spatial variability of the geotechnical parameters affects the P-wave propagation characteristics, ground heterogeneity has not been considered as an influential factor. Thus, the effect of heterogeneous ground on the travel-time shift and wavefront characteristics of elastic waves through stochastic numerical analyses is investigated in this study. The effects of the relative correlation lengths and relative propagation distances on the travel-time shift of P-waves considering various intensities of ground heterogeneity were investigated. Heterogeneous ground fields of stiffness (e.g., the coefficient of variation = 10 ~ 40%) were repeatedly realized in numerical finite difference grids using the turning band method. Monte Carlo simulations were undertaken to simulate P-wave propagation in heterogeneous ground using a finite difference method –based numerical approach. The results show that the disturbance of the wavefront becomes more significant with stronger heterogeneity and induces travel-time delays. The relative correlation lengths and propagation distances are systematically related to the travel-time shift.

Operational Assessment of Joint and Conventional Lane Merge Configurations for Freeway Work Zones

Inefficient traffic operation at work-zone areas typically leads to increased travel time delays, queue length, fuel consumption, number of forced merges, and possibly roadway accidents. Using crash data collected from active work zones in Louisiana between 2003 and 2007, a safety analysis for the conventional lane merge configurations recommended in the Manual on Uniform Traffic Control Devices (MUTCD) revealed that the fatality, injury, and property damage crash rates in the advance warning area of work zones were significantly higher than in other work-zone areas. Intelligent transportation systems offer innovative technological solutions to improve the operational efficiency and safety of work zones through advanced lane merge control strategies that extend beyond the conventional lane merge configuration. This study focuses on the operational efficiency of a newly proposed work-zone configuration, referred to as joint lane merge (JLM), and compares its performance with the conventional lane merge (CLM) configuration. A simulation model (VISSIM) was calibrated with real-world data from an existing work zone on I-55 and used to simulate a work-zone area with both configurations. In total, 25 different scenarios were generated from five different levels of demand and five truck percentages. Performance measures in terms of total throughput and average delay time were compared and statistical analysis was conducted to determine whether the differences in operational performance between both configurations were significant. The results showed that the joint lane merge outperformed the conventional lane merge in terms of maximum throughput and average delay per vehicle for all simulation scenarios considered.

Commuters' Preferences for Fast and Reliable Travel

We employ a semi-parametric estimation approach to analyse observed and unobserved heterogeneity in the value of savings in travel time and schedule delay. Our econometric approach allows for the estimation of unobserved and observed heterogeneity in preferences in a flexible way, meaning that we do not put any structure on how individual characteristics (such as income and age) relate to the value of savings in travel time and schedule delay. Using data from a stated choice experiment, we illustrate the estimation approach and find that there is substantial heterogeneity in the value of savings in travel time and schedule delay. For our data, we find that unobserved heterogeneity is more important than heterogeneity related to individual characteristics.

Real Time Imaging of CO2 Storage Zone by Very Accurate- stable-long Term Seismic Source

To examine the effectiveness of our time lapse method for CCS monitoring, we carried out a field-test in Japan using an ultra-stable seismic source. We injected 80-tons air in total into 100 m depth. We obtained transfer functions between the source and 31 seismometers. All residual waveforms between before and after the injection revealed very large changes on records. A station at 200m distance from the injected-well showed 10ms travel-time delay at 1-day after the injection. The time-reversal imaging showed the clear image for spreading of disturbed area from the injection point to eastward with elapsed times.

Ant colony optimisation with random selection for block transportation scheduling with heterogeneous transporters in a shipyard

This paper considers a scheduling problem of heterogeneous transporters for pickup and delivery blocks in a shipyard assuming a static environment where all transportation requirements for blocks are predetermined. In the block transportation scheduling problem, the important issue is to determine which transporter delivers the block from one plant to the other plant and when, in order to minimise total logistic times. Therefore, the objective of the problem is to simultaneously determine the allocation policy of blocks and the sequence policy of transporters to minimise the weighted sum of empty transporter travel times, delay times, and tardy times. A mathematical model for the optimal solution is derived and an ant colony optimisation algorithm with random selection (ACO_RS) is proposed. To demonstrate the performance of ACO_RS, computational experiments are implemented in comparing the solution with the optimal solutions obtained by CPLEX in small-sized problems and the solutions obtained by conventional ACO in large-sized problems.

Applicability of Emergency Preemption Signal Control under UTIS

Abstract Even thought the firefighters have to hurry to the scene to ext inguish the blaze, the fire engines could not rushed out due to the worst of traffic condition. Traffic signal control is one of th e most important methods to minimize the fire engines’s travel time. The focus of this paper is to develop a traffic control strategy, w hich is emergency vehicle preemption algorithm considering pede strian in order to reduce travel time of emergency vehicle. This algorith m also includes recovering strategy after preemption signal to minimize the other vehicle’s delay. In order to estimate the effectivene ss of traffic control, traffic simulation was performed using V ISSIM micro simulation tool for two different kinds of networks, whic h were non-coordinated corridor and coordinated corridor. The differences of travel time and average delay between emergency vehicle and ordinary vehicle were respectively estimated under pre-existed pretimed signal and preemption traffic control at t wo respective networks. The results of the simulation for the e mergency vehicle, travel time was reduced to 36.8~43.3% under “Add or Su btract” method whereas it was reduced to 30.7~46.0% under “Dwell” method. In addition, in non-coordinated corridor case o f ordinary vehicle, average control delay of “Dwell” method was increased 33.5% whereas it grew 0.5% under coordinated corridor . And “Add or Subtract” method was confirmed that average contr ol delay of ordinary vehicle was increased 0.7% under non-coordina ted corridor whereas it swelled 4.5% under coordinated corridor .key words : Preemption, Emergency Vehicle, Transition, Signal Strategy†본 논문은 대전발전연구원의 “소방차 출동체계와 ITS 연계방안(2012)”의 내용을 수정 및 보완한 것임 * 주저자 : 단국대학교 토목환경공학과 박사수료 ** 공저자 : 단국대학교 토목환경공학과 교수 *** 공저자 : 국립한밭대학교 도시공학과 교수**** 공저자 및 교신저자 : 대전발전연구원 연구위원†논문접수일 : 2012년 7월 5일†논문심사일 : 2012년 9월 10일†게재확정일 : 2012년 9월 20일

Adaptive route choice model for public transit systems: an application of Markov decision processes

Over the past couple of decades the advancements in the areas of information and computational technology allowed for a variety of intelligent transportation systems developments and deployments. This study investigates an advanced traveler information system (ATIS) and (or) an advanced public transit system (APTS) adaptive and real-time transit routing component. The proposed methodology is applied to bus routes with fixed, predefined bus line alignments. It is shown that routing buses on such systems can be modeled in real-time by employing an associated Markov chain with reward model to minimize the impact of congested traffic conditions on the travelers and the overall operation cost of the transit system. A case study using a traffic and transit data from a real-world bus line was used to apply the proposed bus routing approach. It was found that under certain traffic congestion conditions buses should be re-routed to minimize their travel time and the associated system costs. The hypothetical congestion scenarios investigated show that individual bus travel time delays range between 50 and 740 s when the proposed adaptive routing is employed. The proposed methodology is also suitable for application to transit systems that run on a demand-adaptive basis (the bus line alignment changes with the travelers demand). Additional calibration and future integration of the system into specific ATIS and (or) APTS user services will be investigated.

A Comparison of Floating Car vs. Loop Detector Estimated Freeway Travel Time Delay

ABSTRACT Floating car- and loop detector-based methods are two different types of methods frequently used to collect travel time delay information across a freeway network. Sometimes, it is necessary to use them jointly to achieve the necessary freeway network coverage, due to the high labor costs for the floating car-based method and the indispensability of sufficient network instrumentation for the loop detector-based method. For example, both floating car- and loop detector-based methods were once used in the Highway Congestion Monitoring Program in the California Department of Transportation. It is therefore necessary to evaluate whether these two types of methods estimate similarly in terms of total travel time delay. To this end, corresponding delay information estimated using both types of methods from 37 freeway segments in the Greater Sacramento Area were collected and compared. It was found that these two types of methods do not estimate similarly in terms of total segment travel time delay. The mean absolute relative difference (MARD) can be as high as 78%, especially when delay is defined using a lower reference speed, such as 56 km/h. However, in terms of total segment travel time, the loop detector and the modified floating car method estimated similarly. The MARD is 19%. It was also found that the estimation from the different methods did correlate fairly well, which provides a means of conversion when different methods are used to monitor the total delay across a freeway network. As a spin-off, it was also found that a 1.5 km spacing of loop detectors is sufficient to achieve the 19% MARD as compared with the modified floating car method in terms of total travel time estimation.

Comparative analysis of probe‐based ramp metering with detector‐based and pretimed ramp metering

SUMMARYIn this paper, a probe‐based adaptive ramp metering approach has been developed and compared with a detector‐based and pretimed ramp metering approaches using PARAMICS microsimulation model made by Quadstone Limited. Both examined probe‐based and detector‐based ramp metering approaches adopt the same problem formulation; however, they differ by the data source that provides estimates of their input parameters. The probe‐based approach takes as main input space mean speed extracted from vehicle probes moving constantly on the entire freeway. The detector‐based approach takes the density readings directly from point detectors placed upstream and downstream of each on‐ramp. The developed approach formulates the ramp metering rates to simultaneously reduce freeway travel time and decrease delays on ramps. A dynamic weighting scheme is adopted in this formulation to give different weighting schemes to the various freeway sections and the on‐ramps. These weights are able to adjust dynamically based on prevailing and forecasted traffic conditions to give priority in each step to the sections of the freeways or/and on‐ramps experiencing critical traffic conditions. The comparative analysis of the three ramp metering approaches was conducted on an 8‐km freeway section on Highway 2 in Calgary, Alberta, Canada. The results of the analysis indicate that the probe‐based algorithm consistently outperformed the two other approaches in terms of all performance measures. The probe‐based approach is shown to exceed the performance of the detector‐based approach with a market share of vehicle probes as low as 3%. The results of the analysis are promising and show the effectiveness of developing ramp metering control algorithms taking the main input parameters from vehicle probes on the freeway. Copyright © 2012 John Wiley & Sons, Ltd.