Link Flow Evaluation Using Loop Detector Data: Traveler Response to Variable-Message Signs

Evaluation of traffic management strategies for special events using probe data

Don’t shoot the messenger: Traffic-irrelevant messages on variable message signs (VMSs) might not interfere with traffic management

Traffic Management Centers (TMCs) may control dozens of variable message signs (VMSs). Computers may help TMC operators select messages to post to VMSs, in response to traffic conditions. Errors in posting messages (incorrect location, wording, or both) can complicate traffic management and undermine public confidence in the TMC. An experiment was conducted in the TMC Simulator to compare support systems that directly post messages on VMSs with those that simply suggest messages to the operator. The post condition resulted in better performance in terms of getting appropriate messages posted on the correct signs in a timely fashion. Significant delays were sometimes associated with the operator's response to support system suggestions, even though the suggestions were prompt and accurate. We recommend that VMS management support systems be allowed to post messages without requiring operator approval, given that the messages have been previously approved for content, and the error rate of the support system is acceptably low.

Variable Message Signs (VMS), a collective route guidance information provision, are widely used in urban traffic in most metropolitan areas in China, which actually affect drivers’ route choice behavior. In this paper, a disaggregate choice analysis method is used to describe changes in drivers’ route choice behavior. Logit model, based on guidance utility, is applied to determine probability of route diversion, in which, not only traffic condition information characteristics are included, such as survey time, congestion level, but also drivers’ characteristics are taken into account, such as gender, age, driving experience. A case study is presented by taking drivers’ responses to VMS on Shanghai out-ring road, where a lot of stated preference data and revealed preference data is surveyed. Parameters of the above logit model are determined using those stated preference (SP) and revealed preference (RP) data. The result shows congestion level and age are important factors that affect route diversion probability.

The use of variable message signs (VMS) to provide traffic information is widespread, but success depends upon behavioural response to the sign messages. The research described here focuses on user acceptance of VMS located in an urban road network (Southampton, UK), and investigates the public's perceived effectiveness and usefulness of these signs through the use of revealed preference questionnaire surveys and travel diaries. Three hundred and sixty-five commuters regularly driving into Southampton from the outskirts of the city completed a travel diary for a 5-day period as well as a general questionnaire, and 660 infrequent travellers to Southampton completed the general questionnaire. The study showed that it is difficult to capture a meaningful sample size of respondents passing an `active' VMS in a real-life incident scenario. Less than 1% of the commuter sample stated that they had diverted to an alternative route during the travel diary week as a result of VMS information, although this did correspond to 53% of those 45 drivers originally intending to travel past the incident location. The results showed that the VMS messages were well-understood and legible, and also indicated that a default VMS message reporting no problems in the network can indirectly affect a driver's route choice.

Traffic accidents have become an important health and social problem due to the enormous number of fatalities and injuries. The total number of deaths and injuries in the European Union (EU), United States of America (USA) and Japan has been steadily reduced over the last decade. This reduction is mainly attributed to the implementation of a set of road safety measures, such as seat-belt use, vehicle crash protection, traffic-calming interventions and traffic law enforcement. However, the number of accidents has remained uniform due to the increasing number of vehicles and total distance driven (Peden et al., 2004). In addition to passive vehicle safety systems, such as airbags, anti-lock braking system (ABS) and electronic stability control (ESP), new active safety systems have been introduced to improve vehicular safety. To this end, the last decade has witnessed the traffic management industry, engage and promote the integration of information and communications technology (wireless, computing and advanced sensor technologies) into both vehicles and the wider transport infrastructure. These proposals have led to the intelligent transportation system (ITS) concept. At present, different ITS applications have been introduced, such as variable message signs (VMS), located at strategic points (e.g., tunnels and merging highways) or spaced at given distances, to inform drivers about traffic and dangerous situations; automated toll collection systems for highways and parkings; and real-time traffic information broadcasted in the FM radio band. Besides this, onboard ITS applications have improved the assistance and protection mechanisms for drivers: navigation systems, rear and front parking radars, and cameras are extensively used in the vehicle. Vehicles now incorporate sophisticated computing systems, with several sensors interconnected. However, short-range sensors employed in emergency systems, such as forward collision warning and lane keeping assist, are insufficient, specially when these sensors need to extend their communication horizon in emergency cases due to the limitation of their operating range to line-of-sight (LOS) conditions (Vlacic et al., 2001). Therefore, there are safety applications for distance emergency situations, such as blind corners and traffic crossing, where large-range vehicular communication systems are required, e.g., operating rages of about 1000 meters, in both LOS and non-LOS (NLOS) conditions (Gallagher & Akatsuka, 2006). Wireless communications systems which can operate with these constraints are known as cooperative systems on the road. In the cooperative system concept, vehicles and infrastructure exchange safety messages to extend the distance horizon and provide more information in real time to drivers. Cooperative systems involve two

Countermeasure Strategies against Traffic Congestion on Motorways in Japan

The widespread use of vehicle has led to new problems in the city because of the need for these vehicles in the organization of movement and parking, especially in areas characterized by increased congestion in the morning and evening peak, which is one of the problems of the great urban growth that hit the city of Baghdad. Accordingly, this study dealt with identifying the traditional and intelligent organizational means to regulate traffic, and the most important specifications and requirements for their distribution within cities. An applied case study of Maysaloun intersection in Al-Ghadeer municipality in Baghdad city was studied for identifying the streets that suffer from the lack of traditional organizational means and the imbalance in their spatial distribution. Through field surveys of the study area, it was noted that the streets suffer from congestion in the morning and evening rush hours resulting from a spatial distribution deficit and a large deficit in the number of traffic signs that have a significant role in regulating traffic and traffic management. Service levels as a street condition were compared with US HCM standards using the HCS2010 program. It was found that all streets of the study area with a service level (LOS) are lower than level (C) and therefore this condition is met by the applicability of Variable message sign (VMS). Finally, a digital photo map using a satellite image of the study area has been prepared as a proposal showing the streets where the requirements for the deployment of intelligent signs (VMS) and basic traffic signs are available to regulate and control the traffic movement and to fill the deficit and imbalance in the number and spatial distribution.

As part of the Highways Agency's plans to make the best use of existing roads, it is increasingly common for key intersections of the UK strategic road network to be provided with variable message signs (VMS). In the event of an incident affecting part of the network, the VMS can be used to warn drivers of the problem, and possibly to divert them onto alternative routes. Warning messages or diversions are usually selected from a library of plans, prepared in advance, to cater for a range of incidents. It can be difficult for system operators to determine which of the library of plans is most appropriate for a given incident, under the prevailing traffic conditions. To assist operators in making this decision the Highways Agency has developed MOLA (MCONTRM On-Line Assistant), a computer system able to model traffic conditions on a road network in real time and, when an incident occurs, to predict the effectiveness of alternative strategies and recommend to the operator which he should implement. (5 pages)

Feedback contents of previous information feedback strategies in advanced traveler information systems are almost real-time traffic information. Compared with real-time information, prediction traffic information obtained by a reliable and effective prediction algorithm has many undisputable advantages. In prediction information environment, a traveler is prone to making a more rational route-choice. For these considerations, a mean velocity prediction information feedback strategy (MVPFS) is presented. The approach adopts the autoregressive-integrated moving average model (ARIMA) to forecast short-term traffic flow. Furthermore, prediction results of mean velocity are taken as feedback contents and displayed on a variable message sign to guide travelers' route-choice. Meanwhile, discrete choice model (Logit model) is selected to imitate more appropriately travelers' route-choice behavior. In order to investigate the performance of MVPFS, a cellular automaton model with ARIMA is adopted to simulate a two-route scenario. The simulation shows that such innovative prediction feedback strategy is feasible and efficient. Even more importantly, this study demonstrates the excellence of prediction feedback ideology.

Effect of megestrol acetate on uroflow rates in patients with benign prostatic hypertrophy: Double-blind study

A modeling framework is developed to assess the performance of driver information systems. The two main components of the framework are a route choice module and a traffic simulation module. In the route choice module, three types of driver information systems are studied: the pretrip information service, the in-car route guidance system, and the variable message signs. The traffic simulation module controls the dynamics in a road network as traffic evolves over time in response to driver information. The dynamic properties of the framework are demonstrated in a test network and a simplified Singapore road network. The results suggest that there could be an optimal level of subscription to driver information or market penetration. Subscription to real-time driver information services is recommended, but a high level of subscription may result in extra delay. Variable message signs are not as effective as either pretrip information or in-car route guidance at their respective optimal levels of market penetration.

Common bus route navigation system provides distance and transferring information based on the user-determined start point and end point on the map. This paper presents the research and experiment of an advanced bus route navigation system in Beijing, which can additionally provide travel time information from start to end. The travel time is predicted based on statistical and real-time traffic information. In Beijing, about 10000 taxies send GPS data to a traffic information center to generate real-time traffic data, and the center accumulates the historical traffic data for generating statistical database. Field test of our system was carried out in January 2007, and the experiment result shows the real-time and statistical traffic information can be used not only for car navigation system, but also for public transit service. In our experiment, the average error rate of predicted travel time is about 10%, which is comparable to car navigation system.

최근 내비게이션에서는 실시간 교통정보와 과거의 교통정보를 가공하여 미래의 교통정보를 예측하는 패턴 교통정보를 같이 활용하여 빠른 길을 안내해주고 있다. 그러나 현재 사용되는 패턴 교통정보는 과거의 정보를 가공하여 교통정보를 예측하기 때문에 특별한 상황(유고, 날씨 등)에서는 예측이 정확하지 않는 문제점을 가지고 있다. 그래서 본 연구에서는 빠른 길을 찾기 위해 실시간으로 운전자들이 요청하는 경로탐색 데이터를 분석하여 가까운 미래 운전자들이 위치할 도로의 교통 혼잡도를 미리 파악하여 패턴 교통정보 보다 정확한 예측 교통정보를 제시하였다. 연구결과 첫째, 연구지역의 정체경로인 양재에서 마포간 차량속도 비교에서는 기존 상습정체 도로의 속도가중치 정확도가 3km/h에서 18km/h의 오차율이 발생하였지만, 본 연구의 Real 예측 교통 정보를 적용한 결과는 1km/h에서 5km/h의 오차율이 발생하였다. 둘째, 경로 품질에서 기존의 경로보다 최대 약 9분, 평균 약 3분 일찍 목적지에 도착하여 예측 교통정보 결과의 신뢰성을 입증할 수 있었다. 셋째, 기존의 경로탐색 결과 보다 혼잡도를 미리 예측하여 혼잡이 발생할 도로에 대해 회피되는 경로탐색 결과를 도출할 수 있었다. 따라서 본 연구결과의 경로탐색 비교를 통해 교통량에 대한 예측정보를 획득할 수 있었으며 이를 활용하여 실시간 빠른 길 탐색이 가능하고, 향후 교통 흐름을 분산 시키는데도 도움이 될 것으로 판단된다. Recent navigation systems provide quick guide services, based on processing real-time traffic information and past traffic information by applying predictable pattern for traffic information. However, the current pattern for traffic information predicts traffic information by processing past information that it presents an inaccuracy problem in particular circumstances(accidents and weather). So, this study presented a more precise predictive traffic information system than historical traffic data first by analyzing route search data which the drivers ask in real time for the quickest way then by grasping traffic congestion levels of the route in which future drivers are supposed to locate. First results of this study, the congested route from Yang Jae to Mapo, the analysis result shows that the accuracy of the weighted value of speed of existing commonly congested road registered an error rate of 3km/h to 18km/h, however, after applying the real predictive traffic information of this study the error rate registered only 1km/h to 5km/h. Second, in terms of quality of route as compared to the existing route which allowed for an earlier arrival to the destination up to a maximum of 9 minutes and an average of up to 3 minutes that the reliability of predictable results has been secured. Third, new method allows for the prediction of congested levels and deduces results of route searches that avoid possibly congested routes and to reflect accurate real-time data in comparison with existing route searches. Therefore, this study enabled not only the predictable gathering of information regarding traffic density through route searches, but it also made real-time quick route searches based on this mechanism that convinced that this new method will contribute to diffusing future traffic flow.

The purpose of this paper is to develop a real-time planning algorithm for making possible a more proper description of drivers' route choice behavior and processes under real time traffic information in a traffic network. The algorithm uses concepts from Decision Field Theory (DFT) and Bayesian belief network (BBN). DFT is widely known in the field of mathematical psychology and is used to study drivers' multi-attribute cognition and decision process under real time traffic information. BBN is employed to infer updating of road condition under real time traffic information. Using this algorithm, a driver develops his route dynamically until he reaches his preferred destination. The preferences of routes which are directly accessible from the current position are obtained via BBN and DFT. Critical factors that affect drivers' response to real time traffic information are quantitatively studied through interactive simulation and from the viewpoint of cognitive psychology.