Papers

Traffic demand forecasting is an important process for project development. The forecast traffic impact on existing infrastructure is essential to project approval. Accurate traffic forecasts are essential for decision makers. However, there is no follow-up procedure after project approval and construction. This means that there may be no evaluation of forecasting accuracy and subsequently no improvement in techniques over time. Another reason for high traffic forecasting inaccuracy may be the lack of a holistic approach to traffic forecasting. In other words, high forecasting accuracy of the proposed project is important, but it is not enough. The surrounding projects in the region should also be considered when addressing future traffic conditions. A single project may not have a large impact on future traffic conditions, but an aggregation of the traffic from several projects can have a very large effect on future traffic conditions.

A holistic view of the region provides a more accurate estimate of future traffic conditions. This, in turn, provides decision makers with comprehensive information to make qualified decisions, such as approval of projects or approval of sufficient infrastructure in due time and where it is most necessary. The impact that forecast traffic has on existing infrastructure is essential for project approval, so the key question is: Can decision makers rely on project traffic forecasts? It is important to answer this question, and in order to do so an evaluation and analysis of historic traffic forecasting must be conducted. This study intends to determine how accurate traffic forecasting on Oahu has been, and investigate what variables may have an effect on forecasting accuracy. This study has a focus on localized forecasts and impacts because Traffic Impact Assessment Reports (TIARs) do not provide a regional view

Improvement of Travel Time License Investigation using Advanced Correction Algorithm

ABSTRACT

Vehicle tracking methods are widely used for a variety of purposes including collection of travel time and duration of stay data. The collected data are used for planning and management purposes. The type of data depends on the method of data collection. Tracking methods are usually classified into active and passive. The purpose of this research is to discuss the accuracy of manual license plate matching method for vehicle tracking and travel time data collection, and provide correction algorithms to improve the results. The impacts of recordation style and visual similarities between characters (letters and numbers) on the matching errors are investigated. The correction algorithms are compared and evaluated.

The application of correction algorithms – specifically those that are more constrained to filter out false matches – can considerably increase the percentage of matched license plates. To a lesser degree, this processing can improve the statistical values of the license plate datasets such as average, standard deviation and median of travel time and duration of stay in a location.
This study also found evidence that a significant portion of mistakenly recorded letters while recording the license plates are visually similar letters, that by itself underlines the human factor in the accuracy of the method. Digits are not significantly probable to be mistaken because of their visual dissimilarity.
　

Analysis of Downstream Queues on Upstream Capacity Expansion of Urban Signalized Intersections

ABSTRACT

Signalized intersection is a fundamental component of an urban transportation system and appropriate treatments for intersection related congestion and safety issues are increasingly growing in importance. The most direct and intuitive approach to alleviate the recurring congestion is to cope with the peak hour disparity between travel demand and supply at the bottleneck intersections by expanding intersection capacity. However, intersection treatments such as adding lanes, turning movement restrictions, and grade separation that were traditionally applied to improve intersection capacity may not realize the expected benefits of relieving congestion and reducing delay as the traffic conditions at the downstream intersections can be greatly deteriorated by increased upstream arrivals. Additionally, the extended queue generated from downstream intersections can spill back into the upstream intersection and diminish the performance of the upstream treatment. This phenomenon is frequently observed in large urban areas where the traffic volume is heavy, intersection spacing is short and cycle length is long.

This study was conducted to provide traffic engineers with a simple, practical and step-by-step analysis method to identify the occurrence and the type of queue spillback (Cyclic and Sustained), to determine the effects of downstream queues on upstream capacity, and to select the best capacity expansion treatment. The theory and methods for measuring the consequence of downstream queue effects and quantifying the potential capacity cutoff are developed based on the updated queue size and intersection capacity estimation methodologies for signalized intersections in the Highway Capacity Manual 2010 (HCM 2010). A spreadsheet-based computational tool was developed to assist in the process of capacity constraint identification and calculation. A case study is presented to demonstrate the practical use of the analysis method.

Left Turn Prohibition and Partial Grade Separation for Signalized Intersections: Planning Level Assessment

ABSTRACT

The congestion of urban signalized intersections is a major issue, even in cities where advanced traffic signal timing and management systems are in operation. Recurring congestion at signalized intersections is usually caused by the inability of traffic signal controls to serve demand. Left turn prohibition and partial grade separation (low-clearance underpass) are discussed as possible solutions for urban complex and congested signalized intersections that have exhausted other methods for capacity enhancement. Both treatments potentially improve traffic signal efficiency by eliminating or reducing the duration of signal phases, and enhance intersection safety by eliminating certain conflicts. At the same time, they necessitate rerouting of traffic and have implication with respect to accessibility, land values, lane utilization, etc.

A planning-level assessment method to quantify and compare the benefits and costs of these treatments has been developed. The assessment considers the direct effects on intersection delay (using the Highway Capacity Manual 2010 methods) and accident frequency (using the Highway Safety Manual crash prediction methodology) and includes a cost-benefit analysis based on AASHTO’S User Benefit Analysis for Highways Manual. The objective of the planning level assessment is to be substantially comprehensive while using as many nationally accepted default values and conservative assumptions to minimize workload and expedite assessment at multiple locations. Due to the complexity of these layers of analysis for multiple treatments and time periods, a spreadsheet-based computational tool was developed and a case study was used to demonstrate the assessment method.

Challenges in Vehicle Classification

ABSTRACT

Intelligent Transportation System (ITS) technologies are most commonly used to improve the efficiency and reliability of traffic management systems, which accommodate traffic demand and reduce traffic congestion. Advanced technologies for traffic data collection, as an integral element of ITS, provide fundamental traffic information for developing strategies for traffic control, operation, planning and various highway analysis.

Transportation agencies focus more attention on the vehicle classification programs in an effort to meet the increasing need for detailed input in ITS and transportation analysis. Applications and issues of vehicle classification detection are discussed with emphasis on the increasing needs of the data users, sensing technologies for vehicle classification and the challenges to enhance the quality of classification data.

Reliability of Vehicle Volume, Speed and Classification Detection with Non-intrusive Sensors

ABSTRACT

Automatic traffic monitoring improves the availability of traffic data and provides fundamental and essential information for developing strategies of traffic control, operation and planning. Traditional intrusive technologies continue to be widely employed in the United States. However, there is a growing interest and activities in testing and applications of non-intrusive sensing technologies for portable or permanent traffic data collection. There is a need to develop and evaluate non-intrusive sensors that are easier to install, operate, maintain and remove.

We focused on vehicle classification evaluation with video image processing (Autoscope), microwave radar (SmartSensor HD) and active infrared (TIRTL) technology. In this paper, we discuss the reliability of the three sensing technologies with emphasis on the evaluation of volume and speed detection. We interpret the relationship between the performance of volume/speed and classification detection, and present the deficiencies of these sensing technologies.

The main conclusion is that the sensitivity to external influences varies for volume, speed and classification detection. We note that good performance in vehicle classification is a sufficient but not necessary condition for good performance in volume and speed detection.

Evaluation of Smartsensor, TIRTL, and Autoscope for Vehicle Classification

ABSTRACT

The collection of vehicle classification data, particularly truck data, is fundamental in the design and maintenance of highway infrastructures. Furthermore, classification monitoring efforts also improve the availability and reliability of volume data which are the backbone of conducting traffic analyses and utilizing transportation management systems. Because non-intrusive sensors minimize the adverse impact on traffic and surrounding communities (e.g. closing traffic, cutting the pavement) when installed and maintained, the application of non-intrusive classifiers for highway is becoming a trend, along with the rapid development of the non-intrusive technologies. However, there has been no systematic study on evaluating the sensor performance with respect of classification.

Autoscope, a length-based classification sensor with video imaging technology, The Infra-Red Traffic Logger (TIRTL), an axle-based classification sensor with active infrared technology and SmartSensor HD, a length-based classification sensor with microwave radar technology, were tested to evaluate the accuracy and reliability of vehicle classification. This work identifies a set of sensors and locations of deployment as well as applicable classification schemes that may yield a reliable set of classification data for the island of Oahu. The accuracy of traffic sensors for vehicle classification was established with synchronous field observations (direct or videotaped) and mutual comparison of classification data collected synchronously by different sensors. The reliability of sensors under different environmental and traffic conditions is also presented.

In conclusion, the findings extracted from the field demonstrations are summarized. Main finding indicated the following:

· TIRTL is the top recommended sensor due to its easy of setup, low energy consumption and high classification accuracy (92% overall classification accuracy, 96% truck-only classification accuracy).

· Autoscope is recommended for portable data collectors due to mobile, real-time video recording ability and adquate classification accuracy under optimal environmental conditions (92% overall classification accuracy under optimal conditions). Sensor is sensitive to environmental variation and day/nigh cycle.

· SmartSensor HD did not provide reliable classification counts under all of our tests and generated many random errors and imaginary vehicles.

This thesis suggests direction for the further research so that the performance of classification sensors can be more accurately evaluated.

Research on Theory and Model of Inverted Traffic Regional Planning and Demand Forecasting

ABSTRACT

Traffic planning plays an important role in urban and regional planning and traffic demand forecast is crucial technical content in traffic planning. The classic Four-Step theory of traffic planning has been used in China since 1980s, however, more and more conclusions bear out that the Four-Step planning is limited in our country nowadays. The primary problems gripping forecasting reliability of the traffic planning in China today led to a general recognition that the unpredictable factors of traffic planning increase owing to the rapid progress of urbanization, which is pervasive in all levels of the classical theory & model of traffic planning.

Through analyzing different data and examples of urban traffic planning in China, The thesis tries to suggest a new planning theory of urban traffic and aim at avoidance of serious traffic problems resulted from unpredictable urban traffic demand & failed traffic planning. Comparing the discipline of urbanization in the world and the situation in China, the limitations of Four-Step application in a stage of rapid urbanization led to incorrect traffic demand forecast in cities of China, especially in middle and small cities with changeful intensities of land use. With the unique urbanization characters in China, the Traffic Regional Control Planning & Demand Forecasting is under the research. The specific procedures are elaborated in a flow chart listed in the next page.

The main surveyed data of the new theory are traffic volume of crucial road sections in current road network, floor area ratio and distribution of population in every traffic zone, Expensive O-D survey is not necessary by technology of O-D matrix estimation. In the end, the new theory and forecasting models are ready to be used in the project of transport planning in Luogang distract of Guangzhou to confirm the feasibility and effectiveness in real application according to indexes of land use control, forecasting trip generation and in each traffic zone.
　

Research on Characteristics of Pedestrians Crossing Vehicles Flow in Urban Traffic

ABSTRACT

It is a common phenomenon that pedestrians traverse traffic flow in Chinese urban traffic. The phenomenon pointed out in this thesis means the mutual impact between vehicles and pedestrians, especially the behavior that the pedestrians are illegal to cross street in red-light period or cross the driveway in the non- crossing facility area.

The phenomenon of pedestrian crossing vehicles flow is caused by various factors. The mental and behavior factors are used in defining the characteristics of the phenomenon in this thesis. The behavior factors include crossing speed and acceptable time headway (i.e., available crossing time gap) offered by vehicles flow. The mental factors consist of mental effect and reaction within preparatory process and crossing process. This thesis focuses on the logical relation between the external causes (traffic condition, culture of society etc.) and the internal causes (gender, age, and education background of pedestrians etc.).

This thesis also tries to explore the reason why the crossing speed of pedestrians in dangerous situation is little lower than the walking speed in green light period of sidewalk. The interference mutually happen while the pedestrians are walking across vehicles flow in a busy street, in order to illustrate the topic, a comparative table of walking speed and crossing for different age and gender is listed, and the proportion of crossing pedestrians in different crossing times was analyzed in the form of a curve line as well. According to different rising rate of slope at different crossing time gap, the curve and relevant pedestrians is divided into three groups to describe distribution of crossing time gap : the adventure section (from 2.7s to 3.25s), the transition period (from 3.25s to 4s), and the cautions section (above 4s). And then, through analysis of crossing mental characteristics, combining theories of traffic engineering and psychology, a flow chart of whole pedestrian crossing process is also described.

The possible solutions of pedestrian transportation in prohibiting crossing phenomenon are suggested and proposals of detailed ameliorative measures on reasonable distribution of crossing facilities and establishment of safety islands were also highlighted.
　

Achievements and Significance in Traffic Engineering & Transportation System of Straight -Ways in Ch’in Dynasty

ABSTRACT

Both as to scale and skill, no ancient country in the world did more in civil engineering than China. Yet little has been done towards making known the history of it, especially science and technology of traffic at that time .It is less surprising when we defined traffic science as a modern science, and it is widely acknowledged that the development of modern city enables science of road network planning and theory of traffic engineering to progress. Although few systemic engineering theories existed in the dynasty, some of most significant achievements in traffic engineering & transportation system about Straight -Ways in Ch’in Dynasty were presented in this thesis.

In Ch’in Dynasty, besides Straight -Ways which was a military highway between the frontier and capital, road network linking cities, military location, and government centre has been established in 207 B.C. The construction of a vast set of arterial post-roads, speed-ways (imperial, military or trade special roads) and Straight -Ways radiating from the capital at Chhang-an formed radial road network planning. Through the analysis of political need to maintain executive power and centralized administration in Ch’in Dynasty, combining modern theory of road planning in traffic engineering, the thesis gives a detailed explanation about the significance of this road planning form. The achievements of transportation system embodied concept of transportation service and management. Location of service facilities was designed to supply a need of military or trade caravan. Skillful disposal of those facilities in various distance enabled road user to reach next supply post before their food and water were run out. Strict road law was enacted by Ch’in government to manage those imperial highways, and relevant punishments about crossing high-roads illegally, destroying traffic facilities, and even making traffic congestion were executed by powerful management department. The purpose of describing the great achievements of transportation system in this paper is to claim their values for contemporary time.

In addition, since besides the numerous remains of Straight -Ways which has been excavated, there are detailed literary descriptions of theory and practice until now. Based on these valuable discovery and references, methods to construct the highways and mapping skills of former times were also discussed in the article.
　

Causation Analysis on Urban Transportation Problems of Shanghai

ABSTRACT

As one of China’s economic and cultural centers, Shanghai is experiencing urban transportation problems, such as serious traffic congestion and increasing urban population. Since 1990, massive investment in transportation infrastructure is aimed at alleviating the urban transportation problems, attracting passengers for public transit and lowering high population density in downtown. How to effectively improve urban traffic situation and spatially diffuse population is of concern for future policies and planning of city government.
　

This paper first briefly introduces the city of Shanghai and the weakness of existing transportation policies. In the next section, two basic causes (mixed traffic flow and centralized population distribution) of the urban transportation problems in Shanghai were presented and discussed. After a statement of the basic problems, the suggestions on managing mixed traffic and dispersing urban population are also highlighted as theoretical support for future policies and planning.
　

Data used in this paper comes from the Shanghai Statistical Yearbooks, Shanghai Municipal City Planning Administration, and other relevant literatures.

Evaluation of non-intrusive sensors for vehicle classification on freeway

ABSTRACT

The collection of vehicle classification data, particularly truck data, is fundamental in the design and maintenance of freeway infrastructures. Furthermore, classification monitoring efforts also improve the availability and reliability of volume data which are the backbone of conducting freeway traffic analyses and utilizing freeway management system. Because non-intrusive sensors minimize the adverse impact on traffic and surrounding communities (e.g. closing traffic, cutting the pavement) when installed and maintained, the application of non-intrusive classifiers for freeway is becoming a trend along with the rapid development of the non-intrusive technologies. However, there has been no systematic study on evaluating the performance of classification with these sensors.
　

In this paper, Autoscope, a length-based classification sensor with video imaging technology, TIRTL, an axle-based classification sensor with active infrared technology, and SmartSensor HD, a length-based classification sensor with microwave radar technology, were selected to evaluate the accuracy and reliability of vehicle classification. This work identifies a set of sensors and locations of deployment as well as applicable classification schemes that will yield a reliable set of classification data for the island of Oahu. The accuracy of traffic sensors for vehicle classification will be established with synchronous field observations (direct or videotaped) and mutual comparison of classification data collected synchronously by different sensors. To comprehensively understand the ability of sensors for vehicle classification, the reliability of sensors under different environmental and traffic conditions were also presented in this paper.

Transportation Alternatives Analysis for Mitigating Traffic Congestion between Leeward Oahu and Honolulu

ABSTRACT

The rail system currently under consideration for the Honolulu Fixed Guideway project will costover $5 billion, reducing total travel time by an average of 6% and delivering worse traffic congestion than today’s H-1 freeway after completion. Is this the most cost effective solution for Oahu's traffic congestion problem?

Rail transit (Cost: $5 Billion): Using data from the city-generated Alternatives Analysis and simulating a commute from the H1/H2 merge to Aloha tower, a rail transit line would reduce H-1congestion approximately 3%, reducing drive times from 34 to 33 minutes. A rail commuter would make the same trip in approximately 41 minutes. Note that rail takes longer than driving.

HOT lanes (Cost: $1 Billion): The proposed HOT lanes facility is a reversible two- or three-lanehighway on which buses and vehicles with 5 passengers or more travel for free at an average speed of 60mph (vs. rail’s average 25mph). Unused capacity on HOT lanes is made available to private vehicles via an electronically computed toll which adjusts the price to keep lanes full but free flowing. Average toll price during peak commute times is estimated to be $3.50 per vehicle. HOT lanes need less or no tax subsidy; similar systems across the nation are privately funded. HOT lanes would reduce H-1 congestion by 35%, reducing drive times from 34 to 22 minutes. An express bus commuter would make the same trip in 12.7 minutes. The UHCS survey revealed that22% are willing to pay $3 or more to travel congestion-free, thus many are willing to vacate the congested H-1 Fwy. The greatest benefit of HOT lanes would accrue to those who never use them; they would pay no added taxes or tolls yet would experience dramatically reduced congestion.

Pearl Harbor Tunnel (Cost: $3-5 billion): A reversible 2-lane tunnel under the entrance of Pearl Harbor would connect to the Nimitz Viaduct. Drive times from Ewa to downtown would be reduced from 65 to 11 minutes and the load reduction on Ft. Weaver Road and H-1 Fwy. would bring those commuter times down from 65 to 40 minutes. The toll would have to be at least three times higher than for the HOT lanes to pay for the large cost of this option.

Four underpasses throughout urban Honolulu (Cost: $50M): One of the most cost-effective projects: introducing free-flowing underpasses in four of Honolulu’s busiest intersections delivers a substantial reduction in urban traffic congestion. Overall impact on travel times are nearly equal to rail’s performance, at a 99% cost savings.

Rail is the worst global warmer. Excluding New York City, transit averages 310 grams of carbon emissions per passenger mile, compared with 307 for the average 2006 model car and 147 grams from a Toyota Prius. Fuel efficiency trends clearly indicate that vehicles in 2030 will be largely non-polluting, whereas rail will still be drawing its power from today’s fossil-fueled power plants.

Bleak outlook. Rail’s immense construction costs and operating losses will preclude the use of funding for other transportation solutions. This combined with rail’s dismal performance will perpetuate Oahu’s unacceptable levels of traffic congestion for residents and visitors alike. Last but not least, people do not want rail. In a March-May random mail survey conducted as part of an independent research project: on highway noise attitudes people were asked about their attitudes onr ail: 44.6% responded that Honolulu does not need rail versus 36.5% who responded that it does. The remainder had no opinion. More telling was that 66.1% reported that they would not use rail for school or work, whereas 16% reported that they would.
　

Research on Vulnerability of Transportation Network

ABSTRACT

Based on the concept of vulnerability of transportation network, the connotation of vulnerability of transportation network is analyzed at the first two sections, and then the macro layered conceptual model of vulnerability was set up based on the randomness of traffic demand and supply and theory of Analytic Hierarchy Process. In the fourth section, the paper brings forward a micro analytic model to quantify the vulnerability of transportation network. Three essential impact factors (unreliability of transportation network, operating status, and ability of network recovery) were introduced and discussed. Finally taking a simple transportation network as an example, the application of vulnerability analysis method for evaluating the network operating status is illuminated as well.

A Pansystems Policy Model for Logistics

ABSTRACT

Purpose – To present a policy model for logistics systems based on pansystems theory. Design /methodology/ approach –This is a discussion paper exploring the reasonable policy model in order to reach overall synthesis, dynamic evolution and self-adaptive movement of logistics system. Findings –The concrete contents of the study include the description of pansystems policy model for logistics, the submodels consisting of external synthesis model, internal dynamic equilibrium model, policy optimization model, and implement model. Originality/value –Provides theoretical reference for the formulation of logistics policy in a country or region.
　