Lane‐changing and freeway capacity: A Bayesian inference stochastic model

This article presents a new stochastic computational model for determining freeway capacity reduction as a result of lane‐changing activity. The probability density function for the maximum flow that can be sustained on a freeway for a given lane‐changing level is obtained. The results can be used to support freeway management strategies aiming to mitigate the negative consequences of lane‐changing in freeway capacity. A pilot test using empirical data obtained from the B‐23 freeway accessing the city of Barcelona proves the validity of the modeling approach.     

Increasing the Capacity of the Intersection Downstream of the Freeway Off‐Ramp Using Presignals

High volume from urban freeway off‐ramps coupled with extensive traffic weaving and limited capacity at downstream intersections create major bottlenecks in urban road networks. This article presents an integrated design model to eliminate traffic weaving and to maximize the section's overall capacity by using the presignal and sorting area concept. The selection of movements controlled by the presignal, the layout of the section, and the signal timing are optimized in a uniform framework by a mixed‐integer nonlinear program model. The mathematical model was linearized and solved using the standard branch‐and‐bound technique. Extensive numerical analysis and a case study validate the effectiveness of the proposed integrated model in improving capacity with the comparison of conventional design under various geometric configuration and traffic demand pattern scenarios. The proposed model has promising application at locations where the queuing space is long enough and the number of exit lanes is enough to receive the traffic stream from the sorting area.     

Passing Rates to Measure Relaxation and Impact of Lane‐Changing in Congestion

Abstract: Passing rate measurements of backward‐moving kinematic waves in congestion are applied to quantify two traffic features; a relaxation phenomenon of vehicle lane‐changing and impact of lane‐changing in traffic streams after the relaxation process is complete. The relaxation phenomenon occurs when either a lane‐changer or its immediate follower accepts a short spacing upon insertion and gradually resumes a larger spacing. A simple existing model describes this process with few observable parameters. In this study, the existing model is reformulated to estimate its parameter using passing rate measurements. Calibration results based on vehicle trajectories from two freeway locations indicate that the revised relaxation model matches the observation well. The results also indicate that the relaxation occurs in about 15 seconds and that the shoulder lane exhibits a longer relaxation duration. The passing rate measurements were also employed to quantify the postrelaxation impact of multiple lane‐changing maneuvers within a platoon of 10 or more vehicles in queued traffic stream. The analysis of the same data sets shows that lane‐changing activities do not induce a long‐term change in traffic states; traffic streams are perturbed temporarily by lane‐changing maneuvers but return to the initial states after relaxations.     

Determinants of self‐employment among commuters and non‐commuters

We analyse the determinants of self‐employment and focus on the contextual environment. By distinguishing between commuters and non‐commuters we are able to analyse the influence from the work and home environment, respectively. Our results indicate a significant difference between non‐commuters and commuters in terms of the role of networks for becoming self‐employed. Our results indicate that it is the business networks where people work, rather than where they live that exerts a positive influence on the probability of becoming self‐employed. These effects are further robust over educational and occupational categories.     

Measuring traffic lane‐changing by converting video into space–time still images

Empirical data is needed in order to extend our knowledge of traffic behavior. Video recordings are used to enrich typical data from loop detectors. In this context, data extraction from videos becomes a challenging task. Setting automatic video processing systems is costly, complex, and the accuracy achieved is usually not enough to improve traffic flow models. In contrast “visual” data extraction by watching the recordings requires extensive human intervention. A semiautomatic video processing methodology to count lane‐changing in freeways is proposed. The method allows counting lane changes faster than with the visual procedure without falling into the complexities and errors of full automation. The method is based on converting the video into a set of space–time still images, from where to visually count. This methodology has been tested at several freeway locations near Barcelona (Spain) with good results. A user‐friendly implementation of the method is available on http://bit.ly/2yUi08M .     

AN APPLICATION OF FUZZY SETS TO TRANSPORT PROJECT APPRAISAL

This paper reviews some of the theory continuous fuzzy sets or subsets and illustrates, by way of example, an application to project appraisal in land use and transportation planning. In particular, a detailed illustration of the application of continuous fuzzy sets (fuzzy numbers) to the assessment of four alternative routes for a part of a proposed Eastern Corridor between the Cities of Brisbane and the Gold Coast, Queensland, Australia, is presented.     

澳大利亚东海岸主要城市滨水区设计——墨尔本、霍巴特、悉尼、黄金海岸的滨水特色

通过对澳大利亚东海岸主要城市墨尔本、霍巴特、悉尼、黄金海岸的“城市滨水区” 的考察和分析,以“临水岸线”为脉络,以“滨水特色”为切入点,探索了其滨水区在规划设计、岸线营造、滨水设计风格等方面,对于今后中国滨水城市尤其是华南沿海城市滨水区的发展和建设中,加以印证和学习借鉴的参考意义。     

Concentration and Mobility of Knowledge Workers: An Intercity Analysis of Sydney,Melbourne, and Brisbane

This study investigates the knowledge capacity and the competitive relationship between cities in contemporary globalization. Drawing upon the global city thesis regarding advanced producer services and the city network model, this study measures the concentration and mobility of knowledge workers between three Australian global cities: Sydney, Melbourne, and Brisbane. It argues that knowledge workers are important agents in the making of urban knowledge space and intercity knowledge flow. It finds that Sydney's dominance in the Australian urban system has been strengthened despite challenges from Melbourne and Brisbane in certain knowledge sectors. The findings ascertain the linkage between the ranking of a global city and its knowledge capacity. They provide new insights into the current debates on Australian global cities and suggest possible new directions for global city aspirations, in the cases of Melbourne and Brisbane, in particular. Conceptually and methodologically, this study is an effort to bridge the global-city and the knowledge-city discourses, whose cross-fertilization suggests a potential need for new policy thinking.     

Die Wupper‐Talbrücke Oehde – eine moderne Verbundbrücke

The Wupper River valley bridge – a state‐of‐the‐art composite bridge. The German motorway Autobahn A 1 is one of the nation's most important and frequently traveled highways, connecting the country's northern and southern regions. The road currently has two lanes in each direction, which do not provide enough capacity to carry the traffic volume without daily traffic jams and heavy delays. Therefore, the federal government and the Northrhine‐Westfalia Department of Transportation decided to ease the situation by adding one lane in each direction. This total of 6 lanes fits into the master plan of widening major highways around the Ruhr River region. North of Cologne, the Autobahn A 1 crosses mountainous terrain, so several bridges with total lengths between 240 and 420 meters have had to be widened, replaced, or, most commonly, supplemented by a new bridge. Such supplementation was used on the Wupper River Valley Bridge, called Oehde, close to the city of Wuppertal. The bridge illustrates an example of modern composite bridges adopting new methods in construction and design, and also marks an outstanding example of current composite structures in Germany.     

Time‐Varying Lane‐Based Capacity Reversibility for Traffic Management

Abstract: This article presents a new bi‐level formulation for time‐varying lane‐based capacity reversibility problem for traffic management. The problem is formulated as a bi‐level program where the lower level is the cell‐transmission‐based user‐optimal dynamic traffic assignment (UODTA). Due to its Non‐deterministic Polynomial‐time hard (NP‐hard) complexity, the genetic algorithm (GA) with the simulation‐based UODTA is adopted to solve multiorigin multidestination problems. Four GA variations are proposed. GA1 is a simple GA. GA2, GA3, and GA4 with a jam‐density factor parameter (JDF) employ time‐dependent congestion measures in their decoding procedures. The four algorithms are empirically tested on a grid network and compared based on solution quality, convergence speed, and central processing unit (CPU) time. GA3 with JDF of 0.6 appears best on the three criteria. On the Sioux Falls network, GA3 with JDF of 0.7 performs best. The GA with the appropriate inclusion of problem‐specific knowledge and parameter calibration indeed provides excellent results when compared with the simple GA.     

The monetary subjective health evaluation for commuting long distances in Chile: A latent class analysis

Long-distance commuting (LDC) is a growing phenomenon in specialized countries in extractive industries such as Chile. There has also been a growing concern about the potential impacts on the health of long-distance commuters. This paper formalizes the relationship between commuting distance and self-assessed health status and shows the monetary valuation of health costs for commuting long distances using a latent class approach. This econometric approach allows us to capture both preference and threshold heterogeneity. The results show that there are two classes of workers: the first group is not sensitive to commuting distance, whereas the monetary valuation of workers in the second group is equivalent to CLP $431 (US$0.68).     

Die MaChang‐Brücke in Südkorea – Schrägkabelbrücke mit Verbundüberbau für Straßenverkehr

The MaChang Bridge in South Korea – Stay‐cable bridge with steel composite deck for highway traffic. The MaChang bridge is part of the new 4 lane highway connecting the cities of Masan and Changwon crossing over the Masan Bay. This high level crossing has a total length of 1,700 m and is composed of a 550 m long East viaduct, the 740 m long mainbridge and a 410 m long West viaduct. The mainbridge is the dominating structure of this link and consists of a two tower cable‐stayed bridge with a mainspan of 400 m and 170 m side spans. It provides clearance for the 350 m · 64m navigational channel and allows the passage of vessels up to 80.000 dwt.     

Optimal Mainline Variable Speed Limit Control to Improve Safety on Large‐Scale Freeway Segments

The primary objective of this study was to develop a procedure for determining the optimal variable speed limit (VSL) control strategy that aims at reducing both collision risks and injury severity on large‐scale freeway segments. The achieved reduction in collision risks and injury severity were evaluated using real‐time crash risk and severity prediction models. A modified cell transmission model (CTM) that took into consideration the capacity drop and the stop‐and‐go traffic was used to simulate the traffic operations with the VSL control. A computational procedure that incorporated the genetic algorithm and the CTM was proposed for the optimization of critical VSL control factors. Three scenarios with various placements of VSL signs on freeway mainlines were evaluated. The results showed that the optimal VSL control successfully decreased the collision risks by 22.62% and reduced the injury severity of crashes by 14.67%. We also evaluated how drivers’ compliance to speed limits affected the effectiveness of VSL control. The safety effects decreased as drivers’ compliance rate to the VSL control decreased. The finding suggests the use of speed enforcement techniques together with the VSL control to achieve the optimum control effects.     

Ermittlung der Tragfähigkeit und insbesondere der Belastbarkeit einer Spannbeton‐Straßenbrücke mittels Dynamischem Bauwerksmonitoring

Determination of Structural Integrity and Explicit Load Capacity of a Prestressed Concrete Bridge by Means of Dynamic Monitoring The prestressed concrete road bridge Komořany is a 2‐lane crossing of a multi‐track connection of the Czech Federal Railways. The main structure consists of two spans with varying lengths. In the main span a suspended span made of nine prefabricated, prestressed concrete elements (I‐beams) is implemented into the bridge structure via two Gerber joints. The bridge was completed in 1961 and represents one of the first practical applications of prestressed concrete in the former Czechoslovakia. In the course of a one day lasting measurement campaign the vibrational behaviour of the structure was extracted with regard to the global maintenance condition of the structure and compared with analytical calculations. By means of the performed analysis the load‐bearing capacity of the bridge structure had to be defined and therefore recommendations for the further maintenance provisions had to be given. Special attention was required regarding the suspended beam and its implementation into the bridge structure (Gerber joints) as well as the condition of the transversal prestressing of the prefabricated concrete elements.     

Challenges to surface water quality in mid‐sized African cities: conclusions from Awetu‐Kito Rivers in Jimma,south‐west Ethiopia

Rapid urbanization and industrialization, uncontrolled population growth, indiscriminate waste discharge and poor infrastructure are problems that African cities are facing. This paper describes an exemplary case study from Jimma, south‐west Ethiopia. A cross‐sectional study was conducted along the Awetu‐Kito drainage system in Jimma town to assess the level of pollution from urban dwellers and related activities. The study indicates that the Environmental Protection Agency (EPA) norms for biochemical oxygen demand (BOD), dissolved oxygen (DO) and orthophosphates are not met downstream of the major industrial and institutional activities. Small‐scale industries, Jimma University and residential areas contributed 50, 15 and 23% pollution load on the river, respectively. It can be concluded that the pollution effect in Jimma town is mainly as a result of the growing (uncontrolled) industrial activities and not to discharge of household wastewater. Given the same trends of urbanization and population growth, similar development (socio‐economic) indicators and similar climatic conditions, the key findings for Jimma are transferable to other mid‐sized African cities.     

Experimental investigation of a self‐centering precast concrete beam‐to‐column connection with top and bottom friction energy dissipaters

The new friction material, non‐asbestos organic, and Belleville springs are applied to the friction energy dissipaters (FEDs) to improve its friction performance. The new high‐performance FEDs are placed in the top and bottom parts of the self‐centering precast concrete (SCPC) beam‐to‐column connections, which have inherently reduced residual deformation caused by posttensioned tendons, to enhance energy dissipation efficiency. Besides, the reasonable design of the connection between FEDs and backbone members makes it easy for the disassembly of all members, which significantly enhances the repair efficiency after a major earthquake. Theoretical analyses and 14 tests were performed on a full‐scale specimen, which were assembled two times, and the friction pads were replaced one time, to investigate the effects of various parameters on the performance of such FED‐SCPC beam‐to‐column connections. The influence of key design parameters on the hysteretic behaviors, such as stiffness, loss of posttensioned tendons force, self‐centering capacity, and energy dissipation capacity, has been analyzed. The test results indicate that the FED‐SCPC beam‐to‐column connections can achieve significant and reliable energy dissipation levels while maintaining self‐centering capabilities. The experimental and theoretical results can provide certain references for the seismic design and assembly of such structures.     

A data‐driven approach to determining freeway incident impact areas with fuzzy and graph theory‐based clustering

Determining spatiotemporal impact areas of incidents plays a significant role in incident impact analysis. Although existing empirical methods have proven to be promising, they suffer from the drawbacks that limit their wide applications in automated freeway safety management. This study presents a data‐driven approach to automatically determining the spatiotemporal impact areas of freeway incidents. The spatiotemporal contour plots were first constructed using three representative traffic measures. Next, a nonrecurrent congestion area identification method based on fuzzy clustering was developed. To distinguish possible multiple independent blocks in the nonrecurrent congestion area, a clustering algorithm based on graph theory was adopted. The incident impact areas were then determined by conducting a postprocessing strategy. The incident records and the associated traffic flow data, collected on I‐5 freeway segments in San Diego Region, CA, were used to evaluate the proposed approach. Experimental results show the proposed approach can automatically and properly determine incident impact areas while accounting for the uncertainty resulting from traffic variations.     

Assessment of the neighborhood environmental effects of highway improvements through micronetwork simulation

New Cut Road is a major arterial highway serving South Louisville. Until recently, it was a narrow two‐lane highway of rural‐type design carrying up to 14,000 vehicles per day under forced flow conditions. Then construction began to widen the road from Southside Drive to Old Third Street Road, as a result of Urban Corridor Demonstration Program funding. The impacts (traffic, noise, and air pollution) on the neighborhoods surrounding this widening have been measured through micronetwork simulation techniques. Traffic will be diverted from surrounding roads (up to 20 percent) to the widened New Cut facility, thereby eliminating “over‐capacity” conditions in these facilities, adding several years’ life. Further, expeditious movement of vehicles through the New Cut Road “area of influence” will have a beneficial, albeit small, effect on the local air and noise environment. New Cut Road will be a highly cost‐effective, low‐capital‐intensive improvement.     

Seismic response of self‐centering precast concrete frames with hysteretic dampers

With the rapid development of cities and the invasion of major natural disasters such as earthquakes, the resilience city as a new design concept has been paid more and more attention. As an important branch of self‐centering seismic resisting system, self‐centering concrete frame system has been studied by many scholars. These studies prove that self‐centering concrete frame structure has excellent self‐centering ability but poor energy dissipation capacity. Adhering to the working principle of self‐centering structure and considering the development concepts of building industrialization and modularization, this paper proposed a kind of self‐centering precast concrete frame with hysteretic damper (SCPCHD). In order to verify its energy dissipation capacity and seismic performance, elaborate finite element models were established and elastoplastic dynamic time history analyses were carried out. The results showed that the SCPCHD frame has a similar interstory displacement response to the reinforced concrete (RC) frame and the energy dissipation performance of its joint is obviously superior to the RC frame under rare earthquake because the SCPCHD frame has low damage characteristics and excellent damping device. In summary, this paper proves the feasibility and superiority of the SCPCHD frame, providing reliable support for further research.     

Modeling Vehicle Interactions during Lane‐Changing Behavior on Arterial Streets

Abstract: Lane‐changing algorithms have attracted increased attention during recent years in traffic modeling. However, little has been done to address the competition and cooperation of vehicles when changing lanes on urban streets. The main goal of this study is to quantify the vehicle interactions during a lane‐changing maneuver. Video data collected at a busy arterial street in Gainesville, Florida, were used to distinguish between free, forced, and competitive/cooperative lane changes. Models particularly for competitive/cooperative lane changes were developed, depending on whether the following vehicle cooperates with the subject vehicle or not. By referring to the “TCP/IP” protocol in computer network communications, a sequence of “hand‐shaking” negotiations were designed to handle the competition and cooperation among vehicles. The developed model was implemented and validated in the CORSIM microsimulator package, with the simulation capabilities compared against the original lane‐changing model in CORSIM. The results indicate that the new model better replicates the observed traffic under different levels of congestion.