bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of Long-Lasting Perpetual Asphalt Pavement with Life-Cycle Cost Analysis
Authors: Sakhaeifar Maryam S. , Brown E. Ray , Tran Nam , Dean Jeff
Published: March 2014

In 2006, the Oklahoma Department of Transportation sponsored work at the pavement test track of the National Center for Asphalt Technology to compare the performance of two sections that had been designed to determine the necessary thickness for perpetual pavement. One section (Section N9) was designed to be a perpetual pavement at 14 in. thick. The other section (Section N8), at 10 in. thick (according to the AASHTO 1993 design guide), was used to test performance and to identify the thickness needed for perpetual pavement. This paper presents a life-cycle cost analysis for quantifying the benefits of a perpetual pavement section compared with the long-term cost of the thinner section. The life-cycle cost analysis was conducted with RealCost 2.5, which was available through FHWA, and included a determination of quantitative estimates of construction schedule, work zone user costs, and agency costs for initial construction and rehabilitation activities. The perpetual pavement section was found to have had a lower life-cycle cost than the conventional pavement section and to have provided better service to highway users. For better planning of future preservation studies, the estimated present serviceability rating as a function of the international roughness index for two designs (perpetual and nonperpetual) was evaluated. The findings of surface measurements for both sections demonstrate a clear difference between perpetual and conventional pavement serviceability for a given level of roughness and accumulated traffic. These results are also useful for assessing the improvement of conventional pavement after rehabilitation treatments.
Framework for Determining Load Equivalencies with DARWin-ME
Authors: Banerjee Ambarish , Prozzi Jorge A. , Buddhavarapu Prasad
Published: March 2014

This paper presents a methodology for use of mechanistic–empirical design procedures to determine load equivalencies for various axle configurations and loads with a focus on oversize and overweight vehicles. The study uses the DARWin-ME system for pavement analysis and computation of equivalent damage factors (EDFs). In the context of the study, the EDFs for a given axle load and configuration consist of two partial factors: the axle load factor and the group equivalency factor. The framework adopted in this study defines a given axle load and configuration equivalent to a reference axle load based on equivalent pavement responses that results in the same distress level. The EDFs for single, tandem, tridem, and quad axles were evaluated for a wide spectrum of varying loads, and three failure criteria were applied: rutting, fatigue cracking, and roughness. Except in the case of rutting, there was no evidence that EDFs are affected by the structural capacity of the pavement sections. For single axles, it was found that thicker pavement structures are less sensitive to traffic loads. For tandem, tridem, and quad axles, the relationship was nonmonotonic. For fatigue cracking, a linear relationship between the axle load factor and the number of axles per axle group was observed. Finally, for roughness, the EDFs showed no systematic trend for the different structural numbers.
Combined Effect of Three-Dimensional Contact Load and Thermal Gradients on the Cracking Performance of Heavy-Duty Asphalt Pavements
Authors: Wang Guangming , Morian Dennis , Frith Doug
Published: March 2014

Top-down cracking is well recognized as a major distress for heavy-duty asphalt pavements, yet the mechanism is not fully understood. Studies have indicated that nonuniform tire–pavement contact stress may play a significant role in the initiation of top-down cracking, and thermal stress caused by the temperature gradient may contribute to the initiation and development of top-down cracking. These relevant factors were evaluated with a sophisticated three-dimensional viscoelastic finite element model that was developed for studying the cracking performance of heavy-duty flexible pavements under combined three-dimensional tire–pavement contact stress and thermal stress induced by the temperature gradient. It was found that the stress distribution in asphalt concrete layers continuously changed as the pavement was loaded because of the rheological behavior of the asphalt concrete. Significant maximum principal tensile stresses are present at the tire edge at the asphalt concrete surface, which may result in an accumulation of dissipated creep strain energy over time (or with a cumulative number of loads) and may eventually lead to crack initiation. Additionally, near-surface pavement responses associated with top-down cracking under three-dimensional tire–pavement contact pressure are found to be more severe than those from uniform contact pressure. In a comparison with pavements without thermal effect, the negative temperature gradient increases the potential for top-down cracking, and the positive temperature gradient increases the potential for bottom-up cracking. The study provides insight into crack mechanisms, which may improve current heavy-duty asphalt pavement design procedures.
Development of Full-Scale Reflective Cracking Test at the FAA National Airport Pavement Test Facility
Authors: Yin Hao , Barbagallo Donald
Published: March 2014

Asphalt concrete overlays must be designed and constructed to withstand reflective cracking. However, the current FAA overlay design procedure (Advisory Circular 150/5320-6E) does not address this common form of premature failure. This paper presents a research project that studied one of the accepted causes of reflection cracks: horizontal movements concentrated at joints in the existing portland cement concrete pavement. A prototype, the temperature-effect simulation system, was developed at the FAA National Airport Pavement Test Facility so that joint opening and closing caused by temperature changes could be simulated mechanically. A test pavement representing a typical airport overlay structure was constructed to support full-scale tests. Both theoretical and experimental studies were performed to determine key test parameters, critical pavement temperature, joint opening, loading rate, and the bonding condition at the interface of asphalt concrete and portland cement concrete. Preliminary full-scale tests demonstrated that the simulation system could not only generate forces that create precise and repeatable joint openings but also effectively control the pavement temperature. Instrumentation data revealed that once bottom-up reflection cracks were initiated, crack development could quickly progress. When the crack length reached a certain level, the crack propagation rate slowed considerably. Information and data presented in this paper will be of immediate assistance to general aviation airports that carry small and light aircraft and experience significant temperature variations.
Performance Prediction Models for Cracked, Seated, and Overlaid Concrete Pavements in California
Authors: Rahim Ashraf , Fiegel Gregg , Calkins Reed , Lim David S. , Holland J.
Published: March 2014

Crack, seat, and overlay (CS&O) is a rehabilitation technique used on jointed plain concrete pavements in California. Although CS&O is widely used, few studies have attempted to develop performance prediction models for pavements that have been rehabilitated with this technique. This study evaluated CS&O performance for surface roughness and transverse reflection cracking. Performance data for CS&O sections in three geographic regions in California were used to develop regression performance models. These models can be incorporated into the California Department of Transportation pavement management system and used to predict future performance, assist with life-cycle cost analyses, and optimize the allocation of resources. The results of a sensitivity analysis suggest that section age is the most significant factor affecting the deterioration of CS&O pavements. Secondary factors include the annual equivalent single-axle load and layer thickness ratio. Section age as an independent variable would include the impact of environmental loading cycles. Other factors related to subgrade conditions, temperature variations, and construction variability could not be investigated because data were not available. However, their impact is inherent to the models.
Responses and Performance of Stabilized Full-Depth Reclaimed Pavements at the Minnesota Road Research Facility
Authors: Johanneck Luke , Dai Shongtao
Published: March 2014

This paper details the construction and analysis of three stabilized full-depth reclamation (SFDR) sections (Cells 2, 3, and 4) constructed at the Minnesota Road Research Facility on I-94 in 2008. Three test sections with different ratios of pulverized asphalt concrete to granular base were constructed, and the performance of full-depth reclaimed pavements stabilized with engineered emulsion was studied. Emulsion content and base structure varied between test sections. Each test section was designed for 3.5 million equivalent single-axle loads for a period of 5 years. As of June 30, 2012, the sections had been subjected to approximately 2.2 million such loads. Responses were measured with strain gauges embedded at the bottom of the hot-mix asphalt and SFDR layers in each test section. The strain gauges indicated that the bottom of both the hot-mix asphalt and the SFDR layers was subject to horizontal tensile strain from falling weight deflectometer testing and heavy vehicle loading. Pavement performance for rutting, cracking, and international roughness index was measured periodically. The results indicated that all three cells were performing well. The only crack in the three cells was in Cell 3; the roughness index values were well within the acceptable range and rutting, although progressing, was still acceptable. The paper concludes with modeled responses and performance predictions from DARWinME and BISAR. Model predictions indicate that an SFDR layer will provide greater structural benefits and increased performance than will similar structures with unstabilized full-depth reclaimed or granular base layers.
Speed Synchronization Process of Merging Vehicles from the Entrance Ramp
Authors: Wan Xia , Jin Peter J. , Zheng Liang , Cheng Yang , Ran Bin
Published: March 2014

This paper explores the “lane-changing preparation process,” defined as the synchronization process, from a new, integrated perspective. A comprehensive study was conducted to analyze the behavioral characteristics of the speed synchronization process of merging vehicles from entrance ramps by tracking their trajectories in the merge lanes. On the basis of gap selection, merging vehicles were classified as either original gap type or overtaking type, and the existence of speed synchronization was proved by comparing the speed differences of merging vehicles in relation to the putative leader (PL) and the putative follower (PF) vehicles. Several rules of merging vehicles during speed synchronization were established in the behavioral study. The merging vehicles tended to maintain a speed 5 to 7 m/s higher than the speed of the PL so as to overtake unsatisfied gaps in the adjacent through lane. When those vehicles intended to accept a gap, they first adjusted their speeds to be within a 2-m/s difference from their PL and PF vehicles and then merged into the targeted gap within 2 to 3 s. Factors affecting drivers' tolerance of their speed with PL and PF vehicles were modeled with the multiregression method. Significant effects in speed synchronization include the number of rejected gaps, acceleration or deceleration, the speed difference between the PL and the PF, the time headway, the remaining distance in the auxiliary lane, and whether the PL is a merged vehicle. Results from this study may contribute to the understanding of the complex lane-changing behavior in microscopic traffic flow modeling.
Data-Fitted First-Order Traffic Models and Their Second-Order Generalizations
Authors: Fan Shimao , Seibold Benjamin
Published: March 2014

The Aw–Rascle–Zhang (ARZ) model can be interpreted as a generalization of the first-order Lighthill–Whitham–Richards (LWR) model, with a family of fundamental diagram (FD) curves rather than one. This study investigated the extent to which this generalization increased the predictive accuracy of the models. To that end, two types of data-fitted LWR models and their second-order ARZ counterparts were systematically compared with a version of the test for the three-detector problem. The parameter functions of the models were constructed with historic FD data. The models were then compared with the use of time-dependent data of two types: vehicle trajectory data and single-loop sensor data. These partial differential equation models were studied in a macroscopic sense (i.e., continuous field quantities were constructed from the discrete data, and discretization effects were kept negligibly small).
Scenario-Based Approach to Analysis of Travel Time Reliability with Traffic Simulation Models
Authors: Kim Jiwon , Mahmassani Hani S. , Vovsha Peter , Stogios Yannis , Dong Jing
Published: March 2014

This study established a conceptual framework for capturing the probabilistic nature of travel times with the use of existing traffic simulation models. The framework features three components: scenario manager, traffic simulation models, and trajectory processor. The scenario manager captures exogenous sources of variation in travel times through external scenarios consistent with real-world roadway disruptions. The traffic simulation models then produce individual vehicle trajectories for input scenarios while further introducing randomness that stems from endogenous sources of variation. Finally, the trajectory processor constructs distributions of travel time either for each scenario or for multiple scenarios to allow users to investigate scenario-specific impact on variability in travel times and overall system reliability. Within this framework, the paper discusses methodologies for performing scenario-based reliability analysis that focuses on (a) approaches to obtaining distributions of travel times from scenario-specific outputs and (b) issues and practices associated with designing and generating input scenarios. The proposed scenario-based approach was applied to a real-world network to show detailed procedures, analysis results, and their implications.
Validation of a Macroscopic Lane-Changing Model
Authors: Gan Qi-Jian , Jin Wen-Long
Published: March 2014

Systematic lane changes inside a weaving area could lead to accidents and disrupt the entire traffic flow. Recently, a simple macroscopic lane-changing model that determines the number of lane changes from on-ramp flows and the number of lanes was proposed to describe traffic dynamics inside the lane-changing area at a merging section. However, this macroscopic lane-changing model had not been validated with vehicle trajectory data. This study attempted to fill that validation gap. First, lane changes were categorized into two types: left-lane changes and right-lane changes. Then the following two hypotheses derived from the macroscopic lane-changing model were validated: (a) the number of left-lane changes within two adjacent lanes linearly increases from the leftmost lane to the shoulder lane and (b) the number of left-lane changes linearly increases with the flow rate of on-ramp vehicles inside the lane-changing area. Traffic balance among lanes was analyzed, and the two proposed hypotheses were validated for different periods and road geometries by using NGSIM vehicle trajectory data. The validation results confirm that the two linear relationships in the macroscopic lane-changing model exist.
Macroscopic Traffic Flow Model for Estimation of Real-Time Traffic State along Signalized Arterial Corridor
Authors: Lu Yang , Haghani Ali , Qiao Wenxin
Published: March 2014

The estimation of the real-time traffic state of signalized arterial corridors is a challenging, yet insufficiently studied field compared with that of the freeway network. This study developed an innovative traffic flow model for signalized arterials that considered the impact of signal controls. The proposed traffic flow model was then combined with a particle-filtering technique to integrate the field measurements. A comprehensive numerical investigation with a real world data set showed that the proposed model could produce reliable estimates of link density, speed, and queue length at intersections with an acceptable degree of accuracy.
Collisions in Freeway Traffic
Authors: Li Zhibin , Chung Koohong , Cassidy Michael J.
Published: March 2014

Findings from previous studies indicate that a freeway traffic collision is more likely to occur in close physical proximity to the tail of a queue. The implication is that collision likelihood increases when drivers abruptly alter their trajectories (e.g., by decelerating or changing lanes) on encountering the queue. The implication is supported and bolstered with new and detailed data that were painstakingly extracted from two freeway stretches in California. These data show how the likelihood of collision increases as both the spatial and the temporal proximities to the tail of an expanding or receding queue become smaller. It follows that collision risk may be reduced by instructing drivers to begin decelerating while still upstream of queues. Retarding vehicle progress toward a queue's tail could retard the rate by which the likelihood of collision grows with time. Having vehicles approach a queue at diminished speeds may diminish the expected severity of a collision, should one still occur. This information is considered in this development of the ideas behind simple control logic for issuing speed advisories to drivers as they approach a queue. This logic could assist freeway managers in selecting suitable advisories so as to diminish the empirical estimate of collision likelihood at a specified time in the immediate future and by some target amount. In the interim, the likelihood estimates would be based solely on vehicles’ spatiotemporal proximities to queues. Other influences would be ignored for now, although planned experiments to test and improve the present logic are discussed.
Simulation-Based, Scenario-Driven Integrated Corridor Management Strategy Analysis
Authors: Liu Xiaoyue (Cathy) , Zhang Guohui , Kwan Carmen , Wang Yinhai , Kemper Brian K.
Published: March 2014

The U.S. Department of Transportation affirmed the integrated corridor management (ICM) initiative to mitigate traffic congestion on urban corridor networks by systematically leveraging and diverting traffic to better utilize the available capacities of parallel arterials. ICM strategies would be of utmost importance when traffic incidents that may cause significant delays occur on freeways. By effectively diverting upcoming traffic to the adjacent arterials via variable message signs and real-time traveler information systems (e.g., mobile devices), the impact of incidents can be alleviated. To understand fully the effectiveness of ICM strategies, a framework needs to be developed to model, simulate, and analyze ICM operations under different scenarios. This study developed and calibrated a VISSIM simulation model based on field-collected video and sensor data for the South of Downtown area of Seattle, Washington. The analysis aimed to quantify networkwide ICM performance by empirically diverting traffic to adjacent arterials in response to incident management for freeway operations. Multiple scenarios were built into the simulation model to account for different diversion rates as well as recurrent and nonrecurrent congestion situations. When more traffic is diverted into an arterial, the arterial's performance degrades while improvements in travel time and delay for the freeway become marginal. Through quantitative analysis of the delay, throughput, and travel time of freeway segments and the arterial network, the trade-off in the overall system performance was carefully studied and understood. The research findings set up a solid foundation for ICM strategy development and optimization of traffic system operations.
Estimation of Diversion Rate during Incidents on Basis of Main-Line Detector Data
Authors: Hadi Mohammed , Xiao Yan , Rojas Maria Lucia
Published: March 2014

A number of intelligent transportation system technologies are deployed for disseminating information to travelers. One of the most important parameters for assessing the impacts and benefits of these deployments that influence route selection is the diversion rates of travelers. In this research, a method was developed to estimate traffic diversions on the basis of main-line detector data without the need for off-ramp detectors. In addition, the estimation allows the assessment of the guidelines and procedures for disseminating information and evaluating the impacts on alternative routes. The validity of the developed methodology was verified by comparing the estimated values with real-world data. Case studies of the developed method indicated that the average diversion rate was about 10% to 35% for three-lane and four-lane freeways, depending on the number of lanes blocked. A linear relationship between the average diversion rate and the lane blockage ratio was also developed; this relationship indicated that there was a general trend of increase in diversion with the increase in the lane blockage ratio.
Deterministic Framework and Methodology for Evaluating Travel Time Reliability on Freeway Facilities
Authors: Schroeder Bastian J. , Rouphail Nagui M. , Aghdashi Seyedbehzad
Published: March 2014

This paper presents a methodology for incorporating freeway reliability analysis in the Highway Capacity Manual on the basis of Strategic Highway Research Program Project L08. The methodology uses a scenario-based approach in which each scenario represents a unique combination of traffic demands and facility (segment) capacities. Demand impacts consider variability in time-of-day, day-of-week, and month-of-year differences, and capacity impacts quantify effects of various nonrecurring congestion sources, such as weather, incidents, work zones, and special events. The method combines three key components: a data repository, a freeway scenario generator (FSG), and a computational software engine, FREEVAL-RL. The FSG determines the number of scenarios for the reliability analysis on the basis of the facility-specific combination of demand, incident, and weather events. For each scenario, it produces a set of inputs and adjustment factors that are passed on to the FREEVAL-RL engine, along with each scenario's probability. The engine is capable of batch-processing many scenarios and estimates the reliability distribution for the facility. At the core, the computational engine and underlying methodology are consistent with the freeway facilities method in the Highway Capacity Manual 2010, which is capable of estimating undersaturated and congested flow conditions in a multi-period analysis. The method is illustrated with a real-world case study freeway facility in North Carolina. The FSG for that facility resulted in 2,508 scenarios. The resulting travel time distribution is presented, and sensitivity analyses are presented to explore the contributing effects of weather and incidents on the overall reliability of the facility.
Synthesizing Route Travel Time Distributions from Segment Travel Time Distributions
Authors: Kumar Isukapati Isaac , List George F. , Williams Billy M. , Karr Alan F.
Published: March 2014

This paper examines a way to synthesize route travel time probability density functions (PDFs) on the basis of segment-level PDFs. Real-world data from I-5 in Sacramento, California, are employed. The first finding is that careful filtering is required to extract useful travel times from the raw data because trip times, not travel times, are observed (i.e., the movement of vehicles between locations). The second finding is that significant correlations exist between individual vehicle travel times for adjacent segments. Two analyses are done in this regard: one predicts downstream travel times on the basis of upstream travel times, and the second checks for correlations in travel times between upstream and downstream segments. The results of these analyses suggest that strong positive correlations exist. The third finding is that comonotonicity, or perfect positive dependence, can be assumed when route travel time PDFs are generated from segment PDFs. Kolmogorov–Smirnov tests show that travel times synthesized from the segment-specific data are statistically different only under highly congested conditions, and even then, the percentage differences in the distributions of the synthesized and actual travel times are small. The fourth finding, somewhat tangential, is that there is little variation in individual driver travel times under given operating conditions. This is an important finding, because such an assumption serves as the basis for all traffic simulation models.
Use of Sensor Data to Identify Secondary Crashes on Freeways
Authors: Yang Hong , Bartin Bekir , Ozbay Kaan
Published: March 2014

Nonrecurring traffic incidents, such as motor vehicle crashes, increase not only travel delays but also the risk of secondary crashes. Secondary crashes can cause additional traffic delays and reduce safety. Implementation of effective countermeasures to prevent or reduce secondary crashes requires that their characteristics be investigated. However, the related research has been limited, largely because of the lack of detailed incident and traffic data necessary to identify secondary crashes. Existing approaches, such as static methods employed to identify secondary crashes, cannot fully capture potential secondary crashes because of fixed spatiotemporal identification criteria. Improved approaches are needed to categorize secondary crashes accurately for further analysis. This paper develops an enhanced approach for identifying secondary crashes that uses the existing crash database and archived traffic data from highway sensors. The proposed method is threefold: (a) defining secondary crashes, (b) examining the impact range of primary crashes that possibly relate to secondary crashes, and (c) identifying secondary crashes. The proposed methodology establishes a practical framework for mining secondary crashes from existing sensor data and crash records. A case study was performed on a 27-mi segment of a major highway in New Jersey to illustrate the performance of the proposed approach. The results show that the proposed method provides a more reliable and efficient categorization of secondary crashes than commonly used approaches.
Smart Event Traffic Management
Authors: Consoli Frank A. , Rogers John , Al-Deek Haitham , Tatari Omer , Alomari Ahmad
Published: March 2014

In 2008 the City of Orlando, Florida, embarked on construction of a new Amway Center to replace the existing Amway Arena. The new center was designed to host a variety of events such as concerts, arena football, graduation ceremonies, National Collegiate Athletic Association basketball, and the National Basketball Association's (NBA's) Orlando Magic home games. The Amway Center, which opened in October 2010, had a capacity of 19,000 patrons for NBA games. The Amway Center was adjacent to Interstate 4 and State Road 408 in the downtown core. To prepare for the Amway Center's event management challenges, the City of Orlando's Transportation Engineering Department utilized smart event traffic management techniques, which integrated the following system and plan components: intelligent transportation system infrastructure (software and hardware), traffic control device upgrades, regional planning efforts, and state-of-the-art safety and security protocols. These components also helped minimize the environmental impacts of traffic congestion. When designing smart event plans, it is important to consider high-threshold events such as the NBA All-Star Game for system performance and to understand the balance required for operational efficiency and security in today's global climate. In addition, infrastructure performance is critical during high-profile events so that the local economy can benefit and the municipality can stay competitive to attract more of these types of events. Finally, the resultant operational efficiency is vital for reducing the carbon footprint and negative societal impacts.
Impacts to Transit from Variably Priced Toll Lanes
Authors: Pessaro Brian , Turnbull Katie F. , Zimmerman Carol
Published: March 2014

This paper describes the impacts on transit performance from three separate conversions of high-occupancy vehicle lanes into variably priced high-occupancy toll (HOT) lanes in Miami, Florida; Minneapolis, Minnesota; and Atlanta, Georgia. The data showed that the conversions had no negative impact on bus performance. In all three cities, the buses experienced travel time savings after the conversion: 17 min in Miami, 4.5 min in Minneapolis, and 5 min in Atlanta. Similarly, the HOT conversions did not negatively affect bus ridership. Ridership increased over the baseline by 57% in Miami and 13% in Minneapolis. In Atlanta, ridership increased by 11%, and this increase began before the conversion. Bus riders’ overall perception of the HOT lanes has been positive. In surveys, the bus riders from Miami and Minneapolis gave high ratings for travel times and reliability in the HOT lane corridors. Riders in Atlanta rated the bus service as very good but were not as positive about the tolls. Riders disagreed that the HOT conversion had improved their travel or been good for the Atlanta region. These negative responses may be attributable in part to widespread disgruntlement with the HOT concept that existed even before implementation.
Investigation of Lane Flow Distribution on Hard Shoulder Running Freeways
Authors: Samoili Sofia , Efthymiou Dimitrios , Antoniou Constantinos , Dumont André-Gilles
Published: March 2014

In response to an impending demand growth at an existing reactive managed lane system and to provide a timely and more effective temporary hard shoulder activation, this paper presents the development of short-term prediction models. A lane-oriented attribute—namely, the left-lane flow distribution ratio—is introduced to ameliorate the system by capturing the forthcoming stream dynamics and reconfiguring it to be proactive. To assess the impact on the network's performance of implementing a system for hard shoulder running, an exploratory analysis was performed on the basis of data acquired by seven radar sensors located every 500 m along a Swiss freeway section that was not affected by incoming or exiting traffic. A locally weighted regression was employed to provide more accurate insight into traffic behavior by comparing observations derived during the regular operation of the system and a period in which it was suspended, with respect to seasonality patterns. To describe the impending stream motion by examining different time–volume clusters (off-peak and peak hours), two prediction models were specified according to the time range. The preliminary results of the study for several prediction horizons demonstrate an acceptable prediction uncertainty. The hard shoulder activation prediction confirms the analysis of the findings of this research with regard to the impact on operations.
Empirical Study of Lane-Changing Behavior along Different Types of High-Occupancy Vehicle Facilities in California
Authors: Du Yaoqiong , Wu Guoyuan , Boriboonsomsin Kanok , Chan Ching-Yao
Published: March 2014

Lane changing is one important aspect of vehicle maneuvers that has significant impacts on freeway operation. Most of the previous research on lane changing has focused on the microscopic modeling of lane change movements. Very few studies have investigated lane-changing behavior along high-occupancy vehicle (HOV) facilities, especially in the context of comparing different access types. This paper describes work that extracted lane change data with high resolution in both time and space from videos and investigated lane-changing behavior on freeways with different types of HOV access configurations. Furthermore, the extracted lane change data were correlated with lane-by-lane flow and occupancy data from the California Freeway Performance Measurement System. Compared with continuous-access HOV facilities, limited-access HOV facilities were found to have a higher number of lane changes per unit distance and a shorter time gap when the subject vehicle moved out of the HOV lane. Also, most of the lane changes on limited-access HOV facilities occurred within the first half of ingress–egress areas. The insights provided by these results on lane-changing maneuvers along HOV facilities can be used to support traffic operation analyses, calibrate driver behavioral logic in traffic simulation models, and inform the design of lane configurations and access control measures for managed lanes.
Regions, borders, and social policy
Authors: Koff Harlan , Maganda Carmen
Published: March 2014

This first issue of Volume Four of Regions & Cohesion continues a trend of articles that gained momentum in Volume Three, focusing on the territorial aspects of welfare in social cohesion debates. The Summer 2013 issue of the journal presented a collection of articles that specifically discussed the role of borders and border policies in social cohesion politics. Although this collection was not intended to be presented as a thematically specific issue, the simultaneous arrival of these pieces highlighted the importance of borders in defining the territorial limits of cohesion and the ensuing renegotiation of these limits in political debates. For example, the article by Irina S. Burlacu and Cathal O’Donoghue focused on the impacts of the European Union’s social security coordination policy on the welfare of cross-border workers in Belgium and Luxembourg. The article illustrated the limits of this regional policy as cross-border workers do not receive equal treatment
compared to domestic workers in the country of employment. Similarly, an article by Franz Clément in the same issue analyzed the “socio-political representation” of cross-border workers and discusses how such workers can mobilize for socioeconomic rights in institutions aimed at worker protection (such as professional associations, trade unions, etc.). Both articles show that despite formal regionalization of legislation concerning social rights and representation, national boundaries clearly present challenges to cross-border workers who have difficulty negotiating rights in both their country of employment and country of residence.
Hegemony, leadership, and integration in South Africa
Authors: Compton Jr. Robert W.
Published: March 2014

The African National Congress and the regeneration of political power, S. Booysen, 2011. Wits University Press.

Why Nations Fail: The Origins of Power, Prosperity, and Poverty, D. Acemoglu & J. Robinson, 2012. Crown Publishing (Random House).

A Legacy of Liberation: Thabo Mbeki and the Future of the South African Dream, M. Gevisser, 2009. Palgrave-Macmillan.
An Efficient Synthesis of Novel Dihydrothiazol-2-yl-amides via Cyclisation of Propargylic Carbamothioyl-amides
Authors: Saeedi Mina , Goli Fereshteh , Mahdavi Mohammad , Sarihi Pouria , Asadipour Ali , Shafiee Abbas , Foroumadi Alireza
Published: March 2014

An efficient protocol is described for the versatile synthesis of novel dihydrothiazol-2-yl-amide derivatives via the regioselective 5-exo-dig heterocyclisation of N-propargyl carbamothioyl-amides in the presence of 1,4-diazabicyclo[2.2.2]octane (DABCO) in refluxing ethanol. All products were obtained in good yields and short reaction time (10–30 min).
An Efficient Synthesis of Chrysin
Authors: Liu Man , Zhang Ji , Yang Jian , Yang Bo , Cui Wei
Published: March 2014

Two routes for the synthesis of the flavones chrysin are described. In the first 1,3,5-trimethoxybenzene was converted to 2-hydroxy-4,6-dimethoxyacetophenone and then by condensation with benzaldehyde to 2′-hydroxy-4′,6′-dimethoxychalcone. The latter was cyclised with iodine and demethylated with pyridine hydrochloride to form chrysin in 53% overall yield. In the second route, 1,3,5-trimethoxybenzene was acylated with cinnamic acid to form the chalcone which was then converted to chrysin in 30.7% overall yield.
Efficient Access to Benzochromeno[2,3-d]pyrimidine Derivatives from β-enamino Nitriles by Bis(Trichloromethyl) Carbonate and Triphenylphosphine Oxide
Authors: Zou Ye , Li Zhenhua , Su Weike
Published: March 2014

A mild and efficient synthesis of novel benzochromeno[2,3- d]pyrimidine derivatives is described. A number of 8,10-dichloro-7-aryl-7 H-benzo[7,8]chromeno[2,3- d]pyrimidines and 9,11-dichloro-12-aryl-12 H-benzo[5,6]chromeno[2,3- d]pyrimidines were synthesised by the cyclisation of 2-amino-4-aryl-4H-benzo[ h]chromene-3-carbonitriles or 3-amino-1-aryl-1 H-benzo[ f] chromene-2-carbonitriles with bis(trichloromethyl) carbonate and triphenylphosphine oxide in moderate to good yields.
Synthesis and Antitumour Activity of Certain Pyrido[2,3-d] Pyrimidine and 1,8-naphthyridine Derivatives
Authors: Elansary Afaf K. , Moneer Ashraf A. , Kadry Hanan H. , Gedawy Ehab M.
Published: March 2014

In an effort to establish new candidates with improved anticancer activity, we report here the synthesis of various series of 2,4,5,7-tetrasubstituted pyrido[2,3- d]pyrimidines and their related isosteres substituted 1,8-naphthyridines. The cytotoxic activity of the newly synthesised compounds against human breast cancer cell line, MCF7 was investigated. Most of the tested compounds exploited potent to moderate growth inhibitory activity, in particular 7-(4-chlorophenyl)-5-(3-nitrophenyl)pyrido[2,3- d]pyrimidin-4-amine exhibited superior potency to the reference drug doxorubicin (IC50 = 7.5 and 8.48 μM respectively).
Synthesis, Structures and Magnetic Properties of Hydrogen-bond Directed 2D Heterobimetallic Cyanide-bridged Coordination Polymers
Authors: Chen Xia , Kong Lingqian , Wang Ping , Zhao Zengdian , Zhang Daopeng
Published: March 2014

The complexes {[Mn(L1)(H2O)]2[Pd(CN)4]}·2CH3CN and {[Mn(L2)(H2O)]2[Pd(CN)4]}2·H2O [L1 = N,N-ethylene-bis(5-bromicsalicylideneiminate); L2 = N,N-ethylene-bis(5-methxysalicylideneiminate)] have been obtained from [Pd(CN)4]2- and the corresponding Schiff-base manganese(III) compounds. X-ray diffraction reveals that the complexes are constructed into two-dimensional supramolecular networks through intermolecular O–H…O and O–H…N hydrogen bond interactions. The magnetic susceptibilities of the two complexes reveal overall weak antiferromagnetic interactions between the adjacent Mn(III) ions.
The Synthesis of Mauveine a and Mauveine B from N-tert-butyl-p-toluidine
Authors: Plater M. John
Published: March 2014

The oxidation of a mixture of N-tert-butyl- p-toluidine/aniline/ o-toluidine (1: 1.5: 1.5) with K2Cr2O7 in H+/H2O followed by de- tert-butylation with acid gives mauveine A and mauveine B. These compounds dye silk the same shade of red mauve as that of silk dyed by authentic mauveine.
A Facile One-pot Synthesis and Heterocyclisation of (R)-2-amino-3-((aroylcarbamothioyl)thio)propanoic Acids
Authors: Mohebat Razieh , Kafrizi Elahe
Published: March 2014

A series of ( R)-2-amino-3-((aroylcarbamothioyl)thio)propanoic acid derivatives have been synthesised by a one-pot, three-component reaction of L-cysteine with ammonium thiocyanate in the presence of various acid chlorides under solvent-free conditions in excellent yields. These compounds were converted to ( R)-2-thioxothiazolidine-4-carboxylic acid in water under reflux conditions.
Copper-catalysed N-arylation of Pyrrole with Aryl Iodides Under Ligand-free Conditions
Authors: Liu Lili , Wu Fengtian , Liu Yan , Xie Jianwei , Dai Bin , Zhou Zhuoqiang
Published: March 2014

A simple, inexpensive and ligand-free copper-catalysed N-arylation of pyrrole with aryl iodides has been developed giving N-arylated products in moderate to excellent yields. The catalyst loading is relative low (5 mol%) and the catalyst system was stable in air.
Selective Oxidation of Sulfides to Sulfoxides Catalysed by Deep Eutectic Solvent with H2O2
Authors: Dai Dong-yan , Wang Liang , Chen Qun , He Ming-Yang
Published: March 2014

A Brønsted acidic deep eutectic solvent based on choline chloride and p-toluenesulfonic acid (ChCl/ p-TsOH, 1:1) was prepared and utilised for the selective oxidation of sulfides with H2O2 as the oxidant. Broad substrate compatibility, good yields and selectivities, the reusability of the catalyst as well as the gram-scale synthesis are the major advantages of this protocol. Moreover, the use of ChCl/ p-TsOH, instead of neat p-TsOH, can greatly reduce the acid sewage especially in large-scale synthetic processes.
Synthesis, Spectroscopic and Antibacterial Studies of Silver(I) Complexes with Bidentate Phosphorus Ylides
Authors: Sabounchei Seyyed Javad , Pourshahbaz Mahbubeh , Karamian Roya , Asadbegy Mostafa
Published: March 2014

P-coordinated complexes of the type [AgNO3{Ph2P(CH2)nPPh2C(H)C(O)C6H4R}]2 ( n = 1 or 2; R=Cl, Br, NO2 or OCH3), have been synthesised by reactions of AgNO3 with the appropriate phosphorus ylides. The antibacterial effects of DMSO-solutions of all compounds have been evaluated by the agar disc diffusion method against six Gram positive and Gram negative bacteria.
Sensing a Sensor: Identifying the Mechanosensory Function of Primary Cilia
Authors: Prasad Rahul , Jin Xingjian , Nauli Surya
Published: March 2014

Over the past decade, primary cilia have emerged as the premier means by which cells sense and transduce mechanical stimuli. Primary cilia are sensory organelles that have been shown to be vitally involved in the mechanosensation of urine in the renal nephron, bile in the hepatic biliary system, digestive fluid in the pancreatic duct, dentin in dental pulp, lacunocanalicular fluid in bone and cartilage, and blood in vasculature. The prevalence of primary cilia among mammalian cell types is matched by the tremendously varied disease states caused by both structural and functional defects in cilia. In the process of delineating the mechanisms behind these disease states, calcium fluorimetry has been widely utilized as a means of quantifying ciliary function to both fluid flow and pharmacological agents. In this review, we will discuss the approaches used in associating calcium levels to cilia function.
Electromagnetic Design of a New Electrically Controlled Magnetic Variable-Speed Gearing Machine
Authors: Liu Chunhua , Chau K.
Published: March 2014

This paper proposes a new electrically controlled magnetic variable-speed gearing (EC-MVSG) machine, which is capable of providing controllable gear ratios for hybrid electric vehicle (HEV) applications. The key design feature involves the adoption of a magnetic gearing structure and acceptance of the memory machine flux-mnemonic concept. Hence, the proposed machine can not only offer a gear-shifting mechanism for torque and speed transmission, but also provide variable gear ratios for torque and speed variation. The electromagnetic design is studied and discussed. The finite-element method is developed with the hysteresis model to verify the validity of the machine design.
Modeling the Effects of Indoor Passive Smoking at Home, Work, or Other Households on Adult Cardiovascular and Mental Health: The Scottish Health Survey, 2008–2011
Authors: Shiue Ivy
Published: March 2014

Passive smoking has contributed increased risks of cardiovascular disease, mental health, and mortality, but the cumulative effects from work or other households were less studied. Therefore, it was aimed to model the effects of indoor passive smoking from own home, work, and other households in a country-wide, population-based setting. Data in the Scottish Health Survey between 2008 and 2011 after the law banning smoking in public places were analyzed. Information including demographics, lifestyle factors, and self-reported cardiovascular disease and mental health was obtained by household interview. Analyses included chi-square test and survey-weighted logistic regression modeling. After full adjustment, it was observed that being exposed to indoor passive smoking, in particular in more than two places of exposure, was significantly associated with risks of stroke, angina, heart attack, abnormal heart rhythms, and GHQ ≥ 12. The significance remained for angina, GHQ ≥ 12 and probably heart attack in never smokers. The cumulative risks also impacted on sleep problems, self-recognition, making decisions, self-confidence, under strain constantly, depressed, happiness and self-worth. The significance remained for sleep problems, self-confidence, under strain constantly, depressed, and happiness in never smokers. Elimination of indoor passive smoking from different sources should still be a focus in future public health programs.
Comparison of the Osteogenic Potential of Titanium- and Modified Zirconia-Based Bioceramics
Authors: Cho Young-Dan , Shin Ji-Cheol , Kim Hye-Lee , Gerelmaa Myagmar , Yoon Hyung-In , Ryoo Hyun-Mo , Kim Dae-Joon , Han Jung-Suk
Published: March 2014

Zirconia is now favored over titanium for use in dental implant materials because of its superior aesthetic qualities. However, zirconia is susceptible to degradation at lower temperatures. In order to address this issue, we have developed modified zirconia implants that contain tantalum oxide or niobium oxide. Cells attached as efficiently to the zirconia implants as to titanium-based materials, irrespective of surface roughness. Cell proliferation on the polished surface was higher than that on the rough surfaces, but the converse was true for the osteogenic response. Cells on yttrium (Y)/tantalum (Ta)- and yttrium (Y)/niobium (Nb)-stabilized tetragonal zirconia polycrystals (TZP) discs ((Y, Ta)-TZP and (Y, Nb)-TZP, respectively) had a similar proliferative potential as those grown on anodized titanium. The osteogenic potential of MC3T3-E1 pre-osteoblast cells on (Y, Ta)-TZP and (Y, Nb)-TZP was similar to that of cells grown on rough-surface titanium. These data demonstrate that improved zirconia implants, which are resistant to temperature-induced degradation, retain the desirable clinical properties of structural stability and support of an osteogenic response.
Exercise Pretreatment Promotes Mitochondrial Dynamic Protein OPA1 Expression after Cerebral Ischemia in Rats
Authors: Zhang Li , He Zhijie , Zhang Qi , Wu Yi , Yang Xiaojiao , Niu Wenxiu , Hu Yongshan , Jia Jie
Published: March 2014

Exercise training is a neuroprotective strategy in cerebral ischemic injury, but the underlying mechanisms are not yet clear. In the present study, we investigated the effects of treadmill exercise pretreatment on the expression of mitochondrial dynamic proteins. We examined the expression of OPA1/DLP1/MFF/Mfn1/Mfn2, which regulatesmitochondrial fusion and fission, and cytochrome C oxidase subunits (COX subunits), which regulatemitochondrial functions, after middle cerebral artery occlusion (MCAO) in rats. T2-weighted magnetic resonance imaging (MRI) was evaluated as indices of brain edema after ischemia as well. Treadmill training pretreatment increased the expression levels of OPA1 and COXII/III/IV and alleviated brain edema, indicating that exercise pretreatment provided neuroprotection in cerebral ischemic injury via the regulation of mitochondrial dynamics and functions.