Dual Lane Research Articles

GAS turbine sensor fault diagnostic system in a real-time executable digital-twin

In this study, a sensor fault diagnostic system to detect/isolate and accommodate faults in sensors from an industrial gas turbine has been developed. The sensor fault diagnostic module is integrated with a gas turbine real-time executable digital-twin (RT xDT) reported in a previous study. The sensor fault diagnostic module of the digital-twin considers analytical sensor redundancy using a reference engine model to provide redundant estimates of measured engine variables. A Software-in-the-Loop (S-i-L) architecture and Hardware-in-the-Loop (H-i-L) facility are constructed to assess the sensor diagnostic module (fault detection/ fault isolation) during failure in sensors from the engine. The results demonstrated that if the discrepancy between virtual measurement (provided by digital-twin) and sensor measurement exceeds the prescribed tolerance levels, the sensor fault diagnostic logic determines the state of switching between the virtual and engine sensor measurements in a dual lane control configuration of the gas turbine control system. The sensor fault detection system implemented in the gas turbine RT xDT can be deployed onto a distributed control system of industrial gas turbines to diagnose sensor deficiencies and ensure continuous and safe operation of the gas turbine. Consequently, the developed system will increase engine availability and reliability by diagnosing engine operational deficiencies before severe failure.

The Optimal Current Ratio Control of Redundant Electric Drive Systems and Diagnostic Strategies for Disagreement

As research into technology for autonomous vehicles becomes ever more intensive, the need for redundant system designs, as a solution for fail-operational functionality, has also increased. Redundant systems are those involved in maintaining normal operation even when one or more components fails. In particular, in electric power steering (EPS) systems, redundancy is achieved by applying dual-winding (DW), permanent magnet synchronous motors (PMSMs) and dual electronic control units (ECUs). In this study, the torque and efficiency of DW-PMSMs is analysed based on the manner in which the currents in each winding mechanism are combined. It was found that the PMSMs have maximum torque and efficiency when the current ratio was the same between DWs. A diagnostic strategy is proposed whereby the phase current ratio of dual lanes is not matched. The proposed diagnostic process includes the selection of the optimal fault threshold of the current difference between two ECUs and a method for distinguishing which of these was a failure for disagreement. In addition, depending on whether or not failure detection has occurred, a current compensation control method is proposed for reverting to normal operation or for failure operations. The dual-lane system was fabricated and the proposed solutions were experimentally verified.

Aging drivers and post delineated express lanes: Threading the needle at 70 miles per hour

Post-delineated express lanes represent a combination of driving complexities that are particularly difficult for older drivers to navigate. The narrow geometry and high speeds that are common to this treatment reflect a critical test for drivers whose depth perception, contrast sensitivity, and visual processing speed are reduced. The present study was designed to empirically examine the effects of age and color of express lane delineators on driver behavior. Three groups of participants (aged 18–39, 40–64, and 65 + years old) were required to complete a series of simulated driving scenarios consisting of combinations of single and dual lane configurations, with speed and lane position measured at the beginning and midpoint of each express lane. All drivers were pre-screened on various visual functioning abilities. Drivers in the 65 and older group show significant age-related declines in depth perception, contrast sensitivity, and phoria which were subsequently correlated with a wide range of driving measures including deceleration rate, brake time, jerk, speed, and lane position. Age related perceptual declines were statistically correlated with slower driving speed and wider lane deviations, including a statistically significant increase in the number of excursions beyond the typical 12-foot lane width. Based on these findings, the behavior of senior drivers was identified as a distinct design condition that should govern the design of high-speed, narrow geometric conditions. This age group requires wider lane widths, particularly at the beginning of single-lane post delimited sections, wider buffer areas around the post markers, and dual lane configurations wherever possible.

Operational evaluation of Obafemi Awolowo University main gate – Ede Road intersection

Vehicular traffic at Obafemi Awolowo University has increased over the years, resulting in delay at The Main Gate – Ede Road Intersection. This paper evaluated its present level of service with a view to addressing this situation. Geometric survey of the intersection was carried out. Peak hour traffic studies were conducted for a week and the traffic characteristics and volume were determined using standard procedure. The level of service (LOS) of the intersection was thereafter obtained. The geometrics of the intersection showed that, two lanes exist on the East Bound (EB) and West Bound (WB) approaches, as well as a dual lane on the North Bound (NB) and South Bound (SB) approaches. The traffic volume count was 1378, 931, 1168 and 1123 veh/h for the NB, SB, EB and WB respectively. The level of service at the intersection is B, thus implying that it exhibits a slight delay.
 Keywords: Level of Service, Road intersection, Road geometry, Traffic delay

A dual lane piezoelectric ring bender actuated nozzle-flapper servo valve for aero engine fuel metering

Amongst many other high performance flow control applications, servo valves are used to control aero engines by metering the fuel delivered from the fuel pump. Conventionally, a fuel metering servo valve has a pilot stage with an electromagnetic torque motor moving a flapper which differentially restricts a pair of nozzles to create a hydraulic signal (i.e. a pressure difference). These valve pilot stages use mature, optimised technology such that to achieve improvements requires a novel approach. Torque motors in particular present reliability and manufacturing difficulties, and news solutions should ultimately allow a reduction in manual assembly and set-up, improve repeatability, and eliminate failures associated with fine wire devices. In this paper, a pilot stage actuated by piezoelectric ring benders is proposed, designed, built and tested, and test results are compared with a model used to predict pressure-flow characteristics. A particular challenge is the need to include redundancy, and thus a pair of ring benders is used, allowing isolation between duplicated electrical control channels. Another challenge is the mounting of the ring bender, which has to flex to allow the outer edge of the ring bender to deform, yet be stiff enough to adequately react against generated forces. O-ring mounts made from three different elastomer materials are compared in this study. In aerospace, an added complication is the large range of fuel temperature; F70 fluorosilicone O-rings have been chosen with this in mind, and successfully demonstrated in the range −50 °C to +180 °C. With one active and one inactive ring bender to simulate a failure condition, the new dual lane pilot stage achieves +/−50 μm displacement under test, giving control port flows up to +/−0.6 l min−1, and a control port pressure variation of 40 bar using a 100 bar supply pressure difference (supply minus return pressure). This research establishes that a piezoelectric aero engine fuel valve is feasible, and in particular, that piezoelectric ring bender actuators with elastomeric mountings are highly suited to this application.

Unbalanced Multiple Left Turn Lane Usage Modelling: From Individual Choice to Aggregate Volume

Diverse lane preferences of left-turn drivers lead to unbalanced traffic distribution on multiple left-turn lanes. The preferences can be measured in terms of lane usage at macroscopic level and individual lane choice at microscopic level. The data of lane volume and individual lane choices are collected at eight dual or triple left-turn lanes equipped in signalized intersections in China. Linear regression model with dummy variables and discrete choice model were applied to analyse drivers’ lane choosing patterns at macroscopic and microscopic levels, respectively, and results of the two studies are mutually verified and complemented. The drivers’ lane preferences are found to vary with approach configurations, traffic control, and the number of lanes available. Static influential factors, such as turning radius inside the intersection, the design of shadowed lane, and intersection skewedness, as well as dynamic influential factors, including queue length, heavy vehicle in queue back and subject vehicle type, could affect the drivers’ lane preferences. The findings of this study have important implications for intersection design and traffic control in practice.

Derivation of Decision Boundaries for Left-Turn Treatments at Signalized Intersections

A new methodology is proposed to establish practical guidelines for four incremental left-turn treatments: ( a) permissive single left-turn lane, ( b) protected–permissive single left-turn lane, ( c) protected dual left-turn lanes with equal lane use, and ( d) protected dual left-turn lanes with unequal lane use. Decision boundaries were derived from the equilibrium at which the delays of two incremental treatments were equal. The benefits and costs associated with different left-turn treatments—including safety impact and construction and maintenance costs—also were considered. These benefits and costs effectually shift the boundary curves for more realistic decision making.

Impact of Exit Ramp Geometric Treatments at Diverging Diamond Interchanges on Queue Spillback

Diverging diamond interchanges (DDIs) have swept the country as an innovative interchange system since the original U.S. installation in Springfield, Missouri, in 2009. Although the DDI provides many benefits, prior research identified some operational challenges found at some of the first DDIs built around the country. This study explored the challenge of limited capacity for the right turn at the DDI ramp terminal intersection and associated queue spillback concerns that have been observed at several sites. The study investigated the impact of five geometric treatments at a DDI’s right-turn exit ramp, including a channelized turn lane with an auxiliary lane, dual right-turn lanes, right turn on red (RTOR), dual right-turn lanes with RTOR, and a slip lane. The results showed that any treatment that decreased the green-to-cycle length ratio for the right turn from the exit ramp simultaneously reduced queues at the exit ramp and the outbound through movement at the crossover. However, treatments that did not also increase the capacity of the outbound through movement at the downstream adjacent intersection resulted in increased queues at that movement. The study concluded that the design of the DDI must be considered in the context of the entire corridor. To provide the full extent of congestion relief that is possible with a DDI, consideration of the geometrics of downstream, closely spaced, adjacent intersections must be included from the earliest planning stages.

Bridge over Canal Laranjeiras, Laguna, Brazil

On the south of Brazil the main Brazilian highway pass around the town Laguna only on a dual lane carriage way. There are regular traffic congestions with several hours of delay. The federal government invests a lot of money to increase the capacity of the main highway. The bridge over Canal Laranjeiras takes part of these improvements. It has a total length of 2 800m and overpasses two times the railway, the Laguna bay to Imauri and future navigation channel Laranjeiras. Its main part consists of 400m length of cable-stayed bridge with two pylons a 200m main span. The pylons are 76m height and are formed by box section. The cable-stayed part is situated in plan curvature and the main plane of longitudinal stays is supplemented by two planes of transversal stays for each pylon. The paper deals with conceptual design of the bridge and construction methodology.

Comparison of SimTraffic and VISSIM Microscopic Traffic Simulation Tools in Modeling Roundabouts

SimTraffic and VISSIM are two microscopic traffic simulation tools that are capable of modeling arterial roads with signalized intersections and roundabouts. This study compares the performance of the two simulation tools in modeling dual lane and triple lane roundabouts under different scenarios such as traffic volume, proportion of left turning movement, and proportion of trucks in the traffic flow. The two simulation tools did not show statistically significant difference in general. However; in the case of high traffic volumes, VISSIM showed higher average delays than those from SimTraffic compared to nearly identical results in the case of low traffic volumes.

Influence of road markings, lane widths and driver behaviour on proximity and speed of vehicles overtaking cyclists

The proximity and speed of motor traffic passing cyclists in non-separated conditions may be so close and so great as to cause discomfort. A variety of road design and driver behaviour factors may affect overtaking speeds and distances. The investigation presented in this paper builds on previous research and fills gaps in that research by considering the presence of cycle lanes on 20mph and 30mph roads, different lane widths, different lane markings, vehicle type, vehicle platooning and oncoming traffic. Data were collected from a bicycle ridden a distance of one metre from the kerb fitted with an ultrasonic distance detector and forward and sideways facing cameras.Reduced overtaking speeds correlate with narrower lanes, lower speed limits, and the absence of centre-line markings. Drivers passed slower if driving a long vehicle, driving in a platoon, and when approaching vehicles in the opposing carriageway were within five seconds of the passing point. Increased passing distances were found where there were wider or dual lane roads, and in situations where oncoming vehicles were further away and not in a platoon. In mixed traffic conditions, cyclists will be better accommodated by wider cross-sections, lower speed limits and the removal of the centre-line marking.

Dual right-turn lanes in mitigating weaving conflicts at frontage road intersections in proximity to off-ramps

At frontage road intersections located downstream of freeway off-ramps, the use of dual right-turn lanes may provide improved weaving environments for right-turning vehicles from the off-ramp and reduce forced merges toward the desired right-turn bay. This paper investigates the safety impacts of the installation of dual right-turn lanes at frontage road intersections. A two-stage approach is used to estimate weaving conflicts as safety surrogates. In the first stage, micro-simulation models are calibrated based on field data to simulate vehicle trajectories. In the second stage, the trajectories are processed to estimate surrogate safety measures and frequency of weaving conflicts under different conditions. The two-stage approach is validated by correlation analysis between predicted weaving conflicts and actual crash rates. The results show that dual right-turn lanes can reduce weaving conflicts significantly compared to single exclusive right-turn lanes, and the safety benefits increase exponentially as weaving distance is reduced.

Effects of CFRP Strengthening on Dynamic and Fatigue Responses of Composite Bridge

This paper investigates the effect of CFRP strengthening on dynamic and fatigue responses of composite bridge using finite element program ABAQUS. Dynamic and fatigue responses of composite bridge due to truck load based on AASHTO standard are investigated. Two types of CFRP strengthening techniques, CFRP sheets and CFRP deck, are applied to both the damaged and undamaged bridges. For the case of damaged bridge, two through-thickness crack sizes, 3 mm and 6 mm in depth, are assumed at midspan of the steel girders. Furthermore, effects of the number of steel girders on the dynamic and fatigue responses are also considered. The results show that the maximum responses of composite bridges occur for dual lane cases. By using CFRP as a strengthening material, the maximum stress and deflection of the steel girders reduce and consequently increase the fatigue life of the girders. After introducing initial crack into the steel girders of the composite bridges, the fatigue life of the bridges is dramatically reduced. However, the overall performance of the damaged composite bridge can be improved by using CFRP, albeit with less effectiveness. Therefore, if cracks are found, steel welding must be performed before strengthening the composite bridge by CFRP.

Evaluating the Operational Impact of Left-Turn Waiting Areas at Signalized Intersections in China

Transportation professionals in China have started using left-turn waiting areas and lagging left-turn phasing to improve traffic efficiency at signalized intersections. Left-turn waiting areas are usually set up beyond the stop bar at an exclusive left-turn lane or dual left-turn lanes. This design allows left-turning vehicles to enter and wait at the left-turn waiting area after the initiation of the through phase. The operational impact of left-turn waiting areas at signalized intersections was evaluated, and the arrival and departure processes of left-turning vehicles at exclusive left-turn lanes with and without waiting areas were compared. A procedure for estimating the capacity of an exclusive left-turn lane with a waiting area was proposed. Cross-sectional analysis used data collected from 12 approaches at nine signalized intersections to compare the start-up lost time and saturation headways of left-turn passenger cars for four scenarios. The capacities of exclusive left-turn lanes with differently sized left-turn waiting areas were compared. The results indicate that left-turn waiting areas increase the capacity of exclusive left-turn lanes and that the capacity gains would increase with an increase in the storage capacity of the left-turn waiting area.

Critical Gap Analysis of Dual Lane Roundabouts

Roundabouts are increasingly popular because of their performance in terms of safety, capacity, and cost. Roundabouts have the potential to reduce accident risk since the traffic flows merge and diverge at small angles, and low speeds. Under certain conditions, roundabouts also improve the flow of traffic at the intersection, compared to other choices. In this paper we present a methodology for estimating an important input in the calculation of the capacity of roundabouts: the critical gap. The critical gap is the smallest gap that a driver is willing to accept to merge with the circulating traffic and mainly determines the gap acceptance behavior of the driver. The critical gap is not directly observable. Only gaps that drivers have accepted or rejected are observed. These gaps define upper and lower values for the underlying critical gap but not its exact value. The paper builds on previous literature proposing a rigorous statistical methodology for the estimation of the critical gap, and demonstrates its applicationthrough field measurements. It is assumed that the critical gap has a lognormal distribution among the driver population with a mean value that is a function of a number of explanatory variables. Based on these assumptions the critical gap and its distribution can then be estimated using maximum likelihood. A case study in a dual lane roundabout in Stockholm is used to illustrate the proposed methodology using video and other data. The results show that the critical gap depends, among other factors, on the target lane (near or far), the type of the vehicle. The results are aslo compared to values recommended by other studies. © 2011 Published by Elsevier Ltd.

DEK boosts throughput and flexibility with new Dual Lane RTC platform

DEK boosts throughput and flexibility with new Dual Lane RTC platform

Multilane simulations of traffic phases.

The optimal velocity model, as modified by the author, is used in simulations of traffic on a dual-lane highway and a single-lane highway with an on-ramp. The equilibrium solutions of the modified model cover a two-dimensional region of flow-density space beneath the fundamental-diagram curve, rather than just lying on the curve as in the original model. Thus it satisfies a requirement of the three-phase model of Kerner [Phys. Rev. Lett. 81, 3797 (2002)]. Synchronization of velocity across dual lanes due to frequent lane changes is observed in free flow. True synchronized flow, as determined by the region of density-flow space it occupies, is obtained in on-ramp simulations with typical driver reaction times. A gradual change to the formation of a jam is observed for increasing delay times.

MRSI's ENCore offers Dual Lane Encapsulation

MRSI's ENCore offers Dual Lane Encapsulation

Enhancements of Remote Sensing for Vehicle Emissions in Tunnels

The University of Denver’s remote sensing system for vehicle exhaust has been successfully adapted to the measurement of vehicle emissions in a tunnel environment. Two studies conducted at the Fort McHenry Tunnel in Baltimore, MD and the Tuscarora Mountain Tunnel located west of Harrisburg, PA on the Pennsylvania Turnpike are described. The difficulties associated with remote sensing in a tunnel environment have led to a number of improvements in the remote sensing technology. The successful use of a prototype periscope system is described and evaluated along with the first-time measurements of dual lane traffic.

A new fault-tolerant multitransputer configuration for avionics two-lane systems

This paper discusses a new transputer-based fault-tolerant configuration for avionics two-lane systems for gas-turbine engines. The transputer is ideally suited to build a fault-tolerant multi-processing network since it has many parallel processing features. The new configuration, which consists of eight transputers, is called the dual monitor dual lane (DMDL) system. Its performance is tested in detail by simulation and the focus is on fault tolerance. It has higher reliability than the overlapping triad (OLT) two-lane system discussed in the literature. It is also seen that the response time of the system for reconfiguring in the presence of faults is good.