Effect of Lane Narrowing Implemented on an Urban Dual Carriageway on Speed Reduction and Acoustic Environment

The on-going growth in the use of motor vehicles leads to a number of traffic safety problems. Therefore, various traffic calming measures are applied to increase traffic safety in built-up areas. Lane narrowing is one of the techniques used to influence the perception of drivers and make them slow down. With this in mind, the authors conducted traffic volume and speed counts before and after installation of the lane narrowing treatment, covering 100 passing vehicles, at an intersection between an urban dual carriageway and an estate street where over a dozen fatal accidents occurred in the recent years. Traffic noise was also measured, both before and after lane narrowing. The traffic count data were analysed to show speed reduction by ca. 15 km/h, yet in all cases still above 50 km/h, which is the speed limit applicable to built-up areas in Poland. The analysis of the “before” and “after” noise maps showed only minor changes to the distribution of noise. The locations of these changes to the acoustic environment depended on the speed and volume of traffic and, much more importantly, on the topography of the surrounding area, the existing roadside layered landscape and the type of planted vegetation. The detailed analyses of the analysed parameters demonstrated that sustainable design of traffic calming measures on urban dual carriageways must consider not only the desired speed reduction but also the surrounding landscape and the local topography.

Synergy Effect of Factors Characterising Village Transition Zones on Speed Reduction

There are various traffic calming measures that can be installed in village transition zones. So far, focus was placed on diversified use of pavement markings, amounts of horizontal deflection, shape of the installed chicanes or central islands, presence of gateway, etc., and their location along the transition zone. However, the combined effect of the different transition zone factors on speed reductions has been rarely studied so far. Authors put forward a hypothesis of there being some determinants, which in combination influence speed reduction. To corroborate the hypothesis on the combined impact of the transition zone features on speed reduction in the village transition zones and to validate the established relationships the authors conducted verification study in transition zones containing chicanes or central islands. To verify this hypothesis the authors studied twenty transition zones and managed to confirm the hypothesis at 95% confidence level. The authors used previously adopted binary methods, verified the previously defined factors and added a few new determinants. The contribution of this study is a further investigation of the synergy effect of various relevant factors and the findings can assist in planning new transition zones or suggest additional measures to achieve the desired speed reduction in existing transition zones.

SUPERIOR SEAWORTHINESS OF A RESONANCE-FREE FAST OCEANGOING SWATH

The speed reduction, additional resistance or slamming caused by the large amplitude ship motions, should be completely restricted for a large fast oceangoing ship because of the strict time-punctuality and the high value of the cargo. A “Resonance-Free SWATH (RFS)”, which has negative restoring moments due to the extremely small water plane area, is introduced to minimize the motion responses. A motion control system using small fins is necessary for the RFS, which has no stability during high speed cruising. Theoretical estimations and experiments to search for the optimum values of PD control gains have been performed. Unsteady characteristics of fin-generated lift such as the time lag and the interaction among the fins and lower hulls have been measured and they are taken into account in the motion equations. Then, experiments using the RFS model with controlling fins have been carried out to validate the theoretical estimation for the motion responses of the RFS in waves. The theoretical and experimental results agree well with each other. The motion responses of the RFS in regular and irregular head waves are compared with those of other hull forms, such as a mono-hull, an ordinary SWATH and a trimaran. The clear advantage of the RFS regarding the seaworthiness has been found. In summary, the heave motion response of the RFS is reduced to 1/60 and the pitch motion becomes1/8, compared with those of the existing mono-hull ship.

UNSTEADY CHARACTERISTICS OF LIFT GENERATED BY SMALL UNDERWATER CONTROL FIN

Speed reduction or slamming must be restricted for a high-speed oceangoing vessel because of the requirement for punctuality and the high value of the cargo. Speed reduction and slamming are caused by large amplitude motions in waves. A promising ship form for such vessels is so-called “Resonance-Free SWATH (RFS)”, which has negative pitch and roll restoring moments due to the extraordinary small water plane area. As a consequence, the resonance peak is removed from the motion response. The attitude of the RFS with negative restoring moments is adjusted by four pairs of control fins attached to the fore and aft ends of the lower hulls. In previous studies, the steady value of the lift-curve slope is usually used in the motion equation of the frequency domain. However, when working in waves, the controlling fins are not working in a steady state and the lift coefficient is no longer a constant. In addition, there exists a phase lag between the change in the attack angle and the fin-generated lift. In the present study, theoretical predictions using a frequency-domain 3D-Rankine Panel Method, as well as experimental measurement, have been made to analyze the phenomena of the lift generation including the phase lag and the interference between fins, the lower hulls and the struts. The theoretical results agree well with the experimental results in spite of the potential theory being without viscosity. Next, the unsteady characteristics of fin-generated lift are expressed as the function of the encountering wave frequency. Then the effects of the fore fins, the lower hulls and struts on the lift curve-slope of the aft fins are discussed.

VIRTUAL ARRIVAL: A REAL OPTION FOR ENERGY SAVING?

The maritime traffic is the real backbone of the international transport of goods in the world and it is driven by a severe observance of time scheduling. Nevertheless, mainly in relation with the most traveled routes, frequently it might happen that port facilities are congested, and the time schedule for ship load/unload operations is accordingly delayed. In this circumstance the choice is between meeting the original ETA (estimated time of arrival) and then let the ship riding at anchor or slowing down the ship in order to adjust the arrival to the actually needed time window. The latter option is called "Virtual Arrival"[1] because it consists of applying a speed reduction that fits the new time for port operations instead of arriving at the original ETA. The purpose of this paper is to investigate to what extent the Virtual Arrival policy could be a valuable option providing a reasonable energy saving for ships. The potential benefits are considerable and they result in direct saving in fuel consumption, reduction of CO2 emissions and less congested port areas.

Improving the comprehensive performance of miniature MR rotary actuators using a lamellar excitation structure

Miniaturization has increasingly become a crucial prerequisite in various magnetorheological (MR) drive application scenarios. Owing to their high controllability and low response time, MR rotary actuators are developed for numerous feasible actuation solutions. However, the incident low degradation efficiency in the miniaturization limits the application of MR rotary actuators. In addition to torque capacity, structural simplification and easy machinability are also essential for miniaturization. In this study, a novel lamellar excitation structure (LES), which is interleaved with induction coils and ring-shaped iron cores, is proposed to improve the comprehensive performance of a miniature MR rotary actuator. The optimisation of the magnetic field distribution is realised by adopting an equivalent magnetic modelling method. The miniature MR actuator is incorporated into a turbine generator to evaluate the torque capability of the proposed LES-incorporated MR actuator via a kinematic model of the rotating shaft. The LES-incorporated MR rotary actuator demonstrates more favourable deceleration efficiency and torque capacity than conventional MR rotary actuators. The speed reduction per unit power Δn/P can be increased by 500% at most. The torque enhancement ratio-to-volume ratio (TEVR) value of LES is approximately 80 times higher than that of other optimised structures. We believe that this study is significant in improving the comprehensive performance of miniature MR rotary actuators, expanding the applications of MR actuators in miniaturised scenarios.

Assessment of Energy Efficiency and Ship Emissions from Speed Reduction Measures on a Medium Sized Container Ship

Greenhouse gases and other emissions from vessels and related activities in maritime trade have caused significant environmental impacts especially global warming of the atmosphere. Consequently, the International Maritime Organization (IMO) concern significant care to the reduction of ship emissions and improvement of energy efficiency through operational and technical measures. The proposed short-term measure is ship speed reduction in which the ship speed is reduced below its designed value. Therefore, the present paper aims at evaluating the potential energy efficiency and environmental benefits from using speed reduction measure through energy efficiency design index (EEDI), energy efficiency operational indicator (EEOI) and ship emissions calculation models as recommended from IMO. As a case study, a medium sized Container Ship is investigated. The results show that, reducing ship speed by 12.6% will reduce CO2 emissions by about 36%. Moreover, the attained EEDI value will be improved by 31.7% and comply with not only the current IMO requirements but also with the future ones. Additionally, reducing ship speed by 12.6% will reduce EEOI value from its value at design speed by 26.5%. Furthermore, it is noticed that SOx emission will comply with IMO 2020 limit if ship speed is reduced by 6.8% and above.

Responsiveness and Relationships of Shooting Performance to On-Ice Physical Performance Tests

The aim of this investigation was to quantify the acute effects of the execution of the physical performance tests within the ice hockey-specific complex test (IHCT) on shooting performance. Thirty-four professional male ice hockey players with an average of 6.9 years of playing experience were recruited. The slap shot (SS) was found to accelerate the puck with a higher speed and greater precision. After the IHCT, the maximum puck speed of successful goal shots decreased considerably (p < 0.001, d > 1.5). The puck speed percentage decrement after the IHCT did not differ between the SS (6.1, SD = 4.4, −5.5–17.9) and the wrist shot (WS, 6.0, SD = 3.5, −0.9–12.2, p = 0.86, d = 0.03). The magnitude of puck speed reduction in the WS was inversely related to the functional heart rate reserve (r = −0.44, p = 0.02) and the blood lactate elimination rate (r = −0.43, p < 0.02). The linear and COD speed tests on-ice resulted in a higher amount of successful goal shots. These findings highlight the interaction of intense on-ice testing and goal-shooting performance.

Effects of reducing and enforcing speed limits in selected arterial roads in Bogota

In Bogota, the speed limit in five corridors with the highest concentration of traffic crashes victims in the city was reduced from 60 to 50 km/h since November 2018. The average speed reduction in the corridors with speed management was 1.48 km/h during daytime and 3.04 km/h during nighttime. In arterial corridors without speed management, the average speed reduction was 0.7 km/h during daytime and 2.2 km/h during nighttime. The speed management measure influenced a reduction of 16.6% in the number of fatalities and an 10.5% increase of crashes with injuries. The severity of the crashes decreased. The average count of run over crashes was also reduced by 10%. Changes in the geographical distribution of crashes with injuries and fatalities along the corridors with speed management indicate the necessity to implement stricter enforcement measures to increase the effectiveness of speed management operations during nighttime.

Global Sensitivity Analysis Applied to Train Traffic Rescheduling: A Comparative Study

The adjustment of rail traffic in the event of an electrical infrastructure disruption presents an important decision-making process for the smooth operation of the network. Railway systems are complex, and their analysis relies on expensive simulations, which makes incident management difficult. This paper proposes the use of sensitivity analysis in order to evaluate the influence of different traffic adjustment actions (e.g., spacing between trains and speed reduction) on the train supply voltage, which must never drop below the critical value prescribed by technical standards. Three global sensitivity analysis methods dedicated to black box, multivariate, nonlinear models are considered: generalized Sobol indices, energy distance-based indices, and regional sensitivity analysis. The three methods are applied to a simple traffic rescheduling test case and give similar results, but at different costs. Regional sensitivity analysis appears to be the most suitable method for the present application: it is easy to implement, rather fast, and accounts for constraints on the system output (a key feature for electrical incident management). The application of this method to a test case representative of a real rescheduling problem shows that it provides the information needed by the traffic manager to reschedule traffic in an efficient way. The same type of approach can be used for any power system optimization problem with the same characteristics.