Effects of Wheel Rotation on Long-Period Wake Dynamics of the DrivAer Fastback Model

Lattice Boltzmann method (LBM) simulations were performed to capture the long-period dynamics within the wake of a realistic DrivAer fastback model with stationary and rotating wheels. The simulations showed that the wake developed as a low-pressure torus regardless of whether the wheels were rotating. This torus shrank in size on the base in the case of rotating wheels, leading to a reduction in the low-pressure footprint on the base, and consequently a 7% decrease in the total vehicle drag in comparison to the stationary wheels case. Furthermore, the lateral vortex shedding experienced a long-period switching associated with the bi-stability in both the stationary and rotating wheels cases. This bi-stability contributed to low-frequency side force oscillations (<1 Hz) in alignment with the peak motion-sickness-inducing frequency (0.2 Hz).

Did Electric Vehicle Sales Skyrocket Due to Increased Environmental Awareness While Total Vehicle Sales Declined during COVID-19?

Since the beginning of 2020, the COVID-19 pandemic has posed a global threat to humankind. In addition to many cases of illness and millions of deaths, the economy has suffered. Not surprisingly, vehicle sales have declined sharply in most countries by up to 25%. However, the overall sales of electric vehicles (EVs) did not stall; instead, they increased to previously forecasted levels. Is this increase evidence that COVID-19 has promoted sustainable action and strengthened environmental awareness, as researchers have discussed in recently published articles? Or is this merely the effect of monetary incentives by governments, as has been demonstrated in scientific research? This study examines the causes behind the surprising continuous climb of EV sales despite the outbreak of the pandemic by contrasting the influence of COVID-19 on environmental concerns and the usual monetary incentives with their potential complementary effects.

Effect of tire slip losses on the energy demand and fuel consumption of a light-duty vehicle

The contribution of the tire-road slip of traction wheels to the total resistance opposing the motion of a light-duty commercial vehicle has been investigated through the simulation of several homologation and custom driving cycles. The calculation of the contribution of the tire slip losses was based on the estimation of the longitudinal tire slip, by means of Pacejka’s MF5.2 tire model. In this work, the computational steps required to evaluate this contribution were implemented in a previously developed fuel consumption simulation tool. Simulations were performed under several vehicle loading conditions and tire inflation pressures on traction and non-traction wheels, and considering different tire-road adherence conditions, in order to obtain a characterization of the tire slip losses over a wide range of working conditions. An analysis of the results shows that, although the contribution of tire slip losses to the total vehicle energy demand and fuel consumption may be relevant – especially under low-load, low adherence conditions – the sensitivity of the average on-cycle vehicle energy/fuel consumption to changes in the tire inflation pressure is only affected slightly by tire slip losses. Therefore, tire slip losses can be neglected in practice, when the aim of a simulation is to optimize the tire pressure to achieve average vehicle working conditions over a driving cycle.

A Simulation-Based Evaluation of a Cargo-Hitching Service for E-Commerce Using Mobility-on-Demand Vehicles

Time-sensitive parcel deliveries—shipments requested for delivery in a day or less—are an increasingly important aspect of urban logistics. It is challenging to deal with these deliveries from a carrier perspective. These require additional planning constraints, preventing the efficient consolidation of deliveries that is possible when demand is well known in advance. Furthermore, such time-sensitive deliveries are requested to a wider spatial scope than retail centers, including homes and offices. Therefore, an increase in such deliveries is considered to exacerbate negative externalities, such as congestion and emissions. One of the solutions is to leverage spare capacity in passenger transport modes. This concept is often denominated as cargo hitching. While there are various system designs, it is crucial that such a solution does not deteriorate the quality of service of passenger trips. This research aims to evaluate the use of mobility-on-demand (MOD) services that perform same-day parcel deliveries. To test the MOD-based solutions, we utilize a high-resolution agent- and activity-based simulation platform of passenger and freight flows. E-commerce demand carrier data collected in Singapore are used to characterize simulated parcel delivery demand. We explore operational scenarios that aim to minimize the adverse effects of fulfilling deliveries with MOD service vehicles on passenger flows. Adverse effects are measured in fulfillment, wait, and travel times. A case study on Singapore indicates that the MOD services have potential to fulfill a considerable amount of parcel deliveries and decrease freight vehicle traffic and total vehicle kilometers travelled without compromising the quality of MOD for passenger travel. Insights into the operational performance of the cargo-hitching service are also provided.

Risky motorcycle riding behaviour among young riders in Manipal, India

Background Motorcycles are one of the most commonly used transportation modes in low and middle-income countries. In India, motorized two-wheelers comprise 70% of the total vehicle population, and motorcycle users are considered the most vulnerable road users. It is essential to understand the risky riding behaviour and associated factors among the motorcyclists to develop evidence-based traffic safety programs targeting motorcycle riders. The purpose of the current study was two-fold. First, it aimed to determine the appropriate structure of a modified version of the MRBQ among young riders in Manipal, India. Second, it assessed to what extent MRBQ factors were associated with self-reported crash involvement and violations. Methods The motorcycle rider behaviour questionnaire (MRBQ) is a 43-item scale that assesses five aspects of risky motorcycle rider behaviour, i.e., violations, control errors, traffic errors, stunts, and protective equipment. The MRBQ, along with measures of socio-demographic variables and the number of motorcycle crashes, was filled out by 300 young motorcycle riders who were in the age group of 18–25 years and had been riding for at least the past three years (93% males, 92.3% students). Results Five factors emerged out of the MRBQ after an exploratory factor analysis: traffic errors, control errors, stunts, protective equipment, and violations. Cronbach’s alpha for these factors ranged from .66 to .82. Reports of performing stunts and committing violations were positively associated with self-reported near-crash experiences over the past three months. Riders reporting stunts, violations and using a motorcycle of 125-200 cc reported having received more fines in the last three months. These findings were confirmed in both univariate and multivariate binary logistic regression models. Conclusion The study assessed the factor structure of a modified version MRBQ and the extracted factors associations with self-reported crash involvement. The factor structure revealed in the current study is consistent with MRBQ factor structures found in other countries. However, the support for a relationship between MRBQ factors and self-reported crashes was less significant. The findings suggest that if replicated by future studies, local policymakers are advised to focus on the five MRBQ factors while planning future interventions to achieve a reduction in the number of road crashes among motorcyclists.

Exploratory Study of Determinants of the Spread of COVID-19 before Shelter-in-Place Orders

This study explores the impact of relevant characteristics of counties and their relationship with increases in COVID-19 cases before shelter-in-place (SIP) orders in the U.S. The recent emergence of COVID-19 occurs when there is little understanding of the related factors affecting the growth and spread of the disease. These relationships are examined through an analysis of 672 counties before SIP orders were issued. Areas that experienced the most significant transmission of disease are identified, and their characteristics are analyzed. A meaningful relationship was found between the increase of COVID-19 cases and several factors. Average commute time and the proportion of commuters using transit had a positive relationship. Along with other socio-economic factors, such as median house value and proportion of the Black population, several transportation-related factors had a significant association with the transmission of the disease. The decrease rate of total vehicle miles traveled (VMT) before and after SIP orders also had a solid and positive relationship with the expansion of the disease. The findings suggest that planners and transportation service providers must integrate evolving public health considerations into transportation services which affect the increase in the transmission of infectious diseases.

Traffic-related Noise at Roadside Schools: Assessment and Prediction in Urban Setting

ABSTRAK Kebisingan lalu lintas adalah salah satu ancaman bagi kesehatan masyarakat perkotaan. Paparan bising memberikan efek kesehatan jangka pendek dan panjang, dan efeknya berpotensi lebih buruk pada anak-anak yang belajar di sekolah pinggir jalan. Penelitian ini bertujuan untuk mengkarakterisasi kebisingan lalu lintas jalan di sekolah-sekolah yang terletak di jalan-jalan utama di Bandung, Indonesia serta memberikan rekomendasi mitigasi dan adaptasi untuk pengendalian kebisingan. Kebisingan lalu lintas diperoleh di dua sekolah pinggir jalan terletak di dua jalan utama (Jalan Suci dan Djuanda), beserta data volume dan komposisi lalu lintas, serta kecepatan kendaraan. Pengukuran dilakukan antara jam sekolah selama satu hari yang mewakili lokasi trotoar jalan, depan sekolah, dan halaman sekolah. Parameter tingkat kebisingan yang penting (Leq, L10, L50, L90) diukur, dan dilakukan analisis korelasi antara masing-masing parameter kebisingan. Model CoRTN digunakan untuk memprediksi kebisingan lalu lintas pada jarak tertentu dari jalan raya. Sepeda motor merupakan jenis kendaraan dominan secara berturut 79,1% dan 67,1% dari total volume kendaraan di ruas jalan Suci dan Djuanda. Kendaraan berat menyumbang <1%. Mayoritas kebisingan lalu lintas yang diukur sebagai Leq, L10, L50, L90 melebihi batas maksimum untuk pinggir jalan dan zona sekolah menurut standar internasional dan nasional <55 dBA). Model tersebut berkinerja lebih baik di ruas jalan Djuanda daripada Suci. Jumlah lokasi dan waktu pengukuran yang lebih banyak dapat memberikan penilaian paparan tingkat kebisingan lalu lintas yang lebih baik dengan menggunakan model CoRTN. Hasil penelitian ini diharapkan dapat menjadi masukan kebijakan berbasis pengetahuan bagi pemerintah kota dan lembaga untuk mengurangi dampak bising bagi anak didik. Kata kunci: kebisingan lalu lintas jalan, tingkat kebisingan, Model CoRTN ABSTRACT Noise from road traffic is one of the most ubiquitous threats to the public health in urban setting. Its exposures have proven short-and long-term health effects. and potentially worse for vulnerable population such as children studying at roadside schools. This study aimed to characterize the road traffic noise at schools located at major roads in Bandung, Indonesia. Traffic noise were obtained at 2 roadside schools located at two major roads (Suci and Djuanda roads), along with data on traffic volume and composition, and vehicles speed. The measurement was conducted between school hours during one day-time only at locations representative of roadside, front of the schools, and schoolyard. Important noise level parameters such as Leq, L10, L50, L90 were recorded, and correlation analysis between each parameter was conducted. The CoRTN model was then applied to predict the traffic noise at particular distances from the road. Motorcycles were the predominant vehicle type on both road segments: 79.1% and 67.1% of the total vehicle volume on Suci on Djuanda segments, respectively. Conversely, heavy vehicles accounted <1%. The majority of measured traffic noise determined as Leq, L10, L50, L90 exceeded the maximum limit for roadside and school zone set by the international and national standard (>55 dBA). The model performed better in Djuanda road segment than in Suci segment. More measurement locations and time could provide better assessment of exposure to traffic noise levels at roadside schools using the CoRTN model. Keywords: road traffic noise, noise level, CoRTN model

Modeling Traffic Flow, Energy Use, and Emissions Using Google Maps and Google Street View: The Case of EDSA, Philippines

The general framework of the bottom-up approach for modeling mobile emissions and energy use involves the following major components: (1) quantifying traffic flow and (2) calculating emission and energy consumption factors. In most cases, researchers deal with complex and arduous tasks, especially when conducting actual surveys in order to calculate traffic flow. In this regard, the authors are introducing a novel method in estimating mobile emissions and energy use from road traffic flow utilizing crowdsourced data from Google Maps. The method was applied on a major highway in the Philippines commonly known as EDSA. Results showed that a total of 370,855 vehicles traveled along EDSA on average per day in June 2019. In comparison to a government survey, only an 8.63% error was found with respect to the total vehicle count. However, the approximation error can be further reduced to 4.63% if cars and utility vehicles are combined into one vehicle category. The study concludes by providing the limitations and opportunities for future work of the proposed methodology.

Drag Reduction on car side mirrors with the implementation of camera modules

The greatest obstacle in the acceleration of a car through air is aerodynamic drag. With this increased drag is the expenditure of fuel. About 50-60% of a vehicles’ total fuel energy is lost to overcome adverse aerodynamic forces. However, with the increase of fuel prices, many solutions have surfaced. One of these solutions are the implementation of camera modules to replace bulky traditional side mirrors. For this report, a thorough analysis was conducted into the aerodynamic benefits of these newly proposed camera modules in comparison to the conventional solid state mirrors. Specifically, one conventional side mirror along with two newly proposed camera module’s were studied in this thesis report. For this analysis, the overall drag of each module was found using CFD simulation under turbulent conditions at 60 km/h using the Realized K- method. The drag and Cd values found for the conventional side mirror were 3.985 N and 0.38 respectively. The values found for the two camera modules, Models B and C, were 0.526 N and 0.857 N. Their Cd values were found to be 0.312 and 0.365. This shows a potential of the drag reduction of the side mirror by almost 87% if the switch was made to the newer technology. This value also agreed with the prediction by Honda on their technology which has stated a possible drag reduction for this part by up to 90%. However, when observing the bigger picture, it became evident that although this drag reduction is significant for locally, it simply is not enough to make a big impact on the drag reduction of the entire vehicle. With a maximum decrease in the total vehicle drag found to to be only 4%, the reduction in the fuel consumption of the vehicle would only decrease by 0.2 gallons per mile. On the other hand, improvements in parts such as the car rims or the underbelly of the car can result in fuel improvements of upwards of 12%-25%. For this reason, it can be concluded that automobile manufacturers research other possible solutions to reduce the vehicle drag such as with the redesign of the underbelly of the car or wheel arches and rims.

Drag Reduction on car side mirrors with the implementation of camera modules

The greatest obstacle in the acceleration of a car through air is aerodynamic drag. With this increased drag is the expenditure of fuel. About 50-60% of a vehicles’ total fuel energy is lost to overcome adverse aerodynamic forces. However, with the increase of fuel prices, many solutions have surfaced. One of these solutions are the implementation of camera modules to replace bulky traditional side mirrors. For this report, a thorough analysis was conducted into the aerodynamic benefits of these newly proposed camera modules in comparison to the conventional solid state mirrors. Specifically, one conventional side mirror along with two newly proposed camera module’s were studied in this thesis report. For this analysis, the overall drag of each module was found using CFD simulation under turbulent conditions at 60 km/h using the Realized K- method. The drag and Cd values found for the conventional side mirror were 3.985 N and 0.38 respectively. The values found for the two camera modules, Models B and C, were 0.526 N and 0.857 N. Their Cd values were found to be 0.312 and 0.365. This shows a potential of the drag reduction of the side mirror by almost 87% if the switch was made to the newer technology. This value also agreed with the prediction by Honda on their technology which has stated a possible drag reduction for this part by up to 90%. However, when observing the bigger picture, it became evident that although this drag reduction is significant for locally, it simply is not enough to make a big impact on the drag reduction of the entire vehicle. With a maximum decrease in the total vehicle drag found to to be only 4%, the reduction in the fuel consumption of the vehicle would only decrease by 0.2 gallons per mile. On the other hand, improvements in parts such as the car rims or the underbelly of the car can result in fuel improvements of upwards of 12%-25%. For this reason, it can be concluded that automobile manufacturers research other possible solutions to reduce the vehicle drag such as with the redesign of the underbelly of the car or wheel arches and rims.