Different Types Of Vehicles Research Articles

Study on Speed and Time-headway Distributions on Two-lane Bidirectional Road in Heterogeneous Traffic Condition

In the present paper an attempt has been made to have an idea about speed and headway distribution pattern in heterogeneous traffic condition comprising of various motorized and non-motorized vehicles having widely varying speed range. Distribution of speed and time headway has been studied for different density levels namely, 0-20 PCU/km, 20-40 PCU/km, 40-60 PCU/km and 60-80 PCU/km. Statistical validity of each distribution is evaluated by Kolmogorov-Smirnov (K-S) test. Results show that the speed and time headway follow different distribution patterns under different density levels. Moreover speed distribution profile is evaluated for different types of vehicle and time headway distribution profiles are also determined for different vehicle pairs. The findings can be used for developing simulation models for two-way, two-lane roads under heterogeneous conditions.

A heuristic algorithm for the auto-carrier loading problem

This paper studies the auto-carrier loading problem (ACLP) formulated as an integer mathematical programming model in which the associated objective function seeks to minimise the total number of reloads along the scheduled auto-carrier route. This study makes necessary modification of the previous Agbegha et al.'s (1998) formulation. A heuristic algorithm is then proposed and demonstrated in detail with nine instances that have appeared in the literature. The nine instances are the various loading results for examples assigning vehicles on different auto-carrier configurations and, for each configuration, taking into consideration constraints imposed by different types of vehicle. Computational experiments indicate that the proposed heuristic algorithm is superior to Agbegha et al.'s (1998) method by obtaining better or at least the same quality solutions.

A Hybrid Dynamic Programming for Solving Fixed Cost Transportation with Discounted Mechanism

The problem of allocating different types of vehicles for transporting a set of products from a manufacturer to its depots/cross docks, in an existing transportation network, to minimize the total transportation costs, is considered. The distribution network involves a heterogeneous fleet of vehicles, with a variable transportation cost and a fixed cost in which a discount mechanism is applied on the fixed part of the transportation costs. It is assumed that the number of available vehicles is limited for some types. A mathematical programming model in the form of the discrete nonlinear optimization model is proposed. A hybrid dynamic programming algorithm is developed for finding the optimal solution. To increase the computational efficiency of the solution algorithm, several concepts and routines, such as the imbedded state routine, surrogate constraint concept, and bounding schemes, are incorporated in the dynamic programming algorithm. A real world case problem is selected and solved by the proposed solution algorithm, and the optimal solution is obtained.

Analysis of the Effect of Variable Lateral Gap Maintaining Behavior of Vehicles on Traffic Flow Modeling

Vehicular interaction between different types of vehicles, in both the lateral and longitudinal directions, significantly affects the heterogeneous traffic flow modeling. From the field data it has been observed that the drivers vary gaps based on the changing traffic conditions. This variable gap maintaining behavior has been characterized using macroscopic traffic characteristic called area occupancy. Variable gaps are explained through effective vehicle width and it is found to be influenced by various factors. In this study, variable gap maintaining behavior is modeled using the concept of cellular automata (CA), with the help of a modified cell structure. Cell width in the modified cell structure has been varied corresponding to the observed variation in the effective vehicle width. It was found that the results obtained from the model incorporated with the variable gap maintaining behavior are significantly different from that of the uniform-cell-width based CA model. The effect is more significant for urban traffic conditions due to the presence of two-wheelers and three-wheelers.

A Modified Column Generation to Solve the Heterogeneous Fixed Fleet Open Vehicle Routing Problem

In the heterogeneous fixed fleet open vehicle routing problem (HFFOVRP), several different types of vehicles can be used to service the customers. The types of vehicles are different in terms of capacity, fixed cost, and variable cost. In this problem, the vehicles are not required to return to the depot after completing a service and the number of vehicles of each type is fixed and limited. Since this problem belongs to NP-hard problems, in this paper a compound heuristic algorithm called SISEC which includes sweep algorithm, insert, swap, and 2-opt moves, modified elite ant system (EAS), and column generation (CG) is applied to solve the HFFOVRP. We report computational results on 22 problems and solve each problem by using our SISEC. The results which were compared to the results of exact algorithms and the classic CG confirm that the proposed algorithm produces high quality solutions within an acceptable computation time.

Special issue: Smart transportation: Theory and practice

Special issue: Smart transportation: Theory and practice

Implementation of road dust resuspension in air quality simulations of particulate matter in Madrid (Spain)

An evaluation of the concentration levels of Particulate Matter (PM) was carried out in Madrid (Spain) by introducing the emissions from road dust resuspension. Road dust resuspension emission factors (EF) for different types of vehicles were calculated from EPA-AP42, a global resuspension factor of 0.097 g veh-1 km-1 as described in Amato et al. (2010) and a rain-dependent correction factor. With these resuspension EFs, a simulation at street canyon level was performed with the OSPM model without rainfall. Subsequently, a simulation using the CMAQ model was implemented adding resuspension emissions affected by the rain. These data were compared with monitored data obtained from air quality stations. OSPM model simulations with resuspension EFs but without the effect of rainfall improve the PM estimates in about 20 µg m-3 compared to the simulation with default EFs. Total emissions were calculated by adding the emissions estimated with resuspension EFs to the default PM emissions to be used by CMAQ. For the study in the Madrid Area, resuspension emissions are approximately of the same order of magnitude as inventoried emissions. On a monthly scale, rain effects are negligible for resuspension emissions due to the dry weather conditions of Spain. With the exception of April and May, the decrease in resuspension emissions is not greater than 3%. The predicted PM10 concentration increases up to 9 µg m-3 on annual average for each station compared to the same scenario without resuspension. However in both cases, PM10 estimates with resuspension are still underestimating observations. It should be noted that although that accounting for resuspension improves the quality of model predictions, other PM sources (e.g. Saharan dust) were not considered in this study.

Determination of Passenger-Car Units on Two-Lane Intercity Highways under Heterogeneous Traffic Conditions

AbstractThe introduction of the passenger car unit (PCU) concept by the 1965 edition of the Highway Capacity Manual (HCM) enabled researchers around the world to deal with mixed traffic flow. Though some researchers have tried to show the dynamic nature of PCU factors, most of the studies in the world, as well as the latest standards being followed, still provide static PCU values for various types of vehicle categories. The present study demonstrates the dynamic nature of PCU factors on two-lane intercity highways under highly heterogeneous traffic composition. They are estimated based on speed and size of vehicle type in the traffic stream with respect to a standard passenger car. Simultaneous equations are formulated to calculate the speeds of different types of vehicles for a given traffic composition and traffic volume on the road, which lead to the determination of PCU factors. While many plots are made to describe the effect of traffic composition and volume on PCU of a vehicle type, it is felt tha...

Black carbon, particle number concentration and nitrogen oxide emission factors of random in-use vehicles measured with the on-road chasing method

Abstract. The chasing method was used in an on-road measurement campaign, and emission factors (EF) of black carbon (BC), particle number (PN) and nitrogen oxides (NOx) were determined for 139 individual vehicles of different types encountered on the roads. The aggregated results provide EFs for BC, NOx and PN for three vehicle categories: goods vehicles, gasoline and diesel passenger cars. This is the first on-road measurement study where BC EFs of numerous individual diesel cars were determined in real-world driving conditions. We found good agreement between EFs of goods vehicles determined in this campaign and the results of previous studies that used either chasing or remote-sensing measurement techniques. The composition of the sampled car fleet determined from the national vehicle registry information is reflective of Eurostat statistical data on the Slovenian and European vehicle fleet. The median BC EF of diesel and gasoline cars that were in use for less than 5 years decreased by 60 and 47 % from those in use for 5–10 years, respectively; the median NOx and PN EFs of goods vehicles that were in use for less than 5 years decreased from those in use for 5–10 years by 52 and 67 %, respectively. Surprisingly, we found an increase of BC EFs in the newer goods vehicle fleet compared to the 5–10-year old one. The influence of engine maximum power of the measured EFs showed an increase in NOx EF from least to more powerful vehicles with diesel engines. Finally, a disproportionate contribution of high emitters to the total emissions of the measured fleet was found; the top 25 % of emitting diesel cars contributed 63, 47 and 61 % of BC, NOx and PN emissions respectively. With the combination of relatively simple on-road measurements and sophisticated post processing, individual vehicle EF can be determined and useful information about the fleet emissions can be obtained by exactly representing vehicles which contribute disproportionally to vehicle fleet emissions; and monitor how the numerous emission reduction approaches are reflected in on-road driving conditions.

Green vehicle technology to enhance the performance of a European port: A simulation model with a cost-benefit approach

In this paper, we study the impact of using a new intelligent vehicle technology on the performance and total cost of a European port, in comparison with existing vehicle systems like trucks. Intelligent autonomous vehicles (IAVs) are a new type of automated guided vehicles (AGVs) with better maneuverability and a special ability to pick up/drop off containers by themselves. To identify the most economical fleet size for each type of vehicle to satisfy the port’s performance target, and also to compare their impact on the performance/cost of container terminals, we developed a discrete-event simulation model to simulate all port activities in micro-level (low-level) details. We also developed a cost model to investigate the present values of using two types of vehicle, given the identified fleet size. Results of using the different types of vehicles are then compared based on the given performance measures such as the quay crane net moves per hour and average total discharging/loading time at berth. Besides successfully identifying the optimal fleet size for each type of vehicle, simulation results reveal two findings: first, even when not utilising their ability to pick up/drop off containers, the IAVs still have similar efficacy to regular trucks thanks to their better maneuverability. Second, enabling IAVs’ ability to pick up/drop off containers significantly improves the port performance. Given the best configuration and fleet size as identified by the simulation, we use the developed cost model to estimate the total cost needed for each type of vehicle to meet the performance target. Finally, we study the performance of the case study port with advanced real-time vehicle dispatching/scheduling and container placement strategies. This study reveals that the case study port can greatly benefit from upgrading its current vehicle dispatching/scheduling strategy to a more advanced one.

Evaluation of Vehicular Discomfort Measures Produced by Speed Bumps Using Numerical Simulation

In the design of automotive components the use of numerical simulations has contributed to reducing the design time, decreasing the prototypes costs and increasing reliability of the final product. However is necessary a investigation on human body vertical vibrations transmitted by different types of vehicle for the purpose of recognition the danger and guiding to eliminate of risks of discomfort theirs. This study, the object is to compare the discomfort levels of occupants when different vehicles (car, bike and bus) move over a speed bump. The results show that wheelbase, wheel size and vehicle weight can lead to different vehicular discomfort results. Results of the study demonstrated that heavy vehicles occupants (bus or truck) are subject to discomfort greater than occupants of light vehicles (cars and motorcycles) ones.

Traffic composition and variability of road traffic noise levels in the vicinity of Colombo, Sri Lanka

A study was conducted to determine the contribution of different types of vehicles to road traffic noise levels. Measurements were carried out on three different categories of roads at six separate locations, approximately 30 km away from the city of Colombo. At each location, continuous noise measurements were taken for a duration of 13 hours on weekdays and several key noise level descriptors (Leq, L10, L50, L90) were measured simultaneously. It was observed that A-weighted equivalent noise level (Leq) along main roads and secondary roads reached ~70 dB(A), which is the maximum permissible noise level prescribed for road traffic by Japan for residential areas. Similar to previous studies, a linear correlation was observed between Leq and other noise descriptors. Specially L10, which can be related to annoyance, can be estimated with an accuracy of ± 1 dB(A) by measuring Leq. The correlation between the rate of vehicle flow and the measured noise level showed a logarithmic relationship. It is shown that the key noise descriptors can be estimated with an accuracy of ± 2.5 dB(A) by measuring the flow rate of vehicles. The vehicle composition showed that heavy vehicles such as lorries, buses and containers contribute significantly to the average noise levels. J.Natn.Sci.Foundation Sri Lanka 2015 43 (2): 135-140

Improving the Sustainability of Transportation: Environmental and Functional Benefits of Right Turn By-Pass Lanes at Roundabouts

The functional performances of conventional roundabouts (single-lane and multi-lane) and innovative roundabouts (spiral, flower, C and turbo) can be improved through right-turn bypass lanes controlled by stop, yield or free-flow signs. The article presents evaluations of the emissions of air pollutants (carbon dioxide, nitrogen oxides, particle pollution (PM10 and PM2.5)), fuel consumption and construction, management, energetic and environmental costs in roundabouts without or with bypass lanes (controlled by stop, yield or free-flow). The suggested methodology has a general character and can be applied as a multi-parametric criterion for choosing road intersections, although, in the present paper, it has been employed only for a case study. For the aims of this research, we employed recent closed-form formulations to determine roundabout performances; moreover, we used the COPERT IV® software to estimate air emissions in nine different types of vehicles. Numerous traffic simulations were carried out. The variation in the maximum hourly traffic Qmax and annual traffic QTOT provided the appropriate domains of the examined geometric layouts, both in functional and environmental terms and with regard to generalized costs, estimated for a 10-year period. It resulted that the introduction of right-turn bypasses in all arms of conventional roundabouts with a one ring lane and one lane at the entries (single-lane roundabouts) is the most cost-effective when the flows entering the roundabout are higher than Qmax = 2000 veh/h. Moreover, free-flow bypass lanes always provide greater capacity and lower delays than stop- or yield-signaled bypasses. However, with extremely high Qmax values, stop-controlled bypasses guarantee lower fuel consumption, while those with a yield sign lower total costs.

Cruising-for-parking in congested cities with an MFD representation

It has been recently proposed and tested that traffic in large urban regions (neighbourhoods) can be modelled dynamically at an aggregate level, if the neighbourhoods are uniformly congested. By exploiting the insights and the properties of a macroscopic fundamental diagram (MFD), we describe the rush hour dynamically in case of multi-region cities that are not uniformly congested. A cruising-for-parking model is developed that considers the dynamics of different types of vehicles, while travelling towards their destinations or cruising. This model describes the physics of hypercongestion caused by the phenomenon, it shows that cruising-for-parking affects all the users of the system, even those with destinations outside the limited parking region and it provides tools to estimate the direct costs of all users, as these expressed by additional vehicle-hours travelled. Also, it describes the rush hour dynamically while vehicles searching for a spot (properly recognizing that delays are greater when flows are lower, unlike existing economic models).

An Optimal Dynamic Approach to Reconfigurable Logistic System

In Today's globalized world and cutthrought competition distribution costs play an important part in entire logistic network. From inbound to outbound logistics, everywhere focus seems to be on minimizing the distribution cost of goods. Highlighting the cost minimization issue, routing of the logistic activities is very important. In other words a reconfigurable logistic system can help reducing the cost to a significant level in a supply chain.In this paper,we have addressed the important issue of the consolidation and quantity allocation where optimal combination of the goods of diverse nature is achieved. This optimal combination is dependent on variables such as weight and volume of the products and capacity of the trucks. The trucks are distinguishable on the basis of their carrying capacities and have distinct hiring costs associated, i.e. different types of vehicle incur distinct fixed cost for each trip from the warehouse to retailer. It is assumed that retailer has a deterministic demand pattern over a finite planning horizon. Finally, the case is validated through a fast moving consumer good's company where anheuristic approach is used for the optimization.The heuristic provide feasible and effective solution for the mentioned multi-variable problem.

Modeling the critical position of U-turning vehicles at uncontrolled median openings

The present study provides a methodology for identification of the conflict zone between a turning vehicle and on-coming vehicles at uncontrolled median openings on urban roads under mixed traffic conditions. Data for turning movements of different types of vehicles were collected at 13 median openings on 6-lane roads and 8 median openings on 4-lane roads in different cities of India. These data are analyzed statistically and it was found that the critical position (path of the outer wheel) of a vehicle is influenced by the vehicle size and the road width. In the case of 6-lane roads, the critical position of turning vehicle may follow a unimodal or bimodal distribution depending upon the proportion of motorized two-wheelers (2-W) in the turning volume. On 4-lane roads, the gamma distribution was found to fit the placement data at all the eight sections. A simple model is proposed to identify the boundary of the conflict zone at median openings. The geometrical augmentation required at the median opening in order to avoid the conflict between turning vehicles and through traffic in the opposing median lane is also suggested.

Characterization of extremely low frequency magnetic fields from diesel, gasoline and hybrid cars under controlled conditions.

This study characterizes extremely low frequency (ELF) magnetic field (MF) levels in 10 car models. Extensive measurements were conducted in three diesel, four gasoline, and three hybrid cars, under similar controlled conditions and negligible background fields. Averaged over all four seats under various driving scenarios the fields were lowest in diesel cars (0.02 μT), higher for gasoline (0.04–0.05 μT) and highest in hybrids (0.06–0.09 μT), but all were in-line with daily exposures from other sources. Hybrid cars had the highest mean and 95th percentile MF levels, and an especially large percentage of measurements above 0.2 μT. These parameters were also higher for moving conditions compared to standing while idling or revving at 2500 RPM and higher still at 80 km/h compared to 40 km/h. Fields in non-hybrid cars were higher at the front seats, while in hybrid cars they were higher at the back seats, particularly the back right seat where 16%–69% of measurements were greater than 0.2 μT. As our results do not include low frequency fields (below 30 Hz) that might be generated by tire rotation, we suggest that net currents flowing through the cars’ metallic chassis may be a possible source of MF. Larger surveys in standardized and well-described settings should be conducted with different types of vehicles and with spectral analysis of fields including lower frequencies due to magnetization of tires.

EVALUATION OF SPEED–FLOW CHARACTERISTICS ON TWO-LANE HIGHWAYS WITH MIXED TRAFFIC

The HCM (Highway Capacity Manual 2010) classifies two-lane rural highway that passes through developed areas as ‘Class III’ and suggests using Percent Free-Flow Speed (PFFS) as performance measure to define Level Of Service (LOS). Apparently, this performance measure addresses the main limitation associated with using Average Travel Speed (ATS) as a measure of performance. However, larger speed differential under heterogeneous traffic causes error in estimating Free-Flow Speed (FFS) and thus affects PFFS. This implication was examined in the present study using field data collected on a national highway approaching a city. Speed–flow equations were developed and intercept values were compared to the FFS obtained according to HCM guidelines. Comparison confirms a very close agreement between average FFS value and those obtained for different types of vehicle separately except for car. This consequently causes an error in estimating PFFS since the traffic composition consists of significant proportion of car. The possible capacity of the highway section was observed to be around 2300 pc/h for mixed traffic situation.

A Model to Evaluate the Capacity of Public Road Transportation System: A Centenary Review of Transport Planning and Focus on Implementation in Australia, Progress in Planning

Transportation is one the most important pillars of economic growth and development. However, due to geographical and economical conditions, flexibility of road transportation and presence of sufficient infrastructures, the road transportation is one of critical importance in Australia. Vehicles are one part of road transportation and hence, evaluating the capacity of road transportation system or vehicles is very crucial in transportation programming. In the current research, a model is presented for determining the demand to different types of vehicles in various states of Australia. Since a multi-criterion capacity evaluating program has been considered, the idealistic programming method is used in modeling. Due to the nature of the problem, zero and one variables are introduced to the model which, in turn, caused to transform the model to a non-linear complex rational number programming problem. As solving such types of problems is difficult, especially for large values, an innovative method, regarding the structure of the problem, is presented to transform the non-linear problem to a linear one. Moreover, this study is performed for various conditions such as increase of container transportation.

Reducing train-induced ground-borne vibration by vehicle design and maintenance

Wheel out-of-roundness (OOR) and unsprung mass are key railway vehicle parameters influencing the dynamic wheel‒rail contact loads and inducing ground-borne vibration. For a given combination of vehicle speed, track/soil conditions and wheel/rail irregularity level, reducing the unsprung mass leads to a reduction in contact loads and vibration at frequencies above the resonance of the wheelset on the primary suspension. Guidelines for reducing unsprung mass are presented, including alternative designs for the wheelset and the suspension of the mechanical drive system. For locomotives and powered bogies, the potential for reduced vibration level is 2–4 dB by improving the drive suspension design. Based on an extensive field measurement campaign, where the influence of several different types of vehicle on vibration level was measured, it was found that the maximum vibration levels were generated by freight locomotives. For several freight locomotives of the same type, a high statistical variance (up to 20 dB) in measured vibration level was observed indicating a significant spread in wheel tread conditions and OOR. Early detection of out-of-round wheels and corrective wheel maintenance are important measures to reduce vibration levels.