A Rear-End Protection Device for Heavy Vehicles

2003 ◽  
Author(s):  
Ali O. Atahan ◽  
Abhishek S. Joshi ◽  
Moustafa El-Gindy
Keyword(s):  
Finite Element ◽  
Safety Concern ◽  
Heavy Vehicle ◽  
Finite Element Models ◽  
Heavy Vehicles ◽  
Passenger Cars ◽  
Passenger Car ◽  
Impact Performance ◽  
Optimum Height ◽  
Support Conditions

Rear underride crashes, particularly with heavy vehicles, constitute a serious safety concern for passenger cars. Several solutions to this emerging concern have been proposed by responsible agencies. Recent rear-end crashes with heavy vehicles show that a properly used rear underride guard devices can slow down impacting vehicle in a controlled manner. Moreover, with the use of these devices, the severity of crashes can be reduced and loss of lives can be prevented. In this paper, a special underride guard device is designed for heavy vehicle use. The height of the device from ground and support conditions are varied to evaluate and compare the crash performances. Finite element models of these particular designs are constructed and models are impacted by a passenger car model traveling at two different speeds of 48 km/h and 64 km/h. LS-DYNA, a non-linear finite element code capable of analyzing large deformations is used for the analysis. Vehicle decelerations, energy dissipations and passenger car crush characteristics are compared to determine the acceptability of each design. Based on the simulation study, an optimum height from ground and support condition are determined for acceptable impact performance for heavy vehicle mounted rear -end underride guard devices against passenger vehicle impacts.

scholarly journals Comparative Analysis of Effects of Heavy Vehicles on Roads in Southern and Northern Nigeria

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
C. C. Osadebe ◽  
H. A. Quadri
Keyword(s):  
Northern Region ◽  
Design Guidelines ◽  
Traffic Volume ◽  
Southern Region ◽  
Heavy Vehicle ◽  
Heavy Vehicles ◽  
Passenger Cars ◽  
The Road ◽  
Equivalency Factors ◽  
On The Road

The prevalence of flexible pavement deterioration in the country has been adduced largely by highway researchers to trucks or heavy vehicles carrying much in excess of permitted legal limits. This study investigated levels of deterioration of Abuja-Kaduna-Kano road (Northern region) and Port Harcourt-Enugu road (Southern region) caused by heavy vehicles through a 14 day traffic counts conducted at 5 strategic points each in the Northern and Southern regions. Traffic data generated were analyzed with AASHTO Design Guidelines (1993) to evaluate Equivalent Single Axle Loads (ESALs) and Vehicle Damage effects on the road. The Traffic Volume, Average Daily Traffic (ADT), and Heavy Vehicle per day (HV/day) were estimated to be 2,063,977; 147,427; and 12,246 respectively in the Northern region, while in the Southern region they were estimated to be 750,381; 53,670; and 20,951 respectively. Motorcycles, Passenger cars, Mini-buses/Pick-ups, and Heavy vehicles constitute 18.7%, 49.7%, 23.3% and 8.31% of the total traffic volume respectively in the Northern region while in the South they constitute 4.6%, 30.1%, 26.2% and 39.1% respectively. ESALs were estimated according to AASHTO Design Guidelines in the Northern and Southern regions as 547,730 and 836,208 respectively. An average Load Equivalency Factors (LEFs) of 3.43 and 3.02 were estimated for each heavy vehicle plying the Northern and Southern roads respectively and this could explain some failures (alligator cracks, potholes, depressions, linear or longitudinal cracks along the centre line amongst others) inherent on the road.

Analysing the Performance of a Fuzzy Lane Changing Model Using Data Mining

2015 ◽  
pp. 1540-1566
Author(s):  
Sara Moridpour
Keyword(s):  
Traffic Safety ◽  
Traffic Simulation ◽  
Heavy Traffic ◽  
Heavy Vehicle ◽  
Heavy Vehicles ◽  
Passenger Cars ◽  
Lane Changing ◽  
Microscopic Traffic Simulation ◽  
Traffic Characteristics ◽  
Using Data

Heavy vehicles have substantial impact on traffic flow particularly during heavy traffic conditions. Large amount of heavy vehicle lane changing manoeuvres may increase the number of traffic accidents and therefore reduce the freeway safety. Improving road capacity and enhancing traffic safety on freeways has been the motivation to establish heavy vehicle lane restriction strategies to reduce the interaction between heavy vehicles and passenger cars. In previous studies, different heavy vehicle lane restriction strategies have been evaluated using microscopic traffic simulation packages. Microscopic traffic simulation packages generally use a common model to estimate the lane changing of heavy vehicles and passenger cars. The common lane changing models ignore the differences exist in the lane changing behaviour of heavy vehicle and passenger car drivers. An exclusive fuzzy lane changing model for heavy vehicles is developed and presented in this chapter. This fuzzy model can increase the accuracy of simulation models in estimating the macroscopic and microscopic traffic characteristics. The results of this chapter shows that using an exclusive lane changing model for heavy vehicles, results in more reliable evaluation of lane restriction strategies.

Research on Influence of Flexible Parts’ Rigidity to Passenger Car Exhaust System’s Modal

2011 ◽  
Vol 117-119 ◽  
pp. 141-145
Author(s):  
Shou Li Yuan ◽  
Wen Chang Zhang ◽  
Zhi En Liu ◽  
Chao Wang ◽  
Ding Yuan Fu
Keyword(s):  
Finite Element ◽  
Natural Frequencies ◽  
Exhaust System ◽  
Fe Model ◽  
Passenger Cars ◽  
Passenger Car ◽  
Finite Element Software ◽  
Modeling Methods ◽  
Car Exhaust ◽  
Flexible Parts

The finite element modeling methods of a passenger car exhaust system’s flexible parts are introduced. A finite element (FE) model of the exhaust system is established with the finite element software and modal analysis of the FE Model is carried out. Through changing both automotive exhaust hangers’ Z direction of stiffness and bellows’ each direction of stiffness, the data of natural frequencies and vibrating modes of the exhaust system were obtained respectively. Comparing and analyzing the results indicates how the stiffness of exhaust hangers and bellows influences the modal of passenger cars’ exhaust system.

Analysing the Performance of a Fuzzy Lane Changing Model Using Data Mining

2013 ◽  
pp. 289-315 ◽  
Author(s):  
Sara Moridpour
Keyword(s):  
Traffic Safety ◽  
Traffic Simulation ◽  
Heavy Traffic ◽  
Heavy Vehicle ◽  
Heavy Vehicles ◽  
Passenger Cars ◽  
Lane Changing ◽  
Microscopic Traffic Simulation ◽  
Traffic Characteristics ◽  
Using Data

Heavy vehicles have substantial impact on traffic flow particularly during heavy traffic conditions. Large amount of heavy vehicle lane changing manoeuvres may increase the number of traffic accidents and therefore reduce the freeway safety. Improving road capacity and enhancing traffic safety on freeways has been the motivation to establish heavy vehicle lane restriction strategies to reduce the interaction between heavy vehicles and passenger cars. In previous studies, different heavy vehicle lane restriction strategies have been evaluated using microscopic traffic simulation packages. Microscopic traffic simulation packages generally use a common model to estimate the lane changing of heavy vehicles and passenger cars. The common lane changing models ignore the differences exist in the lane changing behaviour of heavy vehicle and passenger car drivers. An exclusive fuzzy lane changing model for heavy vehicles is developed and presented in this chapter. This fuzzy model can increase the accuracy of simulation models in estimating the macroscopic and microscopic traffic characteristics. The results of this chapter shows that using an exclusive lane changing model for heavy vehicles, results in more reliable evaluation of lane restriction strategies.

scholarly journals MICROSIMULATION-BASED PASSENGER CAR EQUIVALENTS FOR HEAVY VEHICLES DRIVING TURBO-ROUNDABOUTS

Transport ◽  
2016 ◽  
Vol 31 (2) ◽  
pp. 295-303 ◽  
Author(s):  
Orazio Giuffrè ◽  
Anna Granà ◽  
Sergio Marino ◽  
Fabio Galatioto
Keyword(s):  
Geometric Design ◽  
Heavy Vehicles ◽  
Passenger Cars ◽  
Highway Capacity ◽  
Passenger Car ◽  
Operational Conditions ◽  
Highway Capacity Manual ◽  
Traffic Conditions ◽  
Scenarios Simulation

Due to its geometric design, turbo-roundabouts impose greatest constraints to the vehicular trajectories; by consequence, one can expect a more unfavourable impact of heavy vehicles on the traffic conditions than on other types of roundabouts. The present paper addresses the question of how to estimate Passenger Car Equivalents (PCEs) for heavy vehicles driving turbo-roundabouts. The microsimulation approach used revealed as a useful tool for evaluating the variation of quality of traffic in presence of mixed fleets (different percentages of heavy vehicles). Based on the output of multiple runs of several scenarios simulation, capacity functions for each entry lane of the turbo-roundabout were developed and variability of the PCEs for heavy vehicles were calculated by comparing results for a fleet of passenger cars only with those of the mixed fleet scenarios. Results show a dependence of PCEs for heavy vehicles on operational conditions, which characterise the turbo-roundabout. Assuming the values of PCEs for roundabouts provided by the 2010 Highway Capacity Manual (HCM), depending on entering manoeuvring underestimation and overestimation of the effect of heavy vehicles on the quality of traffic conditions have been found.

scholarly journals Delay-based Passenger Car Equivalent at Signalized Intersections in Iran

2017 ◽  
Vol 29 (2) ◽  
pp. 135-142 ◽  
Author(s):  
Habibollah Nassiri ◽  
Sara Tabatabaie ◽  
Sina Sahebi
Keyword(s):  
Signalized Intersections ◽  
Simulation Software ◽  
Heavy Vehicles ◽  
Passenger Cars ◽  
Highway Capacity ◽  
Passenger Car ◽  
Highway Capacity Manual ◽  
Operational Characteristics ◽  
Passenger Car Equivalent ◽  
Traffic Operation

Due to their different sizes and operational characteristics, vehicles other than passenger cars have a different influence on traffic operations especially at intersections. The passenger car equivalent (PCE) is the parameter that shows how many passenger cars must be substituted for a specific heavy vehicle to represent its influence on traffic operation. PCE is commonly estimated using headway-based methods that consider the excess headway utilized by heavy vehicles. In this research, the PCE was estimated based on the delay parameter at three signalized intersections in Tehran, Iran. The data collected were traffic volume, travel time for each movement, signalization, and geometric design information. These data were analysed and three different models, one for each intersection, were constructed and calibrated using TRAF-NETSIM simulation software for unsaturated traffic conditions. PCE was estimated under different scenarios and the number of approach movements at each intersection. The results showed that for approaches with only one movement, PCE varies from 1.1 to 1.65. Similarly, for approaches with two and three movements, the PCE varies from 1.07 to 1.99 and from 0.76 to 3.6, respectively. In addition, a general model was developed for predicting PCE for intersections with all of the movements considered. The results obtained from this model showed that the average PCE of 1.5 is similar to the value recommended by the HCM (Highway Capacity Manual) 1985. However, the predicted PCE value of 1.9 for saturated threshold is closer to the PCE value of 2 which was recommended by the HCM 2000 and HCM 2010.

Operational Evaluation of Two-Lane Roundabouts at Freeway Ramp Terminals: Comparison Between Roundabout and Signalized Interchanges

2017 ◽  
Vol 2637 (1) ◽  
pp. 99-113 ◽  
Author(s):  
Zhixia Li ◽  
Madhav V. Chitturi ◽  
Andrea R. Bill ◽  
David A. Noyce
Keyword(s):  
The United States ◽  
Heavy Vehicle ◽  
Simulation Platform ◽  
Heavy Vehicles ◽  
Microscopic Simulation ◽  
Passenger Cars ◽  
Traffic Demand ◽  
Control Delay ◽  
Diamond Interchanges

In the United States, roundabouts have recently been constructed to replace signalized intersections at freeway ramp terminals as both a safety and an operational treatment. In practice, this treatment is in need of guidelines specifying conditions when the roundabout or signalized intersection is more appropriate to assist practitioners in deciding which alternative to choose. In particular, research providing a comprehensive operational comparison between roundabouts and signalized interchanges is lacking. The current research—though a strictly calibrated microscopic simulation platform—analyzes and models the control delay at double-lane roundabouts and signalized interchanges. Both roundabouts and signalized interchanges were modeled in a Vissim simulation platform. Capacity at each roundabout entrance was calibrated and validated separately for passenger cars and heavy vehicles, since both vehicle types have different critical and follow-up headways. The design of the simulation experiments covered 2,880 different scenarios for roundabouts and signalized interchanges with varying ramp and arterial volumes, ramp spacing, and heavy-vehicle percentages. From the simulation results, control delay and level of service of the off-ramp and arterial approaches of roundabouts and signalized diamond interchanges were modeled and compared. Ultimately, guidelines for the selection between double-lane roundabouts and signalized interchanges were developed and presented in the form of look-up tables. These tables provide an easy-to-use tool for practitioners to determine the appropriate double-lane interchange to install under specific combinations of traffic demand, heavy-vehicle percentage, and ramp spacing conditions.

scholarly journals ANALYSIS OF THE STRESSED STATE OF THE AXLE OF A WHEEL PAIR OF A PASSENGER CAR

2021 ◽  
pp. 62-72
Author(s):  
Igor Martynov ◽  
Alena Trufanova ◽  
Vadim Petukhov ◽  
Vadim Shovkun
Keyword(s):  
Finite Element ◽  
Stress State ◽  
Cross Sections ◽  
Geometric Model ◽  
Three Dimensional ◽  
Work Conditions ◽  
Passenger Cars ◽  
Wheel Pair ◽  
Passenger Car ◽  
Finite Element Grid

The paper considers the results of calculations of the axle of the wheel pair of apassenger car for strength and durability from fatigue. The loads acting on the axle of a passengercar during movement at the maximum permissible speed are determined.To solve the problems of studying the stress state of the axle of the passenger car at the firststage, a three-dimensional geometric model of the axis RU1 was developed. The most unfavorableload combination was taken into account in the calculation. The horizontal load was up to 10 kN.The load was applied to the axle necks, respectively, in the vertical and horizontal directions.The calculated model of the car axle RU1 is developed, on the basis of which the finiteelementmodel is created and the stress state of the wheel pair under the action of the main types ofload is investigated. The size of the finite element grid was chosen using a graphoanalytical methodand refined to a size of 2 mm. This feature of the finite element grid allowed to calculate thestresses in the calculated cross sections with greater accuracy and to determine the nature of thestress distribution.It is established that the maximum stresses arising in the axle of the passenger car under the most unfavorable work conditions that are concentrated in the filler in the zone oftransition from the neck to the pre-axle part.The axle was calculated for fatigue. Fatigue tests are usually performed at a uniaxial stressstate, so it is necessary to convert the multiaxial stress state to one scalar value to determine thenumber of cycles to failure at a given voltage amplitude. The load can occur with a constantamplitude.The number of load cycles that the car axle can withstand under operating loads isdetermined. According to the results of the research, restrictions on the service life of the axles ofwheel pairs of passenger cars are proposed.

scholarly journals The effect of the traffic composition on the urban traffic capacity. Passenger car equivalent coefficients

2021 ◽  
Author(s):  
Dmitri Nemchinov ◽  
Dmitri Martiakhin ◽  
Pavel Pospelov ◽  
Tatiana Komarova ◽  
Alexandr Mikhailov
Keyword(s):  
Traffic Flow ◽  
Russian Federation ◽  
Urban Traffic ◽  
Heavy Vehicles ◽  
Passenger Cars ◽  
Passenger Car ◽  
Traffic Capacity ◽  
Equivalent Number ◽  
Passenger Car Equivalent ◽  
Traffic Composition

Predicting the traffic capacity and its elements requires bringing the traffic flow represented by various vehicles to uniformity expressed in the equivalent number of passenger cars, through the use of the passenger car equivalent coefficients (PCE). The currently used in Russian Federation passenger car equivalent coefficients are taken on the basis of studies of the capacity of the Russian Federation, carried out in the 70s - 80s of the last century on rural roads, where most of the vehicles were heavy vehicles. Currently, the traffic flow is mostly represented by passenger cars. The riding qualities of cars, especially trucks, have changed significantly. This situation is especially common to Moscow. In this regard, the question of clarifying the traffic flow composition and revising the passenger car equivalent coefficients becomes relevant. The article presents the methodology and results of studies carried out on the route sections between road crossings to determine the passenger car equivalent coefficients and the traffic composition in Moscow.

Failure analysis of railroad concrete crossties in the center negative flexural mode using finite element method

2017 ◽  
Vol 231 (5) ◽  
pp. 610-619 ◽  
Author(s):  
Hailing Yu ◽  
Brian P Marquis ◽  
David Y Jeong
Keyword(s):  
Finite Element ◽  
Finite Element Models ◽  
Prestress Loss ◽  
Flexural Mode ◽  
Failure Patterns ◽  
Flexural Performance ◽  
Negative Moment ◽  
Failure Loads ◽  
Support Conditions ◽  
Force Displacement

Finite element models are developed for the railroad concrete crossties and are employed to analyze their center negative flexural responses to two center binding conditions: a center negative moment test condition and a hypothetical deteriorated ballast support condition. These conditions can lead to center negative flexural cracks and, eventually, sudden, catastrophic failure of the concrete ties when the loads reach critical magnitudes. When the concrete ties fail completely and consecutively in track, the gage can be sufficiently widened to cause derailment. The finite element results are first validated with the available test data, and the validated finite element models are then employed to obtain and evaluate the cracking/failure patterns and force–displacement characteristics of the concrete ties in the center negative flexural mode in static and dynamic analyses. The finite element analyses predict the critical wheel loads above which catastrophic tie failure is likely to occur, and the dynamic critical failure loads are shown to depend on the center binding ballast support conditions as well as the worn concrete tie conditions. The worn tie conditions that include bottom abrasion and prestress loss can significantly reduce the dynamic critical failure loads and, thereby, adversely affect the center negative flexural performance of the concrete ties.

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