Truck Configuration Research Articles

Improving the Safety of Mobile Lane Closures

Mobile lane closures, which are increasingly used, are a potentially hazardous traffic control procedure for highway maintenance and operations activities. To improve the safety of workers and motorists, Applied Research Associates, Inc., studied driver behavior around full-scale field tests of mobile lane closures. Tests were conducted over a range of traffic, roadway, and driver conditions, and effects of various traffic control components (including truck number, spacing, and configuration; sign messages; and police presence) were evaluated. This report summarizes Phase I results and important findings regarding the behavior of motorists around mobile lane closures. Phase II research is ongoing and will recommend revisions to existing traffic control standards.

A Laboratory Investigation of the Effect of Multiple Axle and Truck Configurations on HMA Mixture Rutting

ABSTRACT Few studies have investigated pavement damage resulting from different axle and truck configurations, and they were generally limited to single and tandem axles. The unconfined compression cyclic load test with loading cycles that simulate different axle and truck configurations was used to examine their relative effect on permanent deformation of an asphalt mixture. The laboratory investigation indicates that the rutting damage due to different axle configurations is approximately proportional to the number of axles. However, the effect of rest period between axles groups within a truck configuration is significant. Calculating truck rutting damage by simply summing the vertical permanent deformation corresponding to its constituent axle groups results in erroneous predictions. The application of Miner's rule results in improved truck rutting damage predictions for a wider range of truck configurations, although it does not account for the effect of rest periods within a truck configuration. Fin...

Air velocity characteristics within vented pallets loaded in a refrigerated vehicle with and without air ducts

During transport using refrigerated vehicles, this being a vital link in the cold chain, the maintaining of even temperature throughout the cargo is essential in order to preserve the quality, safety and shelf life of perishable food. Within the refrigerated container, the temperature level and its homogeneity are directly governed by airflow patterns. The design of the air-distribution system should allow these airflows to compensate heat fluxes exchanged through the insulated walls or generated by the products. In this paper, a reduced-scale model and CFD predictions were used to investigate experimentally and numerically the airflow patterns within a typical refrigerated truck configuration loaded with vented pallets filled with spherical objects. The experiments were carried out using a laser Doppler velocimetry and thermal sphere-shaped probes located inside the pallets. The aim was to investigate air velocity characteristics above and within pallets. The performance of ventilation was characterized with and without supply air duct systems. Both configurations are extensively used in refrigerated transport. Full-scale measurements were also performed within a load of fruit during transport in a refrigerated truck in order to evaluate the temperature distribution under given operating conditions. The numerical modelling of airflow was performed using the computational fluid dynamics (CFD) fluent code and the Reynolds Stress Model (RSM) turbulence model. Numerical and experimental data make it possible to evaluate the air ventilation levels and their heterogeneity between the pallets. The numerical predictions show reasonable agreement with experimental data. The studied supply air duct system improves significantly the homogeneity of ventilation in the vehicle.

A Laboratory Investigation of the Effect of Multiple Axle and Truck Configurations on HMA Mixture Rutting

ABSTRACT Few studies have investigated pavement damage resulting from different axle and truck configurations, and they were generally limited to single and tandem axles. The unconfined compression cyclic load test with loading cycles that simulate different axle and truck configurations was used to examine their relative effect on permanent deformation of an asphalt mixture. The laboratory investigation indicates that the rutting damage due to different axle configurations is approximately proportional to the number of axles. However, the effect of rest period between axles groups within a truck configuration is significant. Calculating truck rutting damage by simply summing the vertical permanent deformation corresponding to its constituent axle groups results in erroneous predictions. The application of Miner's rule results in improved truck rutting damage predictions for a wider range of truck configurations, although it does not account for the effect of rest periods within a truck configuration. Finally, unique HMA rutting damage curves, which can be used for any axle or truck configuration, were developed using strain and energy response parameters.

Development of a Spatial Decision Support System (SDSS) for Route Costing Calculations within the Irish Timber Haulage Sector

Since the 1970s, decision support systems (DSS) have become popular as computer technology has developed. A DSS aims to support the solving of specific problems with both human and computer techniques. The purpose of this research was to design and develop a DSS for application to cost and revenue calculations of contracted timber haulage in Ireland. The DSS allows the costs and revenue of timber haulage to be calculated on a daily basis and on a route-specific basis. This implies that the user interface allows certain criteria to be selected, such as truck configuration, truck model, engine size, horsepower, and design gross vehicle weight. Both the revenue and running costs are directly related to the payload weight and the distance traveled. To generate the routes traveled and provide a sophisticated interface for spatial road map information, a Geographic Information System (GIS) was used; ESRI's ArcView 8.3 provides its own application programming in the form of Visual Basic for Applications (VBA).

Prediction of Truck Type Choice under Strict Overloading Enforcement

An analytical model was developed to predict the variety of truck type choice under strict overloading enforcement. It is assumed that the truck loadage distribution of the entire truck fleet is consistent with the shipment size distribution of the highway network and the offsets of truck's maximum loadage are relevant to the enforcement bounds. The choice decision of truck types was modeled using a discrete choice formulation with variable choice sets conditioned by the shipment size and the truck loadage. In the case study of the Highway Overloading Research Project in Anhui (China) funded by the World Bank, the results indicate that type 2-S2 will become the most prevailing truck configuration instead of type SU2 in the future with the overloading enforcement to be taken effectively. The result was proven by the practice applied in Anhui.

Airflow pattern and temperature distribution in a typical refrigerated truck configuration loaded with pallets

This work is part of a research activity aiming to improve and to optimise air-distribution systems in refrigerated vehicles in order to decrease the temperature differences throughout palletised cargos. This condition is essential in order to preserve the quality, safety and shelf life of perishable products. The present study reports on the numerical and experimental characterization of airflow within a semi-trailer enclosure loaded with pallets. The experiments were carried out on a reduced-scale (1:3.3) model of a refrigerated-vehicle trailer. The performance of ventilation and temperature homogeneity were characterized with and without supply air duct systems. Both configurations are extensively used in refrigerated transport. The numerical modelling of airflow was performed using the Computational Fluid Dynamics (CFD) code Fluent and a second-moment closure, the Reynolds stress model (RSM). The results obtained using the RSM model showed good agreement with the experimental data. Numerical and experimental results clearly show the importance of air ducts in decreasing temperature differences throughout the cargo.

Model Validation for Bridge-Road-Vehicle Dynamic Interaction System

The dynamic response of highway bridges subjected to moving truckloads has been observed to be dependent on (1) dynamic characteristics of the bridge; (2) truck configuration, speed, and lane position on the bridge; and (3) road surface roughness profile of the bridge and its approach. Historically, truckloads were measured to determine the load spectra for girder bridges. However, truckload measurements are either made for a short period of time [for example, weigh-in-motion (WIM) data] or are statistically biased (for example, weigh stations) and cost prohibitive. The objective of this paper is to present results of a three-dimensional computer-based model for the simulation of multiple trucks on girder bridges. The model is based on the grillage approach and is applied to four steel girder bridges tested under normal truck traffic. Actual truckload data collected using a discrete bridge WIM system are used in the model. The data include axle loads, truck gross weight, axle configuration, and statistical data on multiple presence (side by side or following). The results are presented as a function of the static and dynamic stresses in each girder and compared with code provisions for dynamic load factor. The study provides an alternate method for the development of live-load models for bridge design and evaluation.

Numerical and experimental study of airflow in a typical refrigerated truck configuration loaded with pallets

This work is part of a research activity aiming to improve and to optimize air-distribution systems in refrigerated vehicles in order to decrease the temperature differences within the load. The present study reports on the numerical and experimental characterization of airflow generated within a semi-trailer enclosure loaded with pallets. In the studied configuration, inlet and outlet sections were placed in the front of the trailer. This is a very common configuration and is extensively used in refrigerated transport. The experiments were carried out on a reduced-scale model built with a ratio 1/3.3 of a trailer. The numerical modeling of airflow was performed using the computational fluid dynamics (CFD) code Fluent and two levels of turbulence modeling: the standard k– ε model and a model with a second-moment closure, the Reynolds stress model (RSM). Only the results obtained using the RSM model showed agreement with the experimental data.

Effect of Oregon’s Axle-Weight-Distance Tax Incentive

Oregon’s weight-mile tax was amended in 1990 to provide for a lower tax rate for trucks weighing more than 36 320 kg (80,000 lb) to which axles were added. The additional axles within a weight class reduce the amount of road damage. The tax break was largely based on equity considerations, since trucks within a weight class tend to do less road damage if they have more axles. However, the tax reductions also created an economic incentive to add axles and thus reduce road damage. Whether the tax break actually led to an increase in the number of axles within weight classes and a reduction in the amount of road damage is investigated. Statistical data indicate that a small increase occurred in the number of axles in most weight classes and a large increase occurred in mileage by the heaviest trucks with the most axles. These increases reduced the damage per ton shipped on trucks subject to the axle incentive, but to determine if this was due to the weight-mile tax is not possible. A series of structured interviews supplemented the statistical analysis and indicates that the tax incentive is not a major determinant of truck configuration. One reason for this is that regulatory constraints, particularly weight limits, limit the effectiveness of the tax incentives.

A psychophysiological investigation of the effects of driving longer-combination vehicles

Fatigue contributes to driving-related accidents and fatalities. Cardiovascular measures such as heart rate and heart rate variability may serve as early indicators of fatigue. In the current investigation, 24 professional truck drivers drove three truck configurations: single trailer, triple trailer A-dolly, and triple trailer C-dolly on a standard route that lasted between 8 and 10 h. During the driving session, continuous measures of heart rate were quantified on-line. In addition to heart rate, two measures of heart rate variability (i.e. respiratory sinus arrhythmia and the Traube-Hering-Mayer wave or 0.1 Hz oscillation) were derived from the beatto-beat heart rate. Independent of configuration, heart rate increased and the measures of heart rate variability decreased during the driving route. Only heart rate statistically differed among the configurations. Since heart rate is physiologically linked to metabolic output, the results suggest that the observed effect may be due to the physical demands required to drive each truck configuration. In support of this conclusion, the heart rate effect was consistent with the subjective report of task demand. The slowest heart rates were observed while driving the least demanding configuration (i.e. single trailer). The fastest heart rates were observed while driving the most demanding configuration (i.e. triple trailer A-dolly).

Tractor-trailer crashes in indiana: A case-control study of the role of truck configuration

Studies of the crash experience of tractors pulling multiple trailers have reached different conclusions concerning the relationship of truck configuration to crash risk. A previous case-control study found a significant increase in crash risk for double-trailer trucks in the state of Washington. The present case-control study was done of tractor-trailers crashing on Indiana interstates during November 1989–March 1991. Controls were obtained for 25 % of the crash sites and were all tractor-trailers passing the crash sites during a traffic observation session one to four weeks following a crash on the same day of the week for 30 minutes at the same time of day. Logistic regression identified day of week, time of day, urban/rural area, and specific highway as significant predictors of controls' truck configuration. This model was applied to the cases to estimate the expected number of double-trailer cases. For all crashes combined, no increased crash risk was observed for doubles (Standardized Crash Ratio (SCR) = 83). Doubles were significantly underinvolved in multiple-vehicle crashes (SCR = 74), crashes on dry roads (SCR = 61), and crashes on wet (other than snow, ice, or slush) roads (SCR = 54). Doubles were significantly overinvolved in crashes on roads with snow, ice, or slush (SCR = 153). Because truck configuration was highly associated with driver age and work operation attributes among trucks in crashes, the absence of control data on these potential confounders precluded definitive assessment of the intrinsic risk of multiple versus single-trailer vehicles.

Tractor-trailer crashes in Indiana: A case-control study of the role of truck configuration : E. R. Braver, P. L Zador, D. Thum, E. L. Mitter, H. M. Baum and F. J. Vilardo. Insurance Institute for Highway Safety, January 1994

Compositionally induced phase transitions in the system Sr(ZrxTi1−x)O3 were analyzed using a combination of X-ray diffraction, FT-Raman and FTIR spectroscopy. Sr(ZrxTi1−x)O3 system showed at least two tilting of phase transitions, pm3m–I4mcm and I4/mcm–pnma. The structural transition occurred due to tilting of BO6 octahedra. Dielectric constant measured with Hakki–Coleman technique decreased from 253 to 25 with increase of Zr content. The value of τf found 1771 ppm/°C for SrTiO3 which decreased to −82 ppm/°C for the SrZrO3. The dielectric resonator antenna (DRA) was investigated experimentally and numerically using a monopole antenna through an infinite ground plane and Ansoft's high frequency structure simulator software, respectively. The required resonance frequency and bandwidth of DRA were investigated in the composition between 0 ≤ x ≤ 1.0.