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This chapter describes a number of road freight systems operating in Western Australia and the likelihood of drivers suffering fatigue. General freight transport by company drivers involves scheduled services of road trains made up of 2 or 3 trailers. The work is shared by 2 drivers (2-up driving) who cover distances of up to 1750km. The drivers pace themselves and are able to avoid the effects of fatigue. Specialised freight transport is more unpredictable and can require up to 10 hours driving in a day. Livestock transport can require driving a distance of 2400km from Kimberley south to Perth. The stopping requirements for livestock mean that drivers can also rest and fatigue is not a problem. Facilities however are better for those transporting cattle than sheep. For the covering abstract see IRRD 876074.

Intelligent Transport Systems applications for commercial vehicles are aimed at minimizing stops that are not strictly necessary (for weight control, licenses or approvals) and improved logistics for fleet operators, including the use of intermodal transport. This article addresses the development of a system that monitors and informs a road train, that forms in real-time, about the length of a selected route, the travel time on the route, and especially the route fuel consumption. By collecting information from fleets of trucks, the communication interface between the vehicle and the fleet monitoring and information system will cover a large area of interest. The system will receive data from the vehicles and after a specific processing stage, will display optimal routes in terms of fuel consumption.

Three different type of double road trains are selected as simulation model, which is commonly used in developed countries and regions in order to improve the efficiency of road transport and the development of China's logistics industry. The passing ability simulation model of double road train is established based on Auto Turn, and China's current longest tractor-semitrailer is used as a comparison. Simulation models of highway ramp, first class highway and second class highway are established according to the requirement of JTG D20-2006 ‘Design Specification for Highway Alignment’. Adaptability of double road train and highway structure parameter is researched by analyzing different types of double road train turn left, turn right and turn around on the road. The type of double road train which can meet China's standards is recommended. The result can promote the application of double road train and give some advice for improving passing ability.

This paper addresses the development of a system that facilitates the formation of a road train by informing in real-time the drivers of commercial vehicles, especially trucks with cargo, with information about position-related data, the speed of a road train and the necessary conditions to become part of such a train. By collecting information from fleets of trucks, the communication interface between the vehicle and the fleet monitoring server will be extended. The server will receive data from the vehicles and after a specific processing stage, a extended map will be generated with real-time information collected from the cars in traffic. The optimal route generation algorithm will be also extended, by using data received in real time. The data collected by the fleet monitoring server will be provided through a communication protocol to the ITS traffic server.

The paper optimization model of speed mode is presented. Deals with issues of optimization of the motion of heavy trucks at steel products transportations within the urban network. Presented results of the experimental studies allow determination of dynamic loads in the bearing systems

These paper studies the road trains turning process in the hypothesis of Ackerman steering. Both tractor semitrailer and tractor full-trailer combinations are analyzed. Using planar models and geometric relations, the temporal differential equations of the combination are derived considering that the speed and pivoting angle of the steerable wheels are known as time functions.

Public transportation has its own drawbacks: Buses and trains don't start at your home and don't end at your destination, nor do they leave just when you'd like or even guarantee you a seat. To get the best of both worlds, we could teach our cars to work together, as closely grouped cyclists do in a peloton. The lead car could be entrusted to a professional driver to whom the other drivers would of course each pay a small fee; all the other cars would follow it automatically. The cars would all use networked communications coupled with the optical or electromagnetic sensors already installed in some luxury cars to avoid head-on collision, stay in the proper lane, and brake in case of emergency. These systems have been developed at great expense to provide active safety, as distinguished from the passive kind afforded by seat belts. But this investment, having been made, can now be exploited for other things-like allowing you to relax and read the paper. If only we'd let them. Active systems are improving at a splendid rate. Adaptive cruise control, for example, maintains a car's speed while using radar or lidar to keep a safe distance from the car in front of it, thus automating much of the braking and accelerating. The latest generation of this system can follow a lead car from highway speed to a stop and then resume automatically when that car drives away. Soon the system will get additional data from vision sensors and digitized maps and additional support for the steering, allowing it to slow down on curves.

In many underground mines, haulage vehicles (trucks or road trains) carry ore from underground loading stations to the surface. Vehicles travel in declines with occasional passing bays that allow descending empty vehicles to pull off the main path and wait for ascending laden vehicles to pass. The haulage productivity of a mine is affected by the number of passing bays and their locations. We have developed a simulator and a mixed integer programming model to study the optimal location of passing bays and the associated sizing and scheduling of the haulage fleet. This paper presents some practical implications of our study. Refereed/Peer-reviewed

This paper describes a vehicle-to-vehicle (V2V) communication system that is developed in the SARTRE project. The project vision is to develop and integrate technology that enables vehicles to drive in platoons. SARTRE defines a platoon (or road train) as a collection of vehicles where a manually driven heavy lead vehicle is followed by several automatically controlled (both laterally and longitudinally) following trucks and/or passenger cars. The V2V communication system enables forwarding of messages between vehicles to share data such as vehicle speed. In this paper, we present performance measurements of a first prototype of the V2V system. This is an important part of the platooning demonstrator that is being developed in the SARTRE project. We evaluate two antenna placements on the lead vehicle; in front on the driver cabin and in the rear on top of the container. Our results show that the rear placement provides superior results, especially for distances above 70 meters.

Heavy vehicle-train collisions have the potential to be catastrophic in terms of fatalities, environmental disaster, delays in the rail network, and extensive damage to property. Heavy vehicles, such as 'Road Trains' and 'B-Doubles', are vulnerable road users due to their size and mass and require specific risk management solutions. The present study aimed to capture the experiences of heavy vehicle drivers and train drivers at road-rail level crossings, with a view to exploring the contributing factors toward such accidents. A series of semi-structured focus groups was conducted, with a total of 17 train drivers and 26 heavy vehicle drivers taking part. Though there were some differences between the groups in perceptions of the causes of heavy vehicle-level crossing incidents, discussion in both groups centred on design issues and behavioural issues. With regard to design, the configuration of level crossings was found to affect heavy vehicle driver visibility and effective vehicle clearance. With regard to behaviour, discussion centred around wilful violation of crossing protocols, often as a time-saving measure, as well as driver complacency due to high levels of familiarity. The implications of these factors for future level crossing safety initiatives are discussed. Language: en

Accurate prediction of traffic information is important in many applications in relation to Intelligent Transport systems (ITS), since it reduces the uncertainty of future traffic states and improves traffic mobility. There is a lot of research done in the field of traffic information predictions such as speed, flow and travel time. The most important research was done in the domain of cooperative intelligent transport system (C-ITS). The goal of this paper is to introduce the novel cooperation behaviour profile prediction through the example of flexible Road Trains useful road cooperation parameter, which contributes to the improvement of traffic mobility in Intelligent Transportation Systems. This paper presents an approach towards the control and cooperation behaviour modelling of vehicles in the flexible Road Train based on hybrid automaton and neuro-fuzzy (ANFIS) prediction of cooperation profile of the flexible Road Train. Hybrid automaton takes into account complex dynamics of each vehicle as well as discrete cooperation approach. The ANFIS is a particular class of the ANN family with attractive estimation and learning potentials. In order to provide statistical analysis, RMSE (root mean square error), coefficient of determination (R2) and Pearson coefficient (r), were utilized. The study results suggest that ANFIS would be an efficient soft computing methodology, which could offer precise predictions of cooperative interactions between vehicles in Road Train, which is useful for prediction mobility in Intelligent Transport systems.

This review of the dynamics of heavy road–vehicle systems emphasizes directional performance. The review presents information on the following topics: why are articulated vehicles used; units, hitches, and combination vehicles; multiple axle suspensions and steering systems; important performance issues; models and simulation tools; and controlling directional performance. The concluding section summarizes the material presented and provides ideas regarding the application of vehicle system dynamics concepts in developing controllers for road trains.

Three representative types of double semitrailer road train are put forward based on analyzing the application in developed regions such as Europe and U.S.A. Using Auto TURN, vehicle turning clearance circle test simulation models of double semitrailer road trains are established according to GB 1589. The simulation models are used for analysis passing ability according to the requirement of China Standard. Evaluations on the passing abilities are given by comparing with the 18.10m vehicle train performance. Studies are conducted upon modifying the structure types and parameters. Through analyzing the simulation, recommended types are proposed. Simulation results serve as preferences for accelerating the deploying and optimizing the passing ability of double semitrailer road train.

For enhanced efficiency and sustainability, transportation must rely on new technologies. Researchers and engineers work nowadays on many valuable and green transportation ideas. One such idea creates vehicle platoons on freeways to achieve multiple benefits: reductions in gas consumption, vehicle emissions, and traffic congestion through enhanced aerodynamics and road space utilization, as well as improvements in safety and driver comfort through fail-safe mechanisms and moderation of collision damages given similar vehicle speed. The technological enhancements are built into the vehicles. The existing freeway infrastructures do not necessitate modification. Still, the interactions between the human factors, or lack thereof, and the new technologies may directly impact the traditional guidelines for freeway design. Over time, the dedicated freeways of the future, whether rehabilitated or built anew, could satisfy guidelines derived specifically for road-trains. Further, freeways built to current ...

Given the coupled tractor-trailer interacting with each other, road train is a complex system. The study on lateral stability of tractor trailer system is related to several fields such as multi-rigid dynamics, rigid-flexible coupling mechanics, aerodynamics. The research about the tractor-trailer lateral stability involves multi-discipline, multi-dimension, complex system, nonlinear vehicle kinematics and electronic controllability. Overview is made of the current development, method and test means about the tractor-trailer lateral stability study at home and abroad. The effects of parameters use and structure on the tractor-trailer lateral stability study are discussed. At the same time, the lateral acceleration response to step input of steering angle is also analyzed. Digital simulation algorithm of the tractor-trailer dynamics is presented, as well as typical simulation models.

Platooning, the idea of cars autonomously following their leaders to form a road train, has huge potentials to improve traffic flow efficiency and, most importantly, road traffic safety. Wireless communication is a fundamental building block - it is needed to manage and to maintain the platoons. To keep the system stable, strict constraints in terms of update frequency and reliability must be met. We developed communication strategies by explicitly taking into account the requirements of the controller, exploiting synchronized communication slots as well as transmit power adaptation. The proposed approaches are compared to two state of the art adaptive beaconing protocols that have been designed for generic message dissemination. Our simulation models have been parametrized and validated by means of real-world experiments. We clearly show how taking into account specific requirements can be extremely beneficial even in very crowded freeway scenarios.

To analyze the influence of structure parameters on the road adaptability of double semi-trailer road trains, the authors built two double semi-trailer road train (B-train) models using TrackSim. The turning circle test and the road adaptability test were simulated on dry pavement to analyze the relationship between the structure parameters and the turning passing ability. The results show that the structure parameters have significant influence on the road adaptability of double semi-trailer road trains. A B-Train cannot meet the GB 1589-2004 national standard of limits of dimensions, axle load, and masses for road vehicles. However, a B-Train with a dolly and with the same length can meet the requirements, and the passing ability is better. Both double semi-trailer road train models will take up a lane beside itself when miming up to and including third-grade highway/ramps.

Some mining companies are investigating the use of road trains to increase productivity in underground mines. Road trains require dedicated passing bays in declines. The spacing of these passing bays can have a significant impact on haulage productivity. This technical note describes the use of simulation to find the optimal spacing. If the distance between passing bays is sufficiently small then descending trains can be interleaved with ascending trains, which increases productivity. If the spacing is too small, however, productivity can decrease as descending trains wait in passing bays for ascending trains. For a real mine the spacing should be less than the theoretical critical distance to cope with variations in loading and unloading durations. Refereed/Peer-reviewed

The implementation of road trains consisting of multiple hooked semi-trailers presents mechanical realization and traffic related problems. Among these problems, the most basic is the off-tracking problem. This paper proposes a solution based on a kingpin sliding technique, that allows articulated semi-trailers to follow exactly the tractor's path. Simulation results showed that, for highway paths, the off-tracking deviation is completely eliminated.

Technology in road vehicles is continuously advancing. Vehicle-to-vehicle (V2V) communications can alert drivers of the location and movement of other vehicles, and allow those vehicles to react automatically to the behaviour of those vehicles. A natural development of this technology is the formation of `Road Trains' - platoons of vehicles automatically following a lead vehicle driven by an expert driver. Such road trains can potentially improve safety, fuel consumption and use of time (in the following vehicles). This paper describes work undertaken to simulate (in VISSIM) such Road Trains on a UK motorway carriageway. It looks at the effect on the road capacity and congestion of varying proportions and compositions of road trains (HGV only vs mixed HGV and cars). The study concentrated on established road trains on the main carriageway alone, finding a small increase in carriageway capacity approximately proportional to the percentage of all vehicles travelling in road trains.

To analyze the influence of trailer length on passing ability of double semi-trailer road train (B-Train), we built B-Train model by using TruckSim, and confirmed limit steering wheel angle when all wheels of B-Train moved forward and the turning radius was minimum simultaneously by choosing dry pavement. And then, the turning process was simulated to analyze the relationship between the trailer length and the turning channel width at low speed. The results show that increasing trailer length leads to the increase of the turning channel width of B-Train; the turning channel width is larger when the length of the first trailer is increased independently than that when the length of the second trailer is increased independently. In addition, according to the simulation results, we built the relation model between trailer length variation and turning channel width using least-square theory.

Some predictions show an increase of 80-100% of the current volume of goods and passengers should be transported in the EU within the next decade, and most of this increase – despite of the efforts made in promoting the rail and waterway transport – will be added to the already overloaded roads. It seems that the only feasible solution is to increase the vehicle overall length and weight at the lowest complexity, requiring maximum utilization of the existing vehicle units with only small modifications. Although these combinations are typical in other parts of the world (North America, Australia) and even in Northern Europe, the Central-European application is somehow different because of more difficult traffic situations. This is the reason that several aspects of dynamic behavior, especially during braking and in critical situations have to be examined.

Within this paper, an innovative mobility concept is laid out, discussed, and demonstrated using the prototype car EO smart connecting car. The design concepts of a shrinkable as well as dockable car with the ability to move its four wheels freely and independently is described as well as the ability to dock with modules and other cars to form road trains. Furthermore, the software framework controlling the car and all its systems is depicted. Last but not least, the autonomous behavior the car will offer is discussed and future work will be projected.

To study the passing ability of the double semitrailer road train (B-Train) on highways, we have built the B-Train model and the highway model using TruckSim. Based on an optimal driver preview control model, we analyzed the speed influence on the passing ability of the B-Train when running from a straight road to a curve. The result shows the B-Train’s speed range when passing the highway curve with a limited safe turning radius.

The modern automobile industry is a double-edged sword, with human society to the high prosperity, at the same time it's built a peremptory energy crisis, traffic jams fronts. Electric vehicle research, let crisis do see the dawn vehicle technology development. And the electric vehicle road train research is still blank in the domestic, research and development EV road train main functional modules using CAN bus communication independently. The train operates of 3–10 vehicles connection grouping, the number of drivers can be reduced by more than 3 times, the road resources consume for nothing by up to about forty percent, transportation using efficiency of resource utilization keeps great potential.

Forton Lake Opening Bridge is a 170-m-long structure, primarily designed for use by pedestrians and cyclists, but which also carry a road train and emergency service vehicles. The project contains ...

Multi-articulated vehicles consisting of a tractor pulling a large number of (semi-) trailers, also known by the term “road trains”, are a promising alternative for a more efficient mass transportation of goods. One of the major technical problems of road trains is off-tracking, i.e. the deviation of a pulled vehicle from the paths of its preceding vehicles. The novel sliding junction technique can drastically suppress or even eliminate off-tracking but has stringent demands on the control of the junction (“kingpin”) position. The hybrid systems approach to sliding consists in setting a predefined number of discrete sliding deviation levels corresponding to various ranges in the value of the deviation angle between two adjacent vehicles. The resulting control system is an inexpensive, easy to operate alternative that may prove attractive to a manufacturer.

The main task of this paper is to review the principal aspects in organization of interurban long haul service by use of road trains on the basis of the “district” traffic system. The goal of the paper is to determine the most effective methods of trucking operations in order to highlight the regularities that characterize these methods. The paper describes practicable methods of freight flow analysis, some factors and parameters concerning movement of motor‐vehicle trains and original route schedules as well. Of special interest is the obtained algorithm of economically effective trucking operations of motor‐vehicle trains on the route. First Published Online: 27 Oct 2010

Locomotive transportation plays an important role in Botswana. It plays a critical role in the transportation of people, livestock, raw materials and goods. It now faces new challenges in a highly competitive economy in the form of efficiency and the onslaught from road trains, the latter of which often use a subsidised, government funded road network. Whilst perhaps the national railway operator cannot do much to change the advantage enjoyed by the road hauliers, it is on the operational efficiency side that much can be gained by the deployment of appropriate, cutting-edge technical solutions. One operational problem that Botswana Railways (BR) and others using similar technologies for locating presence on site and positions of their trains and cargo, typically the DC Track Circuit and the Axle Counter System respectively, is that the power supply equipment associated with the operations of the two systems is located on unsecured environments, and thus susceptible to vandalism and theft. Vandalism and theft of this equipment on the BR network has escalated over the years, seriously undermining the efficiency and throughput of the network, whilst equally exposing the cargo to potential loss. This work presents a new scheme of locating the positions of locomotives by using Global Positioning Systems (GPS) to track, in real-time, the location of vehicles and equipment The scheme proposes two GPS receivers placed on the train, one on the engine and the other on the last carriage. The receivers placed on the train transmit information back to a control room on an interactive graphical display unit. The results of the simulated communications system will be presented.

This paper shall present the design and development of a family of high power, high-speed transport and combat vehicles based on a common module. The system looks to maximize performance at both high-speed operation and low-speed, heavy/severe-duty operation. All-wheel drive/steer-by-wire autonomous traction modules provide the basis for the vehicle family. Each module can continuously develop 300-400 kW of power at the wheels and has nearly double peak capability, exploiting the flexibility of the electric traction system. The maximum starting tractive effort developed by one module can reach 10-15 tons, and the full rated power can be produced at speeds of 100 mph. This paper will present the design and layout of the autonomous modules. Details will be provided about the tandem electric axles, with electric differentials and independent steering. New innovations in power electronics and electric machines, providing high power operation and affordable production costs will also be discussed. The paper also demonstrates concepts of how the traction module can provide the basis for a broad range of various purpose vehicles, ranging from road trains and/or tank carriers to high-speed (120 mph) attack vehicles.

This paper presents the design and development of a high-power, high-speed "road train" (with both on- and off-road applications). The system looks to optimize both high-speed operation and low-speed, close-quarters driving with the introduction of autonomous power modules. Each trailer in the road train has it own electric traction system. When driving on open roads or in open areas, each traction system receives electric energy from the high-powered tractor. However, the individual traction systems allow for distributed tractive effort, improving upon the classic road train. Further, each module has its own independent steering system, allowing for practical implementation of longer trains. Use of longer trains in open areas allows for reduced operational costs, and increased efficiency. When mobility becomes a primary concern or zero emissions operation is needed, small power supplies can allow independent trailer operation. This paper presents the design and layout of the road train system. Details are provided about the tandem electric axles, with electric differentials and independent steering. New innovations in power electronics, providing high power operation and affordable production costs are discussed. The paper also describes some new concepts for a high-powered tractor.

Land acquisition is the key process for any development projects like road, train and canal route, it required large scale acquisition. Industrial acquisition is the easy process where government can identify the waste land and pass to the industries. While, in case of road, train and canal acquisition may cover agricultural land as well. But, if farmer or owners of land oppose a matter in court it would be unnecessary delay in the project. In this research paper we will use Remote Sensing, GIS and GPS data we could have clear idea of boundary of different survey number so that route could be passed near to border areas. Not only that we would also able to identify important potions of farm like electricity connection, water area, green zone, waste land, and so many other parameters which would play key role once we are optimizing the road if route is optimized from farmers aspects farmer would be very happy will easily allow government for acquisition. As farmer will be ultimate beneficiary or road connectivity with his land. And government is able to save the cost of lots of serve cost by spending large scale engineer man power for site survey and if this acquisition gets faster, project would be on time. So, e-Governance projects can be completed within the time and will not impact additional costing of delay which is normally happening with the current projects.

The integration of larger "innovative" vehicle combinations into the existing infrastructure relies heavily on proving the concept to government and local authorities. Simulation modelling has proved to be a useful tool in showing that an innovative vehicle is a safer and more efficient alternative to conventional equipment. This paper will provide examples of the use of AUTOSIMTM in developing custom yaw/roll and yaw/roll/pitch models for investigating the dynamic performance of combination vehicles. Models will be described for large innovative road trains. Consideration will be given to the modelling of the trailing fidelity of these vehicles on non-planar surfaces, and examples of model outputs for combination vehicles operating on various three-dimensional features will be given. Examples of the application of dynamic performance standards related to stability and control in a number of performance attributes will be considered, and the performance of some innovative vehicle combinations will be compared with that of currently-operating conventional trucks.

Medium Combination Vehicles (MCV's) fall between General Freight Vehicles and Large Combination Vehicles (road trains) with respect to size and weight limits and are being introduced on approved routes in Australia's populated areas. The major issues surrounding MCV's are safety, impact on other road users and environmental effects. This paper is concerned with the important safety‐related area of dynamic stability and describes testing of a B‐double, which is the MCV configuration creating most interest. On the basis of full‐scale testing, tilt testing and computer simulation, it is concluded that the B‐double has (i) predictable steady state rollover behaviour similar to that of a wide sample of six‐axle tractor‐semi‐trailers previously tested, and (ii) superior dynamic stability in transient manoeuvres, as a result of the coupling concept of the B‐double. It is recommended that further investigation of certain aspects of the test results is warranted, particularly the kinematic behaviour of the fifth w...

SUMMARY This paper presents a review of theoretical and experimental works relative to the handling performance of commercial vehicle combinations. A commercial vehicle combination (road train) is defined as a tractor unit and an arbitrary number of trailers. The review contains literature corresponding the most widely used types of trains: tractor-semitrailer, truck-trailer and tractor-semitrailer-semitrailer (doubles). The vehicle dynamic performance has been investigated taking into consideration the following features: directional performance, roll dynamics, braking performance and combined braking and directional performance. With the aim of evaluating the present state of research activities in the field of lateral dynamics of articulated commercial vehicles, the author has compiled some 250 references.

To analyze the influence of structure type on passing ability of car transport vehicle combination, the four basic vehicle combination models of two typical structure types, such as car transport semi-trailer road train and car transport vehicle combination with center axle trailer, have been built by using TruckSim. The turning circle test and the adaptability test on highway have been simulated on dry pavement to analyze the relationship between the structure type and the turning passing ability. The results show that the structure parameters have significant influence on the passing ability of car transport vehicle combination; three of the vehicle combination models can meet the requirements of GB 1589-2004“Limits of dimensions, axle load and masses for road vehicles”; all the four basic vehicle combination models will take up the lane beside itself when running on the up to and including third-grade highway/ramp.

In many parts of the world the freight transport task is primarily undertaken on public roads. The exact share is heavily influenced by the presence of other transport modes (railway, inland waterways) and the topography of the country, and for these reasons the share of road transport varies from approximately 35% (Australia) to over 70% (European Union). Worldwide, there are various regulations regarding the weights and dimensions (and accordingly, axle loads) for heavy vehicles, and as a result, the heavy vehicle industry has developed a range of transport solutions in response, leading to a wide range of vehicle combinations which vary in their design and specification. In 2010, the Joint OECD/ITF transport research Centre (JTRC) working group selected 38 different heavy vehicle combinations from OECD member states, and studied their performance in order to gain an understanding of the influence of their individual characteristics in three key areas; the vehicle's inherent safety, its productivity, and its impacts on infrastructure [5] . Vehicle productivity was described using various metrics involving cargo weight and volume, energy consumption, and travel distance. Higher loading capacity and utilization (lower tare mass), and lower fuel consumption (low rolling and air resistance) can increase the efficiency as much as possible for a given travel speed and distance. Inherent vehicle safety and dynamic performance in various driving maneuvers was addressed using computer simulation, conducted in accordance with the Australian ‘Performance Based Standards’ scheme. Vehicle infrastructure performance was calculated on the basis of axle loads, tyre type and size, as per the ‘COST 334’ vehicle road wear performance analysis method. This paper presents and discusses the results demonstrated by ten of the vehicles investigated in the OECD study. Nine out of ten vehicles represent current and possible future freight vehicles for Europe, and were selected because they have particular relevance given the current debate in Europe on increased masses and weights of freight vehicles. Further, one Australian ‘road train’ vehicle was included, as it represents one of the longest and heaviest vehicle combinations permitted access throughout the world, and is useful for comparative purposes.

Significant fuel savings can be achieved by deliberate design measures on the drive line of commercial vehicles. This paper describes some of the results gained by M*A*N in the course of drive line optimization. First the engine and its accessories will be dealt with. Taking a turbocharged and a naturally aspirated engine as examples, three development steps are explained for each of these versions, and their effects on fuel consumption discussed. Then follows a consideration of the savings potential still possible through optimized design of engine accessories. Transmission design and the selection of suitable rear axle ratios for heavy commercial vehicles is also considered. Finally the results of tests to determine the effect on fuel consumption of drive line optimization are discussed. Tests with heavy long-haul road trains with various drive line configurations are considered, then the possibility of influencing fuel consumption on city buses by drive line optimization are investigated.

Road trains (articulated vehicles hauling one or two trailers, or rigid trucks hauling two or three trailers) provide significant economies in road transport. With over 30 years of experience, road trains are an integral part of road transport in Australia. A recent study defining the dimensional and mass limitations, mechanical requirements, operating conditions and other general requirements that should apply to road trains is discussed. Topics covered include: development and use of road trains; conduct of the study; concepts used in determining what should and should not be required; pavement damage; and fuel consumption (a).