Swept Path Research Articles

Powered mobility aid access on public transport: A validation study of compliance with disability standards

IntroductionPublic transport accessibility is vital for people using powered mobility aids, particularly on buses which have the greatest travel reach into the community. In Australia, a new standard has been developed against which the fit of mobility aids can be determined prior to travel. However, the standard is documented in 2D and real-world tests have not been conducted. The aim of this study was to examine powered mobility aid access on test rigs specified in the standard to determine public transport conformance thus contributing to real-world validation of the standard, and identify the measurements of mobility aids most likely to access public transport. MethodsLife-size rigs were built according to the specifications within the standard to simulate and facilitate five types of test including the:180° turn; Pavement gap; Swept path; Allocated space; and Narrow access path. Thirty-five powered mobility aids were measured and driven through these test rigs and successful completion or collision points were recorded. ResultsNine of the 35 mobility aids were found to be noncompliant with the new standard. The Allocated space test, which represented manoeuvring into a designated travel space was most difficult, followed by completion of the 180° turn test. The measurements of powered mobility aids that are likely to comply with the standard for public transport access were found to be those with diagonal length (D) less than 1280 mm, overall length (L) less than 1110 mm, and a measured turn radius less than 760 mm. ConclusionsThis research provides an empirical validation of the new 2D standard using real-world experimental testing standard by building the associated test rigs and driving a sample of powered mobility aids through them. Future research using field-based validation in bus light rail and trains is warranted.

Optimizing Geometric Design of Standard Turboroundabouts

Previous studies have shown that existing turboroundabout design procedures, in which swept path analyses are conducted at the end of design process, contain certain disadvantages and understatements which can lead to oversized or undersized turboroundabout solutions i.e. low intersection capacity, poor traffic safety, low driving comfort and high construction costs. Within the scope of this study elements of standard turboroundabouts were designed in accordance with the design vehicle movement trajectories obtained by the swept path analyses. Reliability of the software used in these analyses was verified by the real drives at the test site. Geometric design of standard turboroundabouts was conducted with variation of following influential parameters: design vehicle; circulatory roadway radii; approach leg offset and angle value. Design approach applied in this research resulted in optimal intersection design regarding the occupation of surrounding area and the design vehicle swept path requirements. Circulatory roadway radii and approach leg offset and angle limit values applicable on this intersection type are determined, taking into account the real traffic situation. Additional practical contribution of this research lies in the ability of application of research results in revision of existing guidelines for the design of turboroundabouts, as well as in development of new guidelines in countries which still do not have their own regulations on the design of this rather new multilane roundabout type.

Advantages of an Innovative Crossed Four Bar Steering Mechanism of a Novel Vehicle

A crossed four-bar steering mechanism has been considered for a novel four-wheel vehicle which has different wheel locations compared to a conventional four-wheel vehicle. The present paper discusses the advantages of this newly proposed steering mechanism and the novel vehicle. The steering error curve of this novel vehicle has been compared with that of a conventional four-wheel vehicle having Ackermann steering. When both vehicles move on a curved road, the required angle of rotation of the vehicle wheels due to steering effort will be different and depend on the radius of curvature of the road from place to place. It has been found that the vehicle wheels of novel vehicle need to be rotated by smaller angle for steering. The steering error of the novel vehicle is far less. The swept path width will be reduced if the novel vehicle is used instead of the conventional vehicle.

The Process of Setting the Parameters for Ensuring Passage of Oversized Cargos

Engineering and the industry very often produce above-standard products concerning their dimensions and weights. There is often a problem with the transport of these products both within Europe and in subsequent transport all around the world. Because of these reasons, several projects to remedy the situation were implemented in the Czech Republic. The article describes the results of many years of research, which observed ensuring the passage of oversized cargos on roads. Further, the measurements, which were carried out, are presented in this paper − the measurement of an oversized vehicle using Global Positioning System devices, creation and modelling of missing cars in programs to verify the swept path, comparison of created models with the measurement using Global Positioning System devices. Then the results of the implemented researches, the suggested parameters, and modelled cars are used for the suggestion of technical parameters of backbone network of roads. On these roads, the loads are transported. The results are also used for verification of critical points of the route, e.g. problematic places and intersections.

Development of a transportability evaluation system using swept path analysis and multi-body dynamic simulation

In this study, we develop a transportability evaluation system for the transportation process or design process in product development engineering. The system extracts the constraint condition and transportability using swept path analysis and multi-body dynamic simulation. This system consists of two main software modules: a feature curve extraction module and a multi-body dynamic simulation module. The feature curve extraction module extracts the feature curve list of the entire transportation path with swept path analysis to transmit the information to the simulation module. The multi-body dynamic simulation module extracts the constraint condition for the product design process that a designer uses as the transportation constraint in the design process or quick checks the transportability of the product files. The entire structure of the system is accessible by a web-based platform. When the user (designer) inputs the product files and the transportation information, the system gives the constraints and transportability to the user. The entire analysis is performed by a background process on the analysis server. We also propose a multimodal transportability evaluation algorithm that considers design and dynamic conditions.

Review of Roundabout Design Standards and the Development of a Roundabout Design Guideline for Sri Lanka

In Sri Lanka, the geometry of roundabouts has a considerable influence on their operation. The increase in road traffic and the large number of long vehicles that ply on the roads have contributed to the malfunctioning of some of these roundabouts. The objectives of this study were to review the roundabout design guidelines, identify issues in the existing roundabouts and prepare a roundabout design guideline appropriate for Sri Lanka. Twenty four roundabouts located in some of the major cities were selected for the study. The design parameters of the geometries of the selected roundabouts were compared with those recommended in five major design guidelines. Data on the main geometric parameters of each roundabout were collected through field measurements and calibrated satellite images. The dimensions and the design parameters of these roundabouts were compared with those stated in a few international roundabout guidelines. A swept path analysis was carried out on selected roundabout layouts for single unit trucks to determine the adequacy of their entry widths, circulation widths, exit widths and operational speeds. The entry radiiwere higher than those recommended in the international standards. The design parameters of the existing roundabouts that required improvements were identified and suitable values for the selected design parameters have been proposed. Most of the roundabouts meet the minimum requirements specified in the international guidelines for the centre island diameter (100%), circulation width (92%), and exit radius (92%).

Design of Turbo Roundabouts Based on the Rules of Vehicle Movement Geometry

This paper describes a turbo roundabout design procedure based on the rules of design vehicle movement geometry. Previous studies carried out on various junction types have shown that this design approach ensures the usage of optimal roundabout element dimensions as well as safety and comfort during driving. A five-step design procedure is suggested, including a detailed description of relevant influential parameters. They are choosing a design vehicle, implementing the initial roundabout scheme on which the vehicle swept path is analyzed, choosing a method of assigning input parameters for swept path requirements testing procedure, choosing optimal design elements of a standard turbo roundabout, and fastest path vehicle speed analysis.

Experimental Test of an Articulated Lorry Swept Path

The regulatory requirements limiting the physical dimensions of heavy vehicles and driving skills do not guarantee the feasibility of negotiating the tightest curves of compact roundabouts. The specific evaluations needed for the intersection and the assumed design vehicle are often achieved by setting vehicle movement trajectories via computer programs, given the possibility of changing the design parameters both quickly and economically. The basic requirement for using these programs is their reliability, but they do have some weaknesses and flaws because of necessary simplifications, without which running the simulations would not be workable. A field test based on global positioning system instrumentation was conducted to define the area covered by a heavy vehicle turning in a real compact roundabout, successively compared with the simulated swept path. The preparation and the results of the experiment are described in the present study.

Improving the Safety and Road Wear Performance of Heavy Vehicles in South Africa Using a Performance-Based Standards Approach

As a result of successful initiatives in Australia, New Zealand and Canada, the introduction of a Smart Truck or performance-based standards (PBS) approach in the heavy vehicle sector in South Africa was identified by the CSIR as a research area warranting funding because of the potential benefits in terms of transport efficiency, road/vehicle safety and the protection of road infrastructure. The PBS approach involves setting standards to specify the performance required from the operation of a vehicle on a network rather than prescribing how the specified level of performance is to be achieved. A need was identified to design, manufacture and operate a number of PBS demonstration projects in South Africa in order to gain practical experience in the PBS approach and to quantify and evaluate potential benefits. The Smart Truck demonstration projects have been designed and manufactured to comply with the safety standards of the Australian PBS system. These include directional and non-directional manoeuvres such as acceleration capability, slow speed swept path, static rollover threshold and rearward amplification. In order to evaluate the impact of the PBS vehicles on pavements, the South African Mechanistic-Empirical Design and Analysis Methodology was used to calculate the road wear characteristics of various baseline and PBS vehicle combinations. In most cases, the PBS vehicles were found to be significantly more road-friendly per ton of payload than the corresponding baseline vehicles. Modifications for reducing road wear were identified such as load redistribution in order to reduce the load on the steering axle, replacing wide-based single tyres with dual tyres and, where appropriate, replacing a single steer axle with a twin steer axle unit. The paper describes the results of road wear analyses of five PBS vehicles and the corresponding baseline vehicles.