Doctor of Philosophy

dissertationSlips and falls during egress from heavy truck cabs are a major contributor to injury and disability for truck drivers. A large-scale laboratory study was conducted to quantify the dynamics of ingress/egress (IE) for Class 7 and 8 commercial truck cabs. A simulated truck cab was constructed in a laboratory allowing manipulation of many geometric variables affecting ingress and egress. Experienced commercial truck drivers were recruited to participate. Subjective responses and anthropometric information for all participants were obtained along with detailed biomechanical data, including whole-body kinematics and reaction forces on the ground, steps, and handholds. This study involves three-dimensional reconstruction of truck driver egress motions, detailed analysis of spatiotemporal parameters and driver behaviors (i.e., IE tactics), as well as a description of access system egress cycles and methods of analyses. In addition, the influence of cab design and driver anthropometric and behavioral factors on biomechanical parameters are investigated. This research also provides a detailed quantitative description of the driver interaction with the cab elements (steps and handholds) and presents valuable insight into the dynamics of cab egress that will allow for a more accurate definition of etiological risk factors for slipping during truck cab egress. In summary, driver biomechanics largely depends on their interaction with the cab, tactics, foot behaviors, and the quality of contact with the steps. In general, during egress, study participants used the right handhold most frequently, followed by the door handle and then the steering wheel. Findings from this research also indicated that a portion of drivers performed egress facing away from the cab and given the prevalence of high body mass index (BMI) among this population, handhold and step location and design should incorporate the base of support (BoS) and stability metric calculations to allow such population for proper "footing" and allow for their center of mass (CoM) to be as close to the truck as possible in the event the drivers utilized the facing away egress tactic. Finally, BMI is a factor that has been associated as an indicator of increased level of risk. Therefore, driver training should include opportunities to get the drivers' weight lowered and fitness level increased. Additionally, drivers may also benefit from stability and strength training as stair stepping is physically more demanding and requires more stability when compared to walking

Driver's field of view from large vehicles: phase 2 - report

The overall objective of this phase of the study has been to identify problems with drivers’ field of view from current large vehicles. A large survey of drivers, operators and manufacturers was conducted which identified a number of issues pertaining to drivers’ field of view, vehicle design and road environment. On the basis of this information, as well as a continuing review of accident data and analysis of vehicle swept path plots, it has been possible to develop a first stage field of view requirement. The field of view requirement defines areas around a vehicle which the driver should be able to see or otherwise detect objects. At this stage the field of view requirement does not stipulate whether this should be by direct or indirect means. It is an aim of the Phase 3 report to make recommendations for the most appropriate means of achieving the requirement. The development of the field of view requirement has provided the necessary criteria by which current vehicle designs and the adequacy of current Regulations and Directives are being assessed. The assessment of existing Regulations and Directives has already identified inadequacies in their application to large vehicles which points to specific areas for new or amended regulations. The short list of vehicles which will be used to quantify the effectiveness of current vehicle designs has been made. These vehicles have been precisely measured to produce the dimensional data necessary to carry out the Man-Model CAD assessment. The vehicles have been successfully modelled and the field of view assessment is in progress. The development of solutions and methods to improve drivers’ field of view from large vehicles will be undertaken in parallel with the field of view assessment and the findings will be reported separately

Managing risks to drivers in road transport

This report presents a number of case studies in managing risks to road transport drivers. The cases feature a variety of initiatives and interventions to protect drivers.In the road transport sector, as with any other, it is important to pay attention to working conditions in order to ensure a skilled and motivated workforce. Certain characteristics of the sector make it more difficult to practice risk management than in other sectors. But by taking account of how the sector operates in practice, and the characteristics of drivers themselves and the way they work, risks can be successfully manage

Modeling Predictors of Whole Body Vibration Exposure among Saskatchewan Farmers: a Key Step in Low Back Disorder Prevention

Background Farmers experience a high rate of low back pain (LBP), with a lifetime prevalence of up to 75%. Whole body vibration exposure has been recognized as a significant physical risk factor associated with LBP. The agriculture sector has high whole body vibration exposures related to various machine types; however, little research has assessed vibration exposure in farming due to the inconvenience and cost of direct data collection. Prediction modelling is potentially a cost-efficient way to estimate directly measured exposure. Objectives The objectives of this study are to 1) measure the physical exposure of whole body vibration in Saskatchewan farmers and understand its magnitude and variability between farm machinery; and 2) use farm, vehicle, and task characteristics to determine any predictive relationship with directly-measured whole body vibration exposures among Saskatchewan farmers. Methods A 1-year field study with 3 repeated farm visits was conducted for whole body vibration measurements on 21 farms within a 400 km distance of Saskatoon. Whole body vibration was assessed using a tri-axial accelerometer embedded in a standard rubber seat pad according to international standards (ISO 2631-1). Whole body vibration data were summarized by machinery type into standardized metrics of root-mean-squared accelerations (RMS), peak, crest factor, and vibration dose value (VDV). Vehicle characteristics were gathered by on-site observations supplemented by open access vehicle descriptions through manufacturers. Farm characteristics and farmer’s self-reported whole body vibration exposure were collected via questionnaires. A manually stepwise method was conducted to build mixed-effects models for both RMS and VDV outcomes. Results A total of 87 whole body vibration measurements were gathered from 8 machine types: tractor, combine, pickup truck, grain truck, sprayer, swather, all-terrain vehicle, and skid steer. The average measurement duration was 85 minutes. The mean vector sums were RMS 0.78 m/s², peak 19.34 m/s², crest factor 27.64, and VDV 10.02 m/s1.75. The fixed effects of ‘horsepower’, ‘vehicle transmission type’, ‘farm size’, and ‘farm commodity’ explained 44% of the variance in RMS; while ‘horsepower’, ‘seat suspension type’, ‘loading frequency’, ‘tire tread type’, ‘jerk/jolt frequency’, ‘seat bottom-out frequency’, ‘farm commodity’, and ‘farm size’ explained only 20% of VDV variance. Conclusion High mechanical vibration and shocks from a range vehicle types call for action to reduce agricultural whole body vibration. Although VDV is relatively difficult to predict through farm and vehicle features collected in the present study, RMS can be predicted to a moderately useful degree. Predictors identified via modeling can help explain the variances of whole body vibration exposures and may also serve as new surrogates for future whole body vibration exposure assessment

Repeatability of a Checklist for Evaluation Cab Design Characteristics of Heavy Mobile Equipment

Risk factors associated with the development of muscu\uc2\uadloskeletal discomfort and disorders during the operation of heavy mobile equipment include whole-body vibration and awkward and sustained joint postures of the shoulders, neck, and trunk. Cab design may influence awkward postures of the joints, and task duration may influence duration of exposure to awkward and static postures and whole-body vibration. To reduce exposure to risk factors related to the interface between cab design and task, it may be necessary for manufacturers to address cab design. This study assessed the repeatability of a cab design checklist developed to evaluate various design characteristics that can influence exposure to risk factors for musculoskeletal discomfort. The ability of the cab design checklist to identify posture-related deficiencies of design was also assessed. The checklist was used by two administrators across 10 pieces of heavy construction equipment. Video analysis was performed to quantify postures of the neck, shoulder, and trunk; correlation analysis was used to determine whether specific questions from the checklist were associated with the identification of awkward postures. The repeatability assessment resulted in kappa coefficients ranging from 0.52 to 1.0 (good-to-excellent reproducibility) across each piece of equipment, and an overall kappa coefficient of 0.77 (excellent reproducibility) when considering all equipment together. Results from the correlation analysis showed that shoulder flexion posture was correlated with scores from the cab design checklist. However, results of the cab design checklist were not significantly correlated with shoulder abduction or awkward postures of the neck and trunk. Results suggest that the cab design checklist may be useful for identifying cab design characteristics that need further improvement and for identifying design characteristics that increase shoulder flexion. The strength of the repeatability assessment suggests that outcomes of the cab design checklist administered by different individuals may be consistent, independent of the type of equipment being assessed

Development of an Approach for Assessing the Combined Posture and Vibration Risks for Forklift Driving Tasks

This study describes a method for combining two known risk factors for musculoskeletal injuries in heavy machine operators: whole-body vibration and posture. Time spent in specific forklift driving tasks in combinations of neck and trunk postures (from video) with the concurrent vibration exposure (r.m.s frequency weighted acceleration at seatpan) is presented in contingency tables; vibration (low, medium and high) in columns/ posture (neutral, moderate and awkward) in rows. Time spent in different combinations differed between tasks and between joints. For example, 30% was associated with low/neutral trunk postures and 18% for the neck in the engaging the forks task. Meanwhile driving backward with a load inside the truck involved 52% in an awkward/low neck combination and 42% in the same task but without a load. Future research should evaluate this method with more subjects and perhaps other machines in addition to the forklift, and aim to evaluate risk of injury

Driver's field of view from large vehicles: phase 3 - report

In response to DETR’s request to investigate ways and means of improving the drivers’ field of view from HGV’s, coaches and buses, nine representative vehicles were evaluated using CAD man-modelling techniques. Evaluation was made against a benchmark field of view requirement which was developed by ICE Ergonomics and based upon the swept path envelopes of large vehicles whilst manoeuvring and on road layout and design considerations. Each vehicle was assessed using eye-points for the 5th %ile female and 95th %ile male driver. Where a driver’s field of view fell significantly short of the benchmark requirement a number of improvement options were investigated. Predominantly, the options selected were those which were most cost-effective and entailed the use of additional and modified wide angle mirrors on both the near-side and off-side of the vehicle. When reversing, driver’s visual coverage of the blind zone to the immediate rear was provided by a CCTV system. To ensure that the CAD modelled solutions did not have a detrimental effect on other aspects of the driving task, and before road trials were conducted on the public highway, a number of user tests were carried out under controlled experimental conditions. Results showed that the minimum radii of curvature, currently stipulated for rear view mirrors, could be reduced without causing significantly greater numbers of driver judgement errors compared with existing mirror specifications. Final verification of the field of view improvement specification proposed was achieved through road trials using drivers in modified large vehicles

Vibration Analysis of Heavy-Duty Diesel Vehicles

Truck drivers are more susceptible than other workers to lower back pain and spinal disorders caused by whole body vibrations, which are among the most common long term health effects for drivers. The dynamic behavior of trucks can be modeled and simulated to improve the design of the trucks, which can reduce the exposure of drivers to whole body vibrations. The main purposes of this study are to analyze vibrations for different manufacturers and road types, and to create a computer-based model using Adams to predict vibration anywhere on the model using acceleration data collected previously from on-road tests of real vehicles. Another objective of this study is to develop a method for validating an Adams model of trucks tested. Also, this study examines the results predicted by the simulations. This study uses vibration measurements that were made on twenty-two heavy-duty diesel vehicles from four different manufacturers, each driven on the same route, which include rural and interstate roads. Road types and manufacturers are compared using data from an accelerometer located underneath the driver seat. Vertical vibrations in five trucks are simulated using Adams, one truck from each manufacturer and one without a trailer. Vibrations in three orthogonal directions are compared for of the trucks. Results show that the vibrations on the roads of US-27 and I-75 are similar to each other, while the manufacturers show significant differences between one another. Two basic models were developed with Adams that use collected data to “drive” the model. Results are more accurate when the data from the transducers located on the body of interest are used as impact. Only one transducer is needed on the body of interest to provide accurate results. Since the mechanical properties of the trucks tested were not available, the model has not been validated. However, the model could be validated if the specifications of a tested truck were given