Safety, Volume 3, Issue 2 (June 2017) – 5 articles

In the present study, pilot simulations of the phenomena of blast wave and fireball generated by the rupture of a high-pressure (35 MPa) hydrogen tank (volume 72 L) due to fire were carried out. The computational fluid dynamics (CFD) model includes the realizable k-ε model for turbulence and the eddy dissipation model coupled with the one-step chemical reaction mechanism for combustion. The simulation results were compared with experimental data on a stand-alone hydrogen tank rupture in a bonfire test. The simulations provided insights into the interaction between the blast wave propagation and combustion process. The simulated blast wave decay is approximately identical to the experimental data concerning pressure at various distances. Fireball is first ignited at the ground level, which is considered to be due to stagnation flow conditions. Subsequently, the flame propagates toward the interface between hydrogen and air. Full article

The stake-holders in the quad-bike (QB) industry in Australia have failed to reach a satisfactory resolution of the present impasse that exists with respect to the causes and mitigation of the trauma suffered by riders due to QB instability. In an effort to provide purchasers with data enabling them to discriminate between safer and less safe machines, static longitudinal and lateral tests have been conducted by various interested parties; quasi-static lateral tests have also been conducted under some operational conditions. It is argued that while these static tests are valid, under many operating conditions QBs will not reach such unstable slopes due to poor traction. Further, these tests do not include the quasi-static and dynamic factors which also influence the processes associated with operational instability. For these reasons, the static tests do not provide an adequate basis for discrimination between safer and less safe machines. Full article

Prior to 2016, motorcycle licensing in Victoria, Australia, required off-road (range) skills testing only, focusing on vehicle-handling skills. The objective of this research was to develop an education and assessment curriculum commensurate with best practice that included on-road components and increased focus on awareness, judgment, and decision-making skills. No single best-practice curriculum was identified in the published literature. Therefore, to guide development of a new curriculum, a best-practice novice driver education framework, Goals for Driver Education, was adapted into the Goals for Rider Education framework. Applying Training Needs Analysis, the target population of learner motorcyclists was identified as largely male and aged under 30 years, with the target crash problem including a high proportion of single-vehicle loss-of-control crashes. Tailored content was developed based on exemplary Australian and international curricula, behaviour change theory, and adult learning principles; including transitioning from training to coaching and from testing to competency-based assessment. The result is Victoria’s new Motorcycle Graduated Licensing System (M-GLS) education and assessment curriculum, comprising three stages: pre-learner (Motorcycle Permit Assessment), learner (Check Ride), and pre-licence (Motorcycle Licence Assessment). Subject to potential refinements and on-going evaluation, this work lays the foundation for establishing a best-practice approach to novice motorcyclist education for licensure. Full article

Pressure differential systems have the purpose of maintaining tenable conditions in protected spaces for different types of building safe places, like escape routes, firefighting access routes, lobbies, stairwells and refuge areas. The aim of pressure differential systems is to establish airflow paths from protected spaces at high pressure to spaces at lower or ambient pressure, preventing the spread of toxic gas released during a fire. This strategy ought to be supported by a detailed design of the necessary air supply, considering also the cycle of opening and closing doors during the egress phase. The paper deals with the design of a simple pressure differential system intended to be used in a building as a pressurized smokeproof enclosure. Specifically, experimental tests and numerical modelling are conducted with the objective of characterizing the pressure evolution in a small compartment under different conditions and through a cycle of door opening. Experimental tests are conducted in a simple 3-m side cubic enclosure with two doors and no vent openings. While a centrifugal fan blows constant airflow inside the structure, the pressure trend in time is recorded during steady state and transient conditions; additionally, the velocity of the airflow across the doors has been measured by means of an anemometer. Numerical CFD (computational fluid dynamics) simulations are carried out to reproduce the same smokeproof enclosure configuration (both geometrical and boundary conditions) using the fire dynamics simulator (FDS). Furthermore, specific attention is paid to the modelling of the leakage across the doors, directly inserted in the model through a localized HVAC (heating and venting air conditioning) advanced leakage function. Comparisons between experimental tests and numerical simulations are provided. Once the model was correctly calibrated, other geometrical and mechanical configurations have been studied, looking for convenient and efficient positions of the fan in order to fulfill the requirements of the pressure differential, airflow velocity and door handle force. The paper highlights some fundamental aspects on the pressurization and depressurization during steady state and transient phases, trying to identify if there are airflow profiles typical of some geometrical configurations. Full article

One way to avoid detection of law enforcement officials if you are engaging in illegal activities is to wear a seatbelt. Therefore, an unintended consequence of laws allowing people to possess marijuana for medical purposes is that seatbelt use may decline among groups whose possession of marijuana is now legal. We find a decrease in seatbelt use among middle-aged males, providing evidence that drivers use seatbelts as a means to avoid police interaction. We find no such reduction in seatbelt use among those less likely to possess medical marijuana cards. Our evidence supports the contention that drivers use seatbelts more if they fear interaction with law enforcement officials, which is consistent with evidence of heightened seatbelt use among drunk drivers. These findings are important in understanding how to best design traffic safety laws and enforce them. Full article