Skid Resistance of Asphalt Concrete based on Mixture and Aggregate Characteristics: Predictive Model Development for Thailand

This research aims to produce a new predictive model of skid resistance in asphalt concrete, with a particular focus on Thailand. Skid resistance in road pavements is an inherent safety factor affecting vehicle users. Thus improvements in this area will greatly enhance road network safety in Thailand. A skid resistance predictive model, based upon the essential aggregate and mixture characteristics that significantly relate to the skid resistance values of asphalt concrete was developed. In this study, three types of aggregate (limestone, granite and basalt) were collected. These aggregates, obtained from 14 provinces in Thailand were representative of all of Thailand’s aggregates. Petrographic Analysis, Gradation tests, Aggregate Impact tests (AIV), Aggregate Crushing tests (ACV), the Los Angeles Abrasion (LA) test, Soundness tests, Polishing Stone tests (PSV) and the British Pendulum Test (BPT), along with the standard mix design were performed. These procedures determined all the essential characteristics in the mixtures and aggregates of asphalt concrete. The results of the research demonstrate that some aggregate characteristics are statistically significant in their relationship to the skid resistance values of asphalt concrete mixtures. These findings will be embraced in the preventive scheme under the strategic road safety management of the Department of Rural Roads, Thailand

Effect of intravenous corticosteroids on death within 14 days in 10008 adults with clinically significant head injury (MRC CRASH trial): randomised placebo-controlled trial.

BACKGROUND: Corticosteroids have been used to treat head injuries for more than 30 years. In 1997, findings of a systematic review suggested that these drugs reduce risk of death by 1-2%. The CRASH trial--a multicentre international collaboration--aimed to confirm or refute such an effect by recruiting 20000 patients. In May, 2004, the data monitoring committee disclosed the unmasked results to the steering committee, which stopped recruitment. METHODS: 10008 adults with head injury and a Glasgow coma score (GCS) of 14 or less within 8 h of injury were randomly allocated 48 h infusion of corticosteroids (methylprednisolone) or placebo. Primary outcomes were death within 2 weeks of injury and death or disability at 6 months. Prespecified subgroup analyses were based on injury severity (GCS) at randomisation and on time from injury to randomisation. Analysis was by intention to treat. Effects on outcomes within 2 weeks of randomisation are presented in this report. This study is registered as an International Standard Randomised Controlled Trial, number ISRCTN74459797. FINDINGS: Compared with placebo, the risk of death from all causes within 2 weeks was higher in the group allocated corticosteroids (1052 [21.1%] vs 893 [17.9%] deaths; relative risk 1.18 [95% CI 1.09-1.27]; p=0.0001). The relative increase in deaths due to corticosteroids did not differ by injury severity (p=0.22) or time since injury (p=0.05). INTERPRETATION: Our results show there is no reduction in mortality with methylprednisolone in the 2 weeks after head injury. The cause of the rise in risk of death within 2 weeks is unclear