This thesis presents the results of a research effort investigating the effect of belt usage reporting errors of National Automotive Sampling System-Crash Data System (NASS-CDS) investigators on injury risk estimates. Current estimates of injury risk are developed under the assumption that NASS-CDS investigators are always accurate at determining seat belt usage. The primary purpose of this research is to determine the accuracy of NASS-CDS investigators using event data recorders (EDRs) as the baseline for accuracy, and then recalculating injury risk estimates based on our findings. The analysis of a 107 EDR dataset, from vehicle tests conducted by the National Highway Traffic Safety Administration (NHTSA) and the Insurance Institute for Highway Safety (IIHS), was conducted to determine the accuracy of Chrysler, Ford, GM and Toyota EDRs. This accuracy was examined by both EDR module type and vehicle make. EDR accuracy was determined for crash delta-V, seat belt buckle status, pre-impact speed, airbag deployment status and front seat position. From this analysis we were able to conclude that EDRs were accurate, within 4.5%, when comparing maximum delta-V of EDRs that recorded the entire crash pulse length. We also determined that EDRs were 100% accurate when reporting driver seat belt status for EDRs that completely recorded the event and recorded a status for the driver's seat belt. All GM, Ford and Chrysler EDRs in our database reported a pre-impact velocity less than 6 mph different than the NHTSA and IIHS reported pre-impact velocities. We also found that all but 2 (101 out of 103) of the GM, Ford, and Toyota EDRs correctly reported airbag deployment status. Lastly we were able to conclude that seat position status was useful in determining when a smaller sized occupant was the driver or right front occupant. EDRs reported seat position of 5% Hybrid III females as "forward" in every case that seat position was recorded for this smaller occupant size. Based on the analysis of seat belt status accuracy, a comparison of NASS-CDS investigator driver seat belt status and EDR driver seat belt status was conducted to determine the accuracy of the NASS-CDS investigators. This same comparison was conducted on reports of driver seat belt status provided by police. We found that NASS-CDS investigators had an overall error of 9.5% when determining driver seat belt status. When the EDR stated that the driver was unbuckled, investigators incorrectly coded buckled in of 29.5% of the cases. When the EDR stated that the driver was buckled, NASS-CDS error was only 1.2%. Police officers were less accurate than NASS-CDS investigators, with an overall error of 21.7%. When the EDR stated that the driver was buckled, police had an error of 2.4%. When the EDR stated that the driver's belt was unbuckled, police had an error of around 69%. In 2008, NASS-CDS investigators reported that drivers had an overall belt usage rate during accidents of 82%. After correcting for the errors we discovered, we estimate that the driver belt buckle status during a crash is around 72.6%. Injury risk estimates and odd ratio point estimates were then calculated for NASS-CDS investigator and EDR buckled versus unbuckled cases. The cases included only frontal collisions in which there was no rollover event or fire. Injury was defined as AIS 2+. The risk ratios and point estimates were then compared between investigators and EDRs. We found that injury risk for unbelted drivers may be over estimated by NASS-CDS investigators. The unbuckled to buckled risk ratio for EDRs was 8%-12% lower than the risk ratio calculated for NASS-CDS investigators. / Master of Science

The BEIR V preferred relative risk models and standard life-table techniques are used to project lifetime fatal cancer risk factors for average members of the Canadian population. Uncertainties associated with projections are evaluated for: (1) sampling variation (statistical error), (2) extrapolation of risks to low doses and low dose rates, (3) projection of excess lifetime cancer risks beyond the current periods of human observation in epidemiological studies, (4) the transfer of site-specific excess risk coefficients between populations with differing baseline cancer rates, and (5) the effect of differences in the age and sex distributions among occupations in the Canadian "radiation" workforce. Results are used to assess the applicability of the fatal cancer risk estimates recommended in ICRP publication 60 to the Canadian population. It was found that sampling variation, extrapolating to low doses and dose rates, projecting excess risks beyond current periods of observation, and the uncertainty in how to transfer site-specific excess risks between populations all cause substantial variations in lifetime cancer risk projections. Site-specific cancer risk projections may be expected to vary by factors of 2 to 5, depending on the source of uncertainty. Site-specific differences were found in the fatal cancer risk factors projected for "average" male and female workers among different occupations in the Canadian workforce. Site-specific worker averages differed by as much as a factor 3. Female average risk factors for digestive cancers were substantially higher than male workers, while male average risk factors tended to be higher for leukemia and respiratory cancer. Overall however, the majority of worker risk factors were within 2.5% of the site-specific projections for the workforce as a whole. The ICRP-60 nominal fatal cancer risk estimates, tissue weighting factors, and lifetime risk projections for prolonged radiation exposure were all in good agreement with equivalent values derived in this report for the Canadian population. In view of the uncertainties, the results suggest the ICRP estimated cancer risks are as good as any presently available and supports the use of the ICRP recommended values for the planning and regulation of radiation protection in Canada. / Thesis / Master of Science (MS)

<p>Speed choice is one of the more characteristic features of driver behaviour. The speed a driver chooses to travel at determines the degree of difficulty he or she operates under. Higher speeds lead to more accidents, higher accident risk and more severe consequences of an accident. The present thesis examines factors that are associated with drivers’ speed choice. Repeated measures of drivers’ speed showed a reasonably high correlation, but also that stability in speed varied with road layout between measurement sites. Effects of police enforcement were studied on roads with temporary reduced speed limits (from 50 km/h to 30 km/h) during school hours. Lower speeds were found on roads with enforcement and drivers observed on one such road showed a higher perceived probability of detection than did drivers observed on a non-enforced road. However, in a laboratory study higher driving speeds and lower accident risk was associated with enforced roads. Drivers not informed about existing speed limits overestimated the limits to a large extent and chose driving speeds above the limit as did drivers informed about the limits. In an on-the-road survey, fast drivers reported higher driving speed, thought a higher percentage of other drivers were speeding and had a more positive attitude towards speeding than did slower drivers. The results suggest that drivers’ travel speed is influenced by road factors, other road users and enforcement. Furthermore, drivers’ own judgements of what is an appropriate speed are also important for speed choice.</p>

Speed choice is one of the more characteristic features of driver behaviour. The speed a driver chooses to travel at determines the degree of difficulty he or she operates under. Higher speeds lead to more accidents, higher accident risk and more severe consequences of an accident. The present thesis examines factors that are associated with drivers’ speed choice. Repeated measures of drivers’ speed showed a reasonably high correlation, but also that stability in speed varied with road layout between measurement sites. Effects of police enforcement were studied on roads with temporary reduced speed limits (from 50 km/h to 30 km/h) during school hours. Lower speeds were found on roads with enforcement and drivers observed on one such road showed a higher perceived probability of detection than did drivers observed on a non-enforced road. However, in a laboratory study higher driving speeds and lower accident risk was associated with enforced roads. Drivers not informed about existing speed limits overestimated the limits to a large extent and chose driving speeds above the limit as did drivers informed about the limits. In an on-the-road survey, fast drivers reported higher driving speed, thought a higher percentage of other drivers were speeding and had a more positive attitude towards speeding than did slower drivers. The results suggest that drivers’ travel speed is influenced by road factors, other road users and enforcement. Furthermore, drivers’ own judgements of what is an appropriate speed are also important for speed choice.

Diagnostic X-rays are the most important man-made source of radiation exposure for the general population, contributing about 14% of the total annual exposure worldwide from all sources. However, although diagnostic X-rays provide great benefits, it is generally accepted that their use involves some small risk of developing cancer. The risk to an individual is probably small because radiation doses are usually low, but the large number of people exposed annually means that even small individual risks could translate into a considerable number of cancer cases. The aim of this work was to reestimate this risk on the basis of the annual number of CT examinations undertaken in the Czech Republic and typical doses applied. But there wasn't possible to find necessary data for planned reckonings by return, because their archiving isn't obligatory. This study, therefore, only describes common incidence of ionising radiation with human organism and further, all inevitable mathematically-physical equations needed for realization of primary planned investigation, with all necessary datal inputs included. In findings of this work there are drafted and demonstrated procedures, how to obtain and cultivate needed data ,so it was possible to compare it with technical literature.