Methods for identifying sites with potential for preventing traffic fatalities and injuries have ... more Methods for identifying sites with potential for preventing traffic fatalities and injuries have been developed for vehicle-vehicle collisions. This study was funded by the California Department of Transportation (Caltrans) to develop methods for identifying sites where there is potential for significant reductions in pedestrian and bicyclist injury. Data from 1998-2007 from a 16.5-mile section of San Pablo Avenue (SR 123) in the San Francisco East Bay was used as a study area. Several approaches for identifying sites with high potential for reducing pedestrian and bicyclist injury were evaluated and compared, a framework was developed for conducting benefit-cost analyses, and a prototype was developed for a training protocol for conducting analyses of pedestrian and bicyclist safety in a corridor or network. The basic principle followed is that sites with the most potential for reducing injury are those sites where the most injuries can be prevented per dollar spent. Everything else being equal, these sites are the ones with the highest expected number of injuries if nothing is done. Prior history is typically used to make this estimate, but this may not be sufficient, especially if the underlying rates are low. Several approaches to developing statistically stable estimates are explained and compared: (i) extend the number years for both the baseline and follow-up periods, (ii) expand the size of the target sites considered, and (iii) apply Bayesian methods to include a modeled estimate of risk in the calculation. Strengths and weaknesses of each of these approaches are discussed with illustrations from the study area.
Abstract: Methods for identifying sites with potential for preventing traffic fatalities and inju... more Abstract: Methods for identifying sites with potential for preventing traffic fatalities and injuries have been developed for vehicle-vehicle collisions. This study was funded by the California Department of Transportation (Caltrans) to develop methods for identifying sites where there is potential for significant reductions in pedestrian and bicyclist injury. Data from 1998-2007 from a 16.5-mile section of San Pablo Avenue (SR 123) in the San Francisco East Bay was used as a study area.
ABSTRACT Wet pavement-related collisions represent a significant traffic safety concern, due in p... more ABSTRACT Wet pavement-related collisions represent a significant traffic safety concern, due in part to the lack of adequate friction between tire and pavement, known as skid resistance. State agencies employ a skid number (SN) system, based on a standard test ...
Type A/B behavior has been studied extensively as a risk factor for coronary heart disease. This ... more Type A/B behavior has been studied extensively as a risk factor for coronary heart disease. This study tests the hypothesis that Type A/B behavior is associated with ill health in general. All-cause mortality was examined in the original cohort of 3,154 men aged 39-59 years at baseline in the Western Collaborative Group Study in 1960-1961. Morbidity was examined in a group of 2,365 men aged 61-81 years who were surviving members of the cohort in 1982-1983 and who agreed to fill out a self-administered health status questionnaire. On the basis of these data, a three-level general morbidity index was constructed that included coronary heart disease and a number of other chronic conditions. Type A/B behavior was not significantly associated with all-cause mortality over the 22-year follow-up. However, among men 61-71 years of age, behavior type assessed at the baseline examination 22 years earlier (1960-1961) was positively associated with the morbidity index (p less than 0.001). Furthermore, behavior type and the morbidity index showed a dose-response association; extreme Type A personalities had the highest level of morbidity, while those with the fewest Type A characteristics had the lowest level of morbidity. This general pattern of association was not due to the presence of coronary heart disease or to any other particular disease condition in the morbidity index and did not change when an ordinal logistic regression model was used to control for other baseline risk variables. For the older men (aged 72-81 years), the pattern of association was similar but did not reach statistical significance. Thus, in a group of men over 60, a positive association was found between general morbidity status and Type A/B behavior measured over two decades earlier.
Page 1. unstriped, or unmarked, crosswalks. The focus on crosswalk mark-ings is warranted by the ... more Page 1. unstriped, or unmarked, crosswalks. The focus on crosswalk mark-ings is warranted by the long history of debate regarding whether and why the crash risk for pedestrians is higher in marked crosswalks than in unmarked ...
In 1960-1961, 3,154 healthy, middle-aged men were entered into the Western Collaborative Group St... more In 1960-1961, 3,154 healthy, middle-aged men were entered into the Western Collaborative Group Study, a long-term study of coronary heart disease. A 22-year mortality follow-up of this cohort in 1982-1983 accounted for almost 99% of the cohort, and determined that 214 of the men had died of coronary heart disease. The risk of coronary heart disease mortality was studied for several variables measured at baseline, i.e., Type A/B behavior, systolic blood pressure, serum cholesterol level, cigarette smoking status, and age. Using a proportional hazards regression model, systolic blood pressure, serum cholesterol level, cigarette smoking status, and age were highly significant predictors (p less than 0.001) of 22-year coronary heart disease mortality. Type A/B behavior showed no association with 22-year coronary heart disease mortality (standardized relative hazard (SRH) = 0.98, 95% confidence interval (CI) = 0.85-1.12). Systolic blood pressure, serum cholesterol, and age showed relatively consistent positive associations with coronary heart disease mortality over four successive time intervals after the baseline examination. Cigarette smoking showed a significant positive association in the first and second intervals and a nonsignificant positive association in the third and fourth intervals. Type A/B behavior was positively but not significantly associated with coronary heart disease in the first and third intervals, significantly negatively associated (SRH = 0.70, 95% CI = 0.53-0.93) in the second interval and not associated in the fourth interval. The results confirm the importance of the traditional coronary heart disease risk factors, and raise a substantial question about the importance of Type A/B behavior as a risk factor for coronary heart disease mortality.
Previous studies of Mexican Americans have shown mean diastolic and systolic blood pressures and ... more Previous studies of Mexican Americans have shown mean diastolic and systolic blood pressures and prevalence rates of hypertension which are either lower than or similar to those for non-Hispanic whites despite the predominance of obesity in Mexican Americans. However, those results are based on restricted samples from California and Texas. Using data from the Second National Health and Nutrition Examination Survey (1976-1980) and the Hispanic Health and Nutrition Examination Survey (1982-1984), the authors examined ethnic differences in blood pressure and hypertension. Regression analyses, stratified by sex, were used to compare mean blood pressures and rates of hypertension in Mexican Americans with those for whites and blacks. Mean diastolic and systolic blood pressures, as well as the prevalence of hypertension, were lower in Mexican Americans than in non-Hispanic whites or in blacks, with whom they shared a remarkably similar risk profile. This effect was unchanged after adjustment for age, body mass index (weight (kg)/height (cm)2 x 100), and education, indicating that blood pressure differences between Mexican Americans, whites, and blacks were not explained by the established correlates of high blood pressure. There are several possible reasons for lower blood pressure in Mexican Americans, including genetic, life-style, and cultural factors.
Studies of the association between type A behavior and coronary heart disease have yielded incons... more Studies of the association between type A behavior and coronary heart disease have yielded inconsistent findings. A possible explanation for these inconsistent findings is that type A behavior is simply a marker for other behaviors that are truly related to coronary heart disease. Hostility is one such behavior that has been found in several recent studies to predict coronary heart disease and coronary atherosclerosis; however, several other studies have found null results. In the present study, the predictive power of hostility was tested in a study population of hospitalized men (n = 118) and women (n = 40) scheduled for coronary angiography. Potential coronary risk behaviors were assessed in the angiography patients and they were given the type A Structured Interview. Hostility was measured with the Cook-Medley Hostility Inventory and the Behavior Pattern Hostility Index, a measure of hostility derived from the type A Structured Interview. No significant positive associations were found for either Cook-Medley hostility or behavior pattern hostility and coronary occlusion. This was true whether hostility or coronary occlusion was treated as a dichotomous variable or as a continuous variable. In fact, most of the observed associations were opposite to the predicted direction, although none was statistically significant. Replicating cutpoints of the Cook-Medley Hostility Inventory used in other studies that have reported positive associations with coronary heart disease also yielded null findings. The association between hostility and coronary occlusion was slightly modified by age and sex, but the interaction coefficients were not significant. The sample size yielded adequate statistical power to detect the hypothesized associations, and there was no evidence that selection bias, measurement error, or unexamined confounding accounted for the null findings. These results failed to confirm some earlier reports showing a positive association between hostility and coronary artery disease.
Transportation Research Record Journal of the Transportation Research Board, Feb 2, 2015
Page 1. The purpose of this study was to understand the adverse consequences of driving reduction... more Page 1. The purpose of this study was to understand the adverse consequences of driving reduction or cessation among elderly adults. A comprehensive literature search was conducted for studies that (a) included information ...
Methods for identifying sites with potential for preventing traffic fatalities and injuries have ... more Methods for identifying sites with potential for preventing traffic fatalities and injuries have been developed for vehicle-vehicle collisions. This study was funded by the California Department of Transportation (Caltrans) to develop methods for identifying sites where there is potential for significant reductions in pedestrian and bicyclist injury. Data from 1998-2007 from a 16.5-mile section of San Pablo Avenue (SR 123) in the San Francisco East Bay was used as a study area. Several approaches for identifying sites with high potential for reducing pedestrian and bicyclist injury were evaluated and compared, a framework was developed for conducting benefit-cost analyses, and a prototype was developed for a training protocol for conducting analyses of pedestrian and bicyclist safety in a corridor or network. The basic principle followed is that sites with the most potential for reducing injury are those sites where the most injuries can be prevented per dollar spent. Everything else being equal, these sites are the ones with the highest expected number of injuries if nothing is done. Prior history is typically used to make this estimate, but this may not be sufficient, especially if the underlying rates are low. Several approaches to developing statistically stable estimates are explained and compared: (i) extend the number years for both the baseline and follow-up periods, (ii) expand the size of the target sites considered, and (iii) apply Bayesian methods to include a modeled estimate of risk in the calculation. Strengths and weaknesses of each of these approaches are discussed with illustrations from the study area.
Abstract: Methods for identifying sites with potential for preventing traffic fatalities and inju... more Abstract: Methods for identifying sites with potential for preventing traffic fatalities and injuries have been developed for vehicle-vehicle collisions. This study was funded by the California Department of Transportation (Caltrans) to develop methods for identifying sites where there is potential for significant reductions in pedestrian and bicyclist injury. Data from 1998-2007 from a 16.5-mile section of San Pablo Avenue (SR 123) in the San Francisco East Bay was used as a study area.
ABSTRACT Wet pavement-related collisions represent a significant traffic safety concern, due in p... more ABSTRACT Wet pavement-related collisions represent a significant traffic safety concern, due in part to the lack of adequate friction between tire and pavement, known as skid resistance. State agencies employ a skid number (SN) system, based on a standard test ...
Type A/B behavior has been studied extensively as a risk factor for coronary heart disease. This ... more Type A/B behavior has been studied extensively as a risk factor for coronary heart disease. This study tests the hypothesis that Type A/B behavior is associated with ill health in general. All-cause mortality was examined in the original cohort of 3,154 men aged 39-59 years at baseline in the Western Collaborative Group Study in 1960-1961. Morbidity was examined in a group of 2,365 men aged 61-81 years who were surviving members of the cohort in 1982-1983 and who agreed to fill out a self-administered health status questionnaire. On the basis of these data, a three-level general morbidity index was constructed that included coronary heart disease and a number of other chronic conditions. Type A/B behavior was not significantly associated with all-cause mortality over the 22-year follow-up. However, among men 61-71 years of age, behavior type assessed at the baseline examination 22 years earlier (1960-1961) was positively associated with the morbidity index (p less than 0.001). Furthermore, behavior type and the morbidity index showed a dose-response association; extreme Type A personalities had the highest level of morbidity, while those with the fewest Type A characteristics had the lowest level of morbidity. This general pattern of association was not due to the presence of coronary heart disease or to any other particular disease condition in the morbidity index and did not change when an ordinal logistic regression model was used to control for other baseline risk variables. For the older men (aged 72-81 years), the pattern of association was similar but did not reach statistical significance. Thus, in a group of men over 60, a positive association was found between general morbidity status and Type A/B behavior measured over two decades earlier.
Page 1. unstriped, or unmarked, crosswalks. The focus on crosswalk mark-ings is warranted by the ... more Page 1. unstriped, or unmarked, crosswalks. The focus on crosswalk mark-ings is warranted by the long history of debate regarding whether and why the crash risk for pedestrians is higher in marked crosswalks than in unmarked ...
In 1960-1961, 3,154 healthy, middle-aged men were entered into the Western Collaborative Group St... more In 1960-1961, 3,154 healthy, middle-aged men were entered into the Western Collaborative Group Study, a long-term study of coronary heart disease. A 22-year mortality follow-up of this cohort in 1982-1983 accounted for almost 99% of the cohort, and determined that 214 of the men had died of coronary heart disease. The risk of coronary heart disease mortality was studied for several variables measured at baseline, i.e., Type A/B behavior, systolic blood pressure, serum cholesterol level, cigarette smoking status, and age. Using a proportional hazards regression model, systolic blood pressure, serum cholesterol level, cigarette smoking status, and age were highly significant predictors (p less than 0.001) of 22-year coronary heart disease mortality. Type A/B behavior showed no association with 22-year coronary heart disease mortality (standardized relative hazard (SRH) = 0.98, 95% confidence interval (CI) = 0.85-1.12). Systolic blood pressure, serum cholesterol, and age showed relatively consistent positive associations with coronary heart disease mortality over four successive time intervals after the baseline examination. Cigarette smoking showed a significant positive association in the first and second intervals and a nonsignificant positive association in the third and fourth intervals. Type A/B behavior was positively but not significantly associated with coronary heart disease in the first and third intervals, significantly negatively associated (SRH = 0.70, 95% CI = 0.53-0.93) in the second interval and not associated in the fourth interval. The results confirm the importance of the traditional coronary heart disease risk factors, and raise a substantial question about the importance of Type A/B behavior as a risk factor for coronary heart disease mortality.
Previous studies of Mexican Americans have shown mean diastolic and systolic blood pressures and ... more Previous studies of Mexican Americans have shown mean diastolic and systolic blood pressures and prevalence rates of hypertension which are either lower than or similar to those for non-Hispanic whites despite the predominance of obesity in Mexican Americans. However, those results are based on restricted samples from California and Texas. Using data from the Second National Health and Nutrition Examination Survey (1976-1980) and the Hispanic Health and Nutrition Examination Survey (1982-1984), the authors examined ethnic differences in blood pressure and hypertension. Regression analyses, stratified by sex, were used to compare mean blood pressures and rates of hypertension in Mexican Americans with those for whites and blacks. Mean diastolic and systolic blood pressures, as well as the prevalence of hypertension, were lower in Mexican Americans than in non-Hispanic whites or in blacks, with whom they shared a remarkably similar risk profile. This effect was unchanged after adjustment for age, body mass index (weight (kg)/height (cm)2 x 100), and education, indicating that blood pressure differences between Mexican Americans, whites, and blacks were not explained by the established correlates of high blood pressure. There are several possible reasons for lower blood pressure in Mexican Americans, including genetic, life-style, and cultural factors.
Studies of the association between type A behavior and coronary heart disease have yielded incons... more Studies of the association between type A behavior and coronary heart disease have yielded inconsistent findings. A possible explanation for these inconsistent findings is that type A behavior is simply a marker for other behaviors that are truly related to coronary heart disease. Hostility is one such behavior that has been found in several recent studies to predict coronary heart disease and coronary atherosclerosis; however, several other studies have found null results. In the present study, the predictive power of hostility was tested in a study population of hospitalized men (n = 118) and women (n = 40) scheduled for coronary angiography. Potential coronary risk behaviors were assessed in the angiography patients and they were given the type A Structured Interview. Hostility was measured with the Cook-Medley Hostility Inventory and the Behavior Pattern Hostility Index, a measure of hostility derived from the type A Structured Interview. No significant positive associations were found for either Cook-Medley hostility or behavior pattern hostility and coronary occlusion. This was true whether hostility or coronary occlusion was treated as a dichotomous variable or as a continuous variable. In fact, most of the observed associations were opposite to the predicted direction, although none was statistically significant. Replicating cutpoints of the Cook-Medley Hostility Inventory used in other studies that have reported positive associations with coronary heart disease also yielded null findings. The association between hostility and coronary occlusion was slightly modified by age and sex, but the interaction coefficients were not significant. The sample size yielded adequate statistical power to detect the hypothesized associations, and there was no evidence that selection bias, measurement error, or unexamined confounding accounted for the null findings. These results failed to confirm some earlier reports showing a positive association between hostility and coronary artery disease.
Transportation Research Record Journal of the Transportation Research Board, Feb 2, 2015
Page 1. The purpose of this study was to understand the adverse consequences of driving reduction... more Page 1. The purpose of this study was to understand the adverse consequences of driving reduction or cessation among elderly adults. A comprehensive literature search was conducted for studies that (a) included information ...
OBJECTIVE: This study tests the spillover model of the effects of work stress on after-work drink... more OBJECTIVE: This study tests the spillover model of the effects of work stress on after-work drinking, using the variable "length of time to unwind" as a mediator. METHOD: A total of 1,974 transit operators were contacted and 1,553 (79%) of them participated in a personal interview. Complete data on the variables in this analysis were available for 1,208 respondents (84% men). Using latent variable structural equation modeling, a model was tested that predicted that daily job problems, skipped meals and less social support from supervisor would increase alcohol consumption through the mediator, length of time to unwind and relax after work. Increased alcohol consumption was, in turn, hypothesized to increase drinking problems. RESULTS: As predicted, skipped meals and daily job problems increased length of time to unwind and had an indirect positive relationship with overall drinking, even when controlling for drinking norms and demographic variables. Overall drinking was positively associated with drinking problems. Supervisor support at work, however, did not significantly influence length of time to unwind. Difficulty unwinding (longer time to unwind) did not have direct effects on drinking problems; however, indirect effects through overall drinking were observed. CONCLUSIONS: These results provide preliminary support for the mediating role of length of time to unwind and relax after work in a spillover model of the stress-drinking relationship. This research introduces a new mediator and empirical links between job problems, length of time to unwind, drinking and drinking problems, which ground more substantively the domains of work stress and alcohol consumption.
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