Numerous driver, vehicle, roadway, and environmental factors contribute to crash-injury severity. In addition to main effects, interactions between factors are very likely to be significant. The large number of potentially important factors, combined with the complex nature of crash etiology and injury outcome, present significant challenges to the safety analyst, who must select from a large number of factors and specify a comprehensive but feasible set of main factors and interactions for testing in statistical models. In addition, some factors contain a relatively large number of categories (e.g., weather conditions), and the selection of cut-off points for categorization of continuous factors may not be readily obvious (e.g., driver age). It is also important that statistical tests underlying these analyses accurately address the frequent problem of data sparseness. The development and testing of a variable-selection procedure to address each of these problems is the stated objective. Bus-involved crash data for Freeway 1 in Taiwan from 1985 through 1993 were used to screen a set of 39 possible influential factors, along with interactions. The final log-linear model shows that late-night or early-morning driving increases the risk for bus drivers of being severely injured, particularly when the drivers caused the accident or when the drivers were involved in rear-end accidents. Bus accidents involving large trucks or tractor-trailers also increase the risk. An assessment of the importance of considering interactions in crash models is presented as a conclusion.
If real-time driver en route guidance advice does not meet driver preferences (e.g., preference for taking the freeway) or the advice is not correct, drivers are very likely to ignore the information, and the guidance system becomes ineffective in their route choice no matter how advanced the system. There is a need to investigate the factors affecting driver compliance with en route guidance advice. A travel simulation experiment was used to investigate significant factors affecting driver route choice behavior. A linear mixed model was developed for describing the factors affecting driver compliance with guidance advice using the compliance rate over several simulated trips as a dependent variable. The issue of repeated observations is addressed. The system accuracy and subjects’ learning experience in their spatial experience at the same intersection and temporal experience in the same day are also taken into account. The model results show that significant factors are involved: freeway advice, turning advice, congestion occurrence, incident occurrence, subjects’ spatial experience, subjects’ temporal experience, and subjects’ education level; there are several important interactions as well.
This study investigated the travel characteristics of seniors in Taiwan through the use of a questionnaire survey. Survey results revealed that walking was the travel mode used to participate in the three most popular activities among seniors: doing outdoor exercise, chatting with neighbors, and shopping. For an aging society, a safe and barrier-free walking environment was an essential transportation requirement. Access to a transit system with frequent bus service could help ensure participation by elderly citizens in activities at greater distances from their homes. In areas where bus service was infrequent, a demand-responsive service (DRS) bus could serve as an alternative means of transportation for older adults. This study examined factors that contributed to the degree of willingness of elderly subjects to use a DRS bus for their medical trips. The influential factors included age, education, eye and bone problems, transportation mode typically used for medical trips, distance to the closest hospital or clinic, walking distance to the nearest bus stop, and bus frequency. This study suggested that the following areas should have the highest priority for a DRS bus system: areas located 20 min or more from the nearest hospital or clinic, areas located 10 min or more from the nearest bus stop, and areas where bus service is infrequent.
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