Potential For Safety Improvement Research Articles

Exploring crash mechanisms with microscopic traffic flow variables: A hybrid approach with latent class logit and path analysis models

Understanding the occurrence mechanisms of crashes is critical for traffic safety improvement. Efforts have been investigated to reveal the crash mechanisms and analyze the contributing factors from the aspects of vehicle, driver, and operational perspectives. In this study, special attention has been paid to the operational level analyses while bridging the research gaps of: (1) failing to identify the heterogeneous impact of microscopic traffic flow variables on crash occurrence, and (2) focusing on correlation effects without further investigations for the causal relationships. A hybrid modeling approach with latent class logit (LCL) and path analysis (PA) models was proposed to account for the heterogeneous influencing effects and reveal the causal relationships between crash occurrence and microscopic traffic flow variables. Data from Shanghai urban expressway system were utilized for the empirical analyses. First, the LCL model has concluded four latent subsets of crash occurrence influencing factors. Then, PA models were conducted to identify the concurrent relationships (direct and indirect eff ;ects) for the four sets of crash occurrence influencing factors separately. Finally, the results of the LCL model and PA models were compared and the crash-prone scenarios were inferred. And the potential safety improvement countermeasures were discussed.

Comparison of Systematic Video Documentation With Narrative Operative Report in Colorectal Cancer Surgery

Despite ongoing advances in the field of colorectal surgery, the quality of surgical treatment is still variable. As an intrinsic part of surgical quality, the technical information regarding the surgical procedure is reflected only by the narrative operative report (NR), which has been found to be subjective and regularly omits important information. To investigate systematic video recording (SVR) as a potential improvement in quality and safety with regard to important information in colorectal cancer surgery. The Imaging for Quality Control Trial was a prospective, observational cohort study conducted between January 12, 2016, and October 30, 2017, at 3 centers in the Netherlands. The study group consisted of 113 patients 18 years or older undergoing elective laparoscopic surgery for colorectal cancer. These patients were case matched and compared with cases from a historical cohort that received only an NR. Among study cases, participating surgeons were requested to systematically capture predefined key steps of the surgical procedure intraoperatively on video in short clips. The SVRs and NRs were analyzed for adequacy with respect to the availability of important information regarding the predefined key steps. Adequacy of the reported information was defined as the proportion of key steps with available and sufficient information in the report. Adequacy of the SVR and NR was compared between the study and control groups, with the SVR alone and as an adjunct to the NR in the study group vs NR alone in the control group. Of the 113 study patients, 69 women (61.1%) were included; mean (SD) age was 66.3 (9.8) years. In the control group, a mean (SD) of 52.5% (18.3%) of 631 steps were adequately described in the NR. In the study group, the adequacy of both the SVR (78.5% [16.5%], P < .001) and a combination of the SVR with NR (85.1% [14.6%], P < .001) was significantly superior to NR alone. The only significant difference between the study and historical control groups regarding postoperative and pathologic outcomes was a shorter postoperative mean (SD) length of stay in favor of the study group (8.0 [7.7] vs 8.6 [6.8] days; P = .03). Use of SVR in laparoscopic colorectal cancer surgery as an adjunct to the NR might be superior in documenting important steps of the operation compared with NR alone, adding to the overall availability of necessary intraoperative information and contributing to quality control and objectivity.

Safety assessment of Czech motorways and national roads

PurposeCzech motorways and national roads form the primary road network, which is critical in terms of safety. To be able to rationally manage network safety in both planning and operation stages, quality network-wide data and tools are needed. While such tools already exist in some countries, their transferability is limited. Authors therefore collected data and used it to develop tools, which allowed conducting state-of-the-art road safety impact assessment and network safety ranking in the Czech conditions. In addition to primary road network, focus was widened to include also secondary roads, in order to enable assessment of impacts on adjacent road network.MethodsAccident, road and traffic data was collected, using not only existing databases, but also including own collection of traffic volumes on motorway interchanges. Data was used to develop the tools, based on accident prediction models and accident modification factors.ResultsThe final accident prediction models and accident modification factors enabled conducting road safety impact assessment, for which simple on-line tool was also developed. For network safety ranking, accident prediction models were applied according to the Empirical Bayes method, in order to determine potential for safety improvement of the studied road network elements, with the final priority list visualized in an on-line map. Both outputs are shortly presented in the paper.ConclusionsData and sample size limitations lead to some compromises in modelling, such as using fixed proportions of observed accident severities or omitted variables. Nevertheless, the study established the practical framework for both road safety impact assessment and network safety ranking. It may serve as an example for other member countries, which also lack their local tools. Follow-up studies may focus on future model updating and improvements, as well as development of local accident modification factors.

A Novel Technique to Identify Hot Zones for Active Commuters’ Crashes

This paper presents an approach to identify and rank accident-prone (hot) zones for active transportation modes. The approach aims to extend the well-known empirical Bayes (EB) potential for safety improvement (PSI) method to cases where multiple crash modes are modeled jointly (multivariate modeling). In this study, crash modeling was pursued with a multivariate model, incorporating spatial effects, using the full Bayes (FB) technique. Cyclist and pedestrian crash data for the City of Vancouver (British Columbia, Canada) were analyzed for 134 traffic analysis zones (TAZs) to detect active transportation hot zones. The hot zones identification (HZID) process was based on the estimation of the Mahalanobis distance, which can be considered an extension to the PSI method in the context of multivariate analysis. In addition, a negative binomial model was developed for cyclist and pedestrian crashes, where the EB PSI for each mode crash was quantified. The cyclist and pedestrian PSIs were combined to detect active transportation hot zones. Overall, the Mahalanobis distance method is found to outperform the PSI method in terms of consistency of results; and discrepancy is observed between the hot zones identified using both approaches.

Nuclear safety launch approval: Multi-mission lessons learned

Launching a NASA radioisotope power system (RPS) mission requires compliance with two Federal mandates: the National Environmental Policy Act of 1969 (NEPA) and launch approval (LA), as directed by Presidential Directive/National Security Council Memorandum 25. Nuclear safety launch approval lessons learned from multiple NASA RPS missions, one Russian RPS mission, two non-RPS launch accidents, and several solid propellant fire test campaigns since 1996 are shown to have contributed to an ever-growing body of knowledge. The launch accidents can be viewed as “unplanned experiments” that provided real-world data. Lessons learned from the nuclear safety launch approval effort of each mission or launch accident, and how they were applied to improve the NEPA/LA processes and nuclear safety of subsequent RPS missions, are presented. The current emphasis on cost improvements to future NEPA/LA processes are placed into context of these historical nuclear safety improvements, with a caution that certain cost improvements may have the short-term effect of lowering NEPA/LA costs but at the expense of curtailing potential nuclear safety improvements. The reader should note that changes are not made lightly, and a benefit is sought through the change. These improvements may be in other areas besides cost.

A challenge-response endoscopic sinus surgery specific checklist as an add-on to standard surgical checklist: an evaluation of potential safety and quality improvement issues.

The goal of this study was to develop and evaluate the impact of an aviation-style challenge and response sinus surgery-specific checklist on potential safety and equipment issues during sinus surgery at a tertiary academic health center. The secondary goal was to assess the potential impact of use of the checklist on surgical times during, before, and after surgery. This initiative is designed to be utilized in conjunction with the "standard" World Health Organization (WHO) surgical checklist. Although endoscopic sinus surgery is generally considered a safe procedure, avoidable complications and potential safety concerns continue to occur. The WHO surgical checklist does not directly address certain surgery-specific issues, which may be of particular relevance for endoscopic sinus surgery. This prospective observational pilot study monitored compliance with and compared the occurrence of safety and equipment issues before and after implementation of the checklist. Forty-seven consecutive endoscopic surgeries were audited; the first 8 without the checklist and the following 39 with the checklist. The checklist was compiled by evaluating the patient journey, utilizing the available literature, expert consensus, and finally reevaluation with audit type cases. The final checklist was developed with all relevant stakeholders involved in a Delphi method. Implementing this specific surgical checklist in 39 cases at our institution, allowed us to identify and rectify 35 separate instances of potentially unsafe, improper or inefficient preoperative setup. These incidents included issues with labeling of topical vasoconstrictor or injectable anesthetics (3, 7.7%) and availability, function and/or position of video monitors (2, 5.1%), endoscope (6, 15.4%), microdebrider (6, 15.4%), bipolar cautery (6, 15.4%), and suctions (12, 30.8%). The design and integration of this checklist for endoscopic sinus surgery, has helped improve efficiency and patient safety in the operating room setting.

Identifying and Ranking Dangerous Road Segments a Case of Hawassa-Shashemene-Bulbula Two-Lane Two-Way Rural Highway, Ethiopia

According to the study made by United Nation Economic Commission for Africa, Ethiopia stands as one of the worst countries with respect to road safety performance in terms of traffic accident fatalities per 10,000 vehicles (i.e. 95 in 2007/8). Road safety generally depends on humans, vehicles, and highway conditions. These factors influence road safety separately or in combination. One of the basic means to improve road safety is to reduce hazardous conditions of roads. The main objective of this study is to identify and rank hazardous locations and propose appropriate simple and inexpensive countermeasures along Hawassa-Shashemene-Bulbula main two-lane rural road. Accordingly, the road and traffic data were collected from field investigation and Ethiopian Road Authority and accident data were gathered from police stations. Then, the study road equally divided into short sections of 1.5 km and traffic volume and accident frequencies assigned for each road site to predict theoretical frequencies of accident. Empirical Bayes method and Safety Performance Function have been used to estimate an index known as Potential for Safety Improvement (PSI) for each site of the study area to identify and rank road sites. The result showed that out of 43 road segments 22 of them were identified as dangerous road segments. Moreover, based on further criterion established for screening the ranked road sections 8 road segments were found the most dangerous road segments as they have contributed 76% of total PSI values. The degree of haphazardness of a given road segment in the study area has directly associated with the availability of risk indicating road and traffic factors. Finally, it recommends that regulatory body of road safety in the study area should give high priority and immediate response for the improvement of most dangerous road segments.

Assessment for Improvement: Harvesting Operations in Small-Scale Forest on Thai Steep Terrain

Timber harvesting on steep terrain is always a challenge in terms of safety, operating costs, and environmental impact. The motor-manual, cut-to-length method is the most common in harvesting operations in the mountainous areas of Thailand. The motor-manual operations are characterized by various negative features such as high fatality rates, expensive operating costs, and low productivity. The aims of this study were to evaluate the prevailing harvesting operations, to propose new working methods and systems, and to suggest work safety improvement measures. The results indicated an extremely high fatality rate in Thailand compared to the average in other countries. Possible reasons for this may include ineffective safety regulations, inadequate worker training programs, seasonal forestry workers, and a lack of personal protective equipment. Consequently, alternative working methods have been suggested as a system. The proposed working method was intended to improve work safety, enhance productivity and reduce operating costs using by simulation to find best solution. Shifting from a cut-to-length to tree-length processing and moving forward to mechanization was introduced as alternative harvesting systems. The results showed that partly-mechanized systems would significantly improve the productivity. Potential work safety improvement measures may consist of adequate training, personal protective equipment, and technological improvement. Obstacle for implementation is the high investment for forest machines and silvicultural practices.

Improving safety of DP operations: learning from accidents and incidents during offshore loading operations

The risk caused by DP vessels in offshore marine operations is not negligible, due to wide applications of DP vessels in complex marine operations, and the sharp increase of DP vessel population. The DP accidents/incidents on the Norwegian Continental Shelf (NCS) that have occurred after 2000 indicate a need for improving safety of DP operations, which calls for new risk reduction measures. The focus of this paper is particularly on the offshore loading operations with DP shuttle tanker in offloading from floating production storage and offloading (FPSO) vessels on the NCS, but the results may be relevant also for other types of DP vessels in offshore oil and gas operations. In the paper, Man, Technology and Organization (MTO) analysis is applied to investigate the cause and barrier failures of nine reported accidents/incidents occurring over a 16-year period (2000–2015). MTO is based on three methods, including structured analysis by use of an event- and cause-diagram, change analysis by describing how events have deviated from earlier events or common practice, and barrier analysis by identifying technological and administrative barriers which have failed or are missing. The results are categorized into technical failures, human failures, organizational failures, as well as a combination of failures. The main finding is that the majority of the accidents are caused by the combination of technical, human and organizational failures. Critical root causes, results of change analysis and barrier analysis, and combination of failures are focused in the discussion. Recommendations of potential safety improvements are made on the aspects of the assessment of the actual system function, barrier management for marine systems, risk information to support different decision-makings, and the development of an on-line risk monitoring and decision supporting system.

Passengers’ Perceptions of Railway Safety

The aim of the study was to identify the passengers' perceptions of railway safety, with emphasis on the internal safety and potential safety improvements. Train passengers (n=243) in Sweden were s ...

Key challenges in tram/streetcar driving from the tram driver’s perspective – A qualitative study

Tram drivers have a difficult task in controlling one of the heaviest vehicles on the road whilst negotiating a complex road environment with multiple road users. Like all public transport drivers, tram drivers need to ensure passenger safety and to run on time. However, very little research has been conducted evaluating tram driving tasks and even less on evaluating tram drivers opinion on how other road users are affecting tram road safety. Therefore, the aim of this study is to investigate the key tram driving challenges, to identify the key road user factors affecting tram road safety as well as to explore the potential safety improvement initiatives on tram routes from the tram drivers’ viewpoint. The study incorporated five focus groups involving thirty tram drivers in Melbourne. The key themes emerged inductively from focus groups were identified through a data coding process. Outcomes of the focus groups revealed seven major challenges in tram driving: ensuring safety for all people in and around the tram, pressure for running on-time, maintaining constant concentration on roads, predicting other road users’ behavior in advance to avoid any crash incident, preventing passenger falls on board, accepting the operational constraints of trams and managing fatigue workloads. Tram drivers identified that other road users are unaware of safety issues around trams, have a poor understanding of road rules about driving with trams and often violate road rules around trams, and they mentioned this road user behaviors as the key challenges for safe tram driving. Tram drivers proposed rendering greater law enforcement on the tram network to penalize road users who are violating road rules around trams, introducing more safety campaigns and safety education to increase awareness among road users to improve tram road safety. Findings of this research enhance understanding of tram driving challenges, provide an in-depth knowledge of road user factors affecting tram road safety and suggest effective planning strategies for transit agencies to improve road safety.

Ranking cities for safety investigation by potential for safety improvement

ABSTRACTThe authors performed a city-level hot-spot identification by using the 4-year data of 265 cities in California. It is intended to equip road safety professionals with more useful information to compare the safety performance of city as a whole. Potential for safety improvement (PSI) was adopted as a measure of crash risk to compare alternate identification of hot spot (HSID) methods, including the Empirical Bayes (EB) and three full Bayesian (FB) alternatives, negative binomial, Poisson log-normal, and the Poisson temporal random effect, for ranking the safety performance of cities. Five evaluation tests which contain the Site Consistency Test, the Method Consistency Test, the Total Rank Difference Test, the Total Performance Difference Test, and the Total Score Test were applied to evaluate the performance of the four HSID methods. Moreover, two cutoff levels, top 5% and 10% cities, were employed for more reliable results. Overall, the study results are consistent with the results of previous quantitative evaluations focused on micro-level HSID. The three FB approaches significantly outperform the EB counterpart. The method accounting for temporal random effect produces more reliable HSID results than those without considering the serial correlations in collision counts.

Analysis of Traffic Crashes Involving Pedestrians Using Big Data: Investigation of Contributing Factors and Identification of Hotspots.

This study aims to explore the potential of using big data in advancing the pedestrian risk analysis including the investigation of contributing factors and the hotspot identification. Massive amounts of data of Manhattan from a variety of sources were collected, integrated, and processed, including taxi trips, subway turnstile counts, traffic volumes, road network, land use, sociodemographic, and social media data. The whole study area was uniformly split into grid cells as the basic geographical units of analysis. The cell-structured framework makes it easy to incorporate rich and diversified data into risk analysis. The cost of each crash, weighted by injury severity, was assigned to the cells based on the relative distance to the crash site using a kernel density function. A tobit model was developed to relate grid-cell-specific contributing factors to crash costs that are left-censored at zero. The potential for safety improvement (PSI) that could be obtained by using the actual crash cost minus the cost of "similar" sites estimated by the tobit model was used as a measure to identify and rank pedestrian crash hotspots. The proposed hotspot identification method takes into account two important factors that are generally ignored, i.e., injury severity and effects of exposure indicators. Big data, on the one hand, enable more precise estimation of the effects of risk factors by providing richer data for modeling, and on the other hand, enable large-scale hotspot identification with higher resolution than conventional methods based on census tracts or traffic analysis zones.

Changing the Future?: Development and Application of Pedestrian Safety Performance Functions to Prioritize Locations in Seattle, Washington

This study aimed to use robust analysis methods to identify and screen locations at risk for pedestrian crashes and injuries to help Seattle, Washington, a Vision Zero city, broaden treatment priorities beyond only high-crash locations. For this objective, data from the entire network were used to develop safety performance functions (SPFs) for two pedestrian crash types: total pedestrian crashes at intersections (a high frequency type) and a subset of intersection crashes involving through motorists striking crossing pedestrians (a high severity type). Many variables from roadway, built environment, census, and activity measures were tested. A similar but not identical set of variables, including measures of activity and intersection size and complexity, significantly contributed to crash prediction in both models. Pedestrian volume exhibited a curved relationship to crashes and demonstrated a tendency for expected crashes to begin to decline above a threshold value; however, the causes of this relationship were unknown. The SPFs were used in several ranking methods, including SPF-predicted crashes, empirical Bayes estimated crashes, and potential for safety improvement, to aid in prioritization of locations that might have been candidates for safety improvement but that had not necessarily experienced a high frequency of crashes. On the basis of this example, this approach is feasible for jurisdictions that wish to be more proactive in addressing potential crashes and injuries. Jurisdictions must, however, begin routinely collecting the data needed to implement the method efficiently.

Comparative Analysis of Performance Measures for Network Screening: A Case Study of Brazilian Urban Areas

The overall effectiveness of the roadway safety management process relies on a robust method for identifying and ranking sites with major potential for safety improvements. In Brazil, guidelines for hotspot identification are usually based only on crash frequency and Crash Rate as safety performance measures. This study presents a comparative analysis of safety performance measures, considering its limitations of applicability in a sample of signalized intersections from Fortaleza city, Brazil. The performance of each measure to rank the sample intersection was obtained through the rank difference between each safety performance measure and the Excess Expected Average Crash Frequency with EB Adjustment (EEB). In addition, it has taken a temporal analysis based on the consistency of safety performance measures during subsequent time periods. The results have suggested a reasonable matching between the most comprehensive safety performance measure (EEB) and very simple safety performance measures such as crash frequency and Crash Rate. It is recommended to investigate the consistency of the results for longer observation period as well as for a different jurisdiction in Brazil.

Influence of In-Vehicle Adaptive Stop Display on Driving Behavior and Safety

In 2012, 683 000 crashes occurred at stop-sign-controlled intersections, with 2434 of those crashes being fatal and composing 5.3% of all fatal traffic incidents in the United States. Roughly 50% of all fatal crashes at stop-sign-controlled intersections involve crossing over (i.e., running) the traffic control device. With the advent of connected-vehicle technology, it is possible to provide a salient in-vehicle adaptive stop display to a driver. This display could alert a driver when he or she will have to stop at an intersection due to oncoming traffic. The same display could also permit drivers to pass through an intersection without stopping when a conflicting vehicle is not present. The purpose of this paper was to evaluate these potential improvements in safety and mobility through an empirical research study. An in-vehicle adaptive stop display was developed and tested on the Virginia Smart Road. Forty-nine drivers were exposed to multiple intersection scenarios they would experience in the real world while using connected-vehicle technology. The scenarios included variations in adjacent traffic, equipment malfunctions, and total equipment failures. There were no indications of a safety detriment to using the adaptive stop display in terms of compliance (likelihood of driver adhering to the information presented), driver complacency, or driver risk taking. Furthermore, the study indicates that, with a higher measured rate of compliance, an in-vehicle adaptive stop display would have a positive impact on safety.

Factors related to monitoring during admission of acute patients

Understanding the use of patient monitoring systems in emergency and acute facilities may help to identify reasons for failure to identify risk patients in these settings. Hence, we investigate factors related to the utilization of automated monitoring for patients admitted to an acute admission unit by introducing monitor load as the proportion between monitored time and length of stay. A cohort study of patients admitted and registered to patient monitors in the period from 10/10/2013 to 1/10/2014 at the acute admission unit of Odense University Hospital in Denmark. Admissions with at least one measurement were analyzed using quantile regression by looking at the impact of distance from nursing office, number of concurrent patients, wing type (medical/surgical), age, sex, comorbidities, and severity conditioned on how much patients were monitored during their admissions. We registered 11,848 admissions, of which we were able to link patient monitor readings to 3149 (26.6 %) with 50 % being monitored <1.4 % of total admission time. Distance from nursing office had little influence on patients monitored <10 % of their admission time. But for other patients, being positioned further away from the office reduced the level of monitoring. Higher levels of severity were related to higher degrees of monitoring, but being admitted to the surgical wing reduce how much patients were monitored, and periods with many concurrent patients lead to a small increase in monitoring. We found a significant variation concerning how much patients were monitored during admission to an acute admission unit. Our results point to potential patient safety improvements in clinical procedures, and advocate an awareness of how patient monitoring systems are utilized.

Comparison of Italian and Hungarian Black Spot Ranking

Black spot ranking is an important tool for finding the sites with potential safety improvement on the road network. The EU Directive on Road Infrastructure Safety Management also demands the ranking of high accident concentration sites. This paper gives an introduction to localizing high accident concentration sites and the indicators used by Italy and Hungary. Accident and traffic volume data are gathered for motorway sections from both countries. Safety ranking is made using two conventional indicators, absolute number of accidents and accident rate. A more sophisticated ranking using the Empirical Bayes method is applied. Expected average crash frequency with Empirical Bayes adjustment is calculated. Based on the estimation of the crash frequency, the Critical Crash Rate (CCR) was added to identify and rank black spots. This additional performance measure is able to take into account traffic volume as required by the EU Directive. Results of the Empirical Bayes method are compared with the conventional procedures. It is concluded that the results are not comparable; inasmuch as there are modifications in the order of black spots. Based on the comparison of results recommendations are given to change the practice in both countries.

Progress in reliability of fast reactor operation and new trends to increased inherent safety

Abstract The reasons for the renewed interest in fast reactors and an overview of the progress in sodium cooled fast reactor operation in the last ten years are given. The excellent operational performance of sodium cooled fast reactors in this period is highlighted as a sound basis for the development of new fast reactors. The operational performance of the BN-600 is compared and evaluated against the performance of German light water reactors to assess the reliability. The relevance of feedback effects for safe reactor design is described, and a new method for the enhancement of feedback effects in fast reactors is proposed. Experimental reactors demonstrating the inherent safety of advanced sodium cooled fast reactor designs are described and the potential safety improvements resulting from the use of fine distributed moderating material are discussed. One sentence summary: Operating fast reactors have shown excellent in-service behavior within the last 10 years, new designs and methods are available to significantly improve safety.

Multi-level hot zone identification for pedestrian safety

According to the National Highway Traffic Safety Administration (NHTSA), while fatalities from traffic crashes have decreased, the proportion of pedestrian fatalities has steadily increased from 11% to 14% over the past decade. This study aims at identifying two zonal levels factors. The first is to identify hot zones at which pedestrian crashes occurs, while the second are zones where crash-involved pedestrians came from. Bayesian Poisson lognormal simultaneous equation spatial error model (BPLSESEM) was estimated and revealed significant factors for the two target variables. Then, PSIs (potential for safety improvements) were computed using the model. Subsequently, a novel hot zone identification method was suggested to combine both hot zones from where vulnerable pedestrians originated with hot zones where many pedestrian crashes occur. For the former zones, targeted safety education and awareness campaigns can be provided as countermeasures whereas area-wide engineering treatments and enforcement may be effective safety treatments for the latter ones. Thus, it is expected that practitioners are able to suggest appropriate safety treatments for pedestrian crashes using the method and results from this study.