| 1. |
- Flannagan, Carol. A. C., et al.
(författare)
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Comparing motor-vehicle crash risk of EU and US vehicles
- 2018
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Ingår i: Accident Analysis and Prevention. - : Elsevier. - 0001-4575 .- 1879-2057. ; 117, s. 392-397
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Tidskriftsartikel (refereegranskat)abstract
- This study examined the hypotheses that passenger vehicles meeting European Union (EU) safety standards have similar crashworthiness to United States (US) -regulated vehicles in the US driving environment, and vice versa. The first step involved identifying appropriate databases of US and EU crashes that include in-depth crash information, such as estimation of crash severity using Delta-V and injury outcome based on medical records. The next step was to harmonize variable definitions and sampling criteria so that the EU data could be combined and compared to the US data using the same or equivalent parameters. Logistic regression models of the risk of a Maximum injury according to the Abbreviated Injury Scale of 3 or greater, or fatality (MAIS3+F) in EU-regulated and US-regulated vehicles were constructed. The injury risk predictions of the EU model and the US model were each applied to both the US and EU standard crash populations. Frontal, near-side, and far-side crashes were analyzed together (termed "front/side crashes") and a separate model was developed for rollover crashes.For the front/side model applied to the US standard population, the mean estimated risk for the US-vehicle model is 0.035 (sd = 0.012), and the mean estimated risk for the EU-vehicle model is 0.023 (sd = 0.016). When applied to the EU front/side population, the US model predicted a 0.065 risk (sd = 0.027), and the EU model predicted a 0.052 risk (sd = 0.025). For the rollover model applied to the US standard population, the US model predicted a risk of 0.071 (sd = 0.024), and the EU model predicted 0.128 risk (sd = 0.057). When applied to the EU rollover standard population, the US model predicted a 0.067 risk (sd = 0.024), and the EU model predicted 0.103 risk (sd = 0.040).The results based on these methods indicate that EU vehicles most likely have a lower risk of MAIS3+F injury in front/side impacts, while US vehicles most likely have a lower risk of MAIS3+F injury in llroovers. These results should be interpreted with an understanding of the uncertainty of the estimates, the study limitations, and our recommendations for further study detailed in the report.
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| 2. |
- Denby, Bruce Rolstad, et al.
(författare)
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A coupled road dust and surface moisture model to predict non-exhaust road traffic induced particle emissions (NORTRIP). Part 2 : Surface moisture and salt impact modelling
- 2013
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Ingår i: Atmospheric Environment. - : Elsevier. - 1352-2310 .- 1873-2844. ; 81, s. 485-503
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Tidskriftsartikel (refereegranskat)abstract
- Non-exhaust traffic induced emissions are a major source of airborne particulate matter in most European countries. This is particularly important in Nordic and Alpine countries where winter time road traction maintenance occurs, e.g. salting and sanding, and where studded tyres are used. Though the total mass generated by wear sources is a key factor in non-exhaust emissions, these emissions are also strongly controlled by surface moisture conditions. In this paper, Part 2, the road surface moisture submodel of a coupled road dust and surface moisture model (NORTRIP) is described.We present a description of the road surface moisture part of the model and apply the coupled model to seven sites in Stockholm, Oslo, Helsinki and Copenhagen over 18 separate periods, ranging from 3.5 to 24 months. At two sites surface moisture measurements are available and the moisture sub-model is compared directly to these observations. The model predicts the frequency of wet roads well at both sites, with an average fractional bias of -2.6%. The model is found to correctly predict the hourly surface state, wet or dry, 85% of the time. From the 18 periods modelled using the coupled model an average absolute fractional bias of 15% for PM10 concentrations was found. Similarly the model predicts the 90'th daily mean percentiles of PMio with an average absolute bias of 19% and an average correlation (R-2) of 0.49. When surface moisture is not included in the modelling then this average correlation is reduced to 0.16, demonstrating the importance of the surface moisture conditions. Tests have been carried out to assess the sensitivity of the model to model parameters and input data. The model provides a useful tool for air quality management and for improving our understanding of non-exhaust traffic emissions.
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| 3. |
- Gómez, Radhameris A, et al.
(författare)
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A driving simulator evaluation of road markings and symbolic signs on vehicle-pedestrian conflicts
- 2013
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Ingår i: Proceedings of the 16th International Conference Road Safety on Four Continents. - Linköping : Statens väg- och transportforskningsinstitut.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Pedestrians are amongst the most vulnerable of road users. A common way of accommodating pedestrians at non-signalized intersections is through the use of mid-block crosswalks. Pedestrian crashes at marked mid-block crosswalks are often no less frequent than at unmarked mid-block crosswalks.The risk to pedestrians is especially high when a driver’s view of pedestrians in a crosswalk is obstructed as the driver approaches the crosswalk creating a multi-threat situation for the pedestrian. Such a situation is too risky to study on the open road, but not on a driving simulator. Among the most effective and least costly of the safety alternatives are advance yield markings. This study uses a driving simulator to evaluate vehicle-pedestrian conflicts in sight-limited scenarios with advance yield markings and “Yield Here to Pedestrians” symbol signs as well as the standard crosswalk treatments and signs. Measures of drivers’ performance include actual crashes as well as the drivers’ glancing behavior to determine if the drivers approaching a marked midblock crosswalk look for pedestrians in the crosswalk more frequently and sooner in high risk, multiple-threat scenarios when advance yield markings and prompts are present than when standard markings and prompts are used. The results suggest that fewer crashes occur with advance yield markings. And we find that drivers look much more frequently and much sooner for pedestrians with advance yield markings. Uses and limitations surrounding the development of scenarios on a driving simulator and the advantages and limitations of using driving simulation to study problems such as this are discussed.
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| 4. |
- Gómez, Radhameris A., et al.
(författare)
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An evaluation of traffic control devices and driver distraction on driver behavior at railway-highway grade crossings
- 2016
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Konferensbidrag (refereegranskat)abstract
- The U.S. railroad system is made up of over 700 railroads operating on 140,000 miles of track, with more than 130,000 at-grade public railway-highway crossings, or intersections in which any part of a roadway intersects with railroad tracks. Safety at these railroad-highway grade crossings and the related traffic control devices used to communicate with drivers is of major concern. There are three factors that influence a driver’s behavior at a given crossing. First, traffic control devices, including warning devices at the railway-highway at-grade crossings, provide the driver with information. Second, assuming that the driver identifies the warning, the driver’s prior knowledge influences his or her expectancy regarding various railroad-highway grade crossing situations and, therefore, the way in which the driver responds to the hazard presented by the crossing. Finally, the driver’s own physiological (e.g., impaired) and psychological (e.g., distracted) state will modify the role that conspicuity and expectancy have on the driver’s behavior In order to address the gap that exists in our understanding of driver distraction at railway-highway at-grade crossings, two driving simulator experiments were conducted to determine the role that distraction has on the effectiveness of warning devices at grade crossings. In the first experiment, the role of distraction in reducing the benefit of typical crossbucks and flashing lights is evaluated. Participants were either engaged or not engaged in a distracting task, which included either a mock cell phone conversation or an in-vehicle task. Based upon the fact that distractions reduce the advantage of flashing lights and crossbucks, an evaluation of an alternative treatment that might be used to warn drivers of an approaching train was conducted. The question being addressed is whether these alternative markings, known as dynamic envelope pavement markings are an effective application for mitigating the effects of driver distraction at at-grade railway-highway grade crossings. Initial findings point to the fact that even when flashing lights and its respective signage and markings are properly working, a distracted driver is more likely to ignore the cues.
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| 5. |
- Li, Zhixia, et al.
(författare)
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Calibrating VISSIM roundabout model using a critical gap and follow-up headway approach
- 2013
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Ingår i: Proceedings of the 16th International Conference Road Safety on Four Continents. - Linköping : Statens väg- och transportforskningsinstitut.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Roundabouts have been continuously constructed in the U.S. in recent years, as studies have shown their capability of reducing crash risk and severity when compared with signalized intersections. Despite of the safety benefits offered by roundabouts, operational efficiency is required be analyzed when considering building roundabouts. As a prevailing simulation platform for modeling roundabouts, VISSIM have been widely applied in practice to facilitate analyzing the operational performance of roundabouts. Considering that an essential prerequisite to preparing a VISSIM roundabout model is to calibrate the model by adjusting VISSIM parameters, comprehensive calibration guidance is of great importance to practitioners. Previous calibration research has conducted qualitative analysis to study the impact of VISSIM parameters on roundabout capacity. However, parameter values based on field data and quantitative calibration guidelines are more helpful to facilitate fast and accurate modeling of roundabouts. This paper addresses these important needs. Speed trajectories of free-flow entering vehicles were collected in the field using a radar sensor. Location, length, speed distribution, and deceleration rate parameters for the VISSIM Reduced Speed Areas (RSA) were determined through the analysis of the radar data. The impact of VISSIM parameters on critical gap and follow-up headway was quantitatively analyzed through sensitivity analysis of minimum gap for PR, speed distribution and deceleration rate for RSA, and additive and multiplicative settings for the Wiedemann 74 model. Numerical guidelines for calibrating VISSIM roundabout models were ultimately developed, and validated via a case study.
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| 6. |
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| 7. |
- Schwarz, Johanna F. A., et al.
(författare)
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In-car countermeasures open window and music revisited on the real road : popular but hardly effective against driver sleepiness
- 2012
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Ingår i: Journal of Sleep Research. - : Wiley. - 0962-1105 .- 1365-2869. ; 21:5, s. 595-599
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Tidskriftsartikel (refereegranskat)abstract
- This study investigated the effects of two very commonly used countermeasures against driver sleepiness, opening the window and listening to music, on subjective and physiological sleepiness measures during real road driving. In total, 24 individuals participated in the study. Sixteen participants received intermittent 10-min intervals of: (i) open window (2 cm opened); and (ii) listening to music, during both day and night driving on an open motorway. Both subjective sleepiness and physiological sleepiness (blink duration) was estimated to be significantly reduced when subjects listened to music, but the effect was only minor compared with the pronounced effects of night driving and driving duration. Open window had no attenuating effect on either sleepiness measure. No significant long-term effects beyond the actual countermeasure application intervals occurred, as shown by comparison to the control group (n = 8). Thus, despite their popularity, opening the window and listening to music cannot be recommended as sole countermeasures against driver sleepiness.
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| 8. |
- Tang, Yue, et al.
(författare)
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A comparative study of the application of the standard kernel density estimation and network kernel density estimation in crash hotspot identification
- 2013
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Ingår i: Proceedings of the 16th International Conference Road Safety on Four Continents. - Linköping : Statens väg- och transportforskningsinstitut.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Despite a growing number of studies have claimed the network Kernel Density Estimation (network KDE) a more advanced method for crash hotspot identification than the planar Kernel Density Estimation (planar KDE), few conducted comprehensive study to examine their accuracy and practicality on a large-scale basis (i.e. municipal and county). This research attempted to fill the gap by conducting a comparative study of planar KDE and network KDE using the crash data of Hampden County, Massachusetts from 2009 to 2011. A two-tier planar KDE and a network KDE were implemented using the Kernel Density tool in ESRI ArcGIS 10 and SANET 4.1 developed at University of Tokyo respectively. Results showed that (1) Planar KDE is computationally inexpensive and easily accessed. (2) Both methods yielded virtually similar hotspot patterns but with different rankings of the high crash locations. (3) In identifying specific hotspot locations, network KDE could achieve more accurate results and was more timesaving, although multiple runs of planar KDE identified specific locations as well. Accordingly, several suggestions were made for crash hotspot analysis: (1) Since KDE takes the interrelationship among crashes into consideration, it is a more statistically sound approach than traditional methods in crash hotspot identification and can be widely adopted by state and local agencies for initiating safety improvement projects. (2) Planar KDE is recommended to identify general hotspot patterns on large-scale basis for its practicality and efficiency. (3) Network KDE is recommended to identify specific intersections and roadway segments for accuracy.
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