• Journal of Korean Society of Transportation
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• v.25 no.1 s.94
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• pp.73-79
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• 2007

This study deals with traffic accidents at the ramps of trumpet interchanges. The purpose of the study is to analyze the relations between tke turning direction of ramps (and combinations with other factors) and traffic accidents. In Pursuing this analysis, this study gives particular attention to the combination of turning direction and grade and the combination of turning direction and radius of curvature in the case of the trumpet interchange ramps. The null hypothesis tests show that the average accident number and average accident rate ate rejected at the 90% and 95% significance level respectively Also. the null hypothesis tests show that the combinations or turning direction and Evade as well as turning direction and radius are all rejected at the 95% significance level. In summary, right turn movements ate more dangerous than left turns on the trumpet interchange vamps. Also, ramps with a right turn and up grade or with a left turn and radius more than 200m have more traffic accident Potential than other types of ramps.

• Journal of Korean Society of Transportation
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• v.25 no.3
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• pp.123-135
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• 2007

The objective of this study is to analyze the relationship between traffic accidents occurring at trumpet interchange ramps according to accident type as well as the relevant factors that led to the traffic accidents, such as geometric design elements and traffic volumes. In the process of analysis of the distribution of traffic accidents, negative binomial distribution was selected as the most appropriate model. Negative binomial regression models were developed for total trumpet interchange ramps, direct ramps, loop ramps and semi-direct ramps based on the negative binomial distribution. Based upon several statistical diagnostics of the difference between observed accidents and predicted accidents with four previously developed models, the fit proved to be reasonable. Understanding of statistically significant variables in the developed model will enable designers to increase efficiency in terms of road operations and the development of traffic accident prevention policies in accordance with road design features.

• Proceedings of the KOR-KST Conference
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• 2007.11a
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• pp.404-411
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• 2007

• Journal of Korean Society of Transportation
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• v.25 no.6
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• pp.55-63
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• 2007

This research deals with the relations between intersection types and traffic accidents in the case of Korean expressways. The purpose of this research is to test the hypotheses that traffic accidents depend on intersection types and geometric design elements. The main research results are as follows. First, the accident comparisons that are drawn from junctions with interchanges, and trumpet interchanges with other types of interchanges respectively displays no significant meaning. However, the differences among four types of trumpet interchanges are found to be meaningful. In other words, the BO type trumpet interchanges seem to have far more traffic accidents than other types of trumpet interchanges. Second, hypothesis tests show that approximately 90 degree and one lane connection roads have lower accident rates. Based on this research, the following directions can be suggested for the safer types of intersections and geometric design elements in freeway construction. From a road safety point of view, it is advisable not to introduce BO type interchanges. It is also desirable that the intersection angle should be approximately 90 degrees. Furthermore, it would be wise to design one lane roads if the connection road has low traffic volumes.

• Journal of Auto-vehicle Safety Association
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• v.6 no.2
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• pp.23-28
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• 2014

Commercial vehicle ESC assessment for curvature road was conducted. The previous study of ESC activation condition for losing controllability utilizing the test protocols of double lane change and sine with dwell method was conducted without considering the geometric complexity of roadway design. Since critical rollover accidents were frequently observed in the exit ramp zone, variety of curve, slope and bank have been added for analysis conditions. Detailed feature of the ramp including location, dimension and design characteristics have been analyzed from the typical trumpet type ramp design. Analyzing accident data from 2008, two specific ramps have been selected due to their complexity in design and severity in steering operation.

• International Journal of Highway Engineering
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• v.14 no.6
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• pp.85-92
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• 2012

PURPOSES : Since expressways in South Korea are toll roads, many trumpet type interchanges exist, resulting in the installation of loop ramps very frequently. While the travel speed of the main lane is designed to be 100-110 km/h, the structure of a loop ramp is different and is designed for a minimum speed of 40 km/h. In fact, most of the actual travel speeds measured on the ramp exceed the designated speed, which has been a major problem in traffic safety. In this research, a type of pavement marking speed-reduction treatment called the "Peripheral Transverse Line" is installed on expressway loop ramps in order to study the change of driving speeds after the installation. METHODS : To verify statistically the change, this speed-reduction treatment has been installed on the Chungju interchange and the Yeoju junction. The driving speeds before the installation were compared with driving speeds both one month and five monthsafter the installation. RESULTS : As a result, the reductions of the average driving speeds after the treatment were statistically significant. More specifically, the average driving speeds of the Chungju interchange were reduced by 7.1-7.7 % for its tangent road section, and the speeds decreased by 8.5-9.5 % for its curve section. Similarly, in the Yeoju junction, an average speed reduction of 2.9-4.8 % for its tangent section was measured, along with 3.9% long-term speed reduction for its curve section. CONCLUSIONS : Since the pavement marking speed-reduction treatment has been partially proven to be effective from this research, we expect to expand this treatment and re-confirm the effect from a long-term perspective in the future.