• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.2
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• pp.573-582
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• 2014

Since there is no clear installation criteria on minimum spacing between signalized intersection and minor road, many problems have occurred in terms of traffic operation and safety. Even though many studies about entrance/exit intersection have been done in operational aspects, there is no specific and detailed research between the signalized intersection and minor road by now. Thus, this research suggests the optimal spacing between signalized intersection and minor road considering traffic operation and safety. Also, survey on vehicle behavior was conducted in this research. In conclusion, by suggesting the required minimum spacing between signalized intersection and minor road, it can be contribute in establishing and operating the installation criteria between signalized intersection and minor road.

• Journal of Korean Society of Transportation
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• v.25 no.3
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• pp.19-28
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• 2007

Korea's national highways, which emphasize a high level of mobility, serve primarily intercity travel and are used as a detour for freeways. However. at the present. the highways do not have consistent geometric features or other characteristics: for example. some highways have full access control and others have uncontrolled access. Generally, geometric and traffic conditions affect Pronouncedly travel speeds in the highway sections. This study focused on the effect of signalized intersection relative factors on the speeds: signalized intersection densities, signal phases, and volume levels. The study shows that signalized intersection density was the strongest variable affecting the travel speeds: the speeds held fairly constant over intersection densities below 0.3 intersections/km, decreased sharply through intersection density of 0.7 intersections/km. and appeared constant at the lowest level over intersection densities above 0.7 intersections/km. The results also indicate that the effect of signal and traffic volume levels on the speeds was similar to that of the signalized intersection density.

• International Journal of Highway Engineering
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• v.17 no.1
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• pp.91-98
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• 2015

PURPOSES : Although signalized intersections have been considered the best way to control traffic volume in urban areas for several decades, roundabouts are currently being discussed as an alternative way to control traffic volume, especially when traffic is light. Because a roundabout's efficiency depends on the load geometry as well as the traffic volume, design guidelines for roundabouts are recommended only if the incoming traffic volume is very low. It is rare to substitute a roundabout for an existing signalized intersection in urban areas. This study aims to estimate the benefits from the transformation of an existing signalized intersection into a roundabout in an urban area. When there is a more moderate volume of traffic, roundabouts can be effectively used by optimizing signals located at an approaching roadway. METHODS : The methodologies of this paper are as follows: First, a signalized intersection was analyzed to determine the traffic characteristics. Second, the signalized intersection was transformed into a roundabout using VISSIM microscopic traffic simulation. Then, we estimated and analyzed the effects and the performance of the roundabout. In addition, we adjusted a method to improve the benefits of the transformation via the optimization of signals located at an approaching road to control the incoming traffic volume. RESULTS : The results of this research are as follows: The signal-optimized roundabout improved delays compared with the signalized intersection during the morning peak hour, non-peak hour, and evening peak hour by 1.78%, 12.45%, and 12.72%, respectively. CONCLUSIONS : According to the simulation results of each scenarios, the signal-optimized roundabout had less delay time than the signalized intersection. If optimized signal control algorithms are installed in roundabouts in the future, this will lead to more efficient traffic management.

• International Journal of Highway Engineering
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• v.13 no.1
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• pp.59-67
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• 2011

It can prevent traffic accidents in a way as taking precautionary measures for road safety at signalized intersection in advance. Particularly, traffic accidents can be reduced at relatively low cost without redesigning alignments. That is 'Positive Guidance method' which can help prevent traffic accidents through improvement of road facilities at signalized intersection. In this study, potentially higher hazardous signalized intersection due to speeding was selected through site investigation. Field analysis at designated section was conducted and devised a plan for improvements of road facilities. Subjects drove in driving simulator in 3-D virtual reality of designated intersection. Based on data from simulator, statistical analysis(t-verification) was conducted for 'Before and After effectiveness' of speed reduction. As a result, it indicates that speed reduction was effective after improvements at each spot in driving simulator. In the future, hazardous signalized intersections which can be applied for PG method will be effective for road safety based on this research.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.8 no.2
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• pp.27-35
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• 2009

The roundabout was developed in the United Kingdom to rectify problems associated with these traffic circles. In 1966, the United Kingdom adopted a mandatory "give-way" rule at alt circular intersections, which required entering traffic to give way, or yield, to circulating traffic. However, the roundabout used in United States or Europe do not common use in Korea. The purposes of the study is to comparatively analyze the effectiveness of roundabout. In pursuing the above, this study designs the scenarios which can reflect the directional traffic volumes, and analyzes the average control delay of roundabout and 4-leg signalized intersection by SIDRA. The main study results are as follows. First, when the entering traffic volume are less than 2,000pcph, the single-lane roundabout is analyzed to be more effective than 4-leg signalized intersection. Second, when the entering traffic volume are less than 3,200pcph, the double-lane roundabout is evaluated to be more effective than 4-leg signalized intersection. Third, which is installed left and right turn lane at intersection, area for the roundabout is analyzed to be less than that for general intersection area.

• Journal of Korean Society of Transportation
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• v.34 no.4
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• pp.291-303
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• 2016

The number of traffic accidents at intersections has been increased over the past decade, and in 2014, accounted for 44% of the total traffic accidents. In addition, since most of road accident black spots include signalized intersections, the improvement of safety on signalized intersection is top priority for national road safety program in Korea. For the decision of most effective action plan for the safety of signalized intersection, this study conducted meta-analyses to assess the effects of various road safety facilities at signalized intersection on traffic accidents. We selected 19 articles regarding the prediction of traffic accidents at signalized intersection and calculated 34 individual effect sizes on 8 variables included in the articles. The results found that there was a statistically significant negative relationship between the occurrence of traffic accident and the presence of all of road safety facilities except an exclusive left turn bay. It shows that most of the road safety facilities could prevent traffic accidents, and intersection channelization has the most effective on the reduction of traffic accidents followed by left-turn acceleration lane, lightning, crosswalk, exclusive right-turn lane and median barrier.

• Journal of Korean Society of Transportation
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• v.19 no.2
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• pp.21-28
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• 2001

This study is to estimate the through car equivalent for left-turn movement according to left turn radius in the signalized intersection. The saturation flow rate for left-turn movement in 92' KHCM(Korea Highway Capacity Manual) is the same as that for through movement in the signalized intersection where the left turn radius is over 20m. This study uses Duncan 'Test's Test in order to find out the saturated position for queued vehicle in the signalized intersection. It found that the saturated flow rate of left-turn movement in the signalized intersection is less than that of through movement where the left-turn radius is less than 20m. It found that the through car equivalents for left-turn movement according to left-turn radius(8m-20m) are between 1.05 and 1.14.

• 한국ITS학회:학술대회논문집
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• 2010.05a
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• pp.82-86
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• 2010

• International Journal of Highway Engineering
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• v.17 no.1
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• pp.119-127
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• 2015

PURPOSES : Before-and-after studies of red light cameras were conducted with the aim of reducing the number of side right-angle collisions. Three different methods were used for the before-and-after studies, and the analysis results were compared. METHODS : This research used the naive before-and-after method, the comparison-group method, and the empirical Bayes method to study the effects of red light cameras on side-angle collisions. The results of the three before-and-after methods were compared and interpreted in terms of safety indications at signalized intersections. RESULTS : The research results showed that side right-angle collisions can be reduced by installing red light cameras at signalized intersections. All three methods guarantee safety improvements of 25~30% on average. With regard to the results of each method, the naive before-and-after method, the comparison-group method, and the empirical Bayes method showed safety improvements of 25.6%, 27.8%, and 29.7%, respectively. CONCLUSIONS : It was concluded that red light cameras are an effective countermeasure to improve intersection safety. In particular, by installing red light cameras, side right-angle collisions can be reduced by up to approximately 25~30%.

• Journal of Korean Society of Transportation
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• v.26 no.4
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• pp.41-49
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• 2008

Signalized intersection analysis using lane groups often generalizes distinct characteristics of individual lanes. An individual lane level analysis procedure is proposed. The method can assess individual lane LOS without additional data collection efforts. Analysis results of the proposed method were compared with the current HCM analysis results and outputs of aaSIDRA, which can calculate intersection performance lane-by-lane. The results showed individual lane analysis mostly produces similar results with HCM and aaSIDRA. However, lane analysis results for permitted left lanes showed some differences with aaSIRDRA due to the different method of assessing saturation flow rate of the permitted left turn movement. It is expected that the proposed method could complement the weaknesses of current HCM signalized intersection analysis.