• Journal of Korean Society of Transportation
• /
• v.25 no.4
• /
• pp.7-19
• /
• 2007

The purpose of posted speeds is to provide a speed that ensures the safety of vehicle flow according to given road situations. Because of this, posted speeds must be carefully examined, and posted speeds at freeway exits and entrances in particular should consider car characteristics. Posted speeds at freeway exits and entrances must take changing speeds due to curve radiuses into consideration and in this study, an 85th percentile speed becomes the most important element to consider. When it is considered that most traffic accidents occur because of variations in speed between cars, posted speeds should be set after considering car traveling characteristics. Within these dimensions, instead of putting significance on an upper direction regulation or lower direction regulation, speed distributions which fit to the characteristics of each road should be fully considered. Accordingly, this study evaluated appropriate posted speeds that will reduce the dangers of traffic accidents through posted speed regulations of roads now in operation by offering a posted speed setting method theory, using entries at Yangji, Yongin, and Cheongwon interchanges as subjects.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.05a
• /
• pp.69-69
• /
• 2004

고무타이어를 주행륜으로 사용하고 무인운전으로 운행되는 고무차륜 AGT 경량전철 차량의 성능최고 속도는 70km/h이고 운행최고속도는 60km/h로 차량 표준사양에서 결정되어 고시되었다. 그러나 차량이 운행되는 노선의 다양한 곡률반경에 따라 제한속도가 결정되어야 하고, 고무타이어가 손상된 경우를 가정한 안전 제한속도도 결정해야 한다. 본 논문의 목적은 설계 및 제작이 완료된 한국형 표준 고무차륜 AGT 경량전철 차량에 대해 운행노선의 곡선반경에 따른 제한속도, 고무타이어의 손상에 따른 안전 제한속도, 그리고 이상의 조건들에 대한 승객의 승차감을 해석하여 제안하는 것이다.(중략)

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 2000.04a
• /
• pp.668-671
• /
• 2000

본 논문은 노변과 차량간의 RF통신을 이용하여 차량의 속도를 제어하는 시스템이다. 본 시스템에서 노변의 RF송수신기는 운전자에게 도로의 제한속도를 포함하여 사고의 발생, 도로의 결빙과 같은 교통정보를 제공한다. 이때 차량의 속도가 제한속도 이상일 경우에는 차량 내 제어장치가 작동하여 차량의 속도를 제한속도 이하가 되도록 한다. 현재 도로를 주행중인 운전자는 제한속도표지판을 보아야 그 도로의 제한속도를 인식할 수 있다. 그러므로 자칫 제한속도표지판을 인식하지 못하고 지나치는 경우에 운전자는 무의식중에 과속운전을 할 수도 있다. 과속운전으로 인한 문제점은 우리나라에서 일어나는 교통사고의 상당부분을 차지할 정도로 크다. 따라서 본 개발 시스템은 운전자가 과속운전을 할 수 없도록 과속운전시 2∼3차례 경고방송을 하고 그래도 운전자가 속도를 줄이지 않을 경우 자동으로 차량의 속도를 제한속도이하가 되도록 한다.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.21 no.5
• /
• pp.149-161
• /
• 2022

Because the speed limit affects moving speed, it is closely related to traffic accidents as well as traffic flow. The existing speed limit calculation methods consider various engineering factors such as lanes, intersection spacing, driveways, crosswalks, 85 percentile speed, land uses, and roadway geometric characteristics etc. However, it can be said that the engineering analysis is insufficient because the traffic impact analysis considering traffic volume is not carried out. In addition, only 85 percentile speed, which is the spot speed, does not reflect the characteristics of the traffic flow on the road. In this paper, the effect of the speed limit change on the moving speed and the travel speed was analyzed in detail accordinr to the variation of intersection spacing and traffic volume. And by using the results, we proposed a speed limit calculation method that maintains the same service level as before the speed limit change, thereby increasing the speed improvement effect and reducing the difference between moving speed and travel speed. In addition, a variable speed limit operation method according to the change in traffic volume was also suggested. This method is expected to be effective in terms of safety by reducing the speed difference, which affects the severity of traffic accidents, while securing the speed improvement effect, and increasing the speed limit compliance rate of drivers by operating the speed limit that reflects the speed change due to the variation of traffic volume.

• Journal of Korean Society of Transportation
• /
• v.23 no.7 s.85
• /
• pp.35-42
• /
• 2005

Few studies have been carried out to find out the interaction of design speeds, operating speeds, and posted speeds though they have a complementary relationships. As an attempt to find the relationships, this study measured the speeds of the free flowing vehicles at four lane rural highways. In comparison of 95th percentile speeds and inferred design speeds determined from the road design manual with the geometric features of each sites, operating speeds were constantly higher than the inferred design speeds at the sites where the inferred design speed is under 110km/h. and the reverse situation was observed at the sites where the inferred design speed is over 130km/h. In the comparison of operating speeds and posted speeds. the range of the 85th percentile speeds at the sites where posted speeds is 80km/h was distributed from 95km/h to 110km/h. and the range was distributed from the 105km/h to the 120km/h at the sites where posted speeds is 90km/h. Multiple regression analysis was used to develop prediction equations for mean. 85th. and 95th percentile speeds at approach and curve midpoint locations. At the midpoint, only posted speeds influenced the mean, 85th. At the approach locations, the mean, 85th, 95th percentile speeds were influenced by posted speeds and length of the approach tangent.

• 한국ITS학회:학술대회논문집
• /
• 2005.11a
• /
• pp.7-12
• /
• 2005

• Journal of Korean Society of Transportation
• /
• v.26 no.4
• /
• pp.111-121
• /
• 2008

Using variable speed limits (VSL) is a key strategy for preventing traffic accidents and alleviating traffic congestion. This study proposes an algorithm to operate VSLs on freeways for traffic safety. The proposed algorithm consists of two components based on accident likelihood estimation and analysis of safe stopping distance under various environmental conditions. A binary logistic regression technique is used for estimating accident likelihood. It is expected that the proposed algorithm would be successfully applied in practice in support of an integrated traffic and environmental condition monitoring system. Technical issues associated with the field implementation are also discussed.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.23 no.2
• /
• pp.32-49
• /
• 2024

In this paper, we analyzed the impacts of road traffic conditions and speed limit changes on traffic flow and safety. Travel speed and moving speed were set as traffic flow indicators and'moving speed-travel speed',speed deviation, large speed deviation ratio, and number of conflicts were set as safety indicators, and the impacts of changes in road traffic conditions and speed limits on these were analyzed. According to the analysis results, the speed limit had a significant impacts on the traffic indicators, but did not significantly affect the safety indicators. As a result of the statistical validity test, it was proven that the traffic flow index increases as the speed limit increases. However, although safety indicators often increase, their validity has not been proven statistically. Therefore, if the speed limit is set and operated by properly considering the traffic flow status according to various road conditions and changes in traffic volume, it can be said to match the speed at which drivers drive and improve traffic flow and safety. Therefore, it is expected that calculating the speed limit considering the traffic flow indicators and safety indicators presented in this paper and operating the speed limit according to changes in traffic volume will contribute to stabilizing the traffic flow on the road.

• International Journal of Highway Engineering
• /
• v.12 no.2
• /
• pp.63-69
• /
• 2010

Since speed limit enforcement in school zones is the most important to reduce the occurrence of severe child related accidents, school zones typically have a speed limit of 30km/h. However, it is found that the majority of vehicles passing school zones are traveling over 30km/h. This indicates that school zones are not being effectively operated to achieve the main objective which is the reduction of child related accidents. This study aims to identify the factors affecting the violation of speed limits in school zones through the results of field survey from 8 elementary schools. The results showed that time period, the number of lanes, the width of sidewalks, and the status of colored pavement were found to be highly associated with the violation of speed limits in school zones at the 95% significance level. The results of this study may provide some insights for making safe environments around schools.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.15 no.6
• /
• pp.138-149
• /
• 2016

The study reviewed the effects of the variable speed limit under adverse weather conditions by using a driving simulator. The study assumed that the display of the reduced speed limit without any change of the weather condition and the display of the same speed limit under the change of the weather conditions violate the expectancy of drivers, so it brings the negative effects on the safety. The study regards drivers conformance as the index of the degree of the compliance of driver expectancy, and utilizes the cumulative probability density within the certain range of the speed including displayed speed limit as the quantitative measure of effectiveness. The study reviewed this assumptions by using a driving simulator. As the results, the cases assumed to violate the expectancy of drivers showed the negative effects on the driving behaviour of driver relatively.