PURPOSES : This study aims to examine actual cases of providing detour information in accidental situations such as traffic accidents and road construction through a VMS installed on national highways in metropolitan areas with alternative routes, as well as cases of simultaneously providing travel time information on parallel paths such as national and regular highways. For each case, we analyzed whether the provision of VMS traffic information leads to route changes and substantial effects. METHODS : To analyze traffic changes on the main and detour roads based on the detour information provided on traffic accidents in actual cases, the traffic volume and speed on the accident day were compared with those on the same days and at the same time of the day (regular days) based on the VDS data of the main and detour roads. Cases providing more detour information on road construction were investigated by examining three time periods: one week from construction initiation and one week before and after the construction period (regular days). The traffic volume and speed on the main road were compared based on the VDS data, and those on the detour road were compared based on data made available by private entities. Regarding the cases of simultaneously providing drivers with comparative information on travel time over parallel sections of national and regular highways, traffic situation changes in highways were analyzed in the following special traffic control periods (New Year's Day, NY Day), during which congestion is expected due to heavy traffic: before and after the provision of comparative information for 2015 New Year's Day and 2016 NY Day. RESULTS : The detour rate related to route changes based on the detour information for traffic accidents was 35%. On the detour route, the traffic volume increases as traffic from the main road is absorbed. However, the average travel speeds did not differ significantly. When further detour information regarding a road construction project was provided, the detour rate from the main road was 21%. The travel speeds were similar, except on the first day of construction. Almost no changes were observed in the first section of the detour. The speed slightly decreased in the second section but did not significantly hinder the traffic flow. When comparative traffic time information on parallel routes (national highways and expressways) was provided, the traffic volume increased to some extent after the report was provided for every case. However, the data frequency rate in the 5-min unit, which was still under the congestion speed standard (40 km/h), decreased. This indicates that traffic congestion was significantly relieved. CONCLUSIONS : Previous studies on detour rates or route changes based on VMS traffic information have focused on VMS instruments on expressways. Although their estimates were based on simulated situations, this study used actual VMS installed on national highways. In addition, this study utilizes the existing case records of national highway ITS centers, covering traffic situation monitoring, measures for accidental situations, etc., in regular times or special traffic control periods, as well as statistical data, including ITS real-time traffic information. The analysis results of this study accurately represent situations on actual roads and can be utilized to analyze future ITS operation and installation project effects.

PURPOSES : This study aims to evaluate the traffic safety by collecting and analyzing vehicle speed and conflict frequency data based on the provision of information to vehicle drivers and crosswalk pedestrians under right-turn conditions. METHODS : Two evaluation scales, namely speed of access and number of conflicts, were used to quantitatively evaluate the effects of the new information provision method. Data on access speed and the number of conflicts according to information provision were collected and compared before and after information provision. RESULTS : Analysis of the pre- and post-spot speed reduction rates revealed an overall reduction rate of 32.6%. The conflict ratio was 81.0% before information provision but increased to 83.3% after information provision. CONCLUSIONS : When LED display information was provided, the effect of decelerating the approaching speed of vehicles in the rightturn torpedo section was statistically significant, but the reduction in the conflict ratio was not. Factors such as intersection status, traffic volume and vehicle speed, affect the approach speed and increase or decrease the number of conflicts. Regardless of whether information is provided, the average compliance rate of the Road Traffic Act when turning right in the channelization area is 16.7%, which is significantly different from the average compliance rate of 48.4% immediately after the Road Traffic Act was revised in July 2022.