PURPOSES : There are significant differences in traffic accident rates depending on various road conditions and environments. However, the current traffic accident rates on national highways are classified relatively simply, and it is also difficult to accurately calculate the crash modification factor. Therefore, this study aimed to improve the traffic accident rates on national highways by presenting an algorithm for categorizing the traffic accident rates of national highway into four types (older and modern roads, and urban and rural roads). METHODS : The problems in the current rate of traffic accidents were derived, Traffic accident analysis system(TAAS) was used for the traffic accident data, and the road traffic volume statistical yearbook was used for the traffic volume data. After dividing the national highways into older and modern roads and urban and rural roads, the rates of traffic accidents were calculated and compared with the current accident rates. RESULTS : The accident rate of modern roads was found to be lower than that of older roads, and was lower in rural areas than in urban areas. From comparing the results of this study with Korea development institute(KDI) guidelines, older roads and urban roads exceeded the value in the KDI guideline, whereas the rates of modern roads and rural roads were lower than the KDI value. CONCLUSIONS : The accident rate accuracy was improved by subdividing the accident rates into four types. Therefore, it is expected that the accuracy and reliability of economic analysis on road projects will be improved.

PURPOSES : The aim of this study is to determine the maintenance costs for a reasonable preliminary feasibility study, feasibility study, or evaluation METHODS : This study was based on government budget execution and budget execution data for expressways, national highways, cable-supported bridges and long-tunnels. For the expressway, data obtained from the Korea Expressway Corporation were used. For the national highway, data was obtained from the Ministry of Land, Infrastructure and Transport. Similarly, data collected from expressway maintenance costs and the Korea Infrastructure Safety and Technology Corporation were used for long tunnels and cable-supported bridges, respectively. The items for highway maintenance cost were reclassified more rationally to facilitate the calculation of the maintenance costs. The replacement cycle for each item was also calculated based on the budget expenditure data. RESULTS : The results of this study showed the standard maintenance cost model for expressways, national highways, cable-supported bridges, and long-tunnels. In other words, a basis for predicting reasonable maintenance costs was prepared for a feasibility study. CONCLUSIONS : The reliability of the maintenance cost results was improved and it was more consistent with actual costs compared to the results of previous studies. It can be used as a basis for estimating the maintenance cost of a preliminary feasibility study and feasibility evaluation in the future.

PURPOSES : In this paper, pedestrian-oriented time assured traffic operation (POTATO), adopted in Korea at a single crossing pedestrianoriented operating area, is explored and applied to a simulation experiment and test site to verify the operation efficiency. METHODS : Three candidate plans are presented as a method to operate pedestrian-oriented signal operations that can overcome the restrictions on signal controllers in Korea. The selected POTATO and TOD signal operations were compared and analyzed. The delay and pedestrian queues, present length, and number of times were used as comparative indices. RESULTS : Scenario-specific simulations confirmed that the delay, compared to TOD signal operation, was reduced by up to 5 s/ped depending on the vehicle traffic volume and the number of pedestrians. For the vehicle delay, the results increased up to 8.99 s/veh, depending on the traffic volume of the vehicles and pedestrians. As a result of the test site operation, POTATO operation improved by 5.12 s/ped (approximately 46.69% improvement) compared to TOD operation in the hours commuting to school and by 2.84 s/ped in the hours commuting from school (approximately 51.13% improvement). In case of vehicle delay, the delay increased by 2.35 s/veh (approximately 64.39%) in the hours commuting to school and 1.20 s/veh (approximately 21.11%) in the hours commuting from school compared to the TOD operation. CONCLUSIONS : Through simulations and test site pilot operation verifications, the effects of pedestrian delay improvement were more positive if POTATO proposed in this study was low in vehicle traffic.

PURPOSES: The purpose of this study is to compare the lane curing time of natural drying and a lane drying device when painting lines on a highway. METHODS: The painting process was carried out in July 2015 and September 2015, respectively, for the Gimcheon IC - Gimcheon JC. After the painting, measurements were obtained three times at six measurement points located at 20 m intervals on the shoulder line and the dividing line. The curing time was measured for natural drying and drying using a lane drying device, and compared for different pavement types (asphalt, concrete) and paint types (waterborne paint, methyl methacrylate paint). RESULTS : The results of the lane curing time comparison on the highway are as follows. The combination of asphalt and methyl methacrylate paint cured more rapidly during both the natural drying and drying using the lane drying device. Finally, it was cured at least 32.2% and 40.7% faster when using a drying device than in natural drying. CONCLUSIONS: The comparison of lane curing time of the highway showed that the combination of asphalt and methyl methacrylate paint cured more rapidly when using both natural drying and a lane drying device.

Highly developed, European industrial countries normally have a dense network of rural highways. The future focus of roadwork in Germany, where there is a high density of 1.6 km of rural highway per km² of land, will involve upgrading and rebuilding rural highways prone to accidents. As new guidelines are not completely relevant for upgrading existing highways and exceptional permits are often required, there is an increasing need to use simulation in the design process to assess discrepancies from the standards and their effect on traffic safety. Using virtual driving (automatically using a defined driver profile or a driving simulator), it is possible to objectively assess expected driving behaviour using characteristic feature graphs and quantitative parameters derived from them. Zwickau University of Applied Sciences has developed a new multi-stage methodology for upgrading rural highways by using a 3D design working place simulator. The highway is automatically retraced using survey data and genetic algorithms in stage 1 (preliminary review) and is broken down into the horizontal and vertical projection design elements. Stage 2 involves determining the shortcomings on the road by superimposing the design elements, the actual accident figures and virtual driving runs. The actual replanning work occurs in stage 3, taking into account the minimum and maximum standard figures for the design elements. The replanning work is feasible, even if the standard figures are not met along parts of the route, but the graph figures, parameters and virtual driving runs prove that there is no reduction in traffic safety. Otherwise, the route needs to be realigned. After finishing the testing period of the hard- and software components, the methodology and the working place can be used from designing engineers for the preparing process of practical projects.

로드 킬 현황에는 기간과 주기가 명확하지 않아 자료에 신뢰성이 낮기 때문에 로드 킬 저감 연구에 왜곡될 가능성이 높았다. 따라서 이 연구로 현실적인 대안을 제시하고자 한다. 한국도로공사에서 제공받은 자료를 활용, 분석한 결과 최근 5년(2010-2014) 간 전북 권 고속도로에서 발생한 야생동물 로드 킬 사고를 분석하였다. 전북권을 지나는 고속도로 7노선을 선정하여 조사한 결과 중부선(1472개채, 46.90%)이 압도적으로 높았다. 로드 킬을 당한 야생동물 중에 고라니(Hydropotes inermis)가 2010년도부터 2014년까지 84.60%로 다른 동물과 비교가 안 될 정도로 높게 측정되었다. 그리고 계절별 사고 수는 4계절 중 봄(31.73%)과 여름(30.05%)이 가장 많은 것으로 나타났다. 2013년도와 2014년 사고발생 시간 중 오전 7시에 79건 (9.11%)으로 사고건수가 가장 많았고, 오전 04-08시 구간이 323건(37.25%)을 차지하였다. 2010년도부터 2014년도까지 월별 사고 수는 5월(20.36%), 6월(18.67%)로 높게 측정되었다. 향후 지속적인 유사 연구를 통해 고속도로 로드 킬 감소에 야생동물과 국민의 안전 증진에 기여할 수 있을 것이라 판단되며, 이를 위해 부족했던 오차 범위, 사고 주기, 로드 킬 시간, 사고 원인 조사결과 등 자세한 통계가 필요하다.

PURPOSES: The purpose of this study is to develop a methodology to prioritize sidewalk construction on rural national highways. METHODS : In order to determine an appropriate prioritization for sidewalk construction, we developed a specific methodology. The proposed methodology includes three main steps: 1) Analytic Hierarchy Process (AHP) methods, 2) Subjective evaluation of relevant road agencies for the candidate sidewalks along rural national highways, and 3) Field study conduction. Each step has four phases. The primary feature of this methodology is the addition of expert consultation and survey data, as well as a field study. In addition, the method could guarantee flexibility in selection for evaluation criteria. As a result, the proposed methodology could be used as a general procedure for application to other roadway classifications when considering sidewalk construction. RESULTS: In order to demonstrate the reasonableness of the proposed methodology, a case study was performed for exactly 100 candidate sites for sidewalk construction on rural national highways. All required evaluation scores were properly produced for each candidate site. By doing so, decision-makers can determine the priority for sidewalk construction at these sites by reviewing quantitatively and qualitatively considered data. CONCLUSIONS: The results of the case study can be applied to a long-term fundamental plan for sidewalk construction on rural national highways. Furthermore, this methodology could be employed to prioritize a small-scale SOC project(e. g. bicycle or pedestrian roads).

PURPOSES : This study aims to investigate the direct and indirect influence areas from incidents on urban interrupted roadways and to develop traffic management strategies for each influence area. METHODS : Based on a literature review, various traffic management strategies for certain incidents were collected. In addition, the relationship between the measure of effectiveness and the characteristics of incidents was explored using an extensive simulation study. RESULTS : From the simulation studies, traffic delays increased as the number of lane closures increased, and the impact of lane closures was reduced to the direction upstream from the incident site. However, the magnitude of the delay change depended on the degree of saturation. Using these characteristics, the direct and indirect influence areas resulting from incidents were defined, and traffic management strategies were established for each direct and indirect influence area and for each level of incident. CONCLUSIONS: The results of this study will contribute to the improvement of national traffic safety by preventing secondary incidents and by effective adaptation to incident events.

PURPOSES: Performance evaluation of four types of asphalt concrete overlays for deteriorated national highways. METHODS : Pavement distress surveys for crack rate and rut depth have been conducted annually using an automated pavement survey vehicle since 2007. Linear and non-linear performance prediction models of the asphalt concrete overlays were developed for 43 sections. The service life of the asphalt overlays was defined as the number of years after which a crack rate of 30% or rut depth of 15mm is observed. RESULTS: The service life of the asphalt overlays was estimated as 17.4 years on an average. In 90.7% of the sections, the service life of the overlays was 15 years or more which is 1.5 times the life of conventional asphalt concrete overlays used in national highways. The performance of the overlays was dependent on the type of asphalt mixture, traffic volume levels, and environmental conditions. CONCLUSIONS : The usage of stone mastic asphalt (SMA) and polymer-modified asphalt (PMA) for the overlays provided good resistance to cracking and rutting development. It is recommended that appropriate asphalt concrete overlays must be applied depending on the type of existing pavement distress.

PURPOSES : This study aims to draw differences between primary and secondary crashes by comparing crash characteristics and to identify the unique characteristics of secondary crashes for making better effective countermeasures to reduce secondary crashes. METHODS : The characteristics of secondary crashes were compared to those of primary crashes through a two sample proportional test (z-test). RESULTS : The results showed that vehicle-to-vehicle crashes and vehicle-to-person crashes are dominant crash types in secondary crashes. Compared to primary crashes, secondary crashes were likely to occur during nighttime. With respect to season and weather, the proportion of secondary crashes occurred during winter and in snowy weather is relatively higher than that of primary crashes. The main causes of primary crashes were found to be drowsiness, speeding, and exaggerated steering control, whereas main factors affecting the occurrence of secondary crashes were negligence of keeping eyes forward and no keeping a safe distance as expected. CONCLUSIONS : The characteristics affecting the occurrence of secondary crashes are different from those of primary crashes, indicating that proper countermeasures should be established to prevent the occurrence of secondary crashes on highways.

PURPOSES : This study presents the noise level and frequency characteristics investigated in the national highways with the consideration of various measuring conditions and/or methods. METHODS : The noise levels on the asphalt concrete pavement(ACP) and the jointed plain concrete pavement(JPCP) of the national highway were measured and analysed with respect to three variables, i.e., pavement type, surface condition, and measurement distance. The PASS-By method is utilized for the noise measurement and then using CPB spectrum analysis method with 1/3 octave bandwidth, the noise levels and frequency characteristics were calculated for two-second periods before and after the peak noise. RESULTS : Depending on the pavement type, the noise level was changed as the average noise levels are 73.3dB(A) and 78.3dB(A) for ACP and JPCP, respectively. With respect to the effect of surface condition, the average noise levels for crack H(high), M(medium), and L (low) sections are 77.4dB(A), 77.4dB(A), and 78.1dB(A), respectively. Regarding the measurement distance, 1.2meter difference in measuring location reduces 1.6dB(A) of noise level; the average noise levels at 5.3m and 7.5m from the centerline of outer lane are 72.8dB(A) and 71.2dB(A), respectively. It should be noted that the noise levels are slightly different as a function of vehicle speed and type. However, the overall trends for each case was similar. It was found that the domain frequency bands for ACP and JPCP were 400Hz~2000Hz and 500Hz~2000Hz, respectively. CONCLUSIONS : Based on the analysis with the measured noise date from national highway, it was concluded that the noise level and frequency band vary depending on the various conditions. It was also found that some variables significantly affect the noise level while others do not. With further systematic investigation, the comprehensive noise characteristics on the national highway can be achieved. Using such database, it is possible to develop the fundamental noise reduction technology.

PURPOSES : Two-lane highways have one lane in each direction, and lane changing and passing maneuvers take place in the opposing lane depending on the availability of passing sight distance. 2001 Korea Highway Capacity Manual (KHCM) is classified into two classes of two-lane highways (Type I, II), and average travel speed and time-delayed rate are used as measures of effectiveness (MOEs). However, since existing two-lane highways have both uninterrupted and interrupted traffic flow-system elements, a variety of free-flow speeds exhibits in two-lane highways. In addition, it is necessary to check if the linear-relationship between volumes and time-delayed rate is appropriate. Then, this study is to reestablish the relationship between average travel speed, time-delayed rate, and flow. METHODS : TWOPAS model was selected to conduct this study, and the free-flow speeds of passenger cars and the percentage of following vehicles observed in two-lane highways were applied to the model as the input. The revised relationships were developed from the computer simulation. RESULTS : In the revised average travel speed vs. flow relationship, the free-flow speed of 90km/h and 70km/h were added. It shows that the relationship between time delayed-rate and flow appeared to be appropriate with the log-function form and that there was no difference in time-delayed rate between the free flow speeds. In addition to revise the relationships, the speed prediction model and the time-delayed rate prediction model were also developed. CONCLUSIONS : The revised relationships between average travel speed, time-delayed rate, and flow would be useful in estimating the Level of Service(LOS) of a two-lane highway.

PURPOSES : The causes of traffic accidents can be classified into the factors of highway users, vehicles, and driving environments. Traffic accidents result from the deficiency in single or combination of these three factors. The objective of this study is to define the "potentially hazardous sections of highway" in terms of traffic safety considering these three factors. METHODS : The test drivers performed repeated driving on these highway sections. The drivers and passengers recorded the sections on which the driving was uncomfortable, and the speeds on the sections excluding the uncomfortable sections were used for the development of the model. RESULTS : The model is composed of three sub-models for each of the horizontal curve, tangent, and the section where the curve starts/ends. The safe driving behavior coefficients by the horizontal curvature were derived by comparing the maximum operating speeds at which the vehicle may slide or deviate and the speeds at which the drivers feel comfort. The safety speeds on tangent were derived by the length of tangent section considering the driver's desired speeds under the traffic condition on which the drivers hardly influenced by the other vehicles. For the sections where the curve starts/ends, the driving behaviors were classified by the distances between the curves, and the safe acceleration/deceleration speeds were derived on which the drivers enter/exit the curve sections safely. CONCLUSIONS : Safety speed could then be regarded that the model suggested in this study may be useful to define the potentially hazardous highway section and contribute the improvement of highway safety.

차량의 바퀴궤적의 횡방항 변동을 의미하는 원더링(wandering)은 포장의 설계 및 유지보수를 위하여 중요한 요소임에도 불구하고 계측의 어려움 때문에 심도 있게 다루어지지 못하고 있다. 본 연구에서는 왕복 2차로(3.5m차로 폭)와 4차로(3.25m 및 3.5m 차로 폭)인 일반국도 직선 구간에서 차량 바퀴궤적을 조사하여 횡방향 이동 특성을 분석하였다. 조사 결과에서 좌우 바퀴 위치는 서로 다른 분포형태를 보였으며, 포장 설계에 적용할 경우 좌측바퀴에 의하여 얻어진 분포의 특성치가 포장에 미치는 영향이 더 크기 때문에 좌측바퀴의 특성치를 적용하는 것이 합리적인 것으로 나타났다. 좌측바퀴 위치의 평균값은 좌측차선을 기준으로 할 때, 승용 승합차량인 경우 3.25m차로 폭에서 59.5cm, 3.5m일 경우 80.7cm에 위치하였고, 화물차량일 경우 각각 58.4cm와 73.6cm인 것으로 나타났다. 차량 축수에 따른 구분에서 2축 차량의 경우 차로 폭에 따라서 60.7cm와 79.1cm 이고, 3축이상일 경우 44.5cm 및 69.2cm 인 것으로 나타났다. 결국, 바퀴의 중심위치는 차로 폭에 따라 다르며, 그 차는 차로 폭의 차이에 기인하는 것으로 판단된다.

본 연구에서는 다차로 고속도로에서 트럭주행 차로를 제한하는 전략이 교통류 변수(평균속도, 차선변경 횟수, 총교통량의 변화)에 어떤 영향을 미치는 지를 알아보았고, 또한 본 연구에서 제안된 트럭주행 차로를 제한하는 전략에 대한 대안들의 적용 타당성을 알아보았다. 교통 시뮬레이션을 위해 두 가지 형태의 가상 네트워크와 교통수요를 설정했으며, 트럭 차량의 주행을 제한하는 차로의 수에 근거하여 3가지 실행가능한 시나리오를 설정하였다. PARAMICS 시뮬레이션 모형이 주요 분석 Tool로 사용되었다. 통계분석을 통해 시나리오에 따른 교통류 변수에 대한 영향을 분석하였다. 결과적으로, 트럭주행 차로를 제한하는 전략은 다차로 고속도로에서 교통류의 흐름에 긍정적인 영향을 미치는 것으로 나타났다. 또한, 이 연구는 트럭 주행 차로를 제한하는 전략이 성공적으로 시행되기 위해 트럭 차량의 주행을 제한하는 차로의 수의 결정이 중요한 요소가 될 수 있다는 것을 보여주었다.

본 연구는 도로설계 시 차로수 결정에 사용되는 적정 설계시간계수값의 특성분석과 적정 설계시간계수값을 적용하는데 있어 세부기준을 제시하기 위해 국내 일반국도 93개 상시교통량 조사지점에서 8년 동안 수집한 시간교통량 및 AADT 자료를 이용하여 AADT 증가와 시간적 변화에 따른 설계시간계수값의 변화를 회귀식 모형을 통해 분석하였다. 회귀식 모형은 30번째 시간교통량을 독립변수로 AADT를 종속변수로 하는 상수항이 없는 단순회귀식으로 구성하였으며, 회귀식은 차로수 구분(2차로, 4차로)과 AADT 수준(3개 그룹)에 따라 별도로 적용하였다. 분석결과, 제안한 회귀식 모형은 추정오차가 작고 모형의 설명력이 높게 나타났으며, 설계시간계수의 시계열적인 변동특성 분석결과, 설계시간계수는 연도별 변화가 크지 않고 차로수 또는 교통량이 클수록 작아지는 특성이 뚜렷하게 확인되었다. 연구의 한계로는 기존방법에서 채택하고 있는 30번째 혹은 100번째 순위의 설계시간계수는 맞다는 가정하에 분석을 진행한 것으로, 주 5일제 확대에 따른 여가통행 증가, 도로의 지역적 교통특성 등에 따른 설계시간계수 변화를 반영하지 못하고 있어 향후에 국내 실정에 맞는 최적순위의 설계시간계수 제시를 위한 연구가 추가적으로 필요하다.