PURPOSES : The purpose of this study was to investigate directions for future smart city transportation policies and service development by evaluating road service satisfaction levels and predicting future service demand. METHODS : A nationwide survey was conducted in Korea to develop a transportation service evaluation system based on the functions and objects of transportation. The satisfaction level of road service was evaluated using an analytic hierarchy process (AHP), promising service sectors were identified using the revised importance-performance analysis (IPA) technique, and detailed service demands by sector were suggested. RESULTS : The most valuable service value felt by the people was "safety" (weight 0.4), and the overall satisfaction level was 68.9 points, slightly exceeding "normal." As a result of analyzing the promising service sectors by dividing them into urban and rural areas, "handicapped, elderly, and pedestrians" were important in both areas, and "road facility maintenance" was classified as an additional promising sector for rural areas. CONCLUSIONS : People demand that future smart city transportation policies and services should be "people" and "safety" centered. In addition, it is necessary to pay attention not only to the development of new services but also to the improvement of problems with existing services and policies.

PURPOSES : The purpose of this study is to introduce the development of M5 low-level lighting (LLL) with the necessity and justification, mainly the ecological traffic safety merits and the convenience and traffic efficiency of maintenance compared to the existing high mounted pole lightings. The basic photometric property of the developed facility is analyzed. The visual performance is analyzed in terms of visibility distance and subjective opinions from the subjects on several factors related to lighting performance. METHODS : The basic photometric properties of LLL were measured in a tunnel-shaped shield with a visibility meter (LMK 5 Color). The visibility distance between LLL and existing pole-based lighting was observed by 13 subjects under various weather conditions, such as dry, rainy, and wet conditions. In addition, the subjective opinions in terms of several pre-designed factors regarding lighting performance were surveyed. RESULTS : The developed M5 LLL satisfied photometric requirements such as average surface luminance, overall uniformity, and lane uniformity, as suggested by the lighting guidelines. More than 200 m of visibility distances were measured under normal weather conditions for both LLL and existing pole lightings. However, more than 200 m were observed under a wet surface and a rain intensity of 20 mm/h in the case of LLL, but visibility distance was reduced to 48.46 m in the case of pole lightings. A higher visibility distance was observed in the case of amber colored LLL. According to the results of the subjective opinion survey, all types of lightings had favored ratings, and the whitecolored LLL showed the highest ratings under normal weather conditions. However, existing pole lightings had unfavorable ratings under wet surface and rainy conditions, whereas the amber colored LLL had favorable ratings compared to pole lightings in terms of uniformity of illumination, glare, and psychological stability. CONCLUSIONS : The necessity of M5 LLL lies on the cost-effective application to the low standard roadways where the cost is always the main factor to consider in safety facilities and the ecological benefits of roadsides. The developed LLL satisfied the basic optical property suggested by the related lighting guidelines and showed higher performance in terms of visibility distance across various weather conditions compared to the existing high mounted pole lightings.

PURPOSES : This study aimed to examine the relationship between discomfort glare and different types of lighting, including low-mounted lighting and conventional pole lighting. Although roadway lighting has been widely acknowledged as a countermeasure for nighttime traffic safety, discomfort glare, which is incidentally derived from lighting, is one of the key elements to overcome. METHODS : We selected the Unified Glare Rating (UGR), defined as a globally accepted lighting standard, as a measure of the effect of discomfort glare. Artificial rain and fog conditions were reproduced at the Center of Road Weather Proving Ground (CRPG). RESULTS : As a result, we found that the UGR of low-mounted lighting is reduced by 57.96% compared to pole lighting under rainy conditions, and by 39.12% in the case of fog conditions. CONCLUSIONS : It is proposed that discomfort glare was significantly reduced in the case of low-mounted lighting compared to pole lighting under both rain and fog conditions. Discomfort glare hinders the visual performance of drivers, so it may be related to delayed reaction time and inappropriate driving behavior. Therefore, low-mounted lighting is strongly recommended on road sections that have a high frequency of traffic accidents and adverse weather patterns.

PURPOSES : This study aimed to examine the effect of fog on the optical properties of taillights and the relationship between luminous intensity and the visibility distance of taillights on the road. METHODS : Changes in luminous intensity were measured using a light meter. Participants subjectively evaluated visibility distance. The artificial fog was reproduced using weather-generating facilities at the Center of Road Weather Proving Ground (CRPG). RESULTS : As expected, the average luminous intensity under intermediate fog conditions was reduced to 72% compared to normal weather conditions and 44% under heavy fog conditions in the case of the tail lamp-only lit condition. In the case of the tail lamp and brake lamp lit condition, the average luminous intensity was reduced to 76% under heavy fog conditions and 55% under intermediate fog conditions compared to normal dry conditions. In addition, the average visibility distance was reduced by 41% when fog conditions changed from intermediate to heavy in the case of the tail lamp-only lit condition and 39% in the case of the tail lamp and brake lamp lit conditions. Changes in visibility distance corresponding to the gradual change in luminous change were evaluated by participants, and the linearly regressed equations for the relationship between the intensity levels and the visibility distance were derived and examined for their meaning in terms of road traffic safety concerning stopping sight distance. CONCLUSIONS : Luminous intensities were suggested, given the design speeds, to satisfy the minimum stopping distances. In addition, the required speed reduction allowances were suggested given the design speeds if the luminous intensity remains unchanged.

PURPOSES : In this study, the relationship between the types of road pavement markings and the visibility distance under adverse weather conditions was evaluated. METHODS : Rainy and foggy conditions at the weather proving ground were replicated in this study. The researchers recorded the visibility distance corresponding to each experiment scenario comprising the weather conditions and pavement marking types. RESULTS : Visibility distances under adverse weather conditions decreased more than those of normal weather conditions. Under rainy conditions, the average visibility distance across all pavement markings decreased by 33%. However, the average visibility distance across all pavement markings foggy conditions decreased by 46.8%. Based on the test results of the visibility distance, the speed reduction rates corresponding to the adverse and normal weather conditions, i.e., 24% and 36% speed reduction under rainy and foggy conditions, respectively, were established. CONCLUSIONS : This study validated the reduction in the visibility distance affected by weather conditions by applying actual road scale weather proving ground. In addition, speed reduction was recommended for safe driving under adverse weather conditions.

PURPOSES : The purpose of this study is to analyze the impact of the level of the light-environment and the driver's visual ability on the change in the driver's perception of a forward curved section at night. The study also aims to identify factors that should be considered to ensure safety while entering curved sections of a road at night. METHODS : Data collected from a virtual driving experiment, conducted by the Korean Institute of Construction Technology (2017), were used. Logistic regression was applied to analyze the effects of changes in the light-environment factors (road surface luminance and glare) and the driver’s visual ability on a driver's perception of the road. Additionally, analysis of the moderated effect of visual ability on light-environment factors indicated that the difference in drivers’ visual abilities impact the influence of light-environment factors on their perception. A driver's ability to perceive, as a response variable, was categorized into 'failure' and 'success' by comparing the perceived distance and minimum reaction sight distance. Covariates were also defined. Road surface luminance levels were categorized into 'unlit road surface luminance' (luminance ≤ 0.1 nt) and 'lit road surface luminance' (luminance > 0.1 nt), based on 0.1 nt, which is the typical level observed on unlit roads. The glare level was categorized as 'with glare' and 'without glare' based on whether the glare was from a high-beam caused by an oncoming vehicle or not. The driver's visual ability level was categorized into 'low visual ability' (age ≥ 50) and 'high visual ability' (age ≤ 49), considering that after the age of 50, the drive’s visual ability sharply declines. RESULTS : The level of road surface luminance, glare, and driver's visual ability were analyzed to be significant factors that impact the driver's ability to perceive curved road sections at night. A driver's perception was found to reduce when the road surface luminance is very low, owing to the lack of road lighting ('unlit road luminance'), when glare is caused by oncoming vehicles ('with glare'), and if the driver's visual ability level is low owing to an older age ('low visual ability'). The driver's ability to perceive a curved section is most affected by the road surface luminance level. The effect is reduced in the order of glare occurrence and the driver's visual ability level. The visual ability was analyzed as a factor that impacts the intensity of the effect of change of the light-environment on the change of the driver's ability to perceive the road. The ability to perceive a curved section deteriorates significantly in 'low visual ability' drivers, aged 50 and above, compared to drivers with 'high visual ability,' under the age of 49, when the light-environment conditions are adverse with regard to the driver’s perception (road surface luminance: 'lit road surface luminance'→'unlit road surface luminance,' glare: 'without glare'→'with glare'). CONCLUSIONS : Supplementation, in terms of road lighting standards that can lead to improvements in the level of light-environment, should be considered first, rather than the implementation of restrictions on the right of movement, such as restricting the passage of low visual ability or aging drivers who are disadvantageous in terms of gaining good perception of the road at night. When establishing alternatives so that safety on roads at night is improved, it is necessary to consider improving drivers' perception by expanding road lighting installation. The road lighting criteria should be modified such that the glare caused by oncoming traffic, which is an influential factor in the linear change in perception, and the level of light-environment thereof are improved.

PURPOSES : This study evaluated the effects of dynamic road marking (DRM) on the reduction in drivers’ workload under rainy conditions. Changes in workload in two cases were evaluated: only-lane marking and a combination of lane marking and DRM. METHODS : Rainy conditions were simulated by utilizing the full-scale road weather proving ground. Moreover, participants’ eye movements were used as the indicators for workload. RESULTS : Workload in case of the combination of lane marking and DRM was found to decrease by 44.6% compared to the case of onlylane marking, under the rain intensity of 15 mm/h. Moreover, workload decreased by 50.7% in case of the combination of lane marking and DRM compared to the only-lane marking case, under 30 mm/h rain intensity. CONCLUSIONS : This study validated the positive effects of the DRM in workload reduction under rainy conditions.

PURPOSES: The objective of this study is to evaluate the shear and tensile strength properties of adhesive road studs in asphalt and concrete pavements. METHODS: The 300 mm×300 mm×50 mm rectangular specimens were fabricated using asphalt and concrete mixture for installation of road studs. Four 140-mm-radius circular areas were milled on each specimen with depth of 5 mm to install the adhesive road studs. About 100 g of thermal melting adhesive was applied on the milled area, and then the road stud was bonded onto the surface of the asphalt and concrete mixture. Direct shear testing was conducted at a speed of 5 mm/min on the interface between road stud and asphalt and concrete materials. Tensile strength testing was also conducted on the prepared specimens by applying load with increase of 50 kPa per second. These tests were performed not only in dry condition but also in wet condition to determine the effect of moisture on the shear and tensile strengths. RESULTS : According to the shear testing results, the average shear strength of asphalt samples in dry and wet conditions are 0.509 and 0.234 MPa, respectively. From this testing, the shear strength of wet sample was found to be decreased by 50% with respect to that of the dry sample. Similar trends can be observed on the concrete samples. The average tensile strength of asphalt samples was 0.187 MPa at 1.5 mm of displacement in dry condition. The concrete sample has a 0.222 MPa average tensile strength, which is slightly higher than that of the asphalt sample because of the rough surface characteristics of the concrete sample. CONCLUSIONS: It is determined from this study that the shear and tensile strengths of road stud bonded on the surface of asphalt mixture are slightly lower than those on concrete samples. Regardless of the pavement type, the wet conditioning of the sample can decrease the shear and tensile strength by 50% those of the dry sample. In the future, the quality improvement of adhesive and increase of specific surface area should be considered to improve the bonding property between road stud and pavement surface.

도로 교통사고로 인해 매년 5천여 명의 사망자와 30만여 명의 부상자가 발생하고 있다. 도로 교통사고는 도로이용자-자동차-도로 인프라 측면에서의 결함에 따른 것으로, 특히 도로 인프라 가운데 도로교통 안전시설은 도로 자체의 선형 결함 등을 보완하고 야간 등 비정상적인 도로환경에서 운전자의 안전을 보장하기 위해 설치되며 매년 설치물량뿐만 아니라 시설 자체의 성능도 지속적으로 발전되고 있다. 본 연구는 도로교통 안전시설 가운데 야간 및 악천후 시 도로 시인성을 극대화하는 시설인 조명시설과 차량이 차도를 벗어난 경우에 운전자의 안전을 보장하는 차량방호 안전시설이 일체화된 시설물에 대한 성능검증을 위한 연구이며 현재 기존 연구 및 향후 연구계획에 대한 추진 시나리오를 정립하는 단계에 있다. 이를 위해 조명시설이 갖추어야 하는 시인 성능(휘도, 균제도), 차량방호 안전시설이 갖추어야 하는 방호성능(탑승자 방호, 차량 충돌 후 거동, 구조물 변위)에 대한 성능실험을 수행할 계획이다. 본 연구에서 개발코자 하는 조명-차량방호 일체형 안전시설은 첫째 도로 폭이 협소하여 충분한 시설한계(Right-of-Way)가 확보되기 곤란한 지점이나 교량 등 특수구간, 둘째 조명의 높이를 운전자의 눈높이에 맞추어 연속적인 주행환경 확보가 용이하고 도로 생태환경 보호에 유리한 점, 셋째 조명시설과 방호시설을 일체화함으로써 시선유도효과를 극대화하고 시설 간 간섭최소화를 통해 미관확보가 가능하다는 장점이 있다. 본 연구를 통해 도로교통 안전시설 각각의 성능발전뿐만 아니라 상호간 물리적 결합 등을 통해 도로이용자에게 우수한 주행환경을 제공할 수 있는 기회를 확대할 수 있으며 국내 안전시설 기술의 해외진출 시에도 타국제품 대비 상대적인 우수성을 확보할 수 있는 특화사항으로 발전될 수 있을 것으로 본다.

도로조명은 야간 운전자의 전방 시인성을 확보해 주어 안전운전이 가능하도록 하는 대표적 공공 사회 기반 시설이다. 전통적 도로조명인 폴 형태의 가로등은 광원과 노면의 높이차로 인한 구조적･성능적 한계 로 야간 시인성(안전) 확보의 최소 근거인 도로 조명 성능 기준 만족 및 악천후 시 시인성 확보(선형 및 위험요소, 차선확인 등)가 근본적으로 불가하다. 이러한 폴 가로등이 가지는 단점을 획기적으로 개선한 낮은 조명 시스템은 광원 높이 및 적용 광학계의 한계로 등기구 가격 상승 및 도로 조명 기준 만족을 위한 설치 간격조밀화를 수반하여, 가격 경쟁력 측면에서 불리하여 시장 진입 확대에 난항을 겪고 있다. 따라 서, 기존 낮은 조명시스템의 개선을 통해 가격 경쟁력 및 악천후 대응력을 추가로 확보하고, 이와 더불어 전 세계적 이슈로 부각되고 있는 에너지, 환경 문제 대응을 위한 에너지 자립 고성능･저가격의 조명 시스 템 개발이 필요한 실정이다. 이에 본 연구에서는 기존 개발 낮은 조명시스템의 광학계 및 재료･기구적 개 선을 통해 가격 경쟁력 및 안개 등 악천후 시 시인성 성능을 확보하고, 태양광 기반 전력 공급시스템 충전 효율성 및 전력 공급 안정성, 장수명을 확보하기 위한 기술을 개발·적용한 그림 1과 같은 악천후 대응 에너지 독립형 낮은조명 시스템을 개발하여 낮은 조명 시스템의 경쟁력을 확보하고자 한다. 본 연구의 핵심 기술은 첫째, 저가격, 고효율 낮은 조명 기술개발, 둘째, 야간 악천후 대응 최적 시인성 확보 기술 개발, 셋째, 태양광 기반 에너지 자립형 전력 공급기술 개발로서 체계적이고 효율적인 연구 및 테스트, 검·인증 과정을 거쳐 국내･외 시장에 확대･보급하는 것을 목표로 한다. 향후 본 연구의 성과를 활용한다면 안개 상습 취약 구간과 같이 악천후 대응이 필요한 구간 및 교량, 인터체인지 등 높은 조명의 구조적 안정성 확보가 어려운 구간에 활용이 가능하며, 국내 도로조명의 패러 다임 변환으로 도로조명분야 신시장 창출이 가능할 것으로 기대된다.

도로작업구간 사고의 경우 2012년 기준으로 일반국도의 유지 보수 업무를 담당하는 국토관리사무소 관내 도로보수원은 583명으로, 작업중 사상자는 27명으로 보고되어 도로보수원의 약 5%가 사망사거나 부상을 당 하는 것으로 분석되었으며, 이는 고위험군으로 분류되는 소방공무원 직종의 사상자 비율(0.97%)보다 높다. 주요 간선도로망 구축이 마무리되는 가운데, 도로정책은 혼잡해소를 위한 ʻ운영･관리ʼ 중심으로 변화할 것으로 전망(일반국도 보수 예산배정 예: ʻ14년 531백만원에서ʼ 15년 923백만원으로 170% 증가)된다. 따라 서 지속적인 공사장 증가가 예상되며 장기공사보다는 단기 및 이동공사장 빈도증가가 예상된다. 도로 공사구간 임시 교통통제시설 중 임시 울타리(국토교통부, 도로공사장 교통관리지침)는 차량유도 기 능과 작업활동구역으로 일반차량이 진입하는 것을 막기 위한 시설로, 종방향의 차량 충돌에 대해서는 작업 장보호를 위한 충돌 안전거리가 명시되어 있으나 횡방향의 충돌에 대해서는 방호기준이 없는 실정이다. 따라서 공사장 작업인부 등을 보호하기 위한 구조적인 강도성능 등을 포함한 국토교통부에서 정한 차 량방호 안전시설(국토교통부, 차량방호 안전시설 설치 및 관리지침)로써의 기능을 갖춘 방호시설 마련이 필요하다. 특히 단기･이동 공사 빈도증가에 대응한 작업성(설치용이성) 측면에서 공사구간 노면에 매설하 거나 부착하는 시설보다는 차량기반의 이동식 방호울타리 설치가 유리하다. 본 연구는 단기･이동공사에 특히 효과가 기대되는 공사장용 이동식 방호울타리를 개발하는 것을 목표 로 수행중이며, 단순히 작업성뿐만 아니라 횡방향 진입차량 방호를 위한 강도성능을 갖춘 방호울타리를 개발하는데 목적을 두고 있다. 이동식 방호울타리는 국내 자동차 기준을 감안하여 이동시에는 자동차기준 에 부합된 길이로 운행하고 공사장에 설치시는 길이가 확장되어 차량방호 기능을 할 수 있도록 하였다. 이동식 방호울타리는 기구학적 메커니즘에 따라 블록굴절형과 텔레스코핑형으로 구분하였다. 블록굴절형 은 접이식 구조로 도로운행시에는 접혀져 있다가 공사장에서는 펼치는 형식이다. 텔레스코핑은 망원경 구조 로 도로운행시에는 단위체들이 겹쳐있다가 공사장에서는 펼치는 형식이다. 본 연구는 한국건설기술연구원 에서 이론 및 개념설계를 담당하고 기구학적 구동메커니즘 검토 및 시작품 제작을 담당하여 수행하고 있다. 현재 개념설계를 반영한 기구학적 설계 및 시작품 제작 단계에 있으며 유한요소 해석프로그램을 이용 하여 차량방호 성능기준(국토교통부, 차량방호 안전시설 설치 및 관리지침) 만족여부를 검토하고 실물차 량 충돌시험을 시행할 계획으로 있다. 다만, 도로변에 통상적으로 설치되는 방호울타리(가드레일 등)와는 설치장소에 차이가 있고, 공사장에 설치되는 임시적인 시설이라는 관점을 감안하여 도로변 방호울타리와 는 충돌환경적 차이에 대한 고려가 필요하다고 판단하여 이에 대한 기술검토를 병행하고 있다.

도로의 악영향 및 악천후로 인해 교통사고 유발, 도로변 민원 등이 다수 발생하고 있다. 악영향 및 악 천후 요인별로 보면 기상상태 악화(폭우, 폭설, 안개 등)로 인한 교통사고는 1.4% 증가하였고, 치사율도 약 3배 높은 것으로 분석되었다. 도로교통소음으로 인한 사회적 비용은 연간 34조원(2012년)으로 2005년 대비 44% 증가하였고, 민원 발생 42,000건(2009년 기준)으로 인한 사회적 손실도 증가되고 있는 실정이 나, 실질적인 소음저감 혹은 소음 측정을 위한 정량적 실험시설은 부족한 현실이다. 야간 교통량이 전체 교통량 중 차지하는 비율은 약 30% 정도임에도 불구하고 야간 사고 발생건수의 48.5%, 사망자수의 53.5%를 차지하고 있어('11년 기준), 야간 교통량 비중 감안 시 주간대비 위험도 3배에 달하나 실규모 실 증실험은 거의 전무하다. 이와 같이 도로의 악영향 및 악천후에 의한 피해는 심각한 사고 또는 피해를 입히는 것으로 나타났으 며, 이를 예방하기 위한 관련된 연구 및 기술 개발이 진행되고는 있으나 산발적이며 실증실험 등이 없어 과학적인 효과 입증이 어려운 상황이다. 한국건설기술연구원에서는 이러한 사회적 문제로 대두되고 있는 교통사고 등을 근본적으로 해결하고, 국가 기준을 재검토하여 적정 기준을 정립하기 위하여, 기상환경 재현 도로 성능평가 실험시설을 유치하 여 국토교통부 국토교통기술촉진연구사업으로 경기도 연천에 구축중에 있다. 각 실험시설의 목표 사양은 표 1과 같다. 향후 실험시설 구축뿐만 아니라 실험시설 운영계획, 연구 활용계획 및 활성화방안을 수집하여 관련 연구, 성능평가 ․ 인증 사업에 활용할 경우 국내 도로 안전 및 시설 성능 수준이 한층 높아질 것으로 기대된다.