PURPOSES :This study proposes standards for rural access road pavement section and thickness design considering existing access road construction conditions; the study also proposes a complementary policy that can be used for design convenience.METHODS:Various literature review and case studies had been performed in terms of rural access road section and thickness design, both domestically and internationally, and this was followed by domestic rural access road field surveys. KPRP and KENLAYER were used to analyze the commonalities and predict the remaining life. Data on real cost is used to select an appropriate construction method through economic analysis.RESULTS:The economic efficiency of concrete pavement (15×15) was the highest in terms of economic efficiency of performance life and traffic volume. In the case of asphalt pavement, it is considered that the most economical method is to implement micro-surfacing method four times as a preventive maintenance method (once every 10 years and 4.5 years for asphalt concrete pavement and MS construction method, respectively). Repairable asphalt pavement is advantageous for areas where heavy vehicles are expected to pass. In the case of other general areas, it is considered economical to place concrete (15×15) pavement. However, as analytical results on its performance life are unavailable, it is to be considered for study in the future.CONCLUSIONS :This study proposed interim design guidelines based on various domestic and international design guidelines and case studies. However, in order to develop the final design criteria applicable to the field, it is necessary to (a) estimate the bearing capacity of the lower level of the pavement at various sites, (b) estimate the daily traffic volume, (c) implement advanced low-cost pavement technologies, and (d) propose maintenance standards and techniques for long-term performance.

PURPOSES:In this study, field performance evaluation of crack treatment of pavement and the feasibility of surface treatment of pavement are presented. The performance and cost of preventive maintenance methods have been previously verified, and the methods are being used in many developed countries and cities. However, the performance and cost of the system have not been verified in domestic, field applications. Therefore, in order to improve performance, the field performance is evaluated, and a reasonable cost is proposed.METHODS:Visual Inspection was conducted to evaluate the field application and performance of the preventive maintenance method. In addition, the PCI index was calculated from the results of visual inspection of the application area of the surface treatment method, and the performance life of each method was predicted. For the economic evaluation, life cycle cost analysis was performed using the life cycle cost analysis program.RESULTS:In order to evaluate and quantify the field performance of crack repair material, the residue condition of the pavement surface after crack treatment, rather than the performance of the material, is evaluated. In addition, the crack resistance and performance life of surface treatment methods are evaluated. The cost of currently available treatment methods are compared to the common pavement cut and overlay method, and it is determined that the preventive method is not economical based on life cycle cost analysis.CONCLUSIONS:Because of the characteristics of cracking, it is necessary to conduct the evaluation of currently applied methods and the analysis of the cause of damage, by visual inspection. Moreover, in order to evaluate the performance and economic suitability of the currently applied surface treatment methods, it is necessary to acquire information on application sections by monitoring their long-term conditions and performance.

PURPOSES :The purpose of this study was to determine the optimum mix design of the content of 100 % reclaimed asphalt pavement (RAP) for spray injection application with different binder types.METHODS:Literature review revealed that spray injection method is the one of the efficient and economical methods for repairing a small defective area on an asphalt pavement. The Rapid-Setting Polymer modified asphalt mixtures using two types of rapid setting polymers-asphalt emulsion and a quick setting polymer asphalt emulsion-were subjected to the following tests to determine optimum mix designs and for performance comparison: 1) Marshall stability test, 2) Retained stability test, 3) Wet track abrasion test, and 4) Dynamic stability test.RESULTS AND CONCLUSIONS :Type A, B, and C emulsions were tested with different mix designs using RAP aggregates, to compare the performances and determine the optimum mix design. Performance of mixtures with Type A emulsion exceeded that of mixtures with Type B and C emulsion in all aspects. In particular, Type A binder demonstrated the highest performance for WTAT at low temperature. It demonstrated the practicality of using Type A mixture during the cold season. Furthers studies are to be performed to verify the optimum mix design for machine application. Differences in optimum mix designs for machine application and lab application will be corrected through field tests.

OBJECTIVES: Bituminous materials, such as tack coat, are utilized between pavement layers for improving the bond strength in pavement construction sites. The standards regarding the application of bituminous material are not clearly presented in the Korean construction guideline without RS(C)-4. Hence, the objective of this study is to determine the optimum content of bituminous materials by analyzing interlayer shear strength (ISS) from the direct shear tester, which was developed in this research. The shear strength of tack coat was defined with the sort of bituminous materials. METHODS : The mixtures for the shear test were made using marshall mix design. The specimens were vertically and horizontally separated for the direct shear test. The separated specimens were bonded using bituminous material. The objectives of the experiment are to determine the performance of bond and shear properties resulting from slippage, rutting, shovel, and corrugation of asphalt pavements. A machine based on the Louisiana interlayer shear strength tester (LISST) of NCHRP Report-712 was developed to determine the ISS. The applied types of tack coat were RS(C)-4, AP-3, QRS-4, and BD-coat with contents of 0.3ℓ/m2, 0.45ℓ/m2, 0.6ℓ/m2, and 0.8ℓ/m2, respectively. RESULTS: Table 2 gives the results of the direct shear test using the developed shear machine. The BD-coat type indicated the highest average ISS value compared to the others. Between the surface and binder course, optimum tack coat application rates for AP-3, RS(C)-4, QRS-4, and BD-Coat were 0.6ℓ/m2, 0.3ℓ/m2, 0.6ℓ/m2, and 0.45ℓ/m2, respectively. These optimum contents were determined using the ISS value. CONCLUSIONS: The ISS values of AP-3, RS(C)-4, and QRS-4 showed similar tendencies when ISS increased in the range 0.3~0.6ℓ/m2, while ISS decreased when the applied rate exceeded 0.6ℓ/m2. Similarly, the highest ISS value of the BD-coat was observed when the applied rate was 0.45 ℓ/m2. However, shear strength was similar to the maximum value of ISS when the tack-coat application rate of BD-Coat exceeded 0.45ℓ/m2.

OBJECTIVES : The objective of this research is to determine the integrity of pavement structures for areas where voids exist. Furthermore, we conducted the study of voided-area analysis and remaining life prediction for pavement structures using finite element method. METHODS : To determine the remaining life of the existing voided areas under asphalt concrete pavements, field and falling weight deflectometer (FWD) tests were conducted. Comparison methods were used to have better accuracy in the finite element method (FEM) analysis compared to the measured surface displacements due to the loaded trucks. In addition, the modeled FEM used in this study was compared with well-known software programs. RESULTS : The results show that a good agreement on the analyzed and measured displacements can be obtained through comparisons of the surface displacement due to loaded trucks. Furthermore, the modeled FEM program was compared with the available pavement-structure software programs, resulting in the same values of tensile strains in terms of the thickness of asphalt concrete layers. CONCLUSIONS: The study, which is related to voided-area analysis and remaining life prediction using FEM for pavement structures, was successfully conducted based on the comparison between our methods and the sinkhole grade used in Japan.

OBJECTIVES : The objective of this research is to determine the moisture resistance of the freeze-thaw process occurring in low-noise porous pavement using either hydrated-lime or anti-freezing agent. Various additives were applied to low-noise porous asphalt, which is actively paved in South Korea, to overcome its disadvantages. Moreover, the optimum contents of hydrated-lime and anti-freezing agent and behavior properties of low-noise porous asphalt layer are determined using dynamic moduli via the freeze-thaw test. METHODS: The low-noise porous asphalt mixtures were made using gyratory compacters to investigate its properties with either hydratedlime or anti-freezing agent. To determine the dynamic moduli of each mixture, impact resonance test was conducted. The applied standard for the freeze-thaw test of asphalt mixture is ASTM D 6857. The freeze-thaw and impact resonance tests were performed twice at each stage. The behavior properties were defined using finite element method, which was performed using the dynamic modulus data obtained from the freezethaw test and resonance frequencies obtained from non-destructive impact test. RESULTS: The results show that the coherence and strength of the low-noise porous asphalt mixture decreased continuously with the increase in the temperature of the mixture. The dynamic modulus of the normal low-noise porous asphalt mixture dramatically decreased after one cycle of freezing and thawing stages, which is more than that of other mixtures containing additives. The damage rate was higher when the freeze-thaw test was repeated. CONCLUSIONS : From the root mean squared error (RMSE) and mean percentage error (MPE) analyses, the addition rates of 1.5% hydrated-lime and 0.5% anti-freezing agent resulted in the strongest mixture having the highest moisture resistance compared to other specimens with each additive in 1 cycle freeze-thaw test. Moreover, the freeze-thaw resistance significantly improved when a hydrated-lime content of 0.5% was applied for the two cycles of the freeze-thaw test. Hence, the optimum contents of both hydrated-lime and anti-freezing agent are 0.5%.

OBJECTIVES : This study develops an evaluation method, which is useful to inspect pavement condition of specific boroughs. This is because pavement condition is broadly divided into five grades via visual inspection, which does not consider the types of deteriorations, and is decided by an investigator having a subjective viewpoint. This visual inspection method is not a satisfactory method for accurate maintenance when various deteriorations occur. METHODS: The performance model considers several factors such as crack, rutting, and IRI. This method is also modified from borough SPI based on SPI (Seoul Pavement Index). Considering limited budget of borough, PI (prediction index) is suggested, which is related to the grade of pavement condition evaluation and type of materials. Practical correlation review is also conducted with statistical verification by using the Monte Carlo simulation. RESULTS: The results of the study show that modified criteria are reasonable. First, the comparison between the visual inspection result and the SPI result indicates that the R-square value is sufficiently high. Second, through the common section, each evaluation method could be compared, and the result shows considerable similarity, which increases when the range is modified. Finally, PI for predicting remaining life and the random number SPI have common parts, which means that each indicator would be adequate to be used as an evaluation method. CONCLUSIONS : Comparison and analysis results show that the developed evaluation method is reasonable for specific boroughs where financial support is inadequate for the evaluation process by using the newer equipment. Moreover, for more accurate evaluation method, previous visual inspection data should be utilized, and the database of inspection equipment have to be collected.

도심지의 도로포장은 버스 등 중차량 교통하중과 포장 유지보수 시기가 지나 급속히 진행 되고 있는 포 장표면의 노후화뿐만 아니라 도로하부 시설물 보수를 위한 잦은 굴착복구가 진행되고 있다. 이로 인해 포 장체의 구조적 지지력이 감소하여 전형적인 도심지형 도로파손인 포트홀, 균열, 침하 및 소성변형이 급증 하고 있다. 또한 빈번히 발생하는 도심지의 도로파손 유지보수로 적지 않은 예산이 소요되고 있기 때문에 효율적인 유지보수를 통한 공용성 확보가 절실히 요구된다. 따라서 본 연구에서는 도로포장의 표면상태와 포장층의 구조적 지지력과의 연관성을 파악하여 효과적인 유지보수 방안을 제시하고자 한다. 우선 도로포 장 하부상태와 표면상태 분석결과를 도심지 도로파손 원인 분석 및 대응방안 수립 근거자료로 활용하기 위 해서 서울시의 23개 장기공용성구간(Long Term Performance Pavement)중 공용기간이 5년 경과된 구간 을 선정하였다. 선정된 대상구간의 포장 표면상태 조사(Visual Inspection) 결과인 Rutting, Crack, IRI 및 그에 기반한 SPI지수와 FWD시험으로 부터 산출된 잔존수명과의 비교 분석을 수행하였다. 특히, 표면 조사와 동일구간에 현장코어를 통해 얻어진 아스팔트층 두께와 30cm로 가정한 보조기층 두께 및 대표온 도 20℃를 이용, 역산프로그램을 사용하여 포장층의 탄성계수와 잔손수명을 추정하였다. 대상 구간의 잔 존수명과 도로포장 표면상태와의 관계를 도출하기 위해 지지력 기반 우선순위와 표면상태 기반 우선순위 를 비교하였다. 그 결과 표면상태와 지지력의 상관관계는 다음 그림1에 나타난 바와 같이 Rutting, Crack 에 대한 R-square 값이 0.65이상으로 상관성이 비교적 높은 수준이며 IRI(종단평탄성)는 상관성이 가장 낮았다. 이는 포장층이 지지력이 도로 노면의 평탄성에 미치는 영향이 상대적으로 적기 때문이며, 따라서 Rutting, Crack, IRI의 지수가 모두 포함된 SPI는 상대적으로 낮게 나타난 것으로 판단된다. 따라서 포장 표면상태를 나타낸 지수만을 고려하여 유지보수를 시행할 경우 포장층의 지지력이 충분하지 못한 경우에는 예상보다 빠른 시기에 혹은 동일 시기라도 심각한 상태의 포장손상이 나타날 가능성이 높다. Rutting과 Crack에 대한 지지력의 상관도를 볼 때 이미 진행된 도로파손의 유지보수시 표면상태 뿐만 아니 라 포장층 자체의 지지력을 함께 고려하여 유지보수를 시행하여야 향상된 공용성을 기대할 수 있다.

아스팔트 콘크리트 포장의 파손을 지연시켜 주어진 공용수명을 다할 수 있도록 하기 위해서는 공용기간 동안 정기적인 포장 조사를 실시하여 포장표면의 균열파손을 파악하고 적정 균열보수를 적기에 시행하는 것이 중요하다. 현재 도로포장 선진도시에서는 객관적 도로포장의 상태를 평가하기 위해 도로포장상태조 사 매뉴얼(Pavement Condition Survey Manual)을 통해 정기적으로 각 담당기관의 포장조사요원을 교육 하고 정형화된 평가 방법과 기록 문서를 적용하여 조사를 실시하고 있다. 실제 객관적인 현장 조사 및 평 가를 실시하여 파손정도에 따라 적정한 보수공법을 제시하여 정부가 예산을 절감하는데 큰 도움이 되고 있 다. 국내의 경우 자동포장상태 조사장비를 활용하여 균열에 대한 파손평가를 실시하나 균열보수를 실시한 후에 적용 보수재의 지속적인 추적조사가 진행되지 않고 있어 적용공법의 성능을 제대로 파악하고 있지 못 하고 있는 실정이다. 따라서 본 연구에서는 균열보수재가 적용된 구간에 대하여 도보로 육안조사(Visual Inspection)을 실시하여 균열 보수구간의 현장상태를 점검하고 조사 자료를 토대로 다음의 (식 1)과 같이 CCI(Crack repair material Condition Index)를 산정하여 현장 균열보수재의 상태를 정량화 하였다. (그림 1)과 같이 균열 보수재의 파손 형태와 일일 교통량 표준화 값을 기준으로 균열 보수시행 우선순 위를 결정하였으며, 동일한 보수 재료라도 시공시 품질관리에 따라 성능의 차이가 있음을 확인하였다. 그 러므로 본 연구에서는 CCI(Crack repair material Condition Index)를 활용하여 균열 보수 이후 적용된 공법에 대한 상태등급을 산정하고 균열 보수구간의 추가 보수시행 순서를 파악하여 적기의 균열 보수가 실시될 수 있도록 제안하였다.

1960년대 고속도로의 등장 이후 급격한 산업화와 더불어 국내의 도로연장과 교통량 및 중차량 비중의 증가, 기후변화로 인한 집중호우 및 강설 등의 요인으로 포장파손이 가속화되고 있으며 도로의 관리연장 및 노후화 비중의 급증으로 인한 도로유지관리 비용은 지속적으로 증가하고 있다. 예로 서울시의 경우, 건설 후 20년 이상으로 노후화되어서 도로유지관리 비용은 2020년 이후에는 도로건설비용을 초과할 것 으로 예상되지만 유지관기 예산은 감소추세에 있어 체계적이고 효율적으로 도로관리를 수행하고자 1999 년부터 도로포장관리시스템(PMS: Pavement Management System)을 도입하여 합리적이고 투명하게 도 로포장유지관리 예산편성을 수행하고 있다. 하지만 서울시의 도로포장유지보수 예산은 포장의 상태가 가 장 나쁜 구간을 우선 보수하는 보수전략(Worst First)으로 파손의 정도가 심한 구간에 절삭 후 고온의 아 스팔트 콘크리트를 생산 및 재포장하는 방법 위주로 진행되고 있어 한정된 도로포장 유지보수 예산 하에 서는 증가되는 노후 및 파손된 도로포장의 상태를 일정한 수준으로 유지하기가 점점 어려워지고 있다. 이 러한 문제점을 해결하기 위하여 서울시는 미국, 유럽 등 선진국에서 보편화된 예방적 유지보수공법을 도 입하여 도로가 파손되기 전에 미리 예방하여 포장수명을 연장하여 예산을 절감하고자 노력하고 있다. 이 에 본 연구는 서울시에서 시범적으로 적용한 예방적 유지보수공법의 공용성을 평가하고 경제성분석을 실 시하여 예방적유지보수공법의 도로포장 수명연장효과와 이에 따른 예산절감 효과를 검토하였다. 서울시 에 시험 적용한 예방적 유지보수 공법의 공용성 및 경제성을 평가한 결과 도로포장의 상태에 적합한 공법 을 적용하면 도로포장의 공용수명을 효과적으로 연장할 수 있는 것으로 평가되었다. 위의 그림 1과 같이 절삭 덧씌우기 포장을 한경우보다 예방적 유지보수를 활용했을 경우 공용수명이 연 장되는 것을 확인 할 수 있으며 현재 단가로는 경제성 이득을 취할 수 없는 것을 확인하였다. 따라서 본 연구는 예방적유지보수 공법별 공용성에 따른 경제성 확보를 위한 적정단가를 제시하였다.

PURPOSES: The objective of this study was to determine the optimum ratio of mix design, for a reclaimed asphalt pavement (RAP) content of 100%, for spray injection application. METHODS: A literature review revealed that spray injection is an efficient and cost-effective application for fixing small defective regions of an asphalt pavement. Rapid-setting polymer-modified asphalt mixtures prepared from two types of rapid-setting polymer asphalt emulsion were subjected to Marshall stability and wet track abrasion tests, in order to identify the optimum mix designs. RESULTS and CONCLUSIONS : Different mix designs of type A and type B emulsions were prepared using RAP and virgin aggregates, in order to compare the performance and determine the optimum mix design. The performance of mixtures prepared with RAP was superior to that of mixtures containing virgin aggregates. Moreover, for optimum ratio of the design, the binder content prepared from RAP was set to 1~2% lower than that consisting of virgin aggregates. Compared to their Type A counterparts, type B mixtures consisting of a reactive emulsion performed better in the Marshall stability and wet track abrasion tests. The initial results confirmed the advantages associated with using RAP for spray injection applications. Further studies will be performed to verify the difference in the optimum mix design and performance obtained in the lab-scale test and tests conducted at the job site by using the spray injection machine.

PURPOSES : The hydrated lime-modified asphalt, which improves moisture resistance, is normally used for pavements to reduce the number of potholes. However, the method of applying the material properties of the lime-modified asphalt mixture for use in pavements is not covered in the Korean Pavement Research Program (KPRP). The objective of this research is to find a method for the design application of lime-modified asphalt’s material properties to the KPRP. METHODS: The section for test design is selected in some conditions which are related to the level of design regarding Annual Average Daily Traffic (AADT). To define the application methods of hydrated lime in the KPRP, the models of fatigue, rut and international roughness index (IRI) are determined based on the M-EPDG test results from some earlier research results. Moreover, it is well known that dynamic moduli of the unmodified mixture are not different from those of the lime-modified mixture. RESULTS: The performance results of hydrated lime-modified asphalt pavement were not very much different from those of the unmodified pavement, which meant the limited design regulations regarding fatigue failure, rutting deformation and IRI. CONCLUSIONS: The KPRP uses the weather model from the data for previous 10 years. It implies that the KPRP cannot predict abnormal climate changes accurately. Hence, the predictive weather data regarding the abnormal climate changes are unreliable. Secondly, the KPRP cannot apply the moisture resistance of asphalt mixtures. Therefore, a second level of design study will have to be performed to reflect the influence of moisture. It means that the influence on pavement performance can be changed by the application of hydrated lime in asphalt mixture design.

현재 서울시의 아스팔트 포장도로의 수명은 20~30년이다. 기존 포장의 지지력에 기반을 둔 덧씌우기 포장의 수명은 이보다 더 짧다. 이에 따른 본 연구는 MEPDG를 활용한 아스팔트 포장 카탈로그 설계법 개발로서 서울형 설계법을 총 3가지 카탈로그(버스전용차로(Ⅰ), 버스전용차로가 운영되는 도로의 일반차 로(Ⅱ), 버스전용차로가 운영되지 않은 도로의 일반차로(Ⅲ))로 분류하여 연구를 진행하였다. 서울시의 각 도로의 종류에 따른 포장 두께는 다음과 같다. 일반차로 약 100mm~260mm를 보이며 130, 160, 180mm가 가장 일반적인 두께로 조사되었다. 반면, 버스전용차로는 약 140mm~290mm를 보 이며 170, 200, 220mm가 가장 일반적인 두께로 조사되었다. 이를 기반으로 본 연구에서는 영국의 포장 설계 카탈로그에 나온 각 도로별 포장두께를 비교하였다. 이를 조사한 결과 현재 한국의 버스전용차로의 아스팔트 포장 두께는 89mm가 부족하고, 일반차로의 아스팔트 포장두께는 84mm가 부족하였다. 덧씌우기 포장의 수명은 서울시의 경우 6.6년이다. 이는 일반국도의 수명인 10년에 비해 3.4년이 짧다. 전체 도로 중 45%가 조시파손이 생기며 이는 4~5년 이내에 발생한다. 조기파손을 구조적인 측면에서 조 사한 결과, 단기 공용성(덧씌우기 수명 5년 미만)의 10개 구간 중 5개의 구간에서 Crack Depth Ratio(CDR)이 1로 조사되었다. 이중 구조적으로 아스팔트 두께가 최대 145mm가 필요한 구간도 있었다. 반면 장기 공용성(덧씌우기 수명 10년 이상)중 가장 큰 CDR 값이 0.6이며 이 중 아스팔트 두께가 최대 95mm가 필요한 구간이 있다. 본 설계법은 도로의 다양한 교통 특색(연간 일일 평균 교통량, 차종별 분포 율 등), 노상층의 상태, 신규재료의 물성값을 MEPDG 프로그램에 활용하여 정립하였다.

PURPOSES : This research describes how to predict the life cycles of fatigue cracking based on NCHRP Report 704 as well as modified harmony search (MHS) algorithm. METHODS : The fatigue cracking regression model of NCHRP Report 704 was used in order to calculate the ESAL (Equivalent Single Axle Load) numbers up to pavement failure, based on using material parameters, composite modulus, and surface pavement thickness. Furthermore, the MHS algorithm was implemented to find appropriate material parameters and other structural conditions given the number of ESALs, which is related to pavement service life. RESULTS: The case studies show that the material and structural parameters can be obtained, resulting in satisfying the failure endurance of asphalt concrete structure, given the number of ESALs. For example, the required ESALs such as one or two millions are targeted to satisfy the service performance of asphalt concrete pavements in this study. CONCLUSIONS : According to the case studies, It can be concluded that the MHS algorithm provides a good tool of optimization problems in terms of minimizing the difference between the required service cycles, which is a given value, and the calculated service cycles, which is obtained from the fatigue cracking regression model.

PURPOSES : The purpose of this study is to determine the optimum addition rate of SBR latex through the evaluation of durability and strength of SBR latex applied soil pavement. Formerly used materials such as fly ash and cement in soil pavement had resulted in decreased durability due to micro crack by heat of hydration and shrinkage crack in winter. However, that agglutinated polymers help adhesion to aggregate increased comes up with preventing the crack opening when the number of capillary tubes of SBR latex get decreased in the hydration process of cement. Therefore, in this study, it is suggested that the evaluation of the field applicability of soil pavement be conducted through the performance lab test in terms of strength increment, adhesion improvement, and crack resistance based on SBR latex addition rate. METHODS: In order to evaluate the field applicability of soil pavement, SBR latex was added 0 to 3% by 1% increment, with fixed cement contents of 3% and 5%. The resistance of shear failure and crack of soil pavement were evaluated by performing the uniaxial compressive strength test and indirect tensile strength test at -20 and 20℃, respectively. RESULTSCONCLUSIONS: It was found out that from both tests, resistance of shear failure and crack were improved with increment of curing time, and especially more than 2% of SBR latex addition rate and 5% cement content gave better results.

PURPOSES: This study focuses on conducting pavement rehabilitation for more deteriorated roads given a limited government budget. METHODS: Therefore, we apply a optimization programming model of the permutation algorithm used for rehabilitating more deteriorated pavement areas, which is subjected to the limited budget. RESULTS: The permutation algorithm was evaluated in terms of determining the maximized rehabilitation of deteriorated pavement areas, using the newly developed performance models such as fatigue cracking, rutting, international roughness index(IRI) through the surveying data from 2006 to 2012. When compared with a traditional model of the so-called worst-first sequence(WFS) method, the permutation algorithm worked better than the WFS method, resulting in covering more deteriorated pavement areas given the limited government budget. CONCLUSIONS : Through a case study, it could be concluded that the permutation algorithm provides more reliable results in terms of rehabilitating more deteriorated pavement areas given the limited budget.

PURPOSES: This study is to suggest the improvement for bus rapid transit system in Seoul METHODS: The maintenance cost for bus lane damages and plastic deformations are increased by bus passing speed, heavy bus weight, and climate change (localized torrential downpour, subtropical climate) and the accident risk has been increased. RESULTS: Recent analysis of pavement damage indicates that bus lane damage caused by heavy weight is overwhelming and it is urgent to prepare countermeasures. CONCLUSIONS : Pavement data of bus rapid transit system, bus transit numbers and pavement damage elements were analyzed. By analyzing pavement maintenance, design and construction, the countermeasures for the improvement of bus lane pavement and effective maintenance were suggested.