Road Construction Activities Research Articles

Soil steaming to disinfect barnyardgrass-infested soil masses

AbstractReusing soil can reduce environmental impacts associated with obtaining natural fresh soil during road construction and analogous activities. However, the movement and reuse of soils can spread numerous plant diseases and pests, including propagules of weeds and invasive alien plant species. To avoid the spread of barnyardgrass in reused soil, its seeds must be killed before that soil is spread to new areas. We investigated the possibility of thermal control of barnyardgrass seeds using a prototype of a stationary soil steaming device. One Polish and four Norwegian seed populations were examined for thermal sensitivity. To mimic a natural range in seed moisture content, dried seeds were moistened for 0, 12, 24, or 48 h before steaming. To find effective soil temperatures and whether exposure duration is important, we tested target soil temperatures in the range 60 to 99 C at an exposure duration of 90 s (Experiment 1) and exposure durations of 30, 90, or 180 s with a target temperature of 99 C (Experiment 2). In a third experiment, we tested exposure durations of 90, 180, and 540 s at 99 C (Experiment 3). Obtaining target temperatures was challenging. For target temperatures of 60, 70, 80, and 99 C, the actual temperatures obtained were 59 to 69, 74 to 76, 77 to 83, and 94 to 99 C, respectively. After steaming treatments, seed germination was followed for 28 d in a greenhouse. Maximum soil temperature affected seed germination, but exposure duration did not. Seed premoistening was of influence but varied among temperatures and populations. The relationships between maximum soil temperature and seed germination were described by a common dose–response function. Seed germination was reduced by 50% when the maximum soil temperature reached 62 to 68 C and 90% at 76 to 86 C. For total weed control, 94 C was required in four populations, whereas 79 C was sufficient in one Norwegian population.

Environmental appraisal of ferrochromium slag as concrete pavement material

Ferrochromium slag is a waste product in the production of ferrochromium alloy, an important constituent of stainless steel and others. Material characteristics of the slag has been found to be very suitable for civil construction purpose and particularly as road construction material. There is reported leaching of chromium from unbound waste slag at lower pH and finer size of the particles. Experimentally, it is demonstrated that under acid rain pH condition 3 and about 75-µm particle sizing, there is release of chromium about 55.4 –71.2 mg/l as hexavalent chromium and 234.2 –248.5 mg/l as total chromium, which will exceed the discharge standard by regulatory bodies. The manufactured concrete with slag as coarse aggregate has the strength more than 20 % than that of normal concrete. Leachable chromium is suitably immobilized in cement and concrete medium with leachability index more than 12.5 validating the lower elution of chromium and complying with the regulatory requirement. Thus, instead of using unbound slag in road construction activities, concrete bound ferrochromium slag can be utilized in the construction of pavement.

ASSESSING THE ENVIRONMENTAL IMPACT OF ROADWAY’S CONSTRUCTION ON ADJACENT WATER RESOURCES: A CASE STUDY OF THE SOUTHERN PART OF ALBANIA

Water is one of nature’s resources. As urbanisation grows, new roadways and highways are constructed for the transport sector and development. Due to roadway infrastructure, the development of the quality of surface water bodies in close proximity to roads is deteriorating and has become a major environmental challenge. Considered as one of the major nonpoint pollution sources, the construction of new roadways can have short and long-term effects on water quality conditions. This study revealed that road construction activities may be responsible for introducing pollutants in nearby water sources, leading to the deterioration of water quality. The roadway expansion activities affect both the surface and groundwater quality. Furthermore, this study was conducted to assess the effects of a road construction project situated in the southern part of Albania, on physic-chemical parameters of surface water by collecting water samples from Skotini stream. The analysed parameters included pH, dissolved oxygen (DO), biological oxygen demand (BOD5), chemical oxygen demand (COD), electrical conductivity (ECw), total dissolved solids (TDS), salinity, nitrites (NO2-), ammonium (NH4+) and total phosphorus (Ptot). The results revealed that all physic-chemical parameters analysed in the laboratory are between the normal standards classifying these waters as very clean. Further surveillance for quality assessment of water sources near roadway’s construction activities is needed. Various best management practices have been developed and implemented to prevent negative environmental impacts in the transport sector and roadway construction activities. Results of the water quality help strengthen the theory that roadway construction projects in the transport sector, using appropriate best management practices, could yield minimal impact on the overall water quality of surrounding water bodies.

Evaluation of a Mobile Highway Management System at Roadwork Zones

Road construction and maintenance activities cause traffic congestions and delays and present challenges for ensuring the safety of both motorists and road workers. While urban areas are well-equipped with traffic devices, in the case of highways our chances to collect traffic data and control traffic flows may be limited. Then the use of a temporary Highway Traffic Management System seems to be a suitable solution. Although the impacts of its deployment are addressed by many theoretical studies and demonstrated on traffic simulation models, there are not many references dealing with field tests. We provide results of the practical evaluation of the temporary Highway Management System installed and tested on the main highway in the Czech Republic during the road works period. Before-after analysis of collected traffic data was performed to prove the importance and positive impact of the proposed solution. We demonstrate an over 20% increase in the capacity of the roadwork zone and an almost 30 seconds decrease in average delay for one vehicle Highway administrators can use the results to justify investments into the temporary deployment of mobile traffic management systems.

On-site personal protective equipment signage and use by road construction workers in Ghana: a comparative study of foreign- and locally-owned companies

BackgroundRoad construction work has specific risks and safety issues which have not been adequately addressed in most low- and middle-income countries, especially Africa. The objective of this study was to determine the prevalence of personal protective equipment (PPE) use during road construction activities by workers in foreign- owned against locally-owned road construction companies in Ghana.MethodsAn institution-based cross-sectional survey was undertaken during January – March, 2020 to study 389 road construction workers who were actively working on site. They were unobtrusively observed to capture whether or not they wore the appropriate PPE at the time of the survey. The PPE of interest were: hard hat, goggles, shoes, nose masks, hearing protection, gloves and reflective vests/apparel. On-site posted PPE signage was also checked.ResultsMajority of workers were males (96.9%) and labourers (53.5%). Similar numbers of workers in locally-owned (195) and foreign-owned (194) companies were studied. Use of PPE varied considerably by type: shoes (78.7%), reflective vest (44.5%), gloves (30.6%), hard hat (27.0%), nose mask (17.2%), goggles (11.3%) and hearing protection (10.8%). For all types of PPE, use was higher for workers in foreign-owned companies compared with locally-owned companies: goggles (Odds ratio [OR] 55.2), hearing protection (OR 52.0), gloves (OR 23.7), hard hat (OR 20.2), nose mask (OR 17.8), reflective vest (OR 5.3) and shoes (OR 4.1), (p<0.001 for all ORs). No site had any signage to promote PPE use.ConclusionsMajority of workers used shoes. Less than half of workers used other types of PPE and use of some types (goggles and hearing protection) was minimal. Workers in foreign-owned companies were significantly more likely to use all the seven types of PPE than locally-owned companies. Although there is still room for improvement in foreign-owned companies, locally-owned companies should be able to attain similar PPE use to that in foreign-owned companies. Necessary PPE should be provided and site supervisors should encourage workers to wear PPE when on site.

Building Sustainable Pavements: Investigating the Effectiveness of Recycled Tire Rubber as a Modifier in Asphalt Mixtures

Building more sustainable pavements for the future requires knowledge of alternative and innovative materials for utilization in future road construction and maintenance activities. Being mindful of this need, the present study investigates a Reacted and Activated Rubber (RAR) compound modifier with the aim of defining an optimal RAR percentage in Asphalt Concrete (AC) mixes. It is acknowledged that when this type of modifier is incorporated within an AC mix as an alternative for the bituminous binder material, the associated economic, environmental and social benefits are significant. Simply put, the use of RAR modifiers provides the potential to utilize a waste product (rubber tires) as a more sustainable alternative to bitumen within AC mixtures. However, it seems that the information about the overall performance of AC mixes modified with RAR is currently limited. On these grounds, the present study focuses on the surface course layer and evaluates (a) achieved physical characteristics (compaction degree/voids), (b) mechanical characterization results (stiffness moduli) and (c) friction-based properties of tested mixtures incorporating varying RAR levels and different test temperatures. From the evaluation, it is concluded that for the case of the surface course mixture under investigation, the optimal percentage by weight of bitumen for inclusion of the RAR modifier is 10%.

Analysis of the Cost-Effective Road Maintenance Program for the Improvement of Road Value in Kabupaten Gresik Using the Forecasting Method

Roads have a very significant role in enhancing various fields as part of the national transport network. Road management includes road construction, improvement, and technical maintenance activities, which are continuously carried out for the physical maintenance of the road. The role of the road service must be fulfilled so as not to compete with the transportation that passes on the road. Based on the phenomena that have been described, we present the analysis of the cost requirements and methods of road handling in addition to the effectiveness of road stability for the next two years. The research was carried out for a case study of the district major road in Gresik Regency, which is represented in this situation by three main roads. The analysis of a data set is based on the variables of historical data. Then, we analyze using time series with moving averages, exponential smoothing, and trend projection. Next, the method for setting a maintaining strategy of overcoming prediction and its relation to the solidity of the roads, using fuzzy tahani. The results analyzed are confirmed by the recommended output for the next two years.

Detecting and interpreting non‐recurrent congestion from traffic and social media data

A non-recurring incident often negatively affects traffic, which is represented as non-recurrent congestion. However, travellers can usually perceive congestion without knowing the underlying reasons. Accordingly, this paper proposes a data-driven framework for non-recurrent congestion detection and interpretation analysis. First, a statistical algorithm named generalized extreme studentized deviate is introduced to detect non-recurrent congestion by comparing the current traffic speed with the speed threshold learned from historical data. The case study in Beijing shows that the proposed generalized extreme studentized deviate outperforms other prevailing algorithms in terms of detection rate, false alarm rate, and mean detection time. Second, data mining and natural language processing technologies are implemented on data collected from Sina Weibo, a Chinese microblog site akin to Twitter, to classify non-recurring incidents that may be associated with non-recurrent congestion, including traffic accident, road construction, concert, special sport (marathon), and commercial activity. Results show that overall classification accuracy reaches 95%. Finally, the association relationship between the detected non-recurrent congestions and incidents is established via spatiotemporal information matching. This information matching provides a bidirectional verification. On the one hand, nearly 58% of non-recurrent congestion can be explained by incident-related (IR) microblogs. On the other hand, an average of 62% of IR microblogs can be traced by nearby non-recurrent congestions. This paper suggests that social media can be used as a secondary source and integrated with traffic data to enhance the understanding of non-recurrent congestion.

Quantum of Building Demolishied Debris Associated with Urban Road Construction in Gombe City, Nigeria

Demolition activity is deeply embedded in the urban system. In recent times, infrastructural development in Nigeria’s major cities has led to increase in road construction activities associated with demolition of hundreds of houses from which millions of tons of Demolition Waste have been generated. However, it is widely reported in many studies globally that demolition debris is such waste that can be re-used. Though, this is not the case in Gombe due to paucity of information on its composition, size and quantities. Hence, the objective of this study is to determine the volumetric composition of generated demolition debris in Gombe City with a view to knowing the potential quantities available for re-use. The study used both qualitative and quantitative design approach. A simple random sampling technique was employed to select 13 roads which were sub-divided in to Lot 1 (8.33km) and Lot 2 (15.04km) and the period of 2011-2014 was considered for the study. Primary data kept by actors and authorities for the compensation assessment which do not refer to demolition debris quantities were used as the bases for extraction of quantities. Handheld (GPS) instrument was used in establishing coordinates; photographs were taken from different locations showing demolition activities taking place and composition of different materials debris. Results revealed that a total of 1,271 structures were evaluated after partially or fully demolished for street widening and/or to pave way for new road construction, in addition a total volume of 129,993.57m3 of Demolished Debris was generated which composed of 10.00% Concrete, 60.30% Sandcrete and 29.69% clay/mud. In conclusion, there exist huge quantities of building demolition debris from street widening and/or new road construction in Gombe city which can be put in to re-use as a component of urban road construction, where properly managed will go a long way to reducing environmental adverse effect due to excessive exploitation for new material.

KAJIAN PARTICULATE MATTER DAN KEBISINGAN PADA PERMUKIMAN DI SEKITAR JALAN TOL KEDUNGMUNDU SEMARANG

&lt;div&gt;&lt;table cellspacing="0" cellpadding="0"&gt;&lt;tbody&gt;&lt;tr&gt;&lt;td align="left" valign="top"&gt;&lt;p&gt;&lt;em&gt;The construction of toll roads has a positive impact to facilitate the mobility rate of the community. But the construction of toll roads also has a negative impact on the residential area around the toll road, namely air pollution due to the burning of vehicle fuel. PM2.5 and PM10 air particles are particles that damage the working system of the lungs. The health of the environment where settled is an important support that affects health, especially in the era of pandemic covid. Air particle measurement using portable PM2.5 and PM10 Air Quality Tester Detector. The daily average level of PM2.5 particles in residential areas around Semarang's Kedungmundu toll road is 65.44 μg/Nm³, while the PM10 particle content is 95.2 μg/Nm³. PM2.5 levels exceed the standards of the National Ambient Air Quality Standard (BMUA), The WHO Air Quality Guidline and Ambient Air Quality Standards (USEPA). For PM10 exceeds WHO standard. In addition to air pollution, another impact is that these residential areas have noise. The daily average noise value when measuring the sampling time is 62.23 dB, this value is exceeding the standard threshold of the Regulation of the Minister of Environment for residential areas. So the residential area around Kedungmundu Semarang toll road is less feasible for health when viewed from the value of PM 2.5 and PM10 as well as noise. This study aims to determine the level of PM2.5 and PM10 particles as well as noise in residential areas around the Kedungmundu Semarang toll road. Once the measurement results are obtained, it will be used as a reference for planners to provide solutions for settlements that have an impact due to toll road construction activities with dense vehicle intensity.&lt;/em&gt;&lt;/p&gt;&lt;/td&gt;&lt;/tr&gt;&lt;/tbody&gt;&lt;/table&gt;&lt;/div&gt;

Quantifying sedimentation patterns of small landslide‐dammed lakes in the central Oregon Coast Range

AbstractUnderstanding sedimentation patterns in small coastal watersheds due to landscape perturbations is critical for connecting hillslope and fluvial processes, in addition to managing aquatic habitats for anadromous fish and other aquatic species in the Oregon Coast Range (OCR). Changes in sedimentation patterns spanning the last 250 years are preserved in two landslide‐dammed lakes in small watersheds (&lt; 10 km2) underlain by the Tyee Formation in the central OCR. Dendrochronology of drowned Douglas‐fir stumps in both lakes provided precise timing of the damming and formation of the lakes, with Klickitat Lake forming in winter ad 1751/52 and Wasson Lake in winter ad 1819/20. Perturbations from wildfires, logging and road development, and previously underappreciated snow events affect sedimentation rates in the lakes to different degrees, and are identified in the sediment record using cesium‐137 (137Cs), high‐resolution charcoal stratigraphy, local fire records, and aerial photography. Each lake has variable sedimentation accumulation rates (0.05–4.4 cm yr−1) and mass accumulation rates (0.02–1.42 g cm−2 yr−1). Sedimentation rates remained low from the landslide‐damming events until the mid‐19th century, when they increased following stand‐replacing wildfires. Aside from a sediment remobilization triggered by human modification of the landslide dam at Klickitat Lake around 1960, the largest peaks in mass accumulation rates in the mid‐20th century at both lakes in the early 1950s precede major road construction and logging activity in the watersheds. Subsequent sedimentation rates are lower, but variable, and possible effects of logging and road development might be exacerbated by abnormal precipitation and heavy snow events. A comparison of previous studies of landslide‐dammed lakes in larger watershed of the OCR are consistent with our findings of increased sedimentation in the mid‐20th century, as well as higher sedimentation rates in the debris‐flow dominated southern Tyee Formation than in the lower‐relief northern Tyee Formation.

Implementation of principle for responsible investment in distribution of bank credits on infrastructure projects

This research aims to discuss a large amount of credit lending is in line with the potential risk to the environment which is also caused by Toll Road construction activities. Therefore, Banks, Development, and the environment cannot be separated from one to another mainly because the Bank is responsible for taking preventive steps, other than implementing the substance of 5C principles, Bank is also obliged to implement several principles mentioned in POJK 51/2017, one of which is Principle for Responsible Investment. However, there are still no standards for the implementation of these principles or any strict penalties for Banks that are not applying the principle. This creates legal uncertainty, as it causes a potential risk that the Bank indirectly has not any obligation to implement it, yet only as a form of recommendation, whereas on the other hand, infrastructure development still damages the environment as it happened at the construction of Trans Sumatra Toll Road. In contrast to what Indonesia has done, Australia uses a variety of strategies to implement the Principle for Responsible Investment. In line with this issue, this research is using the normative legal research method where it is expected to provide different perspectives that will be useful for maximizing the realization of the Principles for Responsible Investment as part of Sustainable Finance in credit lending practices for Infrastructure development projects. Thus, it aims to make more detailed legal reforms, primarily regarding the standardization and sanctions of Principles for Responsible Investment including its derivative regulations hence that a sustainable environment will be realized.

Characteristics and status of coastal sand dune vegetation on coasts of Shandong Province

<p indent="0mm">Coastal sand dune vegetation is a non-zonal vegetation type, mainly composed of coastal sand dune plants resistant to impoverishment, drought, and mild salinity, which is distributed on the sandy coast of China. There is typical coastal sand dune vegetation on the coasts of Shandong Province. Although the distribution area of coastal sand dune vegetation is small, it has important ecological value and regional significance because of its original nature, protective effect on sandy coast, and various rare and endangered plants. By field investigation and literature review, we studied the characteristics of the composition, structure, distribution, and succession of coastal sand dune vegetation on sandy coasts of Shandong Province. It is classified in to 13 community types. We also analyze the changes and causes of the coastal sand dune vegetation in Shandong Province from 1985 to 2020 in terms of the composition, distribution, and vegetation type. Due to the impact of urbanization, real estate, coastal road construction, sand excavation, tourism, and other human activities, the degradation of coastal sand dune vegetation is serious and widespread. It is very important and urgent to put forward the countermeasures of protecting and restoring coastal sand dune vegetation, such as conducting basic research, implementing specific protection and management. Meanwhile, we put forward specific suggestions on the status of the coastal sand dune vegetation in Chinese vegetation classification and vegetation mapping.

Innovative bitumen technology to reduce impact on air quality

With increasing environmental awareness, air quality is a topic of intense discussion and focus with many environment authorities/agencies setting targets aiming to improve air quality. Reducing the impact on air quality from road construction and maintenance activities plays a part in a holistic approach to improving air quality, particularly in the urban environment. This paper describes an innovative bitumen technology which can help reduce the impact on local air quality from bitumen and asphalt mixtures during asphalt manufacture and pavement installation. It presents laboratory experiments designed to replicate the end-to-end aspects of the bitumen supply chain; starting from refineries and storage depots to paving at road construction sites. The laboratory results have shown substantial reductions in a range of air quality indicators, such as SOx, NOx, particulate emissions, volatile organic content emission as well as in other potential nuisances such as H2S and odour. Full scale field evaluations carried out in major cities have reflected the results obtained in the laboratory and show a reduction in the emission of specific gases and particulates at various points of the asphalt preparation and pavement laying process. This bitumen technology plays a role as part of the holistic solution in improving air quality in the urban environment.

Impact Assessment and Prioritization of Critical Delay Factors for a Road Project

Indian road sector has witnessed significant changes from the year 2014. The new government administrators and the ministry of road transport and highways have brought in various policy reforms, foreign investments and special drive to push the road construction activities. The ministry had initially planned to build roads at a pace of 40 km/day but only achieved construction of 32 km/day. In addition, a number of projects are pending which have been collectively taken up under the newly launched Bhartmala pariyojana scheme. There exist some constraints/factors within various stages of planning and execution, which is responsible for delays. The main focus of this study was to carry out an assessment of the impact of delay factors and prioritize them for a road project. A questionnaire survey followed by informal interviews was carried out to identify and assess the impact of various delays occurring in road projects in India. Data were collected amongst senior project stakeholders from government departments, consultants, contractors, and academicians. The response data were statistically analyzed and the results were used on a sample road project. A 4D virtual model of the entire stretch was made. A list of delays apt for the project was identified and their impacts on planned schedule and cost were found. The data were run on a monte carlo simulation platform for various outcomes on project planned time and cost. The simulation results revealed critical delay factors responsible for major delays in the road project. The critical delay factors are to be properly targeted, handled, and managed to ensure success in project completion. The findings of this study will greatly benefit stakeholders in road construction to identify and control the critical delay factors.

Upcycling Potential of Industrial Waste in Soil Stabilization: Use of Kiln Dust and Fly Ash to Improve Weak Pavement Subgrades Encountered in Michigan, USA

The State of Michigan in the United States often encounters weak soil subgrades during its road construction and maintenance activities. Undercutting has been the usual solution, while a very few attempts of in-situ soil stabilization with cement or lime have been made. Compared to the large volume of weak soils that require improvement and the cost incurred on an annual basis, some locally available industrial byproducts present the potential to become effective soil subgrade stabilizers and a better solution from the sustainability perspective as well. The candidate industrial byproducts are Cement Kiln Dust (CKD), Lime Kiln Dust (LKD), and Fly Ash (FA), out of which only a fraction is currently used for any other secondary purposes while the rest is disposed of in Michigan landfills. This manuscript describes a laboratory investigation conducted on above industrial byproducts and/or their combinations to assess their suitability to be used as soil subgrade stabilizers in three selected weak soil types often found in Michigan. Results reveal that CKD or a combination of FA/LKD can be recommended for the long-term soil subgrade stabilization of all three soil types tested, while FA and LKD can be used in some soil types as a short-term soil stabilizer (for construction facilitation). A brief discussion is also presented at the end on the potential positive impact that can be made by the upcycling of CKD/LKD/FA on sustainability.

Effects of oil palm fibre ash on cement stabilised lateritic soil used for highway construction

ABSTRACT Increasing road construction activities in Nigeria has led to increased demand for lateritic soil (LS), whose properties vary from one location to another, and. The properties of some of this laterite deposits along road alignment can be improved to enable it withstand traffic loads. This paper presents results of the laboratory evaluation of LS stabilised with oil palm fibre ash and cement blends, with a view to determine its suitability as flexible pavement construction material. The mixtures were subjected to British Standard heavy (modified Proctor) compaction energy to determine their strength characteristics. Test results show that the properties of LS improved with oil palm fibre ash and cement treatment. The maximum dry density decreased with corresponding increase in optimum moisture content as the cement content increased from 0% to 6% and the LS content of the mixtures decreased with increased oil palm fibre ash, at a fixed per cent of cement. The peaked California bearing ratio of 190.09% (soaked) recorded for the 80% LS + 14% OPFA + 6% C mix proportion, with 14th day unconfined compressive strength of 785.75 kN/m2, cohesion of 140 kN/m2 and angle of internal friction of 25°, can be used as a base material in road construction. Further work may be encouraged to assess resilient modulus of this material under cyclic load.

Effect of factors of organizational structure influencing nonphysical waste in road projects of developing countries

PurposeThe purpose of this research is to rank the most significant factors of organizational structure that can reduce time and cost overruns (nonphysical waste) in road projects of the developing countries. Additionally, the effect of factors of organizational structure on nonphysical waste in road projects is also measured.Design/methodology/approachFactors of organizational structure causing time and cost overrun are extracted through a content analysis of the published literature. Moreover, a questionnaire survey is carried out involving 128 professionals to assess the effect of organizational structure factors on time and cost overrun. Finally, to obtain a more objective evaluation, relative importance index and regression analysis techniques are utilized, and the most severe factors influencing time and cost overrun are indicated.FindingsThis study found out that top management support and procurement procedures are the most significant factors influencing time and cost overruns in road projects of the developing countries.Originality/valueA small number of studies have been conducted to investigate the effect of factors of organizational structure on time and cost overrun in the construction industry. And even more, its relation with respect to road projects of the developing countries is limited. This research highlights the effect of most significant factors of organizational structure that influence the nonphysical waste in road projects of the developing countries. Therefore, this study adds to the body of knowledge by recommending that all the stakeholders of construction project should pay close attention toward these factors to control the enigma of time and cost overrun. It might also prove helpful, if implemented to its full extent, in all the road construction activities undertaken.

The Correlation Between CBR (California Bearing Ratio) and UCS (Unconfined Compression Strength) Laterite Soils in Palangka Raya as Heap Material

In road construction activities, the use of soil as heap material is commonly practiced. Soils are heaping above soft soils aiming to increase the carrying capacity of the soft soils layer. The parameters for reference are the CBR (California Bearing Ratio) and UCS (Unconfined Compression Strength) scores. But, the test of CBR and UCS takes a long time in the process. Therefore, an approach is needed to obtain the score of CBR and UCS. Then by find out one of the parameters score, will also find out the others parameter scores. Aim to obtain the correlation between CBR and UCS scores, firstly, need to perform test in laboratory. The test conducted to soil samples from Tangkiling village, Bukit Batu district, Palangka Raya City, Central Kalimantan Province. The results showed that the correlation between UCS and CBR scores were, UCS = 0.2416, CBR – 1.2389, with R score was 0.9193. This data showed a very high correlation between UCS and CBR.

Rainfall-induced landslides and debris flows in Mengdong Town, Yunnan Province, China

On 2 September 2018, an intense rainstorm swept Mengdong Town in Yunnan Province of China, inducing a serious landslide and debris flow disaster with 10 deaths and 11 missing. Image interpretation, field survey, and slope stability analysis were used to examine the characteristics and initiation mechanism of this hazard. A total of 1774 landslide scars were identified, the area of which occupied 8.26% of the study region. Due to the spatial inhomogeneity of precipitation, these scars mainly concentrated along valleys in the lower part of the study area. Besides, well-forested hillslopes were more prone to landslides, indicating the limited role of trees in stabilizing slopes in extreme rainfall events. The initiation of landslides is mainly attributed to the week cohesion of the saturated clayey sand beneath the root zone, where the tensile resistance of roots was absent, and the increase of positive pore water pressure. Additionally, 288 landslide scars were situated adjacent to roads, demonstrating that the road construction activity had intensified the landslide disaster. Owing to the relatively low mobility of landslides, a considerable portion of landslide debris deposited on the valley floor in smaller watersheds (< 6.03 hm(2)), while the remaining portion entered high-order channels. In these channels, where stream power was relatively large, the woody debris and soil carried by landslides were entrained by streamflow, and debris flows were formed. Moreover, the magnitude of debris flow was amplified by the vertical and lateral erosion of the stream channel.