The terrain features of Taiwan make it difficult for National Freeways to avoid sections that require excavation of the side slopes. However, the slopes in Taiwan are situated in unfavorable geologic conditions (e.g. proliferation of joints and broken rocks) and susceptible to frequent natural disasters (e.g. earthquakes, torrential rains). To ensure the safety of Freeway slopes and avoid the loss of the properties and lives of road users, the establishment of a life-cycle maintenance and management policy for Freeway slopes is imperative.
The introduction of the National Freeway slope life-cycle maintenance management operation can be separated into two stages. The first stage is from the landslide incident at 3.1k of Freeway No. 3 in April 2010 to December of 2013. Due to the landslide incident on Freeway No. 3, the Bureau began the National Freeway Slope Reinforcement Implementation program to grasp and manage the safety of National Freeway slopes and respond to the need for National Freeway slope life-cycle maintenance management operations. The project includes the complete examination and reinforcement of Freeway slopes, the amendment of Chapter 5 (Slopes) of the Maintenance Manual, and the establishment of the National Freeway slope life-cycle maintenance management system.
Of the above, the complete examination and reinforcement of Freeway slopes had been concluded as of August 31, 2013, resulting in the slopes all satisfying the slope safety requirements. From 2014, according to the regulations in Chapter 5 (Slopes) of the Maintenance Manual promulgated in November of 2013, the slopes are to be managed in different tiers. The National Freeway slope life-cycle maintenance management is achieved through slope patrol, slope monitoring, earth anchor inspection, and slope safety evaluation, which allow immediate discovery of any abnormalities and the subsequent maintenance, reinforcement, and remediation. The results of the Freeway slope reinforcements are collected as case studies by the Bureau to serve as a reference for future staff who are responsible for the slopes.
The second stage began on January 2014, when all Freeway slopes entered the execution phase of the life-cycle maintenance management and continuous tracking of performance and improvements in accordance with the regulations in Chapter 5 (Slopes) of the Maintenance Manual promulgated in November 2014. Unlike most slope maintenance management protocols for this stage inside and outside the country that focus on regulating the patrol of slopes, the National Freeway slope maintenance management policy of the Bureau covers not only maintenance protocols of the slopes, but also archiving and usage of slope data, personnel training, and performance management of slope maintenance work, as shown in the table of contents of Chapter 5 (Slopes) of the Maintenance Manual. The tiered maintenance management of the slopes was also introduced. The slopes are divided according to their urgency into four tiers, A, B, C, and D, as shown in the National Freeway slope tier map. The slope maintenance of each slope corresponds to different frequencies depending on its tier. By combining the data from regular patrol, slope monitoring and earth anchor inspections, as well as the potential factors for slope disaster and slope risk scale, the slope safety evaluation can be fed back, and the slope tiers adjusted accordingly to achieve a rolling management. The initial classification by slope patrol (Ai, Bi, Ci, and Di) can serve as a reference for establishing priority of the maintenance work of the engineering branches. The slope tiers (A, B, C, and D) can serve as a reference for the classification of slope maintenance management tasks. See the classification flow chart.
In addition, to prevent the National Freeway life-cycle maintenance management policy from becoming outdated, the Bureau has amended the contents of Chapter 5 (Slopes) in August of 2016 in response to the operation results from the slope maintenance work between 2014 and 2016, as well as the latest requirements from the authorities. The amendments include the adjustment to the form for regular patrol of slopes and the establishment of the form for regular patrol of the embankment, adjustment to the initialization condition for special patrol of slopes, updates to the earth anchor inspection work, and establishment of basic and intermediate level slopes re-training courses, as shown in the course syllabus of the basic and intermediate level National Freeway slope training. Furthermore, to provide a reference for the precipitation level as condition for triggering the special patrol of slopes, and to improve National Freeway slope disaster early warning, the Bureau had also completed in 2016 the establishment of National Freeway slope precipitation monitoring stations, as shown in the National Freeway slope precipitation monitoring station distribution map. And reference examples of inadequacies for slope patrol items were established to achieve a consistent standard for the classification of the level of influence of slope patrol items.
In response to the introduction of the National Freeway slope life-cycle maintenance management policy, and to improve slope maintenance data management and ability to cope with disasters, the Bureau established the National Freeway slope life-cycle maintenance management system in 2012. The system can record data such as the planning, construction, and maintenance to provide an overview of the current status of Freeway slopes, using a multi-layered panel to display all important information. A varied reporting mechanism for the slope monitoring system was completed, as shown in the 3D panel screen of the National Freeway slope life-cycle maintenance management system. In line with the collection of the various Freeway slope operation data, a National Freeway slope information exchange platform was developed concurrently to consolidate all slope-related reference data, maps, reports and training materials for the purpose of improving the rate of information exchange and resource-sharing across different departments. The data interface structure between the two aforementioned systems are shown in the interface structure figure between the National Freeway slope life-cycle maintenance management system and the information exchange platform. To provide the on-site staff with a convenient recording tool to replace traditional paper records while patrolling slopes, the Bureau also developed the National Freeway Slope Patrol System, as shown in the National Freeway Slope Patrol System screenshot. The system allows electronic records to be directly uploaded to the National Freeway Slope Life-cycle Maintenance Management System, thereby vastly decreasing the amount of operating time for the staff and reducing paper use. Currently the National Freeway slope patrol work is done using tablet computers as the device for accessing the National Freeway Slope Patrol System while working onsite.
In addition, to allow the Bureau's slope management office to quickly grasp the overall real-time situation, the National Freeway Slope Mobile Management Platform was developed. Integrating the information from the existing National Freeway Slope Life-cycle Maintenance Management System, the platform adopts the tablet as the operating environment and provides a mobile decision-making support tool. The system is split into the regular version and emergency version, with themed (e.g., monitoring station, instrument alarm, slope categorization) map layers and search options. In addition to interfacing with the National Freeway Slope Life-cycle Maintenance System, the platform takes geological data from the Central Weather Bureau, the Central Geological Survey, the Soil and Water Conservation Bureau, and the Water Resources Agency and offers superimposed graphics. The panels display the latest, most complete information about the slope as shown in the screenshot of the National Freeway Slope Mobile Management Platform.
The cultivation of the expert knowledge of the National Freeway Slope staff is critical to the effectiveness of the results and proper implementation of the policy of the National Freeway Slope Life-cycle maintenance management. In accordance with the regulations in Chapter 5 (Slopes) of the Maintenance Manual, on top of the basic, intermediate, and advanced training courses about the slopes, the basic and intermediate retraining courses were held in April of 2016. (1) Basic retraining - to better the understanding of the new and amended contents of Chapter 5 (Slopes) of the Maintenance Manual as well as a summary of the original basic course by the Bureau slope staff. Case studies and experience sharing allow slope staff and expert contractors to fully communicate their working knowledge and pass on their experiences. (2) Intermediate retraining - to better the understanding of the updated operation of the National Freeway Slope System, and practical training of the earth anchor inspection and slope categorization and assessment by the Bureau slope staff. Slope maintenance and reinforcement case studies and the sharing of experiences allow slope staff and expert contractors to fully communicate their working knowledge and pass on their experiences.
The Bureau's National Freeway slopes have all entered the life-cycle maintenance management phase since 2014. To maintain the safety of Freeway slopes, aside from actively patrolling and monitoring the slopes annually, among other activities, overall safety evaluation and reinforcement project for the slope and facilities are to be conducted in 4-to-5-year periods to ensure the safety of road users. Plans for the future include improving maintenance management policy, analysis of maintenance data and cloud management to smartify slope disaster prevention, to optimize maintenance cost and performance, while streamlining and digitizing slope management. The ultimate goal is to improve slope maintenance efficiency and reduce the frequency of maintenance.