100th KRIDE Board Meeting

[Audio] The elimination of level crossings through the construction of Rail Under Bridges in the Hebbal-Banaswadi section of the Bengaluru Suburban Railway Project aims to improve rail connectivity in Bengaluru by eliminating existing level crossings and creating safer and more efficient rail operations..

[Audio] The Hebbal-Banaswadi Section of the South Western Railway was chosen as a reference project for this study. The project's concept plan and technical features aim to eliminate six level crossings by building Rail Under Bridges, also known as RUBs. This method involves elevating the embankment to create space for the RUBs, resulting in the construction of five additional underpasses for public use. Moreover, this approach ensures no track drainage issues during monsoons, guaranteeing smooth and safe road and rail operations..

[Audio] The Bengaluru Suburban Railway Project, being executed by K-RIDE, aims to improve rail connectivity in Bengaluru with four corridors. Corridor-2, spanning a total distance of 25.58 kilometers, features four tracks, running from Benniganahalli to Chikkabanavara. The corridor comprises 8.03 kilometers of elevated track and 17.55 kilometers of at-grade track, including six level crossings between Hebbal and Banaswadi. To address this issue, the project seeks to eliminate these level crossings by raising the formation and constructing Rail Under Bridges, accompanied by additional underpasses for public convenience. Work on this project is currently underway, being executed by L&T..

[Audio] Formation raising has been implemented over a distance of 5.964 kilometers. This measure has enabled the elimination of six level crossings within a span of 2.5 kilometers..

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Cross-Section of Formation.

[Audio] The concept plan for this project involves the elevation of the formation to a height of six meters. As a result, the existing six level crossings can be converted into Rail Under Bridges, thereby enhancing public convenience by creating five additional underpasses. Furthermore, the raised formation ensures that there will be no track drainage issues during monsoon periods, thus enabling smooth and safe road and rail operations..

[Audio] The formation for four tracks between Hebbal and Banaswadi stations will be raised up to six meters, with reinforced concrete retaining walls on both sides. The high annual rainfall in Bengaluru, exceeding eight hundred millimeters, necessitates this measure. We have designed a sloped formation profile with a cross slope of one in thirty to ensure proper drainage. Furthermore, geo-membranes will be used beneath the blanket and crushed stone layers to enhance stability, and geo-composite drains will replace backfill material along the retaining walls..

[Audio] The longitudinal side drain at the formation level runs continuously along the length of the project, collecting water from the surrounding area and directing it into a sump located every 200-300 meters, ensuring efficient drainage and preventing water accumulation. Backside outlet drains have been installed at the toe level of the retaining walls to collect water from the formation and embankment, directing it into nearby minor bridges available at distances ranging from 200 to 400 meters. Weep holes have been incorporated into the retaining walls as an additional measure to facilitate drainage. The RUB structure consists of precast segmental and cast-in-situ RCC boxes, designed to withstand loads of up to 25 tons according to 2008 standards..

[Audio] The use of geo-composite drains will provide a reliable and efficient solution for the elimination of level crossings through RUB construction. This innovative technology will enable us to raise the embankment, ensuring a safer and more convenient passage for commuters. By incorporating these drains into our design, we can minimize the risk of waterlogging and ensure a smoother journey for all users..

[Audio] The various methods of eliminating level crossings have their own set of challenges. Building a Road Under Bridge, also known as RUB, poses issues related to land availability, drainage, and sight distance for road users. Constructing a Road Over Bridge, or ROB, involves significant costs, time, and encroachment on approaches, not to mention long ramps and feasibility concerns. Merging with adjacent existing LC gates would require diverting traffic and incurring recurring maintenance costs, which could restrict future railway network expansions. Raising the embankment to provide RUB at existing road level can be suitable when there are many level crossings in a block section, the alignment is within city limits, and there is heavy road traffic. Elevated tracks on viaducts are prohibitively expensive, pose maintenance issues, and may encroach on dense habitations along the railway boundary..

[Audio] The faster execution, better quality control can be achieved due to green field working. This means that there will be minimum disruption to rail and road traffic. Additionally, the cost of construction is less compared to elevated track. Furthermore, waterlogging issues in RUBs are addressed with suitable surface drain network and outfall points, and re-grading of approach roads is not required. Moreover, improved road safety can be ensured owing to straight approaches and the elimination of dead and blind zones. Finally, reduced land requirements for RUB approaches can also be achieved. At the same time, protection of the track against trespassing, whether it's human or cattle, as well as water logging in city areas and garbage dumping can also be ensured..

[Audio] The elimination of level crossings through RUB construction made feasible by raising of embankment is suitable in multi-tracking projects only. This approach requires careful consideration as it involves the raising of existing railway bridges, particularly important or major bridges, which can be a complex and costly process. In addition, this method may cause significant disruption to traffic and prolonged duration if any issues arise with the formation or drainage. Furthermore, the rehabilitation of the formation in such cases can be challenging. We must carefully weigh the benefits against the potential drawbacks when considering this option..

[Audio] The yard remodeling at both ends of the block section may require significant changes to accommodate the new tracks. This includes connecting the new tracks to enable the diversion of train operation from existing tracks. To achieve this, we need to replicate the existing signaling system, which involves installing additional traffic handling facilities such as common loops, cross-overs, and single-line or double-line signaling, depending on whether we're doubling or quadrupling the existing double-track. Furthermore, we'll need to shift utilities like S&T, TRD, Elect-G, and Engg, as well as perform additional cabling work due to the raised embankment and/or raised tracks. Finally, we must ensure the in-service functional aspects of geocomposite drains are properly maintained..

[Audio] The design of RCC retaining walls has been carefully considered to withstand the worst combination of loads, including the effects of pore water pressure conditions. This ensures the stability of the structure and prevents any potential damage. However, this design also poses some challenges when it comes to maintenance. With limited access and restricted space for material stacking, maintenance tasks may become more complicated. Furthermore, in the event of an accident or derailment, rescue efforts may be hindered by the limited access and site constraints..

Weep holes are not provided in the base portion of retaining wall. Approx. 1.5-2.0m depth of retaining wall is left without the weep hole. Weep Holes shall be continued up to top of base slab..

[Audio] The sacrificial retaining wall will be constructed between the proposed track and the existing running track. This structure will ensure the stability of the embankment and prevent erosion. The BSRP side retaining wall will also be built to provide additional support to the embankment. Furthermore, the IR existing boundary wall will be maintained to define the boundaries of the railway property..

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[Audio] The design of the longitudinal drain must take into account the expected surface runoff during severe rainfall events, ensuring a self-cleaning velocity for efficient drainage. It's essential to arrange the outlet of water from the chambers to the outside drain properly, securing the pipes with a retaining wall. Additionally, we need to verify the backside drain's capacity and slope to guarantee its effectiveness. Since the retaining wall is not designed to withstand pore water pressure, the geo-membrane and geo-composite drain play a vital role in efficiently draining water. As per the K-RIDE project team's findings, standard penetration tests and plate load tests were conducted every 200-300 meters along the alignment..

[Audio] The ground subsoil investigation has been carried out according to the specifications outlined in RDSO Specification No. RDSO/2020/GE:IRS-0004. This ensures that we have a thorough understanding of the soil conditions beneath our project site. To prevent any potential issues, suitable anchoring and stitching arrangements will be implemented to secure the last segments of our structure above the running track. Additionally, the RCC box segments will be anchored to the retaining wall on the backside using dowels, and wing walls may be constructed at both approaches. Furthermore, the design of Major Bridge No. 560, featuring a 30.5-meter composite girder, incorporates a transition system at the bridge approach, as per the latest guidelines outlined in GE: R-50 (Rev-2). Finally, trolley refuges will be installed in accordance with the requirements specified in IRPWM..

[Audio] The site observation shows that the formation width is roughly twenty-five meters, allowing for four tracks. This is achieved through a cross slope of one in thirty, resulting in a ballast cushion exceeding five hundred millimeters on the farthest track from the center. To maintain a suitable ballast profile, a ballast wall might need to be designed and built on both sides. Moreover, during the trolley inspection, it was found that weep holes were missing in the base portion of the retaining wall. Approximately one point five to two point zero meters of the retaining wall's foundation remained without weep holes. It is crucial to provide weep holes up to the haunch portion. Furthermore, the foundation of the retaining wall near Chainage five plus four hundred meters appears to be slightly exposed..

[Audio] The specifications outlined in RDSO Specification No. RDSO/2018/GE:IRS-0006, March 2019 will guide us in testing, handling, packing, and installing the Geo-composite drain. Additionally, we will adhere to the guidelines set forth in IS Specification 16352:2020 for the Geo-membrane. To ensure seamless integration, we will prepare a comprehensive drainage plan covering the entire section, including the RUBs, and obtain approval from the OL. Furthermore, we will introduce a sand layer between the crushed stone and geo-membrane to prevent punctures. We will also develop a detailed method statement outlining the procedures for installing the geo-composite and geo-membrane layers, which will be reviewed and approved by the OL..

[Audio] Utility shifting plans must be approved by OL before any work begins. This ensures that all necessary utilities are relocated safely and efficiently. Additionally, RSI analysis must be conducted on Major Bridge Number 560 before its structural drawings can be approved. Unfortunately, this analysis has not yet been completed. Furthermore, a comprehensive maintenance plan must be developed, incorporating mechanized systems for both scheduled and unscheduled maintenance. This plan must also be approved by OL. To facilitate passenger evacuation and the stacking of railway materials, additional formation width will be provided in isolated areas. Finally, a disaster management plan, including procedures for responding to derailments, must be developed and approved by OL's safety department..

[Audio] The importance of continuous guard rails throughout the section cannot be overstated. This will ensure the safety of all users, particularly pedestrians and cyclists who may be using the raised embankment. Furthermore, it is crucial to establish an instrumentation plan to monitor the performance and reliability of this large-scale drainage system. The inclusion of piezometers to check pore water pressure during the monsoon season is a vital aspect of this plan. This will enable us to identify any potential issues early on and take corrective action if necessary. Additionally, it is essential to prepare an alternate drainage arrangement scheme in advance, in the event of malfunctioning of the Geo-composite drain and Geo-membrane layer. This proactive approach will enable us to respond quickly and effectively in the event of any unforeseen circumstances..