Tunnelling under major roads and MRT lines: North-South Corridor construction enters 'most challenging phase'

From rock blasting in Thomson to tunnelling a metre beneath the North-South Line, engineers describe the obstacles slowing down one of Singapore’s largest transport projects.

Construction of the North-South Corridor has been ongoing since 2018 and will be completed in phases. (Photo: CNA/Raj Nadarajan)

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SINGAPORE: Construction of the North-South Corridor (NSC) is entering its "most technically demanding" phase, as work progresses amid challenging ground conditions and the unprecedented scale of its viaduct, the Land Transport Authority (LTA) said on Saturday (Sep 12).

At several locations, the corridor has to be built above and below operational MRT tunnels, including those on the North-South and Circle lines.

Ground conditions have varied considerably along the corridor, with harder rock formations and differing rock profiles complicating foundation, excavation and tunnelling works. This has required additional rock removal, ground stabilisation or changes to construction methods.

Mr Ang Pui Boon, LTA’s second deputy group director for the NSC project, said more challenging ground conditions had been encountered as work progressed.

CNA Games Guess Word Crack the word, one row at a time Buzzword Create words using the given letters Mini Sudoku Tiny puzzle, mighty brain teaser Mini Crossword Small grid, big challenge Word Search Spot as many words as you can Show More Show Less “We therefore have to make adjustments to our design and construction methods to ensure that the work is carried out safely (without) compromising our surrounding infrastructure.” CONSTRUCTION ONGOING SINCE 2018 Spanning more than 20km, the corridor is a multi-modal transport link designed to improve connectivity between the northern region and the city, serving towns such as Sembawang, Yishun, Ang Mo Kio, Toa Payoh, Novena and Rochor, while relieving traffic along Singapore’s north-south transport axis. The project comprises two major structures: an 8.8km elevated viaduct and a 12.3km underground tunnel section. Construction has been ongoing since 2018 and will be completed in phases. LTA previously said the viaduct section is expected to open from 2027.

“We therefore have to make adjustments to our design and construction methods to ensure that the work is carried out safely (without) compromising our surrounding infrastructure.”

CONSTRUCTION ONGOING SINCE 2018

Spanning more than 20km, the corridor is a multi-modal transport link designed to improve connectivity between the northern region and the city, serving towns such as Sembawang, Yishun, Ang Mo Kio, Toa Payoh, Novena and Rochor, while relieving traffic along Singapore’s north-south transport axis.

The project comprises two major structures: an 8.8km elevated viaduct and a 12.3km underground tunnel section.

Construction has been ongoing since 2018 and will be completed in phases. LTA previously said the viaduct section is expected to open from 2027.

SINGAPORE'S LONGEST VIADUCT

At 8.8km long, about 40m wide and roughly 19m tall – more than six storeys – the NSC viaduct will be Singapore's longest. More than 6,000 precast elements have to be fabricated, transported and installed to form the structure, which LTA said presents significant logistical challenges.

Major segment installation is carried out mainly during four- to five-hour off-peak windows at night to limit disruption to motorists and bus services.

At some locations, the viaduct crosses live roads, major junctions and existing transport infrastructure, further limiting the time and space available for construction. Disruptions to these narrow work windows have also affected subsequent activities such as segment installation.

Construction of the North-South Corridor next to residential properties at Yishun Avenue 5 on Jun 8, 2026. (Photo: CNA/Raj Nadarajan)

Foundation works have also taken longer than anticipated at some locations, including Gambas Avenue and Woodlands Avenue 8, which LTA attributed to utility diversions and adverse ground conditions during piling and pilecap construction.

“As the viaduct works are highly sequential, delays to the foundation work have affected subsequent activities, as above-ground works such as columns, crossheads and segment installation can only proceed after the foundation is completed,” LTA said.

With more than 90 per cent of foundation works completed, construction is moving into another complex stage: launching large viaduct segments across existing roads while road traffic continues and safety is maintained.

" The current focus is on above-ground structural works, including the launching operation over the MRT track and major junctions. These activities require meticulous planning and close coordination to ensure they are carried out safely, particularly as the works are undertaken above an operational MRT line and live roads," LTA said.

TUNNELLING BENEATH MRT LINE

One of the project’s most technically demanding sections is at Novena, where the corridor’s tunnel passes both above and below the North-South Line, with clearance as close as 1m.

The southbound tunnel crossing above the North-South Line has been completed using the tunnel box pushing method. But as excavation progressed on the northbound tunnel below the line, fractured rock and groundwater inflows were encountered.

“These ground conditions could not be fully identified in advance, as they are located beneath the existing operational NSL tunnels and only became apparent as excavation reached the lower crossing,” LTA said.

LTA is now using a more controlled mining method, excavating the tunnel in smaller, separately supported sections alongside additional rock removal, grouting and monitoring, with each section stabilised before excavation moves to the next.

Although more time-intensive, LTA said this is necessary to build the tunnel beneath the operational line while protecting the rail infrastructure and maintaining MRT operations.

A man walks past a poster for the North-South Corridor at Woodlands Drive on Jun 8, 2026. (Photo: CNA/Raj Nadarajan)

At Nicoll Highway, the NSC tunnel has to pass over existing Circle Line tunnels, with clearances of only about 1.5m to 2.5m at some locations.

Given this proximity and the presence of soft reclaimed ground, LTA is using specialised pipe roofing and ground improvement measures to stabilise the ground and protect the Circle Line tunnels.

At Kampong Java, stacked tunnels are being built beneath the Kampong Java Flyover on the Central Expressway. The flyover has to be underpinned while construction proceeds beneath it, with workers operating in a low-headroom space under complex and varying ground conditions.

In the Thomson area, hard rock formations and large boulders encountered during excavation have required extensive controlled rock blasting and changes to the design of both temporary and permanent earth-retaining systems.

“Additional rock removal and ground stabilisation works are required before excavation can proceed safely,” LTA said, adding that the measures help control ground movement during deep excavation in densely built-up areas.

Construction of the North-South Corridor along Thomson Road on Jun 8, 2026. (Photo: CNA/Raj Nadarajan)

IMPACT ON RESIDENTS, BUSINESSES

The specialised construction methods are necessary to manage the complexities of working near existing infrastructure, protect workers and commuters, and minimise disruption to the public, LTA said, adding that it will update on the project's completion timeline in due course.

The impact on residents is expected to ease as construction progresses. With heavy foundation works completed, noise levels are expected to continue tapering off, LTA said.

Most upcoming works will also be carried out underground beneath live traffic, cutting noise and the need for multiple traffic diversions.

“LTA recognises that hoardings and noise barriers may affect business visibility and footfall, including in areas such as Novena," it said. "Where feasible, LTA works with affected stakeholders on tailored solutions, including directional signage and advertising banners, and will continue engaging business owners as works progress,” the transport authority said.

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从汤申地区的岩石爆破到南北线地下1米的隧道挖掘，工程师们描述了阻碍新加坡最大交通项目之一的种种障碍。

南北走廊的建设自2018年开始，将分阶段完成。（图片：CNA/Raj Nadarajan）

这段音频由人工智能工具生成。

新加坡：陆路交通管理局（LTA）周六（9月12日）表示，随着工程在具有挑战性的地质条件和前所未有的高架桥规模下推进，南北走廊（NSC）的建设正进入“技术要求最高”的阶段。

在多处地点，该走廊必须建在运营中的地铁隧道上方和下方，包括南北线和环线上的隧道。

沿线地质条件差异显著，较硬的岩层和不同的岩层剖面给地基、开挖和隧道工程带来了复杂性。这需要额外的岩石移除、地基加固或改变施工方法。

陆路交通管理局国家安全委员会项目第二副组长洪培文先生表示，随着工程的推进，他们遇到了更具挑战性的地质条件。

CNA游戏 猜词游戏 逐行破解单词 流行词游戏 用给定的字母组成单词 迷你数独 小谜题，脑力挑战 迷你填字游戏 小方格，大挑战 单词搜索 尽可能多地找出单词 显示更多 显示更少 “因此，我们必须调整设计和施工方法，以确保工程安全进行，且不损害周边基础设施。” 自2018年起持续施工 该走廊全长超过20公里，是一条多式联运交通连接线，旨在改善北部地区与市区之间的交通连接，服务于三巴旺、义顺、宏茂桥、大巴窑、诺维娜和罗卓等城镇，同时缓解新加坡南北交通干线的交通压力。该项目包括两大主要结构：一段8.8公里长的高架桥和一段12.3公里长的地下隧道。工程自2018年起持续施工，并将分阶段完成。陆路交通管理局此前表示，高架桥部分预计将于 2027 年开放。

“因此，我们必须调整设计和施工方法，以确保工程安全进行，且不损害周围的基础设施。”

自2018年以来一直在进行建设

该走廊全长超过 20 公里，是一条多式联运交通连接线，旨在改善北部地区与城市之间的连通性，服务于三巴旺、义顺、宏茂桥、大巴窑、诺维娜和罗卓等城镇，同时缓解新加坡南北交通轴线的交通压力。

该项目包括两个主要结构：一条 8.8 公里的高架桥和一段 12.3 公里的地下隧道。

该项目自2018年开始建设，并将分阶段完工。陆路交通管理局此前表示，高架桥部分预计将于2027年开放通车。

新加坡最长的高架桥

国家安全委员会高架桥全长8.8公里，宽约40米，高约19米（超过六层楼），建成后将成为新加坡最长的高架桥。该桥需要预制、运输和安装超过6000个构件，陆路交通管理局表示，这带来了巨大的物流挑战。

为尽量减少对驾车者和公交服务的影响，主要管段安装工作主要在夜间非高峰时段的四到五个小时进行。

在某些路段，高架桥跨越繁忙的道路、主要路口和现有交通基础设施，进一步限制了施工时间和空间。这些有限工期的中断也影响了后续活动，例如桥段安装。

2026年6月8日，义顺5道住宅区旁的南北走廊正在施工。（图片：CNA/Raj Nadarajan）

一些地点的地基工程也比预期花费的时间更长，包括甘巴斯大道和兀兰8道，陆路交通管理局将此归咎于打桩和桩帽施工期间的公用设施改道和不利的地质条件。

陆路交通管理局表示：“由于高架桥工程具有很强的顺序性，基础工程的延误影响了后续活动，因为只有在基础工程完成后才能进行地面以上的工程，例如桥墩、横梁和管片安装。”

基础工程已完成 90% 以上，施工进入另一个复杂的阶段：在道路交通继续进行且安全得到保障的情况下，架设跨越现有道路的大型高架桥段。

陆路交通管理局表示：“目前的重点是地面以上结构工程，包括在地铁轨道和主要交叉路口上方进行的架设作业。这些活动需要精心计划和密切协调，以确保安全进行，尤其是在运营中的地铁线路和繁忙道路上方进行作业的情况下。”

地铁线下方隧道工程

该项目技术难度最高的部分之一是诺维娜，走廊隧道在此处从南北线上方和下方穿过，净空高度最近处仅为 1 米。

采用箱涵顶推法，南行隧道跨越南北线的路段已完工。但随着北行隧道在南北线下方路段的开挖推进，遇到了岩层破碎和地下水涌入的问题。

“这些地质条件无法事先完全确定，因为它们位于现有南北线隧道下方，只有当挖掘到达较低穿越点时才显现出来，”陆路交通管理局表示。

LTA 现在采用更可控的采矿方法，将隧道开挖成更小、单独支撑的部分，同时进行额外的岩石移除、灌浆和监测，每个部分在开挖到下一个部分之前都保持稳定。

虽然耗时更长，但陆路交通管理局表示，为了在运营线路下方修建隧道，同时保护铁路基础设施并维持地铁运营，这是必要的。

2026年6月8日，一名男子走过兀兰大道上的南北走廊宣传海报。（图片：CNA/Raj Nadarajan）

在尼诰大道，国家安全通道隧道必须跨越现有的环线隧道，某些地方的净空只有大约 1.5 米到 2.5 米。

鉴于距离较近且存在松软的填海土地，陆路交通管理局正在使用专门的管道顶棚和地基改良措施来稳定地基并保护环线隧道。

在甘榜爪哇，中央高速公路上的甘榜爪哇高架桥下方正在建造多层隧道。施工期间，高架桥必须进行加固，工人们需要在净空高度有限、地质条件复杂多变的环境下作业。

在汤姆逊地区，开挖过程中遇到的坚硬岩层和大块岩石需要进行广泛的控制性爆破，并且需要对临时和永久挡土系统的设计进行修改。

陆路交通管理局表示：“在安全进行挖掘之前，还需要进行额外的岩石清除和地基加固工作。”并补充说，这些措施有助于控制人口稠密地区深基坑挖掘过程中的地面移动。

2026年6月8日，汤申路南北走廊建设工程开工。（图片：CNA/Raj Nadarajan）

对居民和企业的影响

陆路交通管理局表示，采用专门的施工方法是为了应对在现有基础设施附近施工的复杂性，保护工人和通勤者，并最大限度地减少对公众的干扰。陆路交通管理局还表示，将在适当时候更新项目的完工时间表。

随着工程的推进，对居民的影响预计将会减轻。陆路交通管理局表示，随着基础工程的完成，噪音水平预计将持续下降。

即将进行的大部分工程也将在地下进行，位于交通要道下方，从而减少噪音和多次交通改道的需要。

陆路交通管理局表示：“陆路交通管理局意识到，围挡和隔音屏障可能会影响商家的可见度和客流量，包括诺维娜等地区。” 该局还表示：“在可行的情况下，陆路交通管理局会与受影响的利益相关者合作，制定量身定制的解决方案，包括设置指示牌和广告横幅，并将随着工程的推进继续与商家保持沟通。”

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