Friday 6 December 2019

Cross Island MRT Line to run directly under Central Catchment Nature Reserve; Phase 1 construction commences on 18 Jan 2023

Direct route cuts travel time and is cheaper to build; tunnel will be 70 metres deep to protect reserve
By Christopher Tan, Senior Transport Correspondent and Audrey Tan, Environment Correspondent, The Straits Times, 5 Dec 2019

The MRT Cross Island Line (CRL) will run directly under Singapore's largest nature reserve, instead of skirting around it.

Announcing its decision yesterday, the Ministry of Transport (MOT) said the direct alignment will see the tunnel going 70m, the height of a 25-storey HDB block, below the Central Catchment Nature Reserve. Initial plans called for a tunnel at a depth of around 40m.

Both options - going directly under or skirting around the reserve - were considered viable after an in-depth study, but nature groups had strongly called for the skirting alignment to avoid affecting flora and fauna in the gazetted reserve near MacRitchie Reservoir.

The MOT said the direct alignment will result in total travel time being six minutes shorter than for the skirting option. For those travelling through the middle segment of the line, the direct alignment will also result in lower fares. The construction cost is expected to be $2 billion less for the direct route.

The ministry added that the direct route will be more environmentally friendly in the long run as it "has lower energy consumption".

The 50km CRL will run from Changi to Jurong, and will serve estates such as Pasir Ris, Ang Mo Kio and Clementi. It is expected to have an initial ridership of 600,000 a day when it is completed by 2031.

The line was announced in early 2013 and preliminary plans showed it running under primary and secondary forests in the Central Catchment Nature Reserve.

Nature groups, alarmed by the potential environmental harm from the construction and operation of an underground MRT line right across the reserve, suggested that it be built along Lornie Road, skirting the reserve.

The Land Transport Authority commissioned a two-phase Environmental Impact Assessment for both alignment options in 2014.

Yesterday, the MOT also outlined measures to mitigate the line's environmental impacts. Tunnelling as deep as 70m below the reserve will ensure work is carried out through hard rock, far from flora and fauna on the surface. No surface works will be done in the reserve, it said, noting that MRT tunnels are typically 20m to 30m underground.

There will be two worksites outside the reserve: one along Island Club Road and another on the western edge of the reserve across from the Pan-Island Expressway.

In a Facebook post, Transport Minister Khaw Boon Wan said the Government had agonised over the alignment as the reserve is "a special part of Singapore", but skirting the CRL around the nature reserve would "cost taxpayers and commuters dearly".

Senior Minister of State for Transport Lam Pin Min told reporters "the environment assessment has shown that both alignments are feasible", but the skirting option would result in longer travel time, additional construction cost and expected higher commuter fares.

"We have therefore decided on the direct alignment," he said.

Asked about a potentially unfavourable effect the direct alignment would have on network capacity factor - a fare adjustment component which takes into account the capacity of a transport service vis-a-vis actual usage - because it goes through nearly 4km of unpopulated area under the nature reserve, Dr Lam said: "That is a separate issue... We will address that subsequently."

Former diplomat Joseph Koh, who is a nature lover, said he would have preferred the skirting alignment, but "it is reassuring that some of the measures we have advocated have been spelt out". These include tunnelling deeper.

Cross Island Line will improve connectivity across island
The 50km line will benefit 1 million commuters, and help develop new work hubs and BTO estates
By Toh Ting Wei, The Straits Times, 5 Dec 2019

The impending Cross Island Line (CRL) is a critical transport infrastructure that will vastly improve the quality of life for commuters who need to cross the island regularly, Transport Minister Khaw Boon Wan said yesterday.

It will meet the needs of one million commuters, with many looking forward to its completion, he wrote in a Facebook post.

"It will interchange with almost all the other MRT lines and hence raise the network resilience.

"The CRL will also support the development of new hubs such as the Jurong Lake District and the new BTO estates in Sengkang, Punggol and Hougang," he said, referencing the HDB estates with Build-To-Order flats.

Plans to build the CRL, which will have more than 30 stations, were first announced in 2013.

It will be Singapore's eighth MRT line and is projected to have an initial daily ridership of 600,000, before increasing to a million in the future.

When completed, the 50km line will connect key employment areas such as Changi Logistics Park and Jurong Industrial Estate, to residential estates, including Pasir Ris, Ang Mo Kio and Clementi.

It will have the highest number of interchange stations, with almost half the stations on the line linked to existing rail stations.

The line will be built in three phases. The first phase of 29km is expected to start next year and be completed by 2029.

It will comprise 12 stations from Aviation Park to Bright Hill. This will serve residential and industrial areas such as Loyang, Tampines, Pasir Ris and Ang Mo Kio.

It is expected to benefit more than 100,000 households.

In addition, the Land Transport Authority has said common recreational spaces, such as Changi Beach Park and Bishan-Ang Mo Kio Park, are to be accessible by public transport.

Transport economist Walter Theseira, of the Singapore University of Social Sciences, said a key benefit of the CRL would be shorter duration of existing trips.

"The way it is being constructed, it can provide a lot of connectivity to other lines," he told The Straits Times. "A lot of time savings will come from people transferring to other lines via CRL, as compared to overloading the older lines like the East-West Line."

The better connectivity would bring another benefit in the long run in terms of redundancy, added Associate Professor Theseira, who is also a Nominated MP.

A rail network with high redundancy can provide reasonable travel choices, such as transfers through connecting train lines, even if some parts of the network experience disruptions.

He said countries with higher levels of such redundancies can afford to shut down rail lines for days to carry out maintenance works, but this is a luxury Singapore cannot afford at the moment.

On building the CRL under the Central Catchment Nature Reserve, he said the fact that the Environmental Impact Assessment shows the environmental impact of direct alignment can be mitigated significantly made the decision a more straightforward one.

The key benefit would be the reduction in travel time by six minutes as opposed to a skirting option.

"The extra six minutes of travel time multiplied by hundreds of thousands of passengers daily, that is the real impact," he added.

"You can always make more money, but the country is unlikely to be able to give people more time."

Cross Island Line: Nature groups worry move may influence other future projects
Route decided after more than 40 engagement sessions between nature groups and authorities
By Audrey Tan, Environment Correspondent, The Straits Times, 5 Dec 2019

Members of nature groups engaged over the Cross Island MRT Line are concerned that the decision to build under Singapore's largest nature reserve could set a precedent for future work in protected areas, even as they acknowledge that measures are being put in place to reduce the impact of works on flora and fauna.

Nature groups and biologists are also disappointed that the line will not skirt the Central Catchment Nature Reserve, instead going under it, and say that the mitigation measures may not be fail-safe.

Asked if the decision would set a precedent for future developments, Senior Minister of State for Transport Lam Pin Min told reporters yesterday that each project will be assessed on a case-by-case basis.

"I think we have to look at each case separately," he said. "For this particular project, we have worked very closely with the nature groups and taken in their input (to reduce environmental impact)."

For example, the tunnel for the Cross Island Line will go 70m under the reserve. This is much deeper than ordinary tunnels, which typically go 20m to 30m underground, said the Ministry of Transport (MOT).

Other concessions have been made by the authorities over the years, including the decision to reduce the number of boreholes drilled in the reserve during preliminary soil tests.

The Cross Island Line, which spans at least 50km, will run from Changi to Jurong, and serve estates such as Pasir Ris, Ang Mo Kio and Clementi. It is expected to have an initial ridership of 600,000 per day when it is completed by 2031.

The line was announced in early 2013, and preliminary plans showed it running under primary and secondary forests in the Central Catchment Nature Reserve.

The nature community, alarmed by the potential environmental harm which the construction and operation of an underground MRT line right across the heart of the reserve could cause, had suggested that the line be built along Lornie Road. This alternative route skirts around the reserve.

The decision on whether the Cross Island Line will go under or around Singapore's largest nature reserve was six years in the making.

It included extensive consultations between the authorities and nature groups - Dr Lam said there were over 40 engagement sessions - which a group of activists noted were constructive "because they were conducted in the spirit of mutual respect". They said: "We have learnt to hear each other out, and we are glad that many of our inputs have been accepted and incorporated."

The MOT said various factors had been considered before it opted for direct alignment - including findings from the environmental study.

The first phase of the study, which looked at the impact of soil works on the flora and fauna of the nature reserve, had determined that preliminary tests could have a "moderate" impact on wildlife if measures to reduce impact were carried out.

The second phase, released earlier this year, looked at the impact of the construction and operation of the line. It also concluded that this impact could be reduced if mitigation measures are carried out.

Biologist N. Sivasothi from the National University of Singapore said he was "naturally very disappointed" at the final outcome, although the engagement process with the authorities had been honest and fruitful over the years.

This engagement had helped to "considerably reduce" the impact of the line on the forest.

"I hope that this type of direct partnership will become the norm, in which we seek common objectives and beyond mitigation of impact alone, contribute towards recovery and rehabilitation of Singapore's ecosystems," said Mr Sivasothi.

Nature Society (Singapore) president Shawn Lum said the nature community had worked with the Government since 2013 "to find a way to achieve national needs", including nature protection and transport infrastructure.

Dr Lum, a botanist, said impact of tunnelling and worksites for the direct line could be kept to a moderate level if mitigation measures are properly implemented, noting that both alignments would have an impact on wildlife and the habitat.

But Herpetological Society of Singapore co-founder Sankar Ananthanarayanan said that while the engagement process has been fruitful and mitigation measures proposed, these may not be fail-safe.

He said: "The full impact of this decision is still unknown and there is a lot on the line. Preserving biodiversity should be a fundamental tenet of our nation building."

Cross Island Line: Concerns about wildlife linger despite plans to reduce impact
By Audrey Tan, Environment Correspondent, The Straits Times, 5 Dec 2019

The Cross Island Line will tunnel 70m under the Central Catchment Nature Reserve instead of around it, the authorities said yesterday, finalising a decision that was six years in the making.

Here are some concerns about the rail project, the mitigation measures taken, and the path forward.


Since the Cross Island Line was announced in 2013, the authorities have been engaging with the nature community on how the environmental impact of the rail project can be reduced.

For instance, two alignments were considered after initial discussions between the Government and nature groups - a 4km direct path, 2km of which will be under the reserve, and a longer, 9km one around it.

An environmental impact assessment was also commissioned to determine how the impact arising from preliminary soil works and the construction and operation of the train line could be reduced.

In deciding to build the line under the reserve, the Ministry of Transport said various factors were taken into consideration before the direct alignment option was selected, including the findings from the environmental study.


A major environmental concern was the potential impact of preliminary soil tests on the reserve.

Such tests involved surveyors going off-trail to collect data using handheld equipment in sensitive vegetated areas. They also required boring holes up to 70m underground to extract soil samples from existing trails.

The Land Transport Authority (LTA) used mitigation measures to reduce the impact, including reducing the number of boreholes drilled in the nature reserve from 72 to 16, and ensuring they remain confined to existing trails.

Mr Tony O'Dempsey, an environmental consultant engaged by the LTA to oversee the works, said the authorities had also significantly cut back on the off-trail geophysical works during the initial works, due to concerns about their impact.

He told The Straits Times these were significant concessions. "Instead of clearing access paths for borehole equipment to enter sensitive areas, they were inserted and operated along the Sime Trail and not a single tree was harmed," he said.

"For the reduced geophysical surveys, we avoided the problem of crushing seedlings and impacting fauna in sensitive core areas of the nature reserve."


The train tunnel for the Cross Island Line will be built 70m under the Central Catchment Nature Reserve - much deeper than the usual 20m to 30m for other MRT tunnels.

Minister for Transport Khaw Boon Wan said in a Facebook post yesterday that this was so that the impact on flora and fauna in the nature reserve "can be almost completely eliminated". This decision will increase the estimated project development cost by at least $20 million, he added.


However, environmental researchers have pointed out that mitigation measures may not be entirely fail-safe. Moreover, there are other impacts on wildlife that are harder to quantify, researchers say.

For instance, the direct alignment will involve clearing two forest patches outside the nature reserve for ventilation structures.

One of these forest patches on the eastern end of the reserve is a stronghold for the critically endangered Raffles' banded langur, a species of monkey which has a population size of 61 in Singapore.

Primatologist Andie Ang, who has studied these animals since 2008, said the population of four male langurs in the area had moved from other parts of the reserve farther north and were using that plot.

"Losing the forest plot could affect their connectivity, which could have an impact on the numbers of this critically endangered primate, which already shows signs of inbreeding," said Dr Ang, a Wildlife Reserves Singapore Conservation Fund research scientist.

She cited how a population of langurs in Bukit Timah Nature Reserve went extinct after the Bukit Timah Expressway was built, separating the Bukit Timah and Central Catchment nature reserves.

"The scenario with the Cross Island Line is similar. Removing the forested plot could reduce connectivity, and the langurs face a similar situation as before," she said.

The Land Transport Authority said it is in discussions with the Singapore Island Country Club to use part of its "non-playing area" instead for that worksite, but this is not confirmed.

Dr Ang said the only successful mitigation measure would be to ensure that the forest plot is not levelled, as this would allow the langurs to continue to use the area to move about.


Strix Wildlife Consultancy co-director Serin Subaraj said that even if mitigation measures are fully implemented without failure, they only reduce, and not eliminate, the impact on the nature reserve.

"The worry is it could set a precedent for other developments to also take place in protected areas," he said.

Asked if the decision would have an impact on future developments, Senior Minister of State for Transport Lam Pin Min told reporters yesterday that each project will be assessed on a case-by-case basis.

Cross Island Line: Upper Thomson residents breathe a sigh of relief
By Toh Ting Wei, The Straits Times, 5 Dec 2019

For the past few years, Mr Sangameswaran, the president of Yew Lian Park Residents' Association, and around 230 households in the Upper Thomson estate have been stressed about the possibility of the Cross Island Line (CRL) being built underneath their homes.

So there was a collective sigh of relief yesterday when the Government announced it would build the new MRT line under the Central Catchment Nature Reserve instead.

"If the skirting option was chosen, a few houses would have been affected... we were fighting it all out," said the 73-year-old, who goes by one name. "Obviously, our residents are now extremely happy the line will not skirt around the Central Catchment."

The Land Transport Authority (LTA) had said previously - without providing details - that if the option to go around the nature reserve was accepted, underground tunnels would go through homes, businesses and buildings, and acquisition might be needed.

Yew Lian Park residents were, therefore, among the many in the area who welcomed yesterday's news that the authorities had chosen the direct alignment for the CRL.

The alternative would have been to build the MRT line around the nature reserve and beneath a swathe of private homes near Upper Thomson Road, such as Yew Lian Park and Windsor Park.

Bishan-Toa Payoh GRC MP Chong Kee Hiong said residents had met the Ministry of Transport and LTA on various occasions to voice their concerns.

"I think for most of the residents, their pressing concern was the acquisition of property and how the construction would affect their property structure," he told reporters yesterday.

"We all know that sometimes there are cracks that may or may not be related to construction, but people are worried about that."

He said residents had concerns at the same time about the impact of direct alignment on the environment, but these were assuaged after they learnt the mitigating measures that would be taken, including tunnelling 70m below ground.

Some residents were also worried about the inconvenience of MRT construction in such close proximity to their homes.

Yew Lian Park resident Daniel Yeo, 46, said the final call on the direct alignment was "the correct decision".

He said: "I would like nature lovers to take a step back and reassess their priorities.

"Singapore is a small place and, of course, we need to (protect) our natural resources, but let's have our priorities right and put our citizens first."

Robust measures to tackle any power issues in Cross Island Line
By Wong Kai Yi, The Straits Times, 6 Dec 2019

The upcoming Cross Island Line (CRL) will be designed such that any power supply issues will be addressed swiftly, the Land Transport Authority (LTA) said yesterday.

A 2km stretch under the nature reserve will have tunnels going 70m below ground level, or the height of a 25-storey Housing Board block.

This will make them the deepest rail tunnels - they currently average 20m to 30m underground - which has led to some questions about what happens in the event of a power disruption.

LTA told The Straits Times yesterday that like for all existing lines, "robust contingency measures for different disruption scenarios" will be put in place.

First, the power supply system, like that for the North-South and East-West MRT lines, is designed with monitoring systems to check on the health of the line, so that irregularities can be detected and rectified promptly.

The CRL's power supply system is also designed with redundancies rendering the likelihood of disruptions to both directions of travel "very remote".

LTA said it has also made provisions for the isolation of potential faults, limiting their impact and allowing power supply at the affected railway track to be quickly restored.

If the power fault affects only one direction of travel along the CRL, a rescue train can be deployed in the other unaffected direction to evacuate commuters to the nearest station.

As part of the CRL's design, partition doors will be built - at regular intervals - between both tunnels to allow commuters to cross over in the event of an emergency.

According to Mr Patrick Beronneau, technical director, major crossings, at engineering consultancy Ramboll Singapore, such cross passages are typically located at intervals of not more than 250m and are equipped with safety doors and communication on both sides.

"As soon as passengers pass through these cross passages, they are basically safe and evacuation time is not critical any more. They can progress to the next surface egress without being exposed to any safety risk," Mr Beronneau said.

LTA said that in the unlikely event that power supply to the whole CRL, or the section in both directions under the nature reserve, cannot be restored quickly enough despite "multiple and layered redundancies", passengers will have to leave the train, called a detrainment.

Motorised trolleys or diesel-driven shunters may be deployed to facilitate the evacuation of those needing help.

It added that LTA is committed to ensuring the safety of commuters.

The CRL will be Singapore's eighth MRT line, connecting residents in places like Ang Mo Kio and Clementi to key industrial areas in Changi and Jurong.

The first phase of 29km will begin construction next year and the whole 50km line is expected to be completed by 2029 in three phases.

On the issue of air supply to the tunnel, Mr Beronneau said the depth of the CRL could result in a "slight increase in air temperature" but it could be controlled by conventional engineering measures.

Assistant Professor Raymond Ong, from the department of civil and environmental engineering at the National University of Singapore, said that major problems during construction can be minimised with proper engineering design and procedures.

He pointed to the case of the Gotthard Base Tunnel in Switzerland, which extends to a maximum depth of 2.45km underneath the Swiss Alps.

Cross Island MRT line: New rail tunnel under nature reserve can be done safely, say experts
Drilling to 70m depth for MRT line will be a first in S'pore, but practice is not uncommon
By Toh Ting Wei, The Straits Times, 6 Dec 2019

Drilling a railway tunnel 70m below ground will be a first in Singapore, but the practice is not uncommon worldwide.

It will come with additional challenges, such as a higher cost, but it can be done safely, tunnelling experts told The Straits Times.

The Ministry of Transport announced on Wednesday that a section of the upcoming Cross Island MRT line will run directly under Singapore's largest nature reserve, instead of going around it.

In order to mitigate the impact on the environment, the tunnel that will pass under the Central Catchment Nature Reserve will be dug 70m below ground.

It will be the deepest MRT tunnel in Singapore, beating the 43m-deep passage linking Bencoolen and Fort Canning stations on the Downtown Line.

On its website, the Land Transport Authority describes the construction of that tunnel as a "challenging feat" that had to take into account safety and structural stability issues, among others.

Experts told ST that while the underground MRT lines in Singapore are generally about 20m to 30m deep, there are examples worldwide of railway tunnels running deeper.

One such example is in Hong Kong, where the deepest underground metro station, Hong Kong University, is also 70m below ground. Tunnel and station depths are usually in a similar range.

Practical requirements, not safety, are the reason railway tunnels are not dug deeper, said Mr Patrick Beronneau, technical director of the major crossings department at engineering consultancy Ramboll Singapore.

"The design of tunnels, their alignment and depth for underground metro lines are generally governed by operational requirements," he said. "That's why the depth should be minimised to optimise platform accessibility.

"However, if other constraints are prevailing, such as unfavourable ground conditions... depths of 70m and more are not uncommon."

Design and engineering firm Arup said conventional tunnel construction methods are still very much applicable and proven at those depths, noting in a response to ST: "The benefits of deeper tunnels often outweigh challenges as the ground will typically be stiffer with depth."

The more ungiving ground could open up possibilities for a variety of tunnel construction methods, it said.

Any impact on the surface will be reduced to a minimum when the tunnel is deep and in competent ground, Arup added.

But Professor Chu Jian from the Nanyang Technological University's School of Civil and Environmental Engineering pointed out 70m was still deeper than normal.

For example, the average depth of the deepest metro line in Tokyo is only 27m.

Prof Chu said building a rail line deeper underground would come with challenges such as higher construction and operational costs, the need for more expensive equipment and higher risks in case of evacuation.

Arup said a key challenge commonly faced during tunnelling at the 70m depth would be groundwater control during construction, but this can be addressed with proper measures and equipment.

Ramboll's Mr Beronneau maintained that any additional challenges are unlikely to be significant.

"For everything less than 100m deep, the difference in technology is insignificant," he said.

"I come from a very mountainous region in Austria, where every tunnel is basically deeper than 70m."

6 years in the making: How the Cross Island Line's direct route was decided
By Nicole Chang, Channel NewsAsia, 4 Dec 2019

More than six years after it was first announced, a key decision on which route Singapore's longest MRT line will take has finally been decided.

The Government on Wednesday (Dec 4) announced the Cross Island Line (CRL) will take a direct route under the Central Catchment Nature Reserve (CCNR) - after years of debate and consultation - instead of an alternative route skirting around the reserve.

Nature groups and environmentalists had raised concerns that the direct route could have an impact on Singapore's wildlife and nature, but on Wednesday the authorities said it had chosen it after in-depth studies.

Here are some key dates leading up to the decision:

Jan 17, 2013: Authorities announce a new Cross Island Line which will run across Singapore, as part of the Land Transport Masterplan 2013. The line will have a targeted completion date of 2030.

Jul 11, 2013: A site visit to the Central Catchment Nature Reserve is conducted with nature group representatives.

Jul 18, 2013: Nature Society (Singapore) releases a position paper saying works for the line will degrade habitats within the Central Catchment Nature Reserve and recommending the design alignment be adjusted.

Jan 21, 2014: A discussion and lunch is held with nature groups.

February 2014: LTA calls a tender for an Environmental Impact Assessment to help authorities make a considered decision on the line's alignment and how it will affect Singapore's wildlife and fauna.

July 2014: LTA awards a tender to global consulting firm Environmental Resources Management to carry out the impact assessment, which will consist of two phases.

January 2015 to October 2015: Various site visits to the Central Catchment Nature Reserve are held, including at least one recce with nature group representatives. Discussions held on the Environmental Impact Assessment report.

Nov 13, 2015: A working meeting is held regarding the draft phase one Environmental Impact Assessment report.

January 2016: Another site visit is held with nature groups.

Feb 29, 2016: Transport Minister Khaw Boon Wan tells Parliament it may take two more years to complete the environment and technical studies, as well as the public consultations needed for the Government to reach a decision on the project and its exact alignment.

He says two possible options were being evaluated – a “direct option” which will see part of the line going below the central catchment reserve, or a longer option which skirts around the area.

May 2016 to September 2017: Site investigations are carried out as part of efforts to assess the feasibility of the two alignment options. These include borehole works carried out near Bukit Golf Course as well as geophysical survey works near Sime Track.

June 2018: LTA says site investigations carried out to study the impact of both alignment options have been completed. Findings suggest wildlife present in the area. The findings will provide input for phase two of the Environmental Impact Assessment, expected to be completed later in 2018.

August 2018 to October 2018: Various site visits carried out including a Central Catchment Nature Reserve walk and a Thomson–East Coast Line tunnel visit.

Jan 25, 2019: Mr Khaw says the first of three phases of the line will open by 2029, and construction will start in 2020.

June to July 2019: Various deep dives carried out into issues such as habitat evaluation, construction activities and mitigation at the work site.

September 2019: A biodiversity roundtable is held with 42 nature groups, including a briefing on the Environmental Impact Assessment findings, engineering schemes and a discussion on how to optimise work sites.

The phase two report of the Environmental Impact Assessment is published. The environmental impact of both potential routes near the Central Catchment Nature Reserve can be “adequately managed” with “comprehensive” mitigation and monitoring plans, says LTA. 

However, the authority says it has not made a final decision yet.

Dec 4, 2019: The authorities announce the Cross Island Line will take a direct route under the Central Catchment Nature Reserve. They say they will continue to work closely with all stakeholders as the design and construction of the line continues.


* Cross Island Line (CRL) Phase 1 construction commences on 18 Jan 2023

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