Twenty years ago, Madam Lee Gaik Hoon and her family were told by the Government that they had to move out of their four-storey flat in Boon Tiong Road.
She was worried about having to adjust to an unfamiliar environment. But her fears were allayed when she learnt that her replacement flat would be on the same road in Tiong Bahru.
"I remember feeling very excited. Our old place had no lifts and only one toilet, so the change was for the better," said the housewife, who moved into her new four-room unit in 1999. That was the very first instance of the Selective En bloc Redevelopment Scheme (Sers), where old Housing Board (HDB) estates are demolished and replacement units are offered to residents.
Madam Lee's family is among more than 39,000 households across 79 sites which have come under Sers since it began in 1995.
The scheme aims to improve residents' living environment and the use of land.
Said HDB deputy chief executive officer Yap Chin Beng, who oversaw Sers' inception: "While we continue to improve the design and facilities in our new projects and new estates, we will also not leave older estates behind."
Ageing flats can be upgraded, or torn down and replaced. Blocks chosen for Sers are usually around 30 years old. But not every site is suitable for redevelopment, hence the name of the scheme.
"The word 'selective' is very important," said Mr Yap.
One key question, added Mr Yap, is: "What is the opportunity for intensifying the use of land?"
For instance, a site near an airbase which faces height restrictions has much less potential than a site that can house 40-storey blocks. Replacement sites must also be available nearby, since the scheme aims to keep residents together in a familiar neighbourhood.
Pioneer Sers planner Tan Chew Ling, now HDB's group director for estate administration and property, said: "A familiar location, neighbours that you like, hawkers that you like - these are things which I think are quite valuable."
Mr Yap added: "We want to preserve the community."
Initially, this meant that Sers was "quite strict" and residents could choose a new flat only in the replacement site. But since 2004, in response to feedback, Sers flat owners have received the same rehousing benefits when applying for new flats elsewhere. Since 2011, they also have priority for these new flats. Of those who applied for new flats elsewhere, an average of 93 per cent had the chance to select one.
On average, about 90 per cent of Sers residents choose a flat at the designated replacement site.
Of these, usually 40 to 50 per cent choose larger flats.
New residents also come in as excess flats in replacement projects are open to public applicants.
In the 1980s and 1990s, HDB noticed that because young residents grew up and moved away, the population in mature estates was ageing.
Said Mr Yap: "Not only are the flats older, the residents are also older! So through this redevelopment, we give opportunities for young families to move into old estates."
For Madam Lim Seow Mui, 56, and her husband Mr Lio Hoi Hock, a 57-year-old goods delivery driver, having younger neighbours is a bonus. "We can ask them about computer-related things, like if we have problems with our iPad," she said in Mandarin.
She also enjoys seeing her old neighbours around.
Of the 80 or so households from their old estate, more than 70 have moved to the new site.
For a decade, she stayed in a two-room flat in East Coast Road, but in late 2011, her block and two others were slated for Sers.
"It was like striking lottery!"
The couple had bought the old flat, hoping that it would be up for Sers. "I used to call HDB to ask when the en bloc would happen," recalled Madam Lim.
They moved into their new three-room flat in Chai Chee Road in June, along with Madam Lim's mother, Madam Soh Sok Hiah, 78.
But not everyone is as pleased. Ms Tan said Sers is one of the hardest HDB programmes to implement because it has a "high impact" on residents' lives.
Compensation is a common sticking point. Mr Yap said calculations are made by professional valuers, but that is still not enough to placate some. "They ask, 'Why isn't my compensation that high?'" he said.
One complaint which took HDB by surprise was that a replacement site, though close, was served by public buses different from the ones residents were used to.
"Now we (try and see) whether we can find similar bus services at the other bus stops," said Ms Tan.
Locations and timings of upcoming Sers projects have always been shrouded in secrecy. HDB staff used to make copies of Sers leaflets on hand-operated duplicating machines instead of sending them to external printers for confidentiality reasons.
"We cannot announce it in advance because our compensation is based on the market price," explained Mr Yap. If people know certain flats are slated for Sers, they may scramble to buy them and drive up resale prices for the area.
All the HDB can reveal about the next Sers project is that there will be announcement videos in Cantonese and Hokkien, alongside the four official languages.
It may be sooner rather than later. In October, new Minister for National Development Lawrence Wong said that "improving our HDB towns built in the 70s and 80s" will be one of his priorities.
With resale prices staying tepid, implying reasonable compensation levels, the time seems ripe for more Sers projects.
Among Sers residents who moved into new flats, support for the scheme has ranged from 85 per cent to 90 per cent since the first survey in 2001, with 87 per cent expressing support in the latest survey in 2013.
"If you do a survey at the time of the Sers announcement, (there will be) a lot of anxiety, a lot of emotions that go into it," noted Ms Tan.
"It's only after they move into the new flat, sit in the living room comfortably, sip a cup of tea... then they will feel that happiness.
"Then they will like Sers."
•Additional reporting by Yeo Sam Jo