Singaporeans travelling to Malaysia using the Causeway and Second Link have been warned to expect delays due to heightened security measures put in place after the Paris terror attacks last month.
The Immigration and Checkpoints Authority (ICA) said there will also be heavier traffic during the year-end school and festive holidays, with an estimated 430,000 travellers using the checkpoints daily during this period.
The ICA uses various methods to manage the heavier traffic, including flexible deployment of staff and diverting traffic to different lanes, such as allowing cars to use lanes normally assigned to lorries.
Condominium manager Wendy Wong, 34, noticed more officers at the checkpoints in recent weeks and believes the heightened security measures are good, but could be inconvenient for travellers. "The Customs get jammed up," said Ms Wong, who travels to Johor three times a month.
Delays at the checkpoints can also be caused by travellers using passports belonging to someone else, or those that are invalid.
These include using passports that were previously reported as lost or stolen, an offence punishable by a fine of up to $10,000, a 10-year prison term or both.
"Such cases will lead to delays and cause inconvenience to the passport holders as well as other checkpoint users," said an ICA spokesman.
Recovered passports should be returned to the ICA, and failure to do so can result in a $3,000 fine or imprisonment of up to two years or both.
There were 620 Singaporeans found using invalid or incorrect passports at the two checkpoints between January and October, and 190 foreigners found using the wrong passports.
In addition, during the same period, more than 3,500 foreigners were found to be carrying expired or invalid travel documents, or no documents at all at the two checkpoints.
This is an increase from the 3,300 cases detected last year.
Such cases will be denied entry.
Travellers who The Straits Times spoke to were undeterred by the delays, saying that they would continue to travel to Malaysia via the two checkpoints.
Mr Nasir Jamaludin, 21, who goes to Malaysia four times a week to shop, experienced jams at the checkpoints even at 1am.
"I will still go to Johor even though the jam is massive," said Mr Nasir, who is currently doing national service.