http://www.tremeritus.com/2013/08/12/reader-frustrated-with-sbs-bus-113/
"The bus driver skipped 2 bus stops and i was one of the deserted commuters that waited for bus 113 for 15 minutes. "
"The next bus arrived 15 minutes later and i still failed to board bus no.113 until 8pm. I was at the bus stop at 7:19pm. "
Your peak hour frequency at 15mins is obviously going to cause passengers unable to board. Even if you pull a double deck, I can tell you it will still be full, and some passengers will still be unable to board.
1-2mins already make a big difference, and further more, is there a need to loop back to Kovan from Lor Ah Soo during the PM peak?
They add DD, but the frequency still damn cui, what's the point? I can give you Double Deck Bendy, but like what you said, the population increasing, at the end of the day, you still need to touch on the frequency. So why not adjust the frequency to see clearly the issue?