If the sheer amount of details that you need to put into the
application forms don't turn you off first, and neither do the
lengthy interviews, then your renumeration will be pegged to the
rank/level that they decided to put you in.
After 5 years is hard to tell, because LTA is not a profit
making entity, so your performance will in no way impact the
revenue LTA makes, because honestly they don't make any. So
anything that would ultimately affect your renumeration in the next
5 years is solely dependant on your work conduct, and agency
KPIs.
LTA is public sector, so again, no such thing called profit
making, or sharing, what other stat boards get, you also get. You
can be the star performer, end of the day, you get only what the
newspaper says stat boards will get.
Bonus as above, tied to the country's GDP. 
LTA will give you a stable and secure job as an engineer.
Honestly, you don't need to do much as long as you meet your KPIs,
and all that blah blah blah. And as such, don't expect big bucks,
or big rewards, just enough to get you by nicely, with mainly
employee perks.
