Air carrier Captain reported the constant construction and poor signage at WSSS/SIN Airport led to the flight crew passing the point where ATC wanted the aircraft to stop.

Narrative

We were assigned to taxi southbound on T and hold short of R1 which is where the passenger airplanes will normally exit their Ramp to sequence with the other planes on T. Although I have been operating in and of Singapore for years; the numerous construction projects are constantly altering what taxiways that are open or closed. As we approached R1; I slowed my taxi speed and was searching for either a hold-short line on T or a R1 taxiway sign. I did not observe any of these. Most signs are either blocked by the construction or just yellow boxes; with no designations. R1 is completely closed; and in its place is a concrete plant and construction buildings.As we were searching; SIN Ground instructed us to hold our current position which we did. We must have just passed the place they intended us to stop; but well short of the well-marked T5 hold point which has signage and a hold-short line across the taxiway. We were then instructed to taxi to the holding point for [Runway] 02C and the flight proceeded as planned. I did not perceive this incident to be anything significant. May I suggest that if they intend to use the R1 hold point on T; that the R1 signage and hold-short line will need to be improved during the construction phase.Cause: Poor signage for the R1 hold place on T taxiway during their construction phase. It used to be very well marked and an obvious hold position as passenger planes would be exiting the Ramp there. Suggestions: The airport construction at SIN is a massive project and every time I fly in there different taxiways are either open or closed. Please ensure that the signage is appropriate if they intend to use that hold-short position.