How is that possible when I presently get exactly 59ms to Starhub servers and 55ms to some others? My first hop ADSL
latency is again exactly 29ms or 30ms at all times. 59 minus 29 should be 30ms.
But it's not 59 - 29, because that would be the same as adding router
1 + router 2 + router 3 + router 4 etc - if you did that your numbers would incorrectly add up to several hundred ms... so your first hop being 29ms in theory means that's the smallest possible ping you can get to anywhere, although even that is not strictly true, since I just ran a traceroute and got 10ms on my first hop but only 9ms on my second.
I suppose part of the confusing thing with my numbers above is using speedtest.net as a gauge - I can actually get 37ms to Australia (I don't know which city exactly, most likely Sydney) using traceroute. On the other hand, speedtest.net would give me maybe 45-55ms for Sydney (most of the speedtest.net servers are hosted by optus, so I used a trace to optus.net.au as a comparison).
As such, from Chennai you can probably expect the numbers I've given above - anything from 45 to 60ms... maybe a little less if you're really lucky - based on the numbers that I've run from the HNS data center in Mumbai - Singapore was somewhere in the vicinity of 60ms from there, so taking 12ms off for the Mumbai-Chennai route we'd probably be talking 48ms from Chennai.
(Please keep in mind that this is just an educated guess - YMMV).