How sure are we about the alignment of SGP AH2? I have found the following sources:
https://www.unescap.org/our-work/transport/asian-highway/database (2015, latest available for Singapore): shows it following BKE to the south end, but then turning west on PIE to 26A and south on Clementi Road, crossing AYE at 9 to end at West Coast Highway
https://agreement.asean.org/media/download/20180207145327.pdf (2018): shows the above as 2 (East) and a 2 (West) using AYE west of 9 and Clementi Road to end at West Coast Highway
https://www.lta.gov.sg/content/ltagov/en/newsroom/2019/7/2/asean-transit-transport-route-signs-to-be-installed.html (2019): states that Singapore was installing signs for 2 (East) and 2 (West) - and
here it is! Others also appear as shown:
AH2(E),
AH2(E),
AH2(W),
AH2(W),
AH2So this pretty much confirms the above, except that the overlap south of AYE is simply AH2, which extends just south of West Coast Highway to West Coast Ferry Road.
I also see no evidence that AH143 exists in Singapore. And in Malaysia,
AH2 is signed along what we have as AH143.
The sole Wikipedia source for AH143 is from 2010 and states "Final route numbering between Malaysia and Singapore is subject to consultation between both countries." The above 2018 link that created 2(E) and 2(W) is said consultation. (Incidentally, that 2010 note also applies to AH18 in Malaysia. The
2010 database shows AH18 using Federal 3 all the way south to the border, but this is from before the Johor Bahru Eastern Dispersal Link Expressway opened in 2012.)