192 was still NAC when the service was amended on 7 Jul 1990.
In its previous era (pre-Boon Lay Int, between 6 Nov 1989 to 30 Jun
1990), this service used to operate from 0630-0900 and 1430-1900 on
weekdays (for saturdays, 0630-0900 and 1200-1630) and no operation
on sundays & PHs.
Tuas Ter, Pioneer Rd, Tuas Cres, Tuas Ave 20, Pionerr Rd, Tuas Ave
8, Ave 9, Ave 12, Ave 1, Ave 3, Tuas Rd, Upp Jurogn Rd, Jln Boon
Lay, Boon Lay Ave, Boon Lay Dr, Corportion Rd, Corporation Dr, KAng
Ching Rd, Yuan Ching Rd, Boon Lay Wsy (Loop)
Return via Corportaion Rd, Boon Lay Dr, Boon Lay Ave, Jln Boon Lay,
Upp Jurong Rd, Tuas Rd, Pioneer Rd, Tuas Cres, Tuas Ave 20, Pioneer
Rd, Tuas Ave 8, Ave 9, Ave 12, Ave 1, Avr 3, Tuas Rd, Pioneer Rd,
Tuas Ter
Between 1 to 6 Jul 1990, the route still remains the same, except
for a slight amenement to and from Boon Lay Int via Boon Lay
Wsy.
From 7 Jul 1990 onwards, the route becae:
Boon Lay Int, Boon Lay Way, Jln Boon Lay, Upp Jurong Rd,
Jln Ahmad Ibrahim, Tuas West Rd, Pioneer Rd and Tuas Rd
(Loop)
Return via Upp Jurong Rd, Jln Boon Lay, Boon Lay Way, Boon
Lay Int.
By this route information, it is clear that the stretch of Tuas
West Rd, Pioneer Rd and Tuas Rd was previously used by 175. It was
known that 192 had skipped the entire avenues in Tuas and continues
its route via Tuas West Rd.
Seems like 254 was later amended to serve bigger coverage
of Tuas.
I believe 192 was initally peak hr sv was because Tuas was still
under developed then