I looked at my 1988 street directory and saw that there were
Hougang Ave 4, 6, 8 and 10 back then. On map 159, you can saw
"Hougang Town Centre" which is in Hougang Central itself, however,
Hougang Central was still un-developed with a few shops during that
time, so the bus interchange was built at Hougang St 21 which was
more developed and had more human traffic. The interchange at
Hougang Central only open for operation in 1994.