Line 4B of the HCMC Metro was a proposed branch line of Line 4 to connect Tan Son Nhat Airport to the metro system.

Alignment: Gia Dinh Park Station (metro line 4) – Nguyen Thai Son – Hong Ha – Tan Son Nhat Airport – Truong Son – Hoang Van Thu park – Lang Cha Ca station.

Total length: 3.2 km underground.
Number of station: 3 underground stations.

Line 4B has since been replaced by Line 6, which follows a similar path to Line 4B. Line 4 has also been rerouted to go directly to Tan Son Nhat, so Line 4 and Line 6 will serve the airport.

HCMC Metro Line 4B links and resources

Management: MAUR (Management Authority For Urban Railways).
Wikipedia: https://en.wikipedia.org/wiki/Line_4B,_Ho_Chi_Minh_City_Metro

HCMC Metro Line 4B maps

[Line 4B map by MAUR.]