More historical details:
To help you keep track:
Telkul Ghat (Howrah) to Dumjur: 01-07-1897 9.20 miles/14.81 km
Dumjur to Bargachia: 02-10-1897 5.87/9.45
Bargachia to Maju: 04-05-1898 5.50/8.86
Maju to Amta: 01-06-1898 6.62/10.66
Bargachia to Jagatbalabpur: 02-10-1897 1.50/2.42
Jagatbalabpur to Autpur: 01-06-1904 8.50/13.69
Autpur to Champadanga 24-08-1908: 6.68/10.75
Kadamtala to Chanditala 02-08-1897: 8.88/14.30
Chanditala to Kistrampur 10-09-1897: 3.75/6.04
Kistrampur to Sheakhala 07-11-1897: 4.75/7.65
Chanditala to Janai 05-05-1898: 2.37/3.82
By 1939, service were stopped between Howrah Ghat and Kadamtala. All the trains started from the latter.
In 1948, a new terminus was constructed at Howrah Maidan. A new alignment was created from there to Dasnagar
This was opened on 01-02-1948 with a length of 4.00 km.
That was common to the HALR and HASR.
For the HASR, a new alignment was also opened on 01-02-1948 from Dasnagar Km 3.2 to Km 6.0 (a length of 2.80 km)
This meant that Kadamtala and Uttar Banthra were no longer in use.
Passenger services on the Chanditala-Janai branch stopped between 1951 and 1963.
The rest of the HALR and HSLR closed from 1971.
Only the Howrah-Amta services were restarted in the 1990s, when the route was converted to broad gauge and electrified. There are several pairs of EMUs running on this route which has seen a major change in alignment at the Howrah end. These trains start from the main Howrah station and proceed along the main line to Kharagpur. At Santragachi, the line to Amta branches off, passes Kona which was on the old HASR and takes up the old alignment near Makardaha. A number of the old stations do not exist now.
Details of the present Howrah-Amta route via Santragachi and Kona can be seen here on this extract from the official SER map: