Photograph courtesy of the Italian Minstry of Agriculture--Istituto Agronomico per l'Oltremare

The picture of Agordat is caption as being taken in 1913.  As such, the railway on the left must be a decauville because the Eritrean Railway would not reach Agordat for another 15 years.

The station, according to East African Handbook, the Savoy is quite run down.

At one time, the line went slightly beyond Agordat to Biscia.

The above map was derived from one in Eritrea 1941.
 

The Italians were trying to reach the Sudanese rail line at Tessenai.  Had the line reached Tessenai, there was a change of gauge.  According to Jane's the Sudan Railway from Tessenai to Kassala (and beyond) line was 1.067 meters (42 inch).  Had the line made it to Tessenai, the passengers would have had to change trains and goods transloaded at Tessenai.

However, I knew of nobody who went beyond Keren.  In 1942, the British tore up the tracks from Biscia to Agordat.