As it emerged on the north side of the huge gape of the Chhappar Rift, the line now called Sind Peshin State Railway turned westward to reach Khanai. Thence south it went to Bostan and Quetta. Late in the 19th century, a large quantity of chrome ore was discovered in the hills south of a little village called Hindubagh (renamed Muslimbagh in the 1960s). When First World War rolled around, the demand for chrome in the manufacture of steel armaments rose dramatically and Muslimbagh hit the map in a big way. Virtually within weeks a railway line sprang out of Khanai to snatch away the output from the mines.
Now, this seventy-four kilometre-long connection was not the ordinary Broad Gauge in use on the North Western Railway. This was, instead, the toy 2 foot 6 inch Narrow Gauge. During the war the line served its purpose well hauling out a huge amount of chrome ore. With the end of hostilities, railway authorities decided to extend the line all the way to Zhob, renamed Fort Sandeman three decades earlier. Thence, it was implied at that time, the line will drop down the Suleman Mountains to the dusty plain of Dera Ismail Khan in order to link up with the ferry of Darya Khan.
Since the line was to follow the contours of the valley of the Zhob River, it was designated the Zhob Valley Railway (ZVR). It was Narrow Gauge all the way, perhaps to easily link with the two systems of the same gauge already in operation beyond Dera Ismail Khan. The one from Mari Ghat (later Mari Indus) to Lakki Marwat where it split for Bannu in one direction and Tank in the other. The other ran from Kohat to Thal in the Kurram Agency.
The line to Zhob became operational in the mid-twenties with the terminus at Khanai. Shortly thereafter, it was extended backward to Bostan and this became the only stretch of Broad and Narrow gauges interlaced on the same sleepers in the entire North Western Railway. This honour was taken away from ZVR in 1942, when the Chhappar Rift line was uprooted once and for all. But with extension back to Bostan and forward to Zhob, it gained two other and greater places of honour for length and height above the sea: at two hundred and ninety-six kilometres long it is the longest Narrow Gauge section in the entire subcontinent and the station of Kan Mehtarzai, sitting at 2222 metres above the sea, is the highest in this gauge in the entire subcontinent.
If ever there was a grim and anxiety-making train journey, it was on the ZVR, especially in mid-winter. Though the tiny steam locomotives were equipped with snow ploughs, it was not unusual during particularly heavy snowfalls for trains to be caught in the drifts. Until the mid-1990s, station masters who had served on ZVR, now long since retired, shared many a canny yarn of winter disasters.
The worst fall of snow came in the winter of 1970 when a passenger train became snow bound just outside Kan Mehtarzai. For some hours the driver struggled to free it, but seeing it was of no avail, he dropped fire and waited for the rescue locomotive sent out from Bostan. When even that got snowed down, travellers gave up and walked into Kan Mehtarzai to catch road transport.
The transport of chrome generated the revenue to keep the line going. But by the early 1980s, it lost out to faster road transport and the line began to die a slow death. The last passenger train on the ZVR ran on 29 May 1985; chrome trains to Muslimbagh for another two years. Several half-hearted attempts to revive this line ensued, but none materialised. The death knell had sounded for ZVR that had hoped to connect Quetta with Dera Ismail Khan.