empty. The new system envisaged the installation of an automatic kiosk (with a button for passengers to press) at each request stop. This alerts the driver about any waiting passengers in advance; if there is no requirement to stop, the train can maintain line speed through the station, thus improving reliability on the whole line. Following the successful trial at Scotscalder, this system was expanded on to cover five more request stops on the line, namely , , , and . The last two kiosks, at and , are expected to be in operation from spring 2023. Services Current passenger services All passenger trains are operated by ScotRail using Class 158/7 "Express Sprinter" diesel multiple units. The exact stopping pattern varies between each station, as not all trains run the full length of the Far North Line. All passenger services on the line start or terminate at . The service pattern is infrequent and very irregular, with intervals between consecutive trains at Inverness varying from just 15 minutes to as long as two-and-a-half hours. As of 2022, on weekdays (including Saturdays), there are 14 trains per day (tpd) arriving at Inverness from the north, and 12 northbound departures: 1 tpd each way shuttling to and from only; 4 tpd to and from (branching off the Far North Line at Dingwall); 1 tpd to and from ; 1 tpd to and from ; 2 tpd arriving from with 1 tpd in the opposite direction; 1 tpd arriving from with no corresponding return service; 4 tpd running the full length to and from via . On Sundays the services are even less frequent, with just 1 tpd (2 in the summer) to/from Kyle of Lochalsh, 1 tpd to/from Invergordon, 3 tpd to/from Tain, and just a single train each way running all the way to/from Wick. With the exception of some Wick services, all trains are timetabled to stop at every intermediate station. Dunrobin Castle station is only open during the summer months; no services call there in the winter. The stations at , , , Dunrobin Castle, , , and are designated as request stops: passengers wishing to board the train at these stations must press a button at a designated kiosk on the platform (except at Altnabreac, where passengers need to flag the train by raising their arm – see above), while those wishing to alight must inform the on-board