Tolong jelaskan mengenai Pengukur tiga dari Lebar sepur ganda

Dalam situasi yang jarang terjadi, tiga alat pengukur yang berbeda dapat menyatu ke halaman rel dan jalur pengukur tiga diperlukan untuk memenuhi kebutuhan operasional stasiun pengukur jarak – paling sering di mana tidak ada cukup ruang untuk melakukan sebaliknya. Akan tetapi, konstruksi dan pengoperasian jalur triple-gauge dan persinyalannya melibatkan biaya dan gangguan yang sangat besar, dan dilakukan ketika tidak ada alternatif lain yang tersedia.

Tabel berikut menunjukkan tempat-tempat di mana triple gauge diperlukan.

Lebih dari tiga alat pengukur

Tiga alat pengukur adalah jumlah maksimum yang ditemukan di jalur kereta api yang beroperasi dan di pekarangan kereta api, tetapi beberapa produsen kereta api menempatkan lebih dari tiga jalur dalam pekerjaan mereka, tergantung pada alat pengukur khusus pelanggan mereka.

Alternatif untuk trek pengukur ganda

Perpindahan barang dan penumpang antara alat pengukur yang berbeda tidak harus melibatkan jalur pengukur ganda: mungkin hanya ada dua jalur yang mendekati kedua sisi platform tanpa tumpang tindih. Di Australia, 13 stasiun break-of-gauge ada pada tahun 1945 sebagai hasil dari persaingan antarnegara bagian yang sudah berlangsung lama: tiga stasiun pengukur yang berbeda telah bertahan sejak tahun 1850-an dan lima ibu kota negara bagian tidak dihubungkan oleh pengukur standar hingga tahun 1995. Huge costs and long delays were imposed by Trans-shipment of freight at break-of-gauge stations, whether manually, by gantry crane or by wheelset or bogie exchange.</ref> During World War II, breaks of gauge in Australia added immense difficulty to the war effort by needing extra locomotives and rolling stock, and more than 1600 service personnel and a large pool of civilians, at transfer points for an annual average transfer of about 1.8 million tonnes of freight.

To cost and inefficiency was added, in the case of passengers, considerable inconvenience. In 1896, at Albury station on the Sydney–Melbourne railway, famed American writer Samuel Clemens (Mark Twain) had to change trains in the middle of a "biting-cold" night in 1896 and there formed his pungent view of "the paralysis of intellect that gave that idea birth".

In some locations, an alternative to building long lengths of dual-gauge track has been to change the wheels on rolling stock, either by dropping and changing wheelsets from four-wheeled vehicles or exchanging bogies (US: trucks) under eight-wheeled vehicles. With this arrangement, a short length of dual-gauge track is only needed within the facility. A benefit is that the contents of fully loaded cars are not disturbed. The scheme was first adopted on the French–Spanish border and in Poland. It introduces delay into transit times compared with dual-gauge operation, but is much quicker than trans-shipping: when introduced in 1962 in Melbourne, Australia, on the route between Sydney and Adelaide, the freight handling time per train dropped from five days to less than two. The process involved disconnecting the brake rigging and bogie centre pins have to be disconnected before the vehicle is lifted and new bogies are wheeled underneath.

In Europe, a similar principle embodies low-profile, small-wheeled transporter wagons, which carry vehicles built for one gauge on a line with a different gauge. A variant is the rollbock (Rollböcke in German), used under two-axle standard-gauge vehicles: each wheelset is carried on a small four-wheeled narrow-gauge trolley. The entire train is converted in minutes at a slow walking pace, each rollbock being automatically matched to its wheelset from underneath.

A further variant is "train on train", in which an entire narrow-gauge train is carried on standard-gauge flatcars on which continuous rail has been fitted.

Differences in gauge are also accommodated by gauge-adjustable wheelsets, which  were installed under some passenger vehicles on international links between Spain and France, Sweden and Finland, Poland and Lithuania, and Poland and Ukraine. In Spain, change-over facilities are extensive, since although  track predominates, and high-speed lines are laid to  standard gauge, there are many lines with narrower gauges ( and others).