Three legally configured goods-vehicle combinations are being checked: a B-train, an A-train, and a heavy rigid truck towing two other trailers. For the third combination, the rear trailer has a GVM of no more than 3.5 tonnes and the whole combination has an actual gross mass below 20 tonnes. All other applicable requirements are met. All operate within the standard dimension limits in Schedule 2, with no approved dimension variation or exemption (including under a 50MAX proforma), and no load projects beyond the vehicles. What is the maximum overall length for each combination, including its load but excluding collapsible mirrors?
現檢查三種依法組成的貨運車輛組合：B-train、A-train，以及一輛重型剛性貨車牽引另外兩輛拖車的組合。第三種組合的最後一輛拖車額定車輛總質量（GVM）不超過3.5公噸，整個組合的實際總質量小於20公噸。三種組合均符合其他適用要求，並依《車輛尺寸與質量規則》附表2的標準尺寸上限行駛，不適用任何獲准的尺寸變更或豁免（包括50MAX規定車型方案下的尺寸變更），貨物也均未伸出車體。包括貨物、但不計可折疊後視鏡時，這三種組合各自的最大總長是多少？
20 metres for each of the three combinations under the stated conditions, not only for the B-train.
在題述條件下，三種組合的最大總長均為20公尺，並非僅B-train適用。
閱讀相關知識
A B-train has two semi-trailers, with the second coupled to a fifth wheel at the rear of the first. An A-train has a semi-trailer towing a full trailer. The other two-trailer arrangement in this question requires a heavy rigid goods vehicle, a rear trailer with GVM no greater than 3.5 tonnes, and actual gross mass of the whole combination below 20 tonnes. These conditions do not replace other coupling, axle, mass, stability or licensing requirements. The 20-metre answer is for the stated operation: certain reduced-width loads projecting behind a rear full trailer can have a different overall-length limit, and overdimension or special-permit operation must be checked separately.
B-train的拖車部分由兩輛半拖車組成，第二輛半拖車透過第一輛後部的第五輪連結裝置連接。A-train的拖車部分為一輛半拖車牽引一輛全拖車。本題中的另外兩拖車結構要求牽引車為重型剛性貨運車輛，最後一輛拖車的額定車輛總質量（GVM）不超過3.5公噸，整個組合的實際總質量小於20公噸；這些條件不取代其他連結裝置、車軸、質量、穩定性或駕照要求。20公尺答案僅針對題述行駛條件：某些從最後一輛全拖車後部伸出的限寬貨物可適用不同的總長上限；超尺寸或特殊許可行駛須另行核查。