Double-Deck Coach

Overview

A double-deck coach is a hauled (unpowered) passenger vehicle that stacks two seating decks inside one carbody to raise capacity without lengthening the train. It carries no traction equipment of its own, a locomotive or a powered end car moves it, so its design problem is fitting two floors, a staircase, doors and a toilet inside the fixed loading gauge while keeping the centre of gravity low enough for stable running. The answer is a dropped centre floor: the underframe sags between the bogies so the lower saloon sits close to rail level, the upper saloon rides above it, and short stairs at each end connect the two. The result carries roughly twice the seats of a single-deck coach over the same length of platform.

How it works

The vehicle is built around the Bilevel Carbody Shell, a welded steel monocoque whose deep fishbelly underframe drops the lower-deck floor while the upper-deck floor and roof close the shell above. Passengers move between levels on the Internal Staircase at each end. The body rests on two Railway Bogie trailer running-gear units, and braking comes from a Friction Brake Unit on every axle, each clamping a Brake Disc (rotor) with a pneumatic cylinder fed from the train brake pipe.

Boarding is through wide Entrance Door entrances on the lower deck, each worked by a motorised operator. Both decks are filled with Seat Assembly passenger seating and served by roof HVAC Roof Unit climate units, one per deck. A Toilet Module provides an accessible vacuum WC with its own water and retention tanks. The Lighting & PA System system runs LED saloon lighting, announcement speakers and passenger-information displays.

At each end a Coupler with draft gear handles coupling loads, and a Gangway Connection with bellows and a bridge plate lets passengers walk between coaches. Large Side Window panes glaze both decks. The Coach Control Box ties the doors, brakes, HVAC and lighting to the train control bus through its boards and connectors, so the coach responds to commands from the driving end.