Principle

Double-decked stock can accomodate 20-40% more seats per train length than single-decked stock. Double-decked train design is today a standard solution for many operation types including regional and suburban trains and more recently high-speed trains. Today, mature and well-experienced concepts for double-decked vehicles exist for all classes of passenger operation.

The height over rail is increased to 4600-4700 mm as opposed to less than 4000 mm for conventional stock. The weight increase has to be minimised in order to limit axle load. Therefore double-decked train design is usually combined with strong efforts to reduce weight. For instance, the TGV Duplex has aluminium bodies in contrast to steel construction in single-decked TGVs.

Examples

In suburban and regional transport, double-decked trains have become a standard option in today's railways. The examples for double-decked main line or high-speed stock are more limited:

• TGV Duplex
• Shinkansen E1.
• IC 2000

Infrastructural compatibility

The infrastructure compatibility of double-decked stock is limited but generally higher than for wide-body stock. However, many tunnels pose serious problems.