Railroad Switch - Turnout Speeds

Turnout Speeds

Turnout speeds are governed by a number of factors.

As a general rule, the finer the crossing angle of a turnout, the higher the turnout speed. In USA, turnouts are rated by number, which represents the ratio of divergence per length as measured at the frog. A rule of thumb is that the rated speed of a switch is twice the number.

• #10 - 15 mph (24 km/h)
• #15 - 30 mph (48 km/h)
• #20 - 40 mph (64 km/h)

Higher speed turnouts have also been used in the USA:

• #26.5 - 60 mph (97 km/h)
• #32.7 - 80 mph (130 km/h)

In Russia and CIS switches a marked with tangent of crossing angle:

• 1/6 - sorting yards only, whenever it is impossible to install a better switch
• 1/9 - 40 km/h (25 mph), the most common switch, installed by default.
• 1/11 - 50 km/h (31 mph), used where passenger trains follow a diverging path. Swingnose crossing may be installed if required.
• 1/18 - 80 km/h (50 mph), used where either non-interruptible movement is required or the mainline diverges from the branch line.
• 1/22 - 120 km/h (75 mph), rarely used, hi-speed lines only.

Other considerations include the type of turnout (e.g. normal or swing nose, or slips etc.), wear and tear issues, and the weight and type of the vehicle passing over. Speeds for a trailing movement may be higher than for a facing movement. In many systems, speed limits vary depending on the type of train - for example, a turnout can have a "normal" speed limit for locomotive hauled trains, and a higher speed for multiple unit or high speed trains.

Turnouts with curved or tangential switch blades have higher speed than old style turnouts with straight switch blades.