3: Whistle Signs
Whistle signs are installed at a wide range of locations such as the approach to level crossings to instruct the driver to use the whistle/horn in order to warn of an incoming train.
Whistle Sign
Easily the most common variant of the whistle sign found on the network, it is the standard variant featuring the letter W on a white background with grey border.
![Image depicting a standard lineside whistle sign.](https://sites.create-cdn.net/siteimages/19/3/4/193478/17/1/3/17139052/1366x768.jpg?1550657548)
Cut-Out Whistle Sign
Certainly a nod towards the older cut-out speed limit signs, these are a relatively recent addition to the network in response to graffiti making standard whistle boards unreadable.
![Image depicting a lineside cut-out whistle sign.](https://sites.create-cdn.net/siteimages/19/3/4/193478/17/1/3/17139053/1366x768.jpg?1550657622)
Continuous Whistle Sign
Introduced to the Scottish Region in the early 1990's, the continuous whistle sign instructs the driver to sound the horn continuously until within around 50 yards of the crossing it protects.
![Image depicting a lineside continuous whistle sign.](https://sites.create-cdn.net/siteimages/19/3/4/193478/17/1/3/17139066/1366x768.jpg?1550657791)