Searching for info on whistle posts

[VeritechCEO]

I'm trying to place Whistle post signs in prototypical places. So, I'm trying to find any and all info one where Whistle posts are actually placed on a railroad. The only thing I know for sure is that they are placed about 1/4 of a mile from crossing, in the US. Where else are whistle posts placed? Also, if you can direct me to web site that can answer this for me, I'd appreciate it! Thank you!

 

[Jokel317]

Railroads I know like the B&O had whistle posts at bridges and/or tunnels. That`s about all I know beside`s the 1/4 of a mile from a crossing rule.