For reliability and safety and speed, switch frogs on heavily trafficked lines have moved away from the passive variety to a kind which supports the wheel continuously on the rolling surface. This is from the Union Pacific main west of Chicago.
British railways (no longer British Railways!) could do with learning a thing or two about good engineering. I've never seen one of these - I'm pretty sure we simply don't have them here. Trains always slow down anywhere where there are turnouts - not always all that much, with predictable results in terms of wear and tear.
What is intriguing about these systems is that they also include heaters and hot air blowers to keep the flangeways and moving parts clear of ice and snow. Mechanically these things are monsters.
I'm familiar with heaters and hot air blowers - for the main blades. They were installing them in the early 1970s while I was doing a temporary contract with British Rail, in 1972-3. But a movable point frog - yup, you can see they're monsters. But a really good idea for main lines. The passive ones are okay for sidings, or in stations where trains are pootling along slowly.
I haven't seen any switches that I would characterize as tongue and groove in Heidelberg, but the tram switches around here are pretty interesting. I'll post some pictures of them this week if I can get out to photograph them. The motormen control them with buttons on their control console, and electromagnets under the cab actuate the throw. The switches are also completely run-through safe, so a trailing point move requires no action on the motorman's part.
I've never seen one in service but remember seeing in Trains maybe 10 years ago that this design was undergoing testing at the "Test track" at Pueblo, Colorado. Reminds me of the Tongue and Groove switch design used in street railways in the early part of the last century. Do you have any pic's of Tongue and Grooves, Chris?
British railways (no longer British Railways!) could do with learning a thing or two about good engineering. I've never seen one of these - I'm pretty sure we simply don't have them here. Trains always slow down anywhere where there are turnouts - not always all that much, with predictable results in terms of wear and tear.
Good to hear from you again!