Is failsafe as much as it used to be?

I seen this on another forum and thought I copy/paste it here ..... I'm curious to read some responses too.

"In the 'old days' of signaling, fail safe was one of the top design
priorities. I was wondering if today's 'modern technology' systems
have made any trade offs that result in a signaling system being not
so fail safe. I ask only cause I don't know.

As an example: In the old days the relays were mounted so that if
there was a failure gravity would pull the contacts to the 'stop'
state versus the 'clear' state. Todays relays are spring loaded, and
often mounted in ways that best suit the crowded cabinet. What if the
spring broke? What if a transistor shorted 'on' or 'off'? What if a
human programer wrote "if yes then" instead of "if no then" in his/her
code? I'm just curious to learn if there has been a little trade off
in fail safe to gain a lot more elsewhere."

I would have to think that there would be a defult that would eather shut things down. Or pop up some sort of warning in a Dispatchers office or in a Locomotive Cab.

SRS125 wrote:I would have to think that there would be a defult that would eather shut things down. Or pop up some sort of warning in a Dispatchers office or in a Locomotive Cab.

Not all railroads utilize cab-signals.

jg greenwood wrote:

SRS125 wrote:I would have to think that there would be a defult that would eather shut things down. Or pop up some sort of warning in a Dispatchers office or in a Locomotive Cab.

Not all railroads utilize cab-signals.

I know

This is still so. One example is a flashing aspect. It is always better (more permissive) than the solid. Advance Approach is more permissive than Approach. Limited vs. Medium speed, and Slow Approach vs. Restricting. If the flasher relay sticks in the on position, it is the more restrictive. If it sticks in off, then you have an imperfectly displayed signal.