by Lucius Kwok
I work in software so that's the kind of engineering I'm most familiar with, and one of the most basic rules of writing software is that new lines of code will have bugs, and many of those bugs will only show up in testing. Another rule is that you don't just throw out old, tested, working code and replace it with new stuff unless it's really broken. The old code may be crufty and ugly to look at, but if it's been tested and used out in the wild, it's gold.
How I feel about these new signal systems is the same as with software. Don't throw out what's working just to have all brand-new stuff. Coded track circuits have been tested and in use for decades. CBTC is still new. It's going to have bugs. Let some small transit system test it out for 5-10 years.
Of course coded track circuits and a transponder/balise system aren't mutually exclusive. In fact, I think that's the best way to go. Take small incremental steps. You should go directly from wayside signals with cab signals to a pure CBTC. Start by upgrading to coded track circuits with CSS and Speed Control, then add more stuff to it if it's necessary.
I think part of the reason PTC and CBTC are touted as solutions is because it's the sales people who are influencing the final decision makers, and not the engineering people. The makers of these systems stand to make a lot of money not only selling them, but, as has been said, also to fix the bugs that will inevitably crop up. It'll be guaranteed employment for the next 10 years for these companies if PTC is mandated.
The privately-owned freight railroads are better at cutting through the marketing crap and see CTBC for what it is. It's the public transit agencies and the state lawmakers who pass laws mandating PTC who get snookered by the sales people. I hope that there's at least one lawmaker in CA who will come to his/her senses and mandate something based on sound engineering principles and that's time-tested instead of something which is clearly designed to grab the headlines and make it look like the legislators are doing something when they haven't a clue.
How I feel about these new signal systems is the same as with software. Don't throw out what's working just to have all brand-new stuff. Coded track circuits have been tested and in use for decades. CBTC is still new. It's going to have bugs. Let some small transit system test it out for 5-10 years.
Of course coded track circuits and a transponder/balise system aren't mutually exclusive. In fact, I think that's the best way to go. Take small incremental steps. You should go directly from wayside signals with cab signals to a pure CBTC. Start by upgrading to coded track circuits with CSS and Speed Control, then add more stuff to it if it's necessary.
I think part of the reason PTC and CBTC are touted as solutions is because it's the sales people who are influencing the final decision makers, and not the engineering people. The makers of these systems stand to make a lot of money not only selling them, but, as has been said, also to fix the bugs that will inevitably crop up. It'll be guaranteed employment for the next 10 years for these companies if PTC is mandated.
The privately-owned freight railroads are better at cutting through the marketing crap and see CTBC for what it is. It's the public transit agencies and the state lawmakers who pass laws mandating PTC who get snookered by the sales people. I hope that there's at least one lawmaker in CA who will come to his/her senses and mandate something based on sound engineering principles and that's time-tested instead of something which is clearly designed to grab the headlines and make it look like the legislators are doing something when they haven't a clue.
