One year in: Denver’s airport train navigates interruptions, a $6 million gate glitch and surprisingly strong ridership After a year, officials say t

[081552]

http://www.denverpost.com/2017/04/09/denver-airport-train-one-year-in/

 

[Dakguy201]

From the article above:

"The challenge at the crossings is fairly straightforward, according to RTD: The arms close too early and open too late."

If that is the problem, I don't understand how adding flaggers to the crossings make the situation any safer.  Perhaps there is some value in that the flaggers presence might cause people who would otherwise go around a gate that is down not to take that action?  

[BaltACD]

Dakguy201

From the article above:

"The challenge at the crossings is fairly straightforward, according to RTD: The arms close too early and open too late."

If that is the problem, I don't understand how adding flaggers to the crossings make the situation any safer.  Perhaps there is some value in that the flaggers presence might cause people who would otherwise go around a gate that is down not to take that action? 

So you have Signalmen change the timings of the closing and opening functions. Duh!

[PNWRMNM]

Gate control is not that complicated. Most gates are controlled by predictive type line side controllers tied to a track circuit. The circuit is long enough to give 20 second down gate ahead of the train, plus mechanical lowering time, plus some length to give the predictor enough data to predict arrival.

The one clue is that the article implies they tried to tie gates into PTC. God only knows what complications that added. The interviewer talked about train taking possession of the crossing from 8,000 feet away. No wonder the gates are down too long.

Base on first para logic, with MAS of 60 MPH, 88 ft/sec, and assuming predictor needs 15 seconds of data (a totally made up figure) circuit needs to be 45 seconds, or 3,960 feet long on each side of the crossing. The nice thing about the predictors is that they can detect slowing and stopping, and release the crossing if necessary. They can also detect speed increases and adjust accordingly.

They seem to have outsmarted themselves and the FRA evidently will not let them fix it.

Mac