I've looked through the TexRail FEIS drawings once again, to identify where TexRail will be double tracking the corridor..
Here's the layout upon initiating service.
Double tracks at DFW station, double tracks at downtown Grapevine, double tracks at Smithfield Station, double tracks plus an additional freight only track at Northside (28th Street) Station, double tracks at ITC, although only one track will have a platform for TexRail cars, and double tracks at T&P Station. You will not be able to speed through the end stations, so that leaves just three stations where express trains can pass other trains, Northside at MP 15, Smithfield at MP 24, and downtown Grapevine at MP 33. FYI, DFW Airport is at MP 36 and T&P is at MP 0. Note these stations are around 9 miles apart, 10 to 11 minutes travel time apart.
They estimate 53 minutes runtime from end to end, and plan 30 minute headways during peak rush hours.
So let's assume a 7 am departure from DFW, it should get to Grapevine in 5 minutes (1 station in between) adds another minute or so, at let's say 7:05, it should get to Smithfield in another 11 minutes, let's say 7:16, it should get to Northside in another 13 minutes (2 stations in between adds 2 minutes), let's say 7:29, and get to T&P in 19 minutes (1 station in between adds 1 minute) at 7:48. Not quite the 53 minutes projected, so i'm around 5 minutes off somewhere. It's easy to figure out approximate times in one direction, now we have to make it work in the opposite direction.
Working backwards from where the trains must meet, 19 minutes displaced at least. So the train leaves T&P at 7:10, arrives 19 minutes later at Northside at 7:29 (a perfect meet), 13 minutes later at Smithfield at 7:42, and 11 minutes later at Grapevine at 7:53 and 5 minutes later pulling into DFW at 7:58.
Now will trains running 30 minutes later in both directions met at the appropriate places at the correct times? Let's start northbound first, leaving T&P at 7:40 we crash around 7:44, unless we meet at ITC using the wrong size platform? If we're lucky we reach Northside at 7:59, Smithfield at 8:12, Grapevine at 8:23, and arriving DFW at 8:29
Now lets look at the 30 minute later southbound, leaving DFW at 7:30, reaching Grapevine at 7:35, reaching Smithfield at 7:46 (we're 4 minutes off at Smithfield (need a little tweaking of my projected times), reaching Northside at 7:59(timing perfect), and completes the run at T&P at 8:18.
With just there 4 train running in both directions 30 minutes apart, we needed Northside, Smithfield, and ITC meets. we avoided needing to have a fourth meet because the trains run the distance in less than an hour, so you could say they're meeting again at DFW and T&P. The only passing siding we didn't need to use in my example was Grapevine. I could have tried forcing a meet there instead of at Northside, who know how that one would have turned out?
I don't see how it is possible to run an express train skipping stations at a faster pace that wouldn't disrupt the timing of all the train meets. And we still have to account for the Grapevine Vintage Railroad, which per chance, will not be running on the corridor during peaks, but when the trains are running at 60 or 90 minute headways instead of 30. It too will have to have a pretty strict schedule for the meets to happen properly,