Thanks. I was also looking for a guess on what the running times on the new tunnel route would be. I've seen maps of the high speed rail line route. I thought it would have been more straight, but it zig-zags a lot.
OK, let's break it down.
By "zig-zag" I am assuming you mean the route jogging over to the Antelope Valley/Palmdale, not its path over the Tehachapis and the San Gabriels, that is quite straight for mountain railroads. The jog over to Palmdale was due to political, not engineering, considerations. Antelope Valley interests lobbied very hard not to be bypassed and were successful. There was an alternative over Tejon Pass, roughly parallel to Interstate 5 and a pretty straight shot between LA and Bakersfield, but politics won out. Also, I have heard that Tejon Ranch was pretty adamantly opposed to it crossing their land and put their thumb on the scale, too.
I don't see any mileage on the routes, so let's estimate it. Call it 160 road miles between LA and Bakersfield via Palmdale. I am starting with road miles rather than railroad miles because the railroad route is significantly curvier, adding miles. Any of the high speed rail route proposals are straighter still. I am treating 15 miles between Union Station and Burbank Airport separately, that's pretty straight either way and there are reasons to break it out as you will see. So about 145 road miles between Burbank, Palmdale and Bakersfield. Let's subtract about 5% given the proposals are straighter and also miss Mojave (apparently poor Mojave doesn't have enough clout). So let's ballpark about 137 miles.
As to speeds, for purposes here I am going to use conventional railroad and speeds for both the last 15 miles between Burbank and LAUS, since I don't see it in the links and often high speed shares tracks with conventional in urban areas. Let's say 70 mph. That is 13 minutes for each. I will use TGV speeds of 350 kph/220 mph for high speed and 110 mph for a San Joaquin. Virtually every piece of equipment Amtrak owns is rated for 110, including the San Joaquins equipment. It is also the FRA Class 6 passenger speed limit.
The high speed therefore can make 137 miles Burbank to Bakersfield in a bit over 37 minutes at 220. Let's call it 38. Add in the 13 minutes LA to Burbank and 3 minutes dwell each at Burbank and Palmdale and that makes LA to Bakersfield at 56 minutes, all in.
A San Joaquin at 110 could make the 137 miles in just under 1:15. Add in the same 19 minutes for station dwells and the last 15 miles, so it would be 1:34. If they could make 220 and 110 respectively for the last 15 miles, it would be 47 minutes all in for high speed and 1:29 for a San Joaquin.
Finally, note that the biggest expense in creating a Burbank-Bakersfield high speed line would be creating the ROW with extensive tunneling, bridging and fills. Laying track, hanging caternary, and acquiring rolling stock would be relatively small in comparison. Tunneling safely through the fractured rock and earthquake faults of the Tehachapis and San Gabriels will be
extremely expensive. To invest that kind of money only to support the upper end of conventional speeds, 110 mph, would seem penny wise and pound foolish to me.
PS, the current proposed operating plan once the Bakersfield-Merced section, now well along in construction, will be to truncate the San Joaquins at Merced with a transfer to the high speed there. The San Joaquins will neither continue on BNSF, nor switch onto the HSR rails south of Merced.