Derailment and Fire at the Tehachapi Loop, California - Trains Magazine

The attraction of getting a 2nd track through the tunnel site is that it would greatly facilitate connecting the 2 existing Walong and Woodford sidings to make a much longer siding or short stretch of double track.  If you can find an aerial view or map of this vicinity 'on-line', that would surely help to understand the suggestion.

Whether that siding extension/ connection would be actually useful - and then whether it would be sufficiently economically worthwhile - to the Operating Depts. of either or both owner UP and trackage-rights tenant BNSF, is another question.  However, from general knowledge it might well be, and would certainly be worth a quick look.

This tunnel is only about 420 ft. long, and I estimate that the cover over it is only in the 30 to 40 ft. range, max.

blue streak 1 and spbed and CshaveRR all mention the existing Walong siding, which is stated to be only about 4,800 ft. long, and ends at the eastern portal of this tunnel.  Beyond the tunnel going west, it's about 7,000 ft. = 1.3 miles along the track to the start of the Woodford siding.  There's lots of curves and maybe a bridge or two - but no tunnels in that distance. 

Going the other way, from the eastern end of the Walong siding, it's only about 800 ft. on a sharp curve to another short - 300 ft. or so - tunnel, then a winding single track on a 'sidehill' configuration for some distance to the next siding.

Almost anything is possible - and even if so, some of those things are not economically feasible - but I'd be asking those questions real quick and hard right now.  Maybe this isn't quite yet the time to actually do it - permits, budget approvals, reimbursement from BNSF if the derailment was its fault or responsibility, etc.  But, rather than repair the tunnel lining and thereby just perpetuate that bottleneck and maintenance headache, and operational liability/ contingency for when - not if - the next major earthquake occurs in that vicinity, I'd just go ahead now and 'daylight' at least the portions of it right up to the roadbed for the upper track, if at all possible. 

- Paul North.

"This Fascinating Railroad Business" (title of 1943 book by Robert Selph Henry of the AAR)