The Alhambra trench does predate the Reno trench; however El Paso predates them both. Note that all 3 trenches, as well as the Alameda Corridor, featured the Southern Pacific. I've always found humor in the fact that western cities that grew up around a railroad now try to move the railroad out, as if its' the railroad that built in the wrong place. Of course the railroad does benefit also, through decreased grade crossings and increased track speeds. The Alhambra Trench also reduced track grade through the area.
Regarding Reno, my wife & I watched the E/B Amtrak Zephyr perform its' station stop & smoke break on October 10th. The Espee depot at street level is still used; I'm guessing elevators have been installed to bring passengers & baggage down to track level. To me something special about Reno was covered up when the trench was dug; the trains splitting town & blowing the horn constantly for 4 miles, the classic Reno photo of a train crossing Virginia St. with the " Biggest Little City " arch, watching the drunk gamblers dodging the trains, getting a funny look when asking for a hotel room FACING the tracks @ The Sundowner. Now you can walk down Virginia St. and not even know the tracks are there, unless you know when to look down. The trench is covered for several blocks, as if to hide Reno's shame.