Dark skys loom over a Westbound Z9 at the natural crossovers at Frost.

BNSF 6656, BNSF 6657, BNSF 6658, & BNSF 6655 on their maiden trip west. Photographed at 11:43.

An NS GEVO and two Dash 9s lead a P-train uphill on Main 2 at Frost at 1224.

A westbound manifest roars out of the Mojave Narrows toward the natural crossover at Frost.

A trio of SD45-2s leads a manifest up the flyover at Frost on the eastern slope of Cajon Pass.

A westbound UP unit train curves through Frost with a matched set of AC4400's: all wearing flags.

Now running left handed, BNSF 5441 west flies over the north track near Frost on the Cajon Sub.

Three SD45s, one from Rio Grande and two from UP, along with two Santa Fe pushers on the rear, lift a heavy Kaiser coal train up the steep incline at Frost.

In November 1974, a consist of clean power leads an eastbound down through the desert at Frost on the way to Barstow.

As the arid Mojave looms in the background, 5543 West roars upgrade out of Frost as its attacks Cajon Pass' eastern slope.