Union Pacific first reached Chicago in 1982, by acquiring the Missouri Pacific Railroad. MP had previously acquired the Chicago & Eastern Illinois Railroad. In 1993, SD40-2's #3267 and #3141 lead a northbound freight through Thornton Jct., approaching Dolton Yard.
Southbound, approaching Dolton from Chicago in the year 2000, is a UP switch run with GP15-1 #1632 and MP15 #1388
Dolton is a busy place for freight trains, and frequent blocking of crossings. But that still is no excuse for this act of stupidity, witnessed prior to the passage of the above UP switch run.