Shortly after leaving Guatemala City north for Puerto Barrios (remember the railroad runs north from the Mexican border to Barrios) you cross the Viaducto de Las Vacas. Can't remember how high it is, but if you were riding on top of a boxcar it tended to cause you to lie down on the walkway and hang on for dear life. Yeah, they let us ride on top of boxcars. And I can remember jumping from car to car and from the first car to the (slippery) tender top with the Jefe de Trenes to set up the next photo stop. Fun days.