This account takes place on the Buffalo Bayou-Brazos & Colorado Railroad, the very first part of what would eventually become the Southern Pacific. Construction began in 1853 but only made it from Harrisburg (south east of Houston) to Alleyton, on the Colorado River across from Columbus, Texas, by the time the Civil War broke out. Sir Arthur James Lyon Fremantle, "Three months in the Southern States, April-June 1863"
If you click on the link above (Orange/Bold/Italic/Underlined) you will find his entire journey from crossing the boarder from Mexico to Texas, so as to avoid running a blockade, to crossing the Union lines in Maryland (with a pass from Robert E. Lee) on his way to New York City to catch a ship back to England.
That trip must have been quite a shock for an Englishman. The method of crossing rivers by low level bridges was also used by Queensland Railways, the idea being that during a flood any debris in the water would be washed over the bridge leaving it undamaged but it didn't always work that way by the many accounts of bridges being washed away. The most notable was the bridge over the Burdekin River at Inkerman in north Queensland replaced by a high level rail/road bridge in 1957, shown in this photo beside the new bridge in 1958. http://www.queenslandplaces.com.au/...gecache/watermarked/exhibits/slides/PAP62.jpg Crossing it during a flood must have been an interesting experience. http://www.qhatlas.com.au/photograph/townsville-mail-through-floodwaters-burdekin-bridge-1936
The Brazos River bridge actually had a floating section in the middle that could be detached and moved out of the way when a stern wheeler steam boat was paddling by. They could not afford an iron or stone bridge to clear the navigation channel. After the Civil War they eventually erected an iron bridge. The first use for it, before the rail was installed, was a gallows to hang a convicted horse thief.
