Tower Bridge bridge's upper walkways. The pedestrian walkways are above the river at high tide. The main bridge deck carries two lanes of road traffic between two low-level pedestrian walkways across both suspension spans and the opening bascule section of the bridge, with the walkways separated from the roadway by fences. The roadway passes through each of the two towers, whereas the low-level walkways pass around the outside of the towers. One of the chimneys on the bridge, which are often mistaken for lamp posts, connects up to an old fireplace in a guardroom of the Tower of London. It is long-disused.
Grand Tower Pipeline Bridge out across the river where welders connected them together. Each pipe weighs 5 tons and it took 72 pipes to span the river, adding to around 360 tons of dead weight. The abutments to support this weight go to the bedrock, 50 feet deep on the Illinois side and 154 feet on the Missouri side. The site at Grand Tower/Wittenberg was chosen because the river is narrow and deep there, and the limestone bedrock could be easily reached. Grand Tower Pipeline Bridge The Grand Tower Pipeline Bridge is a suspension bridge carrying a natural gas pipeline across the Mississippi River