Ask CITYVIEW

I was reading your story on Des Moines bridges and saw that one of the bridges was raised several feet. How do you raise a bridge?

The bridge in reference has been called The Red Bridge, Des Moines Union Railway Bridge, and now the Principal Riverwalk Red Multi-Use Trail Bridge. In short, it takes cranes, jacks — and a lot of time. Here’s the full explanation we received from Steven Naber, Des Moines City Engineer:

“The Principal Riverwalk Red Multi-Use Trail Bridge (originally constructed as a railroad bridge in 1891) was raised 4.5 feet to reduce the upstream flood profile of the Des Moines River. 

“The bridge was raised utilizing cranes and hydraulic jacks at each pier location. The jacks were attached to the existing bridge piers, and elevated the bridge in small increments (inches) over a period of a couple months (about three weeks of jacking up the bridge, and the balance to raise the concrete piers). In this photo, taken during construction in December 2016, you can see the jacking support plates on the piers where the jacks would be placed to elevate the bridge.

“This could be compared to jacking up your car with four jacks at all four wheels very slowly (except for this bridge project: there were roughly 30 jacks, each with 55 tons of lifting capacity, used to raise the bridge weighing roughly 1.2 million pounds). Once the bridge was elevated with the jacks and cranes, the piers were raised with reinforced concrete up to the bridge support height.

“The construction contractor, Cramer & Associates, started elevating the bridge on Dec. 19, 2016, and by March 1, 2017 the bridge was resting on new supports 4.5 feet higher.”

Last month you answered questions about roadkill and mentioned that some animal carcasses are sent to Metro Waste Authority. What happens there?

Here’s the response we received from a MWA spokesperson: “State regulations specify that disposal of deceased animals must occur as soon as reasonably possible, generally considered to be within 24 hours of death. When a deceased animal is brought to one of Metro Waste Authority’s landfills, the carcass is immediately buried.”

Now, if you really want to go down a rabbit hole, look into animal rendering services. It’s defined by the USDA as “an off-site process that uses heat to convert animal carcasses into safe, pathogen-free feed protein and other valuable end products while reducing the negative effects of the carcasses on people and the environment.”