ADOT breaks down how freeways are designed to handle monsoon storms

Posted at 4:36 PM, Jun 17, 2022
and last updated 2022-06-27 16:03:20-04

When monsoon storms hit, they hit fast and hard, making conditions on Valley freeways potentially dangerous for drivers.

Keaira Bonds says he biggest fear is hydroplaning.

"Your car is going left and right, you scared if you're gonna hit this person, you got your kids in the car... Nothing is right, so you really can't drive you have to stay at home," Bonds said, while filling up at a Phoenix gas station.

ADOT spokesperson, Doug Nintzel, keeps a close eye on the daily forecast during the monsoon.

"There are gonna be those times when you have two inches of rainfall in just an hour," Nintzel said. "There is a lot of work that goes into getting the water off the freeways as quickly as possible."

He says the system starts with how the freeways are designed.

"The freeway is built with a cross slope towards the center and then it slopes to the outside, so that water drains off onto the shoulders, into our catch basins, ultimately into the drainage system," he said.

When it comes to drainage, several factors play a role, like if it's a urban or rural freeway and if the roadway is on higher or lower ground.

"A lot of the freeways are above ground level and that really helps with drainage in that if the roadway is higher, it goes into the drainage systems along the shoulder, and those drainage systems are gravity controlled. But in areas where were below grade, or below ground level, we need the help of the pump stations," Nintzel said. "Those pump stations are designed to accept the water that's flowing into them. They lift the water out with the use of these pumps and that water winds up going into either nearby basin or it is then passed into channels, ultimately its headed to the local area riverbeds."

Recurring trouble spots for flooding, Nintzel says, are the I-17 underpasses along with Greenway and Thunderbird roads.

Driver, Wyatt Holsclaw says he's been caught in monsoon storms before.

"We have days and times where the streets get flooded and you can't drive," he said.

Between rain, wind, dust, hot oily roads and ponding water, Nintzel says the advice for driver's is simple.

"Slow down in those storms," he said.

Nintzel says ADOT continues to learn from each water situation on the roads, like the US-60 water main break in Tempe.

"What we learned about was the force of the water. When that pipeline gave way, it really did force a movement of a material under the freeway," he said. "That's why there was a complete reconstruction of the westbound lanes that took place."

But when it comes to our summer storm season, "Our freeways hold up very well in general terms, when it comes to the monsoon," Nintzel said.

But it was Holsclaw that summed it up the best.

"Monsoon season is definitely nothing to play around with," he said.