Cliff Avenue clog? State project responds to traffic needs at I-229

KELOLAND.com Original

SIOUX FALLS, S.D. (KELO) — More people, more cars, more traffic on Cliff Avenue.

The average daily traffic count on six stretches of Cliff Avenue from 33rd Street south to the Sioux Falls city limits increased by about 38,000 from 2016 to 2020, according to data from the city’s traffic engineering department.

The city will widen a stretch of Cliff Avenue from 49th Street to 56th Street next year. The South Dakota Department of Transportation plans to change I-229 interchange at the Cliff Avenue exit, or exit 4, in 2025.

The city’s Cliff Avenue project is part of a $4 million project. The estimated cost for the state project is $40 million as of Oct. 27, said Steven Gramm of the S.D. DOT.

Both projects are designed to help address the growth in traffic associated with growth in southern Sioux Falls and northern Lincoln County.

“As Sioux Falls and Harrisburg continue to grow, it puts more demands on roads,” said Gramm, the planning squad leader for the S.D. DOT.

Residents, whether commuting to work or traveling to other activities, are using Cliff Avenue as a way to get to their destination by continuing on the avenue or by exiting or entering Interstate 229.

Cliff Avenue on at the intersection with I-229 on Oct. 27.

Traffic uses I-229 because it can be easier to use to get across or around Sioux Falls than arterial or other streets, S.D. DOT engineer Jeff Brosz said.

The stretch of Cliff Avenue between the north and south ramps of I-229 had an average daily traffic count of 28,030 in 2020.

More turning lanes

At 5 p.m. and 7:45 a.m. weekdays, the Cliff Avenue exit area is congested.

“We’re adding a turn lane on the ramps to allow for more storage,” Gramm said. “There will be more lanes to turn right or left in the northbound offramp The southbound offramp will have two left lanes and still have one right turn lane.”

There isn’t as much traffic pressure to turn right off the southbound ramp, Gramm said.

Southbound motorists on Cliff will have a single left lane to go north on I-229. Northbound motorists will have two lanes to go south on I-229.

Graphic from the S.D. DOT’s Interstate Modification Justification Report Interstate 229 – Exit 4 (Cliff Avenue).

DOT average daily traffic (ADT) counts are taken through one 24-hour-period in the designated year, Brosz said. The ADT for the northbound and southbound off and on ramps show increases of as much as 2,000 vehicles from 1998 until 2017.

For example, the southbound offramp had 1,127 ADT in 1998 and 3,499 ADT in 2017. The ADTs could show some larger swings from year to year, Brosz said. If a traffic count was done in the summer at the Cliff Avenue exit, the numbers would likely drop from a prior year because Lincoln High School would not be in session, he said.

Gramm said the I-229 Cliff Avenue Exit improvement would be similar to the 12th Street and I-29 interchange.

A big change for 41st Street

The DOT plan will also re-align 41st.

The realignment will “help separate traffic from that intersection,” Gramm said.

41st Street is north of the northbound offramp and southbound onramp and almost directly across from the southbound offramp. It’s on the west side of Cliff Avenue and near Lincoln High School to the east.

Gramm said northbound motorists on Cliff will have a dual left lane to turn onto 41st Street. There will also be a right-turn lane into Lincoln High School.

The intersection of Cliff Avenue with 33rd Street is north of the 41st Street intersection.

The intersection of Cliff Avenue with 33rd Street taken at about 1:20 p.m. on Oct. 27.

ADTs from the intersection of Cliff Avenue with 33rd to the I-229 north ramp grew from 15,700 in 2016 to 23,002 in 2020.

Gramm said traffic entering or leaving the 41st Street intersection can cause confusion with other motorists. Motorists aren’t certain if the traffic will stay on Cliff Avenue or exit quickly to the southbound I-229 onramp.

41st traffic can also cause traffic that wants to turn left onto the I-229 southbound onramp to back up, Gramm said.

41st Street traffic “is one of the complaints we heard from people,” he said.

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