WisDOT’s “urban” freeways carry just 34% of I-94 traffic

The “large urban freeways” WisDOT cites to justify its east-west I-94 expansion project carry an average of just 34% of I-94′s traffic load, according to WisDOT data.

Some 135 highways WisDOT includes in its accident rate comparisons carry less than 10% of the traffic I-94 does; 511 carry less than 20%.

WisDOT is proposing reconstruction and expansion of I-94 from 70th Street to 16th Street. In the Environmental Impact Statement for the project, WisDOT says that “Crash rates in the I‐94 East‐ West Corridor are mostly at least 2 to 3 times higher than the statewide average for similar roadways, and several sections are more than 4 times higher than the statewide average.”

The various-size road pieces that WisDOT includes in the average are all considered “large urban freeways,” even when they are not. The list includes, for example, a stretch of Highway 43 in Rock County that carries an average of 1,012 cars per day, or a whopping 0.67% of the average traffic count in the I-94 project area.

Here’s a table summarizing the number of highways in WisDOT’s “large urban freeway” category and the share of I-94 traffic they carry. 

Methodology — I got the I-94 traffic count from the WisDOT’s draft EIS, which puts the weekday traffic count at 143,000 to 160,500 for the stretch proposed for reconstruction. I took the average of those two numbers — 151,750.

Then I got from WisDOT the list of “large urban freeways” it includes in determining statewide crash averages. That list of 1,694 highway segments included individual historical average daily traffic counts. There were 192 segments with no daily counts recorded, so I threw those out, leaving me with 1,502 segments to work with. I simply simply divided the historical daily count by the I-94 average of 151,750 cars per day to figure out what percentage of I-94 traffic each segment carried.