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US 12 project need

The purpose of the US 12 improvement project was to address the safety and capacity deficiencies along the highly traveled two-lane roadway between Sauk City and Middleton.

Crash history

Historically, the number of crashes along US 12 from Sauk City to Middleton had been high. Between 1985 and 1996 there were 2,010 crashes - nearly one crash every two days. Of this total, 615 crashes resulted in non-fatal injuries and 23 involved at least one fatality. Thirty people lost their lives during this period.

Nearly 50 percent of all crashes occurred during daylight hours, which includes morning and afternoon peak travel times. Alcohol-related crashes accounted for less than 10 percent of all crashes. Rear end and off-road crashes combined accounted for approximately 60 percent of the total number of crashes.

Crash history table from 1985 to 1996 (48 KB)

Roadway deficiencies

US 12 had substandard curves that followed the rolling terrain of the area. As a result, 55 percent of the corridor was marked with no-passing zones. Most of the rural, public intersections had substandard intersection angles, poor visibility and inadequate turn lanes for vehicles turning off of or onto US 12.

The roadway also had segments with inadequate ditch capacity leading to erosion and flooding. The intersection of US 12 and County P, which had a history of frequent flooding, had a storm water detention basin constructed as part of this project.

Capacity deficiencies

The term "capacity" refers to the number of vehicles that can safely travel on a segment of roadway under varying weather conditions. The capacity status of a highway is affected by its traffic volumes, the kind of traffic and the geometric layout of the roadway. 

The current Average Daily Traffic (ADT) volume on this corridor was over double the average statewide volume for similar two-lane highways. The increasing volumes had caused the road to become congested and unsafe.

US 12 ADT projections for 2005 and 2025 (44 KB)

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Questions about the content of this page:
Southwest Transportation Region, madison.dtd@dot.state.wi.us
Last modified: August 21, 2006