Interstate 155 (Illinois)

Interstate 155 (I-155) is a north–south spur of I-55 that provides an Interstate connection for the Illinois cities of Peoria and Lincoln. The northern terminus is just east of Peoria, at I-74 exit 101 in Morton. The southern terminus, which is northwest of Lincoln, is located on I-55 at exit 127. The highway is 32.13 mi long.

I-155 was created to replace Illinois Route 121 (IL 121). Prompted by safety concerns at a major intersection near Morton, state transportation officials replaced the entire route with a limited-access freeway. The Interstate was built in several segments from 1970 to 1992, a period that included a 10-year delay due to a lawsuit over right-of-way. I-155 fully opened to traffic on October 29, 1992.

Route description
I-155 runs north from I-55 just northwest of Lincoln, intersecting U.S. Route 136 (US 136) east of Emden. 5 mi north of US 136, eastbound IL 122 joins I-155 traveling north, directly east of Delavan. The two highways run concurrent for 4 mi before IL 122 runs east to Hopedale. Further north, the highway crosses the Mackinaw River beside a steel truss bridge serving old IL 121.

East of Tremont, I-155 intersects IL 9. 4 mi later is Main Street, the first of three northbound exits to Morton. (There are only two southbound exits, at Queenwood Road and IL 98/Birchwood Street). The highway passes to the west of Morton before intersecting I-74 at a trumpet interchange about 8 mi southeast of downtown Peoria.

Surrounded mostly by prime land used for farming soybeans and corn, I-155 is a four-lane freeway through rural central Illinois. In addition to Morton, Peoria, and Lincoln, I-155 also serves a number of small farm towns located between Peoria and Lincoln. The largest city directly served by I-155 is Tremont; however, the highway mainly carries traffic traveling to and from Peoria and Springfield.

History
I-155 was built on the right-of-way of former IL 121. In the early 1960s, the Illinois Department of Transportation (IDOT) opened IL 98, an east–west, two-lane highway running west from downtown Morton to Pekin. Within a few years, the intersection of IL 98 and IL 121 would be known as the "Killer Corner", as traffic volumes increased between Springfield and Peoria on IL 121. Between when IL 98 was opened and when the corner was closed in 1989 for construction of a full interchange, 15 people were killed as a result of automobile accidents at the corner. Led by key supporters—US Representative Robert Michel, former IDOT transportation engineer Jack Harland, and pro-freeway organization "Route 121 by '91" chairman Jim Unland—IDOT initiated plans to upgrade IL 121 to a four-lane freeway. The proposed freeway was assigned as FAP 406. Near Hopedale, a short portion of IL 121 was reconstructed in the early 1970s to replace a bridge over the Mackinaw River. The interchange with I-55 was built but barricaded to traffic.

In 1976, an injunction won by Peoria attorney Timothy Swain Sr. halted further construction on the highway for 10 years. The lawsuit was filed by Swain regarding the amount of right-of-way the freeway would consume on his 440 acre farm near Delavan. A US District Court judge sided with IDOT on building the road, but the US Court of Appeals for the 7th Circuit overturned the decision, forcing IDOT to rewrite its environmental impact statement regarding the Swain farm. In 1986, IDOT struck a deal with Swain, agreeing to reroute the road and take only 40 acre of land, ending the lawsuit and resuming construction activities. A portion of the road from I-55 to Hartsburg opened on December 15, 1989, about 7 mi in length. The freeway was opened in full on October 29, 1992, at a ceremony attended by Governor Jim Edgar. The total cost of construction for I-155 was $130 million (equivalent to $ in ). Of this, $10 million (equivalent to $ in ) was provided by federal funding.

Illinois initially applied for the new freeway to be designated Interstate 37, but, on December 7, 1990, the request was deferred by the American Association of State Highway and Transportation Officials (AASHTO), pending approval by the Federal Highway Administration (FHWA) to add the freeway into the Interstate System. In addition, AASHTO suggested using a three-digit number when the application was resubmitted. Later, the state submitted another application to AASHTO for the freeway to be named Interstate 155. On June 9, 1991, the AASHTO application was approved and granted when I-155 was completed.