ITD has completed a third east- and westbound lane between the Garrity and Meridian interchanges. The new six-lane divided interstate will reduce congestion and improve safety for motorists.

The current widening work includes enough room for a future fourth lane. ITD will open the fourth lane after the Ten Mile Interchange and Garrity Bridges projects are complete and it is safe to open a new lane.

Construction began in early 2008 and was completed in late 2009.

• The first 2.4 miles of the third lane opened in August 2009 between the Ten Mile Overpass and Meridian Interchange.
• The next 2.6 miles opened in October 2009 between the Garrity Interchange and Black Cat Road.
• About one mile of the third lane will open in Spring 2010 under the Ten Mile Overpass. ITD has delayed the opening of this area to facilitate safe construction of the new Ten Mile Interchange.

The construction schedule has been accelerated by 6 to 8 months by dividing the work into phased contracts. Accelerated construction practices save taxpayer dollars by increasing competition and averting escalating costs.

The two prime contractors for the widening project were Knife River Corporation and Idaho Sand & Gravel. Additional contractors included Thueson Construction (median work from Garrity to Ten Mile), McAlvain (Ten Mile Creek widening) and Graham Construction & Management (rebuilding the Robinson & Black Cat bridges).

The 2001 I-84 Corridor Study by the Community Planning Association of Southwest Idaho (COMPASS) and ITD recommended widening I-84 between Garrity Boulevard and Meridian Road.

The project required reconstructing the existing Robinson and Black Cat bridges to accommodate additional lanes on I-84. The bridges were complete in April 2009.