Problematic I-10/Baseline Road interchange may be solved at ADOT's Aug 8 meeting, or not

ADOT is evaluating potential design alternatives designed to improve traffic flow for vehicles.

PUBLISHED AUG 3, 2024

The virtual meeting, which will include a presentation by ADOT’s study team, will start at 6pm.

Phoenix, Arizona: The Arizona Department of Transportation (ADOT) will host a virtual meeting the evening of Thursday, August 8, to provide an update and gather public input about planned improvements at the problematic Interstate 10 traffic interchange with Baseline Road.

ADOT is evaluating potential design alternatives designed to improve traffic flow for vehicles, pedestrians and cyclists ahead of recommending a preferred alternative.

The virtual meeting, which will include a presentation by ADOT’s study team, will start at 6pm. You can register to attend the meeting here. The meeting also will allow ADOT study team members to answer questions and accept public comments.

ADOT is studying potential improvements to traffic flow and safety at the I-10/Baseline Road traffic interchange. Due to the high traffic volume and congestion in the area, the current interchange design may no longer be adequate to meet the needs of the traveling public.

This project is planned in two phases. Phase I consists of determining the recommended configuration for the Baseline Road interchange. Phase II will consist of final design of the interchange and preparation of construction documents.

ADOT is considering three potential interchange design configurations for the I-10/Baseline Road Interchange project: a Modified Diamond Interchange (MDI), a Diverging Diamond Interchange (DDI) and a No Build Alternative (do nothing option). These alternatives will be discussed in detail during the August 2024 public meeting.

No Build Alternative

This alternative would not make any improvements to the existing interchange or to Baseline Road. The No Build alternative would not reduce congestion along Baseline Road. The existing roadway and traffic signals would remain unaltered and there would not be any property impacts.

Modified Diamond Interchange (MDI)

The existing I-10/Baseline Road Interchange is a Tight Diamond Interchange, also known as a Compact Diamond Interchange. It is the most commonly used interchange type for freeway connections to local roads, and many of the existing interchanges within Maricopa County use this design.

This alternative would have a smaller footprint than the DDI alternative.

The MDI alternative would keep the interchange and ramp configuration as they are, while adding some modifications to improve traffic operations, including adding new right turn lanes on Baseline Road at I-10 and additional lanes on the exit and entrance ramps. This alternative would have a smaller footprint than the DDI alternative, and would impact fewer existing properties. The MDI would also be less expensive than the DDI.

Diverging Diamond Interchange (DDI)

A Diverging Diamond Interchange (DDI) is a relatively new type of interchange that provides efficient traffic movements and reduces conflict points between traffic movements to improve safety. A DDI increases traffic flow by temporarily transitioning traffic to the left side of the road, allowing through-traffic and left-turning traffic to proceed through the interchange simultaneously, eliminating the need for a signalized left-turn.

DDIs are particularly effective at locations that have high volumes of left-turn traffic on and off of freeway ramps and left-turn related safety challenges.

Of the three alternatives, this alternative would have the largest footprint and would impact more existing properties. This alternative also includes the removal of the traffic signal at Wendler Drive and revising access to be right-in, right-out. The DDI would be more expensive than the MDI.