2011 Top 10 Roads - No. 2

Nov. 9, 2011
Full frontage - Frontage road completed and combined with ramps
PROJECT: I-19 East Frontage Road and Interchange Improvements, Canoa Road to Continental Road
LOCATION: Green Valley, Ariz.
OWNERS: Pima County DOT and Arizona DOT
DESIGNER: Psomas
CONTRACTOR: Borderland Construction Co. Inc.
COST: $18 million
START DATE: July 16, 2009
COMPLETION DATE: Feb. 3, 2011

Not only did the I-19 East Frontage Road have a 1.5-mile gap in it, between the Canoa Road and Continental Road interchanges, but the existing road was 30 years old and did not meet Arizona Department of Transportation (ADOT) standards. The twoway frontage road did not have shoulders for disabled vehicles. The I-19 northbound ramp at the Continental Road interchange was so close to the frontage road that there was no room for traf? c signals. As a consequence of the less-than-ideal situation, the Continental Road interchange operated with signi?cant delays.

After considering seven alternatives, the design team for ADOT and the Pima County DOT decided on an innovative braided ramp that combined the northbound on- and off-ramps and the frontage road into a single intersection with Continental Road. This is the ?rst time this solution has been used on Arizona’s interstate highways, and the state plans to consider it again for problem interchanges with two-way frontage roads and growing traf?c volumes.

The project included constructing three new bridges, widening an existing bridge and widening Continental Road under I-19. They widened Continental Road under the bridge from 80 to 114 ft without adversely affecting the existing bridges. The widening was critical to the success of the project. Without it, the level of service at the Continental Road interchange would not have improved signi?cantly.

Five different structural alternatives were analyzed, and grouted micropiles selected. The micropiles were placed using continuously threaded hollow core rods 50 ft in depth and grouted from the bottom up. They were placed 3 ft apart and staggered using a standard soil nail drill rig. Each abutment has 156 micropiles, creating a rigid soil mass and allowing the removal of the sloped embankment with the placement of a retaining wall.

Using micropiles also allowed construction to be phased with lane closures and permitted the bridge to remain open to traf? c throughout construction.

Sponsored Recommendations

The Science Behind Sustainable Concrete Sealing Solutions

Extend the lifespan and durability of any concrete. PoreShield is a USDA BioPreferred product and is approved for residential, commercial, and industrial use. It works great above...

Powerful Concrete Protection For ANY Application

PoreShield protects concrete surfaces from water, deicing salts, oil and grease stains, and weather extremes. It's just as effective on major interstates as it is on backyard ...

Concrete Protection That’s Easy on the Environment and Tough to Beat

PoreShield's concrete penetration capabilities go just as deep as our American roots. PoreShield is a plant-based, eco-friendly alternative to solvent-based concrete sealers.

Proven Concrete Protection That’s Safe & Sustainable

Real-life DOT field tests and university researchers have found that PoreShieldTM lasts for 10+ years and extends the life of concrete.