DENVER (CBS4) – The Colorado Department of Transportation reached a milestone Friday when a third and final northbound lane on Interstate 225 opened between Parker Road and Mississippi Avenue.

There’s still work left: Southbound lanes aren’t completed and more infrastructure must be built for a light-rail extension from 9 Mile Station to the new Iliff station. It’s part of a $63 million project.

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CDOT says it hopes the completion of the northbound lanes will bring motorists who avoided the area back to I-225 to alleviate traffic problems nearby.

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Crews in other parts of the state are also reaching construction milestones.

– New westbound lanes of Pena Boulevard leaving Denver International Airport opened to traffic on Friday. The airport is rebuilding highly traveled and deteriorated sections of the road between Second Creek and E-470. It’s part of a $9.6 million project that should finish in November.

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– On Monday morning, crews will blast rock to further widen the westbound sections of the twin tunnels on Interstate 70 near Idaho Springs. Later in the week, there will be one final blast. Since April, construction crews have used 85 blasts to widen the westbound tunnel to 53 feet. The blasts are part of a wider effort to alleviate traffic headaches heading into the mountains. The entire project is projected to be completed next summer.