Here are four key transportation projects Northwest Austin residents should know.

I-35 construction

In early February crews started work on the structure for the southbound I-35 to southbound US 183 flyover bridge. The work required crews to conduct alternating lane closures. The project also includes adding two other flyovers to connect I-35 and US 183 and other improvements between Rundberg Lane and Hwy. 290.

Timeline: January 2018-mid-2021

Cost: $124.2 million

Funding source: Texas Department of Transportation

Parmer Lane diverging diamond

Construction is underway for the northbound and southbound I-35 bypass lanes at Parmer Lane. In February, crews closed the right lane of westbound Parmer to start the reconstruction of the bridge. This lane reduction will remain through the spring. The project is adding a diverging diamond interchange that will facilitate safer turning movements.

Timeline: July 2019-mid-2021

Cost: $32.5 million

Funding source: TxDOT

RM 620 upgrades

TxDOT plans to host an open house meeting this spring to provide residents with an update on work proposed between the Colorado River and US 183. The agency has been refining options laid out in its 2017 feasibility study. The refinement process includes looking at the right of way and economic and social effects of any construction.

Timeline: construction TBD

Cost: TBD

Funding source: TBD

SH 130 at Toll 290

The first of three new flyovers connecting SH 130 and Toll 290 opened Jan. 11, eight months ahead of schedule. Drivers with an electronic toll tag will pay 61 cents to use the southbound SH 130 to westbound Toll 290 flyover. The other two flyovers will be complete by late 2021.

Timeline: December 2018-late 2021

Cost: $127 million

Funding sources: Central Texas Regional Mobility Authority, TxDOT