Substantial improvements to Interstate 94 between Minneapolis and St. Paul start next week, requiring lane and ramp closures strung out over the next year, state transportation officials announced Thursday.

The work between Nicollet Avenue in Minneapolis and the Cretin/Vandalia exit in St. Paul begins Tuesday and will restrict the interstate to three lanes in both directions through most of the project. It is the second phase of an effort to improve I-94 between downtown St. Paul and downtown Minneapolis.

Work at the outset will consist of reconstructing inside lanes (those closest to the median), shoulders and medians. Also planned is work to maintain or improve drainage, guardrails, lighting and bridge piers. Attention is expected to turn in late August to the outside lanes and shoulders.

Various ramps will close temporarily for resurfacing during these months as well. Additional lane closures in both directions will occur overnight as needed throughout the project.

Plans call for work to be suspended in late November, then resume next May. That's when there will be four all-lane weekend closures -- alternating directions each weekend -- between Nicollet and Cretin/Vandalia for resurfacing the inside lanes.

The project is expected to be completed by the end of June 2012.