Work on the expansion of a dark fiber broadband network into Marshall County could start this spring following approval by the county council of funds for the project. St. Joseph County Metronet wants to extend the dark fiber infrastructure into Marshall County. It will mean extremely fast Internet speeds for both business and residential customers. County officials say having that infrastructure in place will significantly boost economic development. The county has agreed to contribute $500,000 toward the project. St. Joseph County is also funding $250,000, and several local businesses are also kicking in some cash. The Marshall County Council yesterday approved the advertisement of the proposed appropriation, but final approval is still needed when they meet next month.