All six zones of the Minneapolis Wi-Fi Internet access network are to be completed March 11 -- about four months later than originally planned -- although some significant dead areas within those zones will remain for a while, city officials and network builder US Internet said.

The map below shows network construction progress on Feb. 13. The dead zones ("challenge areas") are in black. The largest of those zones is around Lake of the Isles, Loring Park and Lowry Hill; smaller ones can be found along Lake Street and Interstate 35W and along the Mississippi River.

The dead zones are caused by problems with 124 light poles that are needed to support Wi-Fi hot-spot equipment, said Joe Caldwell, marketing vice president of US Internet in Minnetonka. The beginning of service in the dead zones depends partly on negotiations between the city and Xcel Energy over pole use. The biggest dead zone contains about 20 percent of the 8,000 people who preregistered for service, Caldwell said.

Another map showing where Wi-Fi service can be ordered can be found by going to www.usiwireless.com and clicking on the Stone Arch Bridge photo.

The delays were caused by technical issues such as antenna strength, foliage barriers and reception problems inside stucco houses, plus time lost after the 35W bridge collapse.

When the dead zones are filled, the Wi-Fi network will provide service to 95 percent of the city's land area, Lynn Willenbring, the city's chief information officer, said in a letter written last week. High-rise buildings won't receive a signal above the third floor unless separate agreements are signed with US Internet.

Steve Alexander covers technology for the Star Tribune. E-mail your technology questions to tech@startribune.com or write Tech Q&A, 425 Portland Av. S., Minneapolis, MN 55488-0002. Please include a full name, city and phone number.

This Feb. 13 Wi-Fi progress map shows areas soon to go live, such as near Lake Nokomis, and dead zones (in black) that lack service because of a shortage of adequate poles for equipment. Some dead zones will persist until summer.