As MDOT, the city and the Federal Highway Administration modify the environmental assessment between now and spring, they are consulting with residential co-ops on the east side, apartment complexes, General Motors Co., Blue Cross Blue Shield of Michigan, Eastern Market Corp. and other downtown stakeholders.

Challenges to be addressed include how future developments at the riverfront, jail site and former Brewster-Douglass site could impact the plan; congestion; and how a new roadway would impact surrounding communities.

The changes would also open development opportunities on newly vacant land on either the east or west side of the boulevard, said Lewis of the city's planning department.

The state would likely sell or give that vacant land to the city, he said.

City officials "would prefer" to focus on east riverfront development plans nearby, so they probably wouldn't aim for development on the former I-375 land in the short-term, other than landscaping, he said. That landscaping could be replaced with new construction later on.

If the boulevard is oriented east toward residential areas, it would open up land for commercial use alongside the central business district, Lewis said. If the boulevard is oriented west, it would create space on the east side of the roadway that would allow the city to "create a wall of development, if you will, that completes that residential district ... provides an ending, a formalized cap, to the neighborhoods."

The I-375 project has $2.2 million budgeted for its preliminary engineering phase; $15 million for the design phase; and $150 million for construction, which would likely start in 2022, Loree said. About 82 percent of the funding is federal and 18 percent is coming from the state. The figures don't yet reflect the two "practical alternatives" and are very likely to change, he said.

Crain's previously reported that the reconstruction south of Gratiot would cost $80 million. The $150 million estimate takes into account the I-75 interchange, as well.

About 80,000 vehicles use I-375 daily, according to the state. The mile-long stretch is a main east-side link to I-96, the Lodge Freeway and the Detroit-Windsor Tunnel.

It was built more than 50 years ago. Construction led to the razing of Detroit's noted Black Bottom and Paradise Valley neighborhoods on the city's lower east side.