As the Oak View Group (OVG) and former Seattle Mayor Ed Murray negotiated a memorandum of understanding on a $600 million privately financed renovation of Key Arena at Seattle Center, OVG agreed to an additional $40 million for transportation mitigation around Seattle Center.

As Seattle-area business interests continue to vie for an arena with amenities able to draw both NBA and NHL teams to the city—the Seattle NBA team left for Oklahoma City in 2008—transportation has proven one of the key ingredients in plans to either build or renovate an arena in the city.

Investor Chris Hansen has for years tried to get a brand-new arena built in the SoDo neighborhood of Seattle nearby the homes of both the Seattle Seahwaks of the NFL and the Seattle Mariners of MLB, also offering to pay $40 million in transportation improvements in what is already known as the stadium district. Opposition has said that money isn’t enough to alleviate concerns for the Port of Seattle. The Mariners have also come out against a new arena next to their baseball stadium. Hansen has run into further complication by not having inroads to bring a NBA team to the city, which his MOU running out with the city later this year.

By renovating the still in-use Key Arena, OVG assumes all costs and overruns on the project and would take over operations of the building. “The completion of the MOU provides a level of certainty that Seattle has never had before, and OVG, the City Council, elected officials and the residents of Seattle must now turn our attention to the NHL and NBA and make it undeniably clear that we are more than ready for them to come to Seattle,” says OVG co-found and CEO Tim Leiweke in a statement.

OVG has billionaire David Bonderman, a potential NHL franchise investor and graduate of Seattle’s University of Washington, as part of the investment team on the renovation.

In the potential agreement, OVG takes on private money to develop the arena and handle any cost overruns on the project. It will also be responsible for day-to-day and long-term capital upkeep and take over operations of the First Ave. N Garage. The city is guaranteed $2.6 million per year, the current revenue of the arena.

On the transportation side, the $40 million may not be even half of what OVG puts into the project. Leiweke told local media that OVG may spend about $100 million trying to create transportation solutions in the Uptown and South Lake Union areas. Along with the $40 million earmarked specifically for transportation in the downtown arena project, about $30 million of the arena construction budget is planned for transportation and Leiweke said millions more could go toward transportation, per the lease agreement.

With environmental work starting this year, if OVG can get final approval from the City Council, OVG hopes to start construction on the project in 2018 and have the building—and updated transportation—ready in 2020.

Follow Tim Newcomb on Twitter at @tdnewcomb.