CityArchRiver is raising much of the rest.

Foundation leaders said Thursday that they had now logged $200 million in donations and pledges toward the $250 million goal for construction and endowment.

The structural work for the park over the highway was largely funded via state and federal transportation dollars.

MoDOT’s Venker said landscaping, which includes Luther Ely Smith Square — that unused block of park just west of the Arch — should start in the next couple of weeks.

MoDOT first has to finish the bridge’s drainage system, which will pipe excess water off the bridge and connect to two underground water cisterns, of 30,000 and 35,000 gallons each, to be used to water the new park.

Venker said it was the first time MoDOT had ever built such a bridge.

Soon, workers will truck in 15,000 cubic yards of soil, 6,000 cubic feet of foam fill, materials for 944 linear feet of bench seating, and 223 trees.

The trees, in particular, have proven themselves a tricky proposition. Some will be planted in the park, in earth. But others will be planted on the bridge itself.

Designers solved the problem this way: