Oklahoma transportation officials will seek private-sector assistance to close the last gap in the Gilcrease Expressway, a highway that loops around downtown Tulsa. Under a plan announced on March 10, private investment would fund about a third of the $240-million, 4.5-mile tolled project, which would include a bridge across the Arkansas River. The city will lead investor selection, although specifics are still being developed, says an Oklahoma Turnpike Authority spokesman. The agency will design, build and maintain the new section. Construction could begin in 18 to 24 months. State feasibility studies for tolling only the bridge portion predicted that traffic volume would fail to generate sufficient revenue, but relying solely on conventional funding sources would potentially delay work for another 30 years.
Because it can moderate the damaging effects of earthquakes, base-isolation is a technique used primarily in seismically active regions. ENR takes a look at some of the largest applications of base-isolation technologies in the world.