Stacked lanes are among hundreds of potential projects state and local officials are weighing as they plan for improvements to I-405 over the next 20 years. Other possibilities include bus and carpool lanes, high-capacity transit and trains. In Bellevue, stacked lanes would theoretically join the overpass system, and motorists wanting to stop in Bellevue all would share one interconnected Bellevue ramp. Tying interchanges together also appeals to the Federal Highway Administration. Such a plan would improve safety by cutting down on merging traffic, in which accidents are most likely to happen.
Safety is one advantage, limiting expansion of the freeway's corridor is another.
An undetermined amount from local taxes and sales tax on cars also would be sought. That money would pay for further design work. Planners expect the current population of 500,000 to grow to 700,000, with 150,000 new jobs by 2020. That would increase traffic volume by 56 percent. The most sensible, cost-effective projects then will go before regulators, public officials and neighbors living along the routes.