The closure began at 10 p.m. and will last 90 days. Earlier this month, the northbound 405 Sunset Boulevard off-ramp was shut down and will remain closed for four months.
The good news is, the Wilshire Boulevard ramp closure is the last of its kind for the entire freeway improvement project. The ramp will be replaced with a larger one that can handle 300 percent more vehicles.
The new ramp will be 3,100-feet long, compared to the old one that was only 800 feet.
"Ramp Jam" is part of the $1 billion 405 Freeway widening project, which is a year delayed and $75 million over budget.
According to one study, since the Sunset Boulevard ramp closure, it's been taking 12 minutes to travel four miles on the 405 Freeway. The same route used to take four minutes.
Transportation officials say they are well aware of the inconvenience the closures cause of Angelenos.
"Motorists are advised to plan ahead and find your alternate route in advance," said Metro spokesman David Sotero.
Drivers are recommended to drive southbound on Sepulveda Boulevard and get on the freeway at Santa Monica Boulevard or Cotner Avenue