WESTWOOD (CNS) - Motorists on the northbound San Diego (405) Freeway  lost one offramp and gained another as of today, as Caltrans has permanently  sealed the Montana Avenue offramp in Westwood.

But the northbound 405's Sunset Boulevard offramp, closed for the past  four months, was set to reopen by 6 a.m. today. That is the last temporary ramp  closure from the three-year ordeal as 10 miles of the 405 were rebuilt between  West Los Angeles and Sherman Oaks.

All is not smooth yet, however: Another set of overnight freeway  closures is scheduled for late tonight and Tuesday nights, as work is done on  the northbound 405 lanes.

The Montana Avenue exit was scheduled to be blocked off last weekend to  allow its demolition and the widening of the 405 without bending adjacent Sepulveda Boulevard toward houses and the Los Angeles National Cemetery.

The ramp was a frequent escape route to Sepulveda for motorists heading  to the San Fernando valley. It provided direct access to the surface street.

Drivers can reach the same area by taking the Wilshire Boulevard  westbound ramp, one exit earlier, or the Moraga Drive ramp, two exits later.  Those who try to take the Sunset Boulevard offramp when it reopens will find it  does not directly connect to either Sepulveda or Montana.

The Montana offramp's obituary, as written by the Metro public relations  team, notes it was ``a Los Angeles resident since 1956'' and said it was 550  feet long and weighed 718 tons.

On the freeway, northbound closures will start at midnight tonight and  Tuesday night, and last until 5 a.m. the following mornings -- Tuesday and  Wednesday. They are aimed to give construction workers safe room to work in the  median during roadway widening, according to Metro.

At midnight tonight, northbound lanes will be closed from Santa Monica  Boulevard to Wilshire. On Tuesday night, the 405 north will be closed again,  this time from Wilshire north past Sunset to Moraga, Metro officials said.

Associated ramp closures will begin as early as early as 7 p.m. Monday  and Tuesday nights, and freeway lanes will start to disappear at 10 p.m. those  nights, according to Metro.

The new seismically updated Sunset Boulevard offramp from the northbound  405 will allow up to 50 vehicles to line up on the ramp to await a green  metering signal, twice as many as the old one, officials said.