Missouri Department of Transportation officials issued one more reminder for Jefferson City motorists on Thursday: Make sure you know the Rex Whitton Expressway will be closed this weekend, between Madison Street and Clark Avenue.
The four-lane highway, which carries U.S. 50 and 63, will be closed from 7 p.m. tonight until 6 a.m. Monday, so MoDOT's contractor - Columbia's Emery Sapp and Sons Inc. - can demolish the Chestnut and Jackson street bridges over the highway.
The Jackson Street overpass was closed to traffic Thursday. The Chestnut Street overpass is to be closed at 9 a.m. today.
"We don't close roads like this - shut them down completely - very often," Central District Engineer Dave Silvester said. "It's a very rare event - in this case, for the safety of the job, the safety of the traveling public, the contractor, the MoDOT folks who are involved."
There will be no big explosion - or any explosion at all.
Instead, the two bridges built in the 1960s will be knocked apart, a little bit at a time.
"The demolition will involve chipping away at the structures with heavy equipment," Patty Lemongelli, the Central District construction and materials engineer, explained. "It's not, necessarily, a quick process.
"It's going to be very monotonous and very tedious."
And very noisy, she said.
Both bridges will be demolished at the same time, Resident Engineer Terry Imhoff said.
Once the Expressway is closed tonight, Lemongelli said, the contractor "will put several inches of sand" on the highway under both bridges, "to protect it from being damaged by the falling debris."
That work is expected to take a few hours before the overpass demolition begins.
And once the two bridges are down, the contractor will "clean up the area and will open the highway back up to traffic," she said.
If the U.S. 50/63 Expressway isn't re-opened to traffic by 6 a.m. Monday, there's a penalty in the contract for each 15 minutes' delay.
MoDOT has posted numerous warning signs about the work and directional signs for the marked detour.
Under the department's policy, the posted detours involve state-owned roads - eastbound traffic is directed southward onto westbound U.S. 54 to Route B, then Route B to Wardsville and left on Route M through Wardsville and Taos to reconnect with U.S. 50/63.
Westbound traffic is directed to get off the four-lane highway at the Route J/M interchange, turn left on M through Taos and Wardsville to Route B, then right on B to U.S. 54 just south of Jefferson City, and eastbound 54 north to the expressway.
"We're especially encouraging, or advising, trucks to take that route," Lemongelli said.
Jefferson City police, the Cole County sheriff and the Highway Patrol all will be monitoring the traffic situation this weekend, along with MoDOT and local public works officials, she said.
But officials expect local traffic "and those familiar with the area just to take the local city streets around - particularly McCarty," Lemongelli noted.
Until the 1960s, when the Whitton Expressway was built, East McCarty Street carried U.S. 50 and 63 into Jefferson City from the east - and parts of the street have been rebuilt and widened in recent years.
Still, Lemongelli said, "Our city streets really aren't designed for trucks to navigate easily and safely through. (And) the heavy trucks could cause some additional damage to McCarty - so we're really advising that the heavy truck traffic take the (marked) detour."
The weekend was chosen for the work because traffic usually is not heavy - especially at this time of year.
The two-year, $20.3 million Lafayette Interchange project includes a diamond interchange between the U.S. 50/63 Expressway and Lafayette Street and adding one lane in each direction between Monroe and Lafayette streets and between Lafayette and Clark Avenue.
Six bridges will be replaced or rebuilt, including the Jackson and Chestnut street overpasses, which eventually will be rebuilt over the widened highway.
This weekend's closure is expected to be the only time during the two-year construction project when the complete highway is blocked for a long period of time.
Imhoff noted there will be some temporary shutdowns - around 10-15 minutes at a time - "to set the girders" when the new overpasses are built.
The Chestnut Street overpass is scheduled to be replaced this summer. But Jackson Street - where a lot of rock has to be removed to make room for the additional lanes - isn't scheduled to be replaced until August 2016.
Imhoff said the girder-placement work for both bridges mostly will come "at low traffic-volume times, so the inconvenience will be pretty minimal."
There also will be some periods during the construction when the two lanes of traffic in each direction is cut to a single lane, Lemongelli said.
The project is set to be finished in Fall 2016.