Here’s some interesting background on the “bathtub” section of the Parkway East, dredged up from the archives of former Post-Gazette transportation guru Joe “Mr. Know-It-All” Grata, from January 2005:

The bathtub is the depressing (as in gloomy) 1,900-foot-long depressed (as in a trough) westbound section along the Monongahela River lip of the Golden Triangle.

When the river spills onto the road and fills the bathtub with water, as it did during Hurricane Frances, Hurricane Ivan and recent heavy rains locally, the parkway westbound is of no benefit to anyone without a boat. Drivers are forced to detour on Fort Pitt Boulevard in the heart of the city to get to the Fort Duquesne or Fort Pitt bridges and points beyond.

When the Parkway East was planned in the late 1940s, the interstate highway system was in the talking stage. When the parkway was built in the early 1950s, it was a road to the suburbs, connecting to Business Route 22, west of Monroeville. It was never meant to carry today’s volume of cars or 40-ton commercial trucks.

Engineers located the highway along the Monongahela River at the edge of Downtown because there was nowhere else to put it. The city asked the state to shoehorn the westbound lanes, just above river level, between the Mon Wharf and the westbound lanes of bifurcated Fort Pitt Boulevard and to build the high concrete walls that support the boulevard.

In 1980, while he was engineer in charge of the PennDOT District 11 office, Roger Carrier conceived and built the first flood wall, only a couple of feet tall. He also ordered today’s stronger, taller (6 feet) wall as part of Parkway East reconstruction in the mid-1980s.

When the Mon River hits 18 feet, water is even with the edge of the Mon Wharf. At 19 feet, it laps at the foot of the Parkway East floodwall. At 25 feet, or flood stage, the water spills over the wall and into the bathtub.

I don’t mean to confuse you, but when the water reaches 21 feet, PennDOT’s gravity drain system no longer works. PennDOT closes valves to prevent the water from backing up through the drains and flooding the highway. Any water that leaks through, plus any rainwater that accumulates on the road, flows into a basin at a low point, where two automatically activated sump pumps send it back over the wall and into the river.

When the water level gets to 25 feet and comes over the wall, 1,000 pumps wouldn’t save the parkway.

So what about (then-City Councilman Doug) Shields’ demand that PennDOT build a higher wall?

Sorry, but PennDOT thought of that years ago, when planning took place for reconstruction of the parkway in the Downtown area. Engineers determined that 6 feet was as high as they could build the wall without having the bathtub float. What?

That’s correct, PennDOT District 11 Executive Karl Ishman and Deputy Executive for Maintenance Andy Kost explained last week.

“PennDOT didn’t arbitrarily decide the height of the flood wall,” Ishman said. “They measured how much hydrostatic pressure, or water pressure in the ground, that it would take to make the section float like a barge.”

That’s all to preface that PennDOT is closing the bathtub nightly again this week. Westbound traffic on the Parkway East will be forced to exit at Grant Street and use Fort Pitt Boulevard to return to the parkway at Stanwix Street. The closure begins at 9 p.m. Monday through Thursday, with the road reopened by 5 a.m. daily. During the same hours, the on-ramp from Grant Street to the westbound parkway is also shut down.

PennDOT seems to be doing a lot of redding up this week.

Cleaning will close a lane of the inbound Liberty Tunnel starting at 10 p.m. Monday through Thursday. Work concludes by 5 a.m. daily.

Washing of the bridges that carry Interstate 79 over Route 19 just south of Exit 76 in Marshall will cause short-term lane and shoulder closures in both directions on both roads starting at 8 p.m. Wednesday and Thursday. The work ends by 5 a.m. daily.

Washing and inspection of the I-79 Neville Island Bridge will cause short-term lane and shoulder closures on the southbound side from 8 p.m. Monday through Wednesday until 6 a.m. the following days. Same restrictions are possible on the southbound on- and off-ramps at Grand Avenue from 7 a.m. to 3 p.m. weekdays through Aug. 17.

Elsewhere on Interstate 79 -- and we're thinking it might be faster to just tell you where NO work is going on -- minor deck repairs will be made on the bridges that carry the highway over Red Mud Hollow Road and Nicholson Road in Franklin Park from 9 a.m. to 3 p.m. Wednesday and Thursday. Lane closures are possible between the Parkway North split and Mount Nebo Road.

PennDOT is constructing ADA-compliant sidewalks at two Commonwealth Place intersections in Downtown Pittsburgh. Crews will be working at the intersections of Liberty Avenue and the Boulevard of the Allies with Commonwealth and the ramps to and from the Fort Pitt Bridge, with short-term lane closures and restrictions possible from 9 a.m. to 3 p.m. weekdays through late August.

Replacement of brick pavers on Grant Street, Downtown, will cause two weekend closures at Third and Fourth avenues. The street will close at 6:30 p.m. the next two Fridays and reopen by 6 a.m. the following Mondays. Traffic will detour to parallel streets.

Water line work on Route 885 in West Mifflin will close the spur ramp from eastbound Lebanon Church Road to southbound Route 885 after 7 p.m. all week. Police and flag crews will direct traffic. Work ends by 6 a.m. daily.

Repairs to the bridge that carries Route 837 over railroad tracks near Kennywood in West Mifflin will continue on Tuesday. Traffic will be reduced to a single lane in both directions between Herman Avenue and Hoffman Boulevard from 6 a.m. to 4 p.m. (northbound restrictions will begin at 9 a.m.) weekdays through Aug. 21.

Brief lane closures are possible at several locations on I-79, the Parkway North and Route 28 during guide rail repairs that will occur from 9 a.m. to 3 p.m. Monday through Thursday. The work on I-79 is between the Parkway West and Wexford interchanges; on the Parkway North between I-79 and Perrysville; and on Route 28 between RIDC and Millerstown.

Interstate 80 will have lane restrictions both ways between I-79 and Route 19 through noon on Friday for pavement work.

Repeating an item from last week, Greentree Road in Scott will have lane closures in both directions between Cochran Road and McMonagle Road from 9 a.m. to 3:30 p.m. weekdays through late December for a giant water main replacement project by Pennsylvania American Water. This sounds like a traffic migraine in the making -- you probably want to use an alternate route.

Short-term lane closures are possible on Bridge Street in Etna after 9 p.m. weekdays through late this month as crews do concrete patching in the area of the northbound Route 28 off-ramp, North Main Street and the recently opened bridge over Pine Creek. Work ends by 5 a.m. daily. Alternating one-way traffic will be in effect from 6 p.m. Friday to 6 a.m. Monday in the same area.

The traffic pattern in the Route 65 paving zone in Emsworth will change early Tuesday but it'll still be one lane in both directions between Camp Horne Road and Terrace Drive. You'll be using the right lanes instead of the left starting at about 5 a.m. The pattern will stay in place around the clock through late August.

Inspection of the Route 51 bridge over the Mon at Elizabeth (aka the Regis Malady Bridge) may cause lane closures from 9 a.m. to 3 p.m. Wednesday.

Redgate Road in Aleppo and Haysville will close long-term beginning at 7 a.m. Wednesday for sewer line installation between Route 65 and Merriman Road. Projected reopening: early October.

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