Retro Metro -- January 26, 1978 -- Red Line

[coneyraven]

METRO BEGINS WISCONSIN AVENUE STATIONS
The Washington Post

Construction will begin within the next two weeks on two Wisconsin Avenue Metro subway stations, at Tenley Circle and Friendship Heights, which will provide 14-minute rides to downtown Washington when the subway line to Rockville and Shady Grove opens in 1982.

The underground stations, to be blasted out of solid rock more than 100 feet beneath Wisconsin Avenue, will take three years to build.  The construction will cause some vibrations for residents in the area and minor traffic problems along Wisconsin and Western Avenues, according to Metro officials.

The six-lane avenues, will be reduced to four narrow, 10-foot lanes during much of the construction period around Tenley Circle and for part of the construction period in the Friendship Heights section.  Some sections of roadway will be placed on raised decks, particularly along Western Avenue to allow for construction machinery below.

The subway tubes themselves already have been tunneled under much of Northwest Washington, with one tube now complete under Wisconsin Avenue to the Beltway.

There will be some noise and dust problems around both stations, primarliy from heavy trucks removing rocks and dirt from the underground excavation, but Metro contractors will use no purely residential streets as hauling routes.

The $60.5-million construction contract limits noise levels.  However, Metro officials are alerting residents that "vibrations may be felt from blasting, but these will be kept at a safe level to avoid damage to nearby houses and buildings."

While construction will continue 24 hours a day on the stations, blasting is permitted only between 7 a.m. and 10 p.m. Mondays through Saturdays and 2 p.m. to 10 p.m. Sundays.

Access to all busnesses and homes will be maintained during construction although a few parking spaces, primarily along Wisconsin and Western Avenues, will be eliminated, Metro officials say.

Both stations will provide above-ground "kiss-and-ride" unloading areas for commuters -- 18 "kiss-and-ride" spaces at Friendship Heights and 41 at Tenley Circle -- and loadng bays for Metrobuses.

The stations are expected to be used by 25,000 to 28,000 riders daily by 1990, according to Metro estimates.

The Tenley Circle station will have entrances on either side of Wisconsin Avenue, with escalators carrying passengers down to a mezzanine just above the subway platforms.  An elevator entrance is to be built north of Albemarle Street on the east side of Wiscnsin.

The Friendship Heights station will have one main escalator entrance at the nothwest corner of Wisconsin and Western Avenues, where buses and "kiss-and-ride" cars can stop.  Three additional subway entrances are planned, one from each of the remaining three corners of the Wisconsin-and-Western intersection, but these are deigned to serve stores and businesses in the area and will not be built by Metro.

[coneyraven]

Oren, I thought you'd like this one...

[Sand Box John]

I wrote this essay some years ago to describe the process on how the line and station were built between Rock Creek and Pooks Hill road:

Common construction technique use in the stations on A Route Red line

The list of station below are constructed using the same technique and are virtually the same architecturally;

Woodley Park-Zoo
Cleveland Park
Van Ness
Tenleytown
Friendship Heights
Bethesda
Medical Center

The Stations are island platform station of the same dimension 600' X 26' 4 1/2" 182.88m X 8.03m. The track centers through station are 36' 10" 11.22m. The stations are built in gallery excavated using blast mining technique out of the bedrock. The train halls have a precast 4 coffer concrete arch vault. The station train hall precast concrete coffer arch and end walls serve no structural purpose, as the roof in the excavated gallery is self supporting.

Line Tunnels

The train tunnel were excavated before the stations were excavated, a TBM (Tunnel Boring Machine), (adeptly named 'the mole' by WMATA and the contractors that used it) was use to dig all the train tunnels from Rock Creek next to Taft Bridge on Connecticut Avenue to Pookshill Road and Rockville Pike (MD-355) just south of Capital Beltway (MD I-495).

The boring machine had a convex face 21' 6.4m in diameter with 45 free-wheeling tungsten steel disks. It was trusted in to the face using hydraulics with a force of over 1,000 tons. As the head rotates the cutting disk pulverize the rock. More then a 100' 30.48m of tunnel could be excavated in a eight hour shift. During the excavation of these tunnels three shift a day five day a week were used. The same boring machine was used by all the contractors that excavated the two tunnels by transferring the lease from one contractor to the next.

Most of the pulverize rock 'muck' was removed from from the tunnels with a 3' 0.91m gauge diesel 'muck' train to a rotary dump next to Taft Bridge in Rock Creek Park. A large rubber tired front loader with with 5 cubic yard 3.82277 cubic meter bucket was used to load the 'muck' in to dump trucks, it was then trucked away. Some of it was trucked to an asphalt plant in Crofton in Anne Arundel County MD.

The first tunnel excavated was the outbound track 1 tunnel from Rock Creek to the fan shaft west of Connecticut Avenue on Yuma Street NW. Then the boring machine was backed back to Rock Creek and the inbound track 2 tunnel was excavated. At this point the boring machine was backed to the double crossover south of the Van Ness station moved over to the outbound track 1 tunnel moved forward to the Yuma Street vent shaft.

The second contractor then pushed the boring machine north to Friendship Heights then backed back to the Van Ness crossover and excavated the inbound Track 2 tunnel to Friendship Heights.

At the Friendship Heights crossover the boring machine was moved over to the outbound track 1 tunnel and the third contractor excavated to the Medical Center and it was again backed back to the Friendship Heights crossover and moved over to excavated the inbound tunnel track 1 tunnel to Medical Center.

At Medical Center crossover the boring machine was moved over to the outbound track 1 tunnel and last contractor pushed the boring machine to Pookshill Road and Rockville Pike (MD-355) just south of Capital Beltway (MD I-495). Then the contractor turned the boring machine 180° and excavated the inbound tunnel track 2 to the Medical Center crossover. The boring machine was then dismantled and removed from the tunnel through the vent shaft at the south end of Medical Center station.

The first two contractors removed the spoil from the site in the open excavation south Woodly Zoo Park station in Rock Creek Park. The third contractor removed his spoil through a fan shaft on the south ends of their contracts. The fourth contractor removed his spoil from the outbound track 1 tunnel through a fan shaft on the south ends of his contract and the remainder of the spoil was removed from the open excavation at Pooks Hill Road.

After the temporary tracks used to remove the spoil were removed the concrete track bed and tunnel lining are poured. Little ore no shoring was used in the line tunnels.

Station gallery

After the line tunnels and vent shafts were excavated at the stations a third pioneer tunnel was excavated at the crown of the station train hall by a smaller boring machine leaving a tunnel about 4' 1.21m wide by 8' 2.43m high. The crown pilot tunnel was excavated between the vent shaft plenum roughly 800' 243.84m long to leave enough room for 600' 182.88m station train hall and another roughly 100' 30.48m on either end of the train hall to accommodate maintenance, power, train control, and other mechanical rooms. The muck from the station along Connecticut Avenue was removed from the site in Rock Creek Park. The three contractors that did the station along Wisconsin Avenue and Rockville Pike removed their muck at vent/fan shafts within their contract areas.

The remainder of the rock to create the gallery that the finished station is build in was excavated by blast mining method. Unlike the connecting tunnels between the stations the train hall galleries do have shoring on the walls and roof. 4 H steel unites support the roof and walls. The whole thing look like an inverted U. These shoring units are placed at about 4' 6" 1.37m on centers in the train halls with transverse rods holding them in place. A wire mesh is then applied and then all of the surfaces are covered with shotcrete.

Station finish

After the station gallery is excavation and completed and lined the station train hall track bed floor invert is poured. The roughly 288 precast station train hall units are installed. The end walls and maintenance, power, train control, and other mechanical rooms are built. Then the station platforms, end walls, mezzanines, and entrance passageway concrete work is completed. Once all of the concrete work is completed the finish work is done consisting of platform, mezzanines, and entrance passageway surfaces, train control, Station managers kiosk, fare collection equipment, elevators, escalators, lighting and other mechanical systems.