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DART Segment NC-1B City Place Station

Preliminary design of station including mezzanines, cross adits, ventilation structure; final design with FEM structural computations
Estimated cost: Commencement:
December 27, 1992
Completion date:
December 27, 1996
Dallas, TX
United States
Technical data:

2 single track tunnels, 17.000 ft each, 21 ft Diameter, 2 mined station tubes with multiple passenger and utility cross adits, 3 escalator tunnels, mezzanine, 2 emergency access shafts and connecting tunnels, 4 ventilation structures (tunnels, shafts, chambers).

Geology description:

Austin Chalk Formation,Terrace Sands, weathered and unweathered Limestone (Austin Chalk).

Bid cost: Final cost:
Service areas:

The Dr. G. Sauer Corporation was responsible for the NATM design of the lower escalator, station tunnels, cross adits and emergency access shafts at City Place Station, the only underground station in the Dallas' Light Rail System. Excavation of the station chambers took place 85 ft (26 m) below the road deck of the new North Central Expressway cutting and within 115 ft (35 m) of the adjacent foundations of the multistory City Place tower block. The large 59 ft x 59 ft x 23 ft (18 m x 18 m x 7 m) domed mezzanine level chamber is one of the largest free span caverns constructed in medium soft rock in the US to date. The two station platform tunnels are 79 ft (24 m) apart (centerline to centerline) and involve several cross adits of various sizes with relatively narrow pillars of chalk between. Through a series of comprehensive calculations, the size of openings, excavation sequences, size and advance of headings, the shotcrete and cast-in-place concrete lining requirements were specified.

3D View of CityPlace Station
Cross Section through Station Tunnels, Cross Adit and Escalator Shaft
Cross Adit and Escalator Shaft
Station Enlargement
Shotcrete Robot
Waterproofing of Running Tunnel
Reinforcement and Formwork for Final Lining of Cross Adit
Steel Shutter for Running Tunnel
Final Lining Pour
Finished Running Tunnel
Finished Escalator
Main Drainage
Final Excavation
Initial Lining at the Junction
Raw Tunnel at the Junction
Waterproofing Installation
Final Lining at the Junction
Application of Trowel-Smooth Shotcrete Final Lining
Robotic Application of Fiber Reinforced Shotcrete
Head Wall Final Lining
Junction Final Lining
Cross Adit Final Lining
Junction Final Lining
 Mined portion of southeast entrance and chamber at mezzanine level
Final liner after removal of formwork
Waterproofing in the shaft
Set up of form
Main tunnel drain at cross passage
SW entrance after correction of width and excavation of escalator pit
Inclination of SW entrance prepared for mud slab pour
Cross adit and station tunnel after top heading excavation
Left rib in SE entrance with partial formwork for split pour of arch
Detail of drain pipe penetrating membrane
Clean out detail for drainage system
Formwork for main emergency exit cross adit at intersection with shaft wall
Waterproofing application and rebar installation
Formwork for first pur of walls in main emergency exit shaft chamber
Ventilation tunnel intersection with conduits in invert slab
Wooden forms for trumpet shaped cross adit