Underground Parking Garage Construction Layout Surveying
Commercial Land Surveying Services
Project Description
On this project, DeMarr Engineering was entrusted with a critical construction layout surveying task. The project required accurately locating a four‑story underground parking garage, below street level, in order to precisely lay out the outrigger pad locations for a 700‑ton mobile crane.
The crane was to be set up directly above the underground parking garage, requiring structural reinforcement directly beneath the crane pads and extending four levels below grade. Any positional error would have placed extreme loads outside the designed structural capacity of the underground structure.
Survey Control & Existing Conditions
The first task for DeMarr was to survey existing conditions at street level and extend accurate survey control four stories below ground. This work established the precise location of underground garage walls and columns relative to the roadway above.
From the control setup and existing conditions survey field work, the DeMarr team prepared an Existing Conditions Plan with a Proposed Crane Pad Location Overlay Plan, allowing the project team to evaluate feasible crane placement options.
In the exhibit, the asphalt roadway is shown with a dark gray hatch, while the underground parking garage walls are highlighted in yellow. Two crane pad locations, shown in orange, were designed to bear directly over structural components of the garage. DeMarr coordinated closely with both the crane contractor and the project structural engineer throughout this process.
Construction Layout & Field Marking
Once the proposed crane pad locations were approved, DeMarr marked the underground parking garage walls and crane pad locations on the street surface using temporary spray paint, providing clear and direct layout references for the crane operator.
Below ground, DeMarr transferred the crane pad locations to all four levels of the underground parking garage. Because the garage was part of a newly constructed office building valued over several hundred million dollars, the property owner requested that non-permanent markings be used on the finished concrete parking surface.
To accommodate this requirement, DeMarr used non‑permanent chalk markings to layout underground reinforcement locations for the contractor.
A single mistake in reinforcement locations would have had catastrophic consequences. There was no margin for error.
Setup of 700-ton LTM 1650-8.1 Mobile Crane on location marked by DeMarr
Chalk Marking Layout for Crane Pad Reinforcement Underground
Temporary Structural Reinforcement of underground garage
Results & Expertise
For critical infrastructure and high‑risk construction activities, DeMarr Engineering brings the experience, technical skill, and attention to detail necessary to deliver precise results under challenging conditions.
Whether our land surveying and civil engineering services take us to the top of a high‑rise building or four stories underground, the DeMarr team is equipped to execute the mission safely, accurately, and reliably.
If you need a civil engineer or land surveyor for your commercial construction project in DC, VA, or MD, contact DeMarr today.