3D Sewer Manhole Models for Machine Control

A site contractor preparing a residential subdivision for machine control needed every sewer manhole as a clean 3D model, with all pipe connections at the correct inverts, packaged as one Trimble Business Center project for their field controllers.

The approach

• Matched each manhole on the layout to the plan data, and produced a coordinate and invert table for all 52 structures
• Built one precast template from the manufacturer's fabrication sheets, then set each manhole's riser height to its rim, with bases by pipe size and inlet count
• Modeled junctions, internal drops, upstream ends and a plugged stub exactly as shown on the plans
• Set up the ground coordinate system (scale factor 1.0002507, GEOID18) in TBC 2024.10 to match the client's controllers
• Checked every manhole against the plans: rims, base depths, inverts, opening angles and positions

The result

• 52 manholes across an off-site 12 in line and an on-site 8 in network, 6.6 to 35.7 ft deep
• One DWG per manhole, editable in Civil 3D 2023
• One TBC project ready for upload to Trimble Connect
• A summary sheet for quick cross-checking in the field