Autodesk Civil 3D 2027.1 Update

Drainage Design and Analysis are significantly expanded: tailwater conditions can now be set per rainfall event, outfall elevation curves can be created and stored, and known flows at structures can be used as an inflow to an analysis.

Catchment feature settings have also been extended to cover all runoff and time-of-concentration methods.

Data Shortcut References are now managed in a dedicated Dref tab within External References, with clear reasons for broken links, suggested repair paths, and single or bulk repair for both cloud and local drawings.

Dynamo for Civil 3D is updated to Dynamo Core 4.1.2, and the .NET API is expanded for profiles, feature lines, ponds, and underground storage.

Important fixes to customer issues are also addressed.

Autodesk Assistant

Improved Object Counting

• Query the number of objects in a drawing using natural language, without counting them manually

Context-aware units in reports

• Assistant-generated reports now display explicit, context-aware units for reported values. Units align automatically with the source drawing, settings, and product conventions, so measurements and calculated values are reported accurately.

Expanded model data queries

• Improved Assistant understanding of design models. Here’s the updated list:
• Catchments
• Channels
• Ponds
• Underground storage objects
• Profile views
• Section views
• Drawing coordinate system information
• Text objects and their content
• Layer properties and settings
• Block attributes
• Closed polylines
• Additional Civil 3D object properties and model data

Insights in the Assistant

• When the Tech Preview is turned on Insights, or personalized learning content tailored to your actions in Civil 3D, are now available within Assistant

Connected References for Data Shortcuts (DREFS)

Drefs tab within External References palette

• This release includes the addition of a dedicated Dref tab within External References for managing Data Shortcut references, in the same place as Xrefs.

Broken-link visibility

• Added clear broken-link reasons, such as source DWG not found, object not found, or out of date
• Added a Suggested Path column that surfaces the cloud-recommended target source drawing

Filtering

• Added a Missing toggle to show only missing or broken references
• Added column-based filtering (for example, Saved Path contains “file_name”) with add/remove rules

Cloud repair

• Added repair suggestions for missing cloud references after a source DWG is renamed or relocated
• Added manual single-link repair
• Added manual bulk repair
• Added detection of additional broken references when you accept a suggestion
• Added detection of additional broken references resolved by the same source drawing or source folder when you repair manually

Local repair

• Added manual single-link repair on local (non-Forma Data Management) drawings
• Added manual bulk repair on local drawings
• Repair outcomes and cleanup
• Added a clear failure summary when suggestion-based auto-resolve cannot complete, including a fail count
• Added actionable failure feedback when a repair fails
• Added the ability to remove unnecessary broken links

Drainage and Analysis Tools

• Added an option to include Rainfall, Runoff, and Storage Curve graphs to the Excel reports exported after running a drainage system analysis
• Added support for a known flow to a structure, used as an inflow to the drainage analysis.
• Added the ability to set tailwater conditions and change the tailwater elevation or elevation curve for each rainfall event being analyzed. Improved the Analyze Drainage System command to support tailwater conditions set to:
• Crown of the outfall
• Free, calculated as the lesser of critical depth and normal depth
• Normal depth
• Critical depth (not supported by the analysis engine; a warning notifies you that it will be calculated as a free tailwater condition)
• Average, (dc+D)/2 (not supported by the analysis engine; a warning notifies you that it will be calculated as a free tailwater condition)
• Added the ability to create, edit, and store elevation curves for outfall tailwater conditions
• Improved the apply-results function to return the maximum flow rate in a pipe to the Flow Rate property, and the corresponding return period (when IDF rainfall is used) to the Return Period property
• Improved the error page messaging for unhandled analysis errors, with the ability to download an error log
• Added the ability to cancel exporting data after a drainage system analysis
• Improved the Rainfall Manager dialog box with fixes to borders, columns, and tooltips
• Added a banner to Drainage Analysis when only known flows are used, alerting you that the maximum rainfall runtime will be used for analysis

Dynamo for Civil 3D

• Added a new Alignment.SetType node to set the type of an alignment.
• Added a new Pond.Mesh node that returns the mesh geometry of a pond.
• Upgraded Dynamo Core to version 4.1.2 and Dynamo Player to version 8.3.5.

Miscellaneous Enhancements

Horizontal Regression

• Added a Help button to the Horizontal Regression Analysis windows for quick access to documentation without leaving the application

Underground Storage

• Added a new .NET API, UndergroundStorage.GetSolid(), which returns the 3D solid geometry (Solid3d) of an Underground Storage (UGS) object

Pressure Pipes

• Added API support to read and modify ProfileViewBandItem.DataSourceId for profile view bands whose type is Pressure Data, so the pressure network ObjectId used as the band data source can be retrieved and set through the .NET API

Gravity Pipes

• Exposed the TailwaterCondition and TailwaterElevation properties to the Structure .NET APIs for outfall structures
• Added a new TailwaterConditionType enum with the values Elevation, Equation, Crown, NormalDepth, and CriticalDepth
• Added a structure template folder setting to the Pipe Network Catalog Settings dialog box, so you can point Civil 3D to structure template content stored outside local ProgramData (such as a ContentLibrary in Forma Data Management) and use gravity pipe network catalogs built with Autodesk Inventor parts

Alignments

• Added a setter for the AlignmentType property in the Alignment class

Performance

• Fixed an issue that prevented picking a feature line when multiple GSF viewports were present
• Other performance improvements

API Enhancements

Profile

• Added new methods to the ProfileEntityCollection class:
• AddFloatingTangentByGradeAndLength()
• AddFreeCircularCurveByLength()
• AddFreeCircularCurveByRadius()
• AddFreeCircularCurveByThroughPoint()
• AddFreeSymmetricParabolaByThroughPoint()
• AddFixedSymmetricParabolaByHighLowPointRadiusAndLength()
• AddFixedCircularCurveByHighLowPointRadiusAndLength()
• Added new vertical constraint types to the Autodesk.Civil.DatabaseServices.EntityVerticalConstraintType enum:
• HighLowPointRadiusAndCurveLength
• PreviousGradeAndLength
• NextGradeAndLength

Feature Line

• Added a GetFlattenCurve() method, which returns a new lightweight polyline representing the feature line geometry projected (flattened) to the XY plane. The caller must dispose of the returned polyline when finished.
• Added a reverse() method, which reverses the direction of the feature line (start and end swap; curve parameterization is reversed). The feature line must be open for write in the current transaction.

Pond

• Added a Pond.GetMesh() API for retrieving the mesh geometry of a pond
• Added two new methods to the StageStorageCollection class:
• GetAreaAtDepth()
• GetVolumeAtDepth()

Alignments

• Fixed an issue in which PVI labels would not be added for offset alignments in certain cases.
• Fixed an issue in which Civil 3D could crash when adding an offset alignment.
• Fixed an issue in which repairing a Corridor data reference could cause Civil 3D to crash.

Assembly/Subassembly

• Fixed an issue with an extracted corridor that contained wrong crossing alignments.
• Fixed an issue in which the assembly, subassembly, and assembly offset were placed at incorrect coordinates in a UCS.
• Fixed an issue in which Enum parameter values were silently replaced with incorrect values when a custom subassembly PKT was updated to SAC 2026.

Autodesk Assistant for Civil 3D

• Fixed an issue where Auto Apply (AA) could crash when users performed consecutive clicks or double-clicked the AA icon before the AA panel had fully loaded.

Catchments

• Added a missing icon for the volumetric runoff coefficient in Catchment settings.
• Fixed an issue in which Catchment tabs did not stay at the top of the dialog and remain visible when scrolling.

Cloud Collaboration (BIM 360)

• Fixed an issue where configuring the same Tool Palette (.ATC) file in both classic (local) and project-aware (cloud) locations could overwrite the local configuration.

COGO Points

• Fixed an issue in the COGO Editor where creating a traverse polyline from manually entered raw data generated incorrect boundary geometry in Civil 3D.

Corridors

• Fixed an issue in which station information was missing when grip editing a corridor.
• Fixed an issue in which corridor auto feature lines were incorrectly connecting across gaps between adjacent regions.
• Fixed an issue where object snap did not work for corridors in xref or paper space viewports.
• Fixed an issue in which corridor transitions with custom subassemblies were not functioning in specific areas in Civil 3D.
• Fixed an issue where the corridor region station values were incorrect after importing an alignment.
• Fixed an issue in which Civil 3D hung during corridor solid updates.
• Fixed a Corridor code set Material Area Fill Style display issue in Civil 3D.
• Fixed an issue in which extending a corridor by station input did not update every part of the corridor.
• Fixed a crash when repairing a corridor reference with Data Shortcut Manager.

Data Shortcuts

• Fixed an issue where Data Shortcut XML files could be unexpectedly modified when opening a host drawing, resulting in broken references for other users. This fix addresses a known scenario but may not cover all cases.

Drainage-Analysis

• Improved the highlighting of a drainage system being analyzed to re-highlight the system components after selecting and changing an individual object and then returning to Analyze Drainage System.

Drainage-Rainfall

• Fixed untranslated strings in the Rainfall Manager user interface.
• Fixed an issue that caused the Rainfall Manager to crash when editing values out of order in an IDF table.

Dynamo

• Fixed an issue in which the FeatureLine.Curve2D node would return null for intersecting feature lines.
• Fixed an issue in which the Object.Geometry node would fail for rotated viewports.
• Fixed an issue in which the Hatch.Area node would show a warning when used on a hatch created by the Hatch.ByCurve node.
• Fixed an issue in which object creation nodes did not respect the binding data storage settings.
• Fixed an issue in which the Pick Point node would select the wrong coordinates in non-English versions of Civil 3D.
• Fixed an issue in which changing the input catchment group for the Catchment.ByPoints node would not update the group.
• Fixed an issue in which the Layout.ViewportByPoint node would fail to return the correct viewport.
• Fixed an issue in which selecting a clipped viewport in Dynamo could return the wrong value.
• Fixed an issue in which, upon first use in Civil 3D, Dynamo's first-run prompts would appear twice and two versioned data folders (4.0 and 13.9) would be created under %APPDATA%\Autodesk\C3D 2027\Dynamo.
• Fixed an issue in which the Multileader.ArrowheadLocations node would fail to return the correct arrowhead points in certain cases.
• Fixed an issue in which units were not preserved in drawings created by the Object.Export and Block.Export nodes.
• Fixed an issue in which True/False property values would not be imported correctly from a CSV file when using the pset_utils.py module.

Feature Line

• Fixed an issue where Civil 3D could become unresponsive (hang) when creating daylight feature lines from corridor-extracted feature lines.
• Fixed an issue in which Set Grade/Slope Between Points did not work with options for a Feature Line in Civil 3D 2026 DEU.
• Fixed an issue in which Civil 3D would hang when modifying the grading fill slope of a drawing.

Grading

• Fixed a freezing issue in the Civil 3D application that was caused by a PG topology issue and an ASM issue.
• Fixed an issue in which Civil 3D hung when the grading boundary was close to a PI.

Gravity Pipes

• Deprecated Section View-related APIs.
• Improved performance when opening DWG files not created from a Civil 3D template (such as Revit-exported DWGs) with a large pipe network parts catalog set as the default. Opening such files is now significantly faster.
• Fixed a crash during a pipe network interference check.

Horizontal Regression

• Fixed an issue in Horizontal Regression Analysis where negative Design Speed values could be entered, resulting in invalid Design Speed values in Alignment properties.
• Fixed an issue where, during Horizontal Regression Analysis, the UNDO command restored a deleted alignment along with its previous slider parameter settings.
• Fixed an issue where, in Horizontal Regression Analysis, changing the algorithm via the toggle switch updated sliders immediately, even before the user confirmed the decision.
• Fixed an issue in the Horizontal Regression Analysis dialog where long text entries could disrupt the layout by resizing or wrapping adjacent fields.
• Fixed an issue in Horizontal Regression Analysis where unit conversion was not applied in input fields.

Hydrology (H&H)

• Fixed an issue in Hydraflow Hydrographs that prevented pond storage values from being updated when set to manual.

LMV

• Fixed an issue in which the initial view in the LMV viewer would be incorrectly rotated 90º for the extracted Civil 3D DWG.

Model Viewer

• Fixed an issue in which the Model Viewer Objects/Settings panel did not display well if the OS text size was not set to 100%.
• Fixed an issue in which corridor material did not display in Model Viewer if corridor links had multiple codes and the first code did not have a material.

Other

• Fixed a crash that occurred when using "Save Block As" in the Block Editor.
• Fixed a crash that could occur when using the station tracker in a drawing after running CLOSEALLOTHERS and moving the pointer over the station tracker again.

Performance

• Fixed an issue with object display in the Object Viewer.

Pond

• Fixed a translation issue in one of the tooltips that displayed after exporting the storage data for a Pond or Underground Storage object.
• Fixed an issue in which the style for a data referenced Pond could not be edited.
• Fixed an issue in which dynamic feature lines were being moved when a Pond contour was deleted.
• Fixed an issue in which the valid range for Pond freeboard input was incorrect.
• Fixed an issue in which the "Slope" keyword in the QuickEditPond command did not work in the German version of Civil 3D.

Pressure Pipes

• Fixed an issue where Civil 3D would crash when changing a network-referenced surface and alignment without the network layout toolbar.
• Fixed an issue where deleting a Gradient override in a Pressure Pipe Elevation Plan could cause the selected style to revert unexpectedly.
• Fixed an issue where the pressure pipe crown elevation was inaccurately labeled as "Crown Elevation" in structure properties and labels instead of "Outside Crown Elevation."
• Fixed an issue where the pressure network data source could not be selected for a Pressure Data band when creating a Profile View.
• Fixed an issue where pressure network pipe runs in Civil 3D were created on the wrong layer.

Profile View

• Fixed an issue where Civil 3D would crash when attempting to use the 'Nearest' object snap on Profile View-Projection Objects.

Rail Design

• Fixed an issue where Cant values could display with different precision depending on how the Cant Tabular Editor was opened or when overridden by Ambient Settings in Feature Settings. Values are now displayed consistently in all cases.
• Fixed an issue where changes to the Description in Turnout properties were not persisted and did not appear in the Turnout label.
• Fixed an issue where changes to the Description in Turnout Plan Label properties could not be saved.
• Fixed an issue where the Theoretical Triangle Hatch appeared floating far from the Rail Turnout in 3D view, instead of being correctly aligned as in plan view.
• Fixed an issue where setting the Turnout Style marker to <none> would cause the field to become blank and uneditable after reopening the dialog. Users can now properly set and change marker styles, including the <none> option, without the setting becoming locked in an invalid state.

Subassembly Composer

• Fixed an issue in which a shape did not accept the links in a loop geometry that was created with a closed shape in Subassembly Composer.
• Fixed a problem in which opening a PKT file in Subassembly Composer took a long time.

Superelevation

• Fixed an issue where edited Superelevation Tabular Editor values did not save correctly on the first save.
• Fixed an issue where superelevation values could display with different precision depending on how the Tabular Editor was opened or when overridden by Ambient Settings in Feature Settings. Values are now displayed consistently in all cases.

Surfaces

• Fixed an issue in which only the first DEM file was removed when deleting multiple files.
• Fixed an issue in which a DEM raster inserted into a DEM surface was ignored.
• Fixed a regression issue in which Civil 3D crashed when importing a large TIFF for some data.