🌄 Mainline Railworks HOn3 Tunnel Track & Portal System

Bring realistic mountain railroading to your HOn3 layout with Mainline Railworks HOn3 Tunnel Track Sections and Tunnel Portals. Designed to integrate with Mainline Railworks sectional track, these components help modelers route trains through mountains, rock cuts, and other scenic terrain while maintaining consistent track geometry.

Whether you're building a complete tunnel or adding a finished entrance to an existing tunnel section, the modular system gives you flexibility to create the tunnel configuration your layout needs.

Tunnel track sections and portal options are sold individually unless otherwise specified.

🚂 Why This Matters

Tunnels add depth, visual interest, and operational possibilities to a narrow-gauge railroad. They let trains disappear into mountain scenery, pass through rugged terrain, and emerge somewhere unexpected.

With separate tunnel track and portal options, you can choose the components that best suit your layout—whether you need a dedicated track section with an integrated entrance or simply want to finish the end of an existing tunnel.

🛤️ Tunnel Track Options

Mainline Railworks HOn3 tunnel track uses the same sectional geometry system as the rest of the HOn3 track lineup, making it easier to incorporate tunnels into your layout.

🟡 Straight Tunnel Sections

• Sold individually.

• Ideal for straight tunnel approaches and passages through terrain.

• Useful for hidden track routing, staging connections, and return loops.

• Designed to align with compatible Mainline Railworks HOn3 sectional track.

🔵 Curved Tunnel Sections

• Sold individually.

• Available in multiple radius and angle configurations.

• Useful for routing track through curved mountain terrain or around compact layouts.

• Can be combined to create tunnel runs suited to your available space.

📐 Curved Track Angle Options

Curved sections are available in the following angle configurations:

• A — 22.5°: 16 sections per full circle; useful for balanced curves and general layout planning.

• B — 11.25°: 32 sections per full circle; provides finer adjustments when positioning track.

• C — 45°: 8 sections per full circle; useful for tighter layouts where larger directional changes are needed.

Available radius options depend on the specific tunnel track section.

🚪 HOn3 Tunnel Portal Options

Choose the portal style that best fits your tunnel construction.

V1 — Integrated Tunnel Portal Track Section

The V1 portal combines a 4.5-inch section of HOn3 track with a dedicated attached tunnel portal in one convenient component.

• Provides a defined tunnel entrance or exit.

• Combines the track section and portal into one piece.

• Simplifies placement when planning a tunnel entrance around the supplied track section.

• Ideal for new tunnel construction or layouts where a dedicated portal track section fits the design.

V2 — Snap-On Tunnel Portal Face

The V2 portal is a standalone portal face designed to snap onto the end of a compatible tunnel section.

• Portal face only; tunnel track is not included.

• Allows you to finish the entrance or exit of a tunnel section without using the integrated V1 design.

• Provides more flexibility when incorporating portals into an existing tunnel arrangement.

• Useful for custom tunnel construction and modular scenic projects.

Choosing between V1 and V2: Select V1 when you want the dedicated 4.5-inch track section with its attached portal. Choose V2 when you want a separate portal face to fit onto the end of a compatible tunnel section.

🏔️ Perfect For

• HOn3 mountain and narrow-gauge railroads

• Logging and mining branch lines

• Shelf layouts with limited space

• Hidden staging tracks and return loops

• Scenic tunnels through hills, ridges, and rock formations

• Custom tunnel projects and modular layouts

• Modelers expanding a starter loop into a more detailed railroad

🔧 Key Features

• Straight and curved HOn3 tunnel track options

• Multiple curved track angle configurations

• Two distinct tunnel portal designs

• V1: 4.5-inch track section with an attached portal

• V2: standalone snap-on portal face

• Individual components for flexible tunnel construction

• Designed to integrate with compatible Mainline Railworks HOn3 sectional track

• Suitable for a wide range of scenic and operational layout designs

⚙️ Compatibility

• Designed for Mainline Railworks HOn3 sectional track using Code 80 rail.

• Integrates with compatible straight, curved, feeder, and other HOn3 track sections.

• Supports tunnel construction on temporary, modular, and permanent layouts.

• Portal fit and clearance should be checked against your specific rolling stock and tunnel construction before final installation.

➕ Pairs Well With

• HOn3 Curved Track Sections — route track through mountain scenery.

• HOn3 Straight Track Sections — create straight tunnel runs and approaches.

• HOn3 Feeder Track Sections — provide power connections for your track layout.

• HOn3 Starter Loop Sets — expand a basic layout into a scenic railroad.

• HOn3 Bumper Track Sections — finish sidings and terminal tracks.

🛠️ Builder Tip

Plan the tunnel's track alignment before installing the surrounding scenery. Test the assembled track with your longest locomotive and rolling stock before enclosing it, paying particular attention to curves, portal clearance, and access for maintenance.

For a new tunnel entrance that includes its own track section, choose V1. For a more flexible scenic build using a compatible existing tunnel section, V2 offers a separate snap-on portal face.

📏 Custom Tunnel Options

Building a specialized mountain scene or an unusual tunnel configuration? Contact Mainline Railworks to discuss potential custom tunnel track or geometry options for your layout.