[McAdoo Tunnel.]

[McAdoo Tunnel.]

[McAdoo Tunnel.]

[McAdoo Tunnel.]

[McAdoo Tunnel.]

[McAdoo Tunnel.]

Building the McAdoo Tunnel, Under the Hudson River, New York.

McAdoo Tunnel under North River, New York

[William McAdoo.]

[Tunnel construction.]

[Tunnel construction.]

Queensboro Tunnel.

Southbound express tunnel.

Typical Pressure Tunnel Construction Shaft [Catskill System.]

[Construction of the Pennsylvania Railroad tunnels under the Hudson.]

Queensboro Tunnel.

Queensboro Tunnel.

[North tunnel shield.]

Bonticou Grade Tunnel Portal and Bonticou Crag [Catskill System.]

[Holland Tunnel.]