A few original granite stringers, used in 1830 instead of wooden ties, have been exposed along the right-of-way bypassed by the tunnel. The existing tracks appear in the distance, and the tunnel portal is hidden on the right.

The same stringers as seen looking the opposite direction.

In the distance is part of Union Dam.

The alignment had curved within sight of Union Dam. The dam had been disused for at least 20 years when, in 1972, floods from Tropical Storm Agnes breached it and carved out the route around it seen here. Over subsequent years, the river washed away so much of the bank that stone-in-wire-mesh cages seen at the bottom were dropped along the shoreline to reduce erosion. The stone has obscured any surviving stringers in this spot.

The original dam near this location was built by the Union Manufacturing Company about 1808. The company's founder, William Patterson, for whom the Patterson Viaduct is named, would later become a director of the B&O. A successor company, WJ Dickey, built the concrete dam seen here around 1914.

Link to older picture: mill race

At low water, this does not look like a formidable obstacle for kayakers, but at other times it is. The dam's remains are scheduled for removal.

In the distance is a bridge that carries US Route 40 over the Patapsco River between Baltimore and Howard counties.

Links to older pictures: 1960s, 1970s

The 1936-built bridge for US 40 is scheduled for replacement.

The bridge crosses high above the Union Dam tunnel. It required a fair amount of fill that has obscured much of the OML's original alignment underneath. The small stream on the far bank at right is named Miller Run.

Links: replacement, facts

This photo offers the reverse perspective, looking downstream from US 40 before the dam was damaged by floods. The railroad is hidden by the trees on the right.

Under the snow, the original alignment curves in from the left to meet the present day trackage.

Despite cutting off much of the curve, the Union Dam tunnel still forces a sharp bend in the rails at the tunnel's North (West) portal.

Floods from 1972's Tropical Storm Agnes wreaked havoc all along the Patapsco Valley, and the railroad was no exception. With Union Dam tunnel's north (west) portal in the distance, the green line marks my estimate of the OML's original route. The area eroded by the flood had likely been landfilled by the B&O when straightening the alignment as part of the tunnel construction. Nature eventually reclaims what man borrows.

I'm surprised the track is jointed as I thought the OML has been continuously welded by 1972. Also note the fresh ballast dropped by Chessie. The OML would lie dormant for several years while repairs were finished.