This map depicts the area from Daniels west to Davis at the left. The Patapsco River weaves through the middle, separating Baltimore and Howard counties. Green marks the 1830 alignment, magenta 1838, and black the current.

Prior to Davis Tunnel (east portal seen in the distance) the OML negotiated a path around the hill. This is roughly the location those tracks would have met with today's.

The green (original) and magenta lines diverge slightly due to a small realignment that I'm guessing took place around 1838, the time of other such improvements in this area.

At Line Run, streamside hewn stones and mounded earth indicate the original alignment had been here (green). A short distance downstream (magenta), a fine arched bridge survives, evidence of a second alignment. The top of this bridge can be glimpsed at center right.

The disused Line Run bridge can be found along the abandoned second alignment just northeast of Davis Tunnel. Adding to the suspicion that this bridge is not the original alignment are the buttresses and excellent dry fit of stonework, signs of the work of an experienced crew. Compare this photo with the nearly identical one in Impossible Challenge II, page 341.

If you follow this stream back to the active line, you'll find another arched bridge. It's newer as evidenced by the mortared stone blocks, and was built around the same time as the nearby Davis Tunnel.

Looking back to the tunnel's west portal, the original alignment curved from around the hill, swung further "inland" from the river, and then rejoined the current right of way behind the photographer.

The shelf above this culvert illustrates how the 1830 alignment sat at a lower elevation. When the B&O built the tunnel route, they kept this culvert and lengthened it toward the river. Davis Tunnel is off in the distance.

Another view of the culvert; this one just missed qualifying for an arched structure. This irregular stones and lack of mortar flag it as original circa 1830 construction.

A short distance west of here the two alignments rejoin and stay together until the B&O's next Old Main Line straightening project, one that created McKeldin falls.