This MARC train has just discharged evening commuters (distant right) at Dorsey Station.

Looking SW finds platforms of Dorsey Station, the newest on the main line. A B&O list from 1889 puts Sand Switch Station here.

Dorsey's is a passenger station only, so freight trains don't stop here -- except in still photographs.

That's MD 100 traversing overhead.

With luck, you'll see a CSX train from MD 100, such as this one passing the clock-towered station building.

The MARC locomotive fleet includes 26 Motive Power MP36PH-3C units, a design popular in commuter rail. The Motive Power brand is built by Wabtec Corporation, an American company formed by the 1999 merger of the Westinghouse Air Brake Company (WABCO) and MotivePower Industries Corporation. In a Dirty Jobs episode, Mike Rowe visits Motive Power to assist building one of these MARC locomotives.

CSX operated MARC from inception in 1984 until October 2012; since then Bombardier has taken on the job.

CSX removed Dorsey's CPL signals November 5, 2011.

Link: CPL removal photo

Tucked away beneath Dorsey Station is this small masonry arched bridge as seen from the downstream side.

The upstream side of the bridge shows stone masonry of the style B&O employed during the 1830s. The only other surviving Washington Branch original stone arch bridge is found in Elkridge. There may have been another at what became Union Station Plaza in Washington, DC, as seen on IC2 page 58, but it has been either dismantled or buried.

Here's the view from the platform as CSX 605 scoots under Route 100.

At photo time, modern milepost 13 was affixed to the railing at the far end of the platform, but the original stone mile marker was nowhere to be found. I suspect it was removed during construction of either the station or MD 100.

CSX shares the "Camden Line" with commuter trains between Baltimore and Washington. Dorsey Station opened in 1996 and became one of MARC's busier.

A few plants decorate the station interior, which will soon reopen to greet afternoon commuters.

The station building is sited at the southwest corner of the platforms.

CSX 8749, inherited from Conrail, speeds by atop this attractive stone and brick bridge just southwest of the Dorsey Station. You can even see it without getting out of your car. Simply drive north on OConnor Drive from Route 103. According to Harwood, this bridge dates to 1870.

This bridge also marks a corner of Howard County. From here south to Laurel, the railroad determines the Howard-Anne Arundel county line. As you might have guessed, the railroad pre-dates Howard County, which split off from Anne Arundel in 1850. I am not sure if the pair of tracks is officially located entirely in one of the two counties, or if the county line runs in between them. The ADC maps indicate the railroad is in Anne Arundel county, but a B&O schedule lists the tracks and stations as being in Howard.

Except for a less-than-one-mile stretch near Mt. Airy, all of Howard County's borders are defined by either railroads or rivers.

The Deep Run Bridge is second only to the Thomas Viaduct as the line's largest surviving stone/brick arch bridge.

Some sort of bridge has been here since the line's 1835 opening, and though the varied coloring on the bricks suggests a later expansion, closer examination reveals that to not be the case. Instead, this bridge was rebuilt in whole circa 1870 when brick arches were popular with B&O. The rebuild may have been concomitant a then-new B&O Dorsey Station that needed a siding track.

Train watching along the Washington Branch is far more productive than along the quieter Old Main Line. Here CSX 8777 roars south (west) past MARC's Dorsey Station with a long line of containers in tow. That's the Maryland 100 overpass in the distance.

Built in 1937, this utilitarian bridge carries the tracks over Dorsey Road, Maryland 103 (formerly 176). Disused stairways on both sides of the road led up to the platforms at B&O's Dorsey Station, which had stood off photo left on this side of the tracks The bridge has room for three tracks, but has never carried more than two.

Four-signal sets like this are commonly found at crossovers between tracks. The black overhead wire, which is nearer than the signals, recalls the location of the Dorsey Road grade crossing.

This straight run is one reason the stretch has been signposted for locomotive speed calibration, as will be seen a few panels below.

Next stop Jessup Auto Terminal as seen later in this tour...

Yes, Citibank is into locomotives too. Most units were leased to BNSF to haul oil, but on this day one found its way east to assist its ES44AC cousin CSX 3010 with autoracks.

Link: CREX 1338 pics

As the smallest Class 1 railroad, Kansas City Southern (KCS) is an infrequent visitor this far east. On this day, KCS 4604 and KCS 4689 were toting autoracks. During 2021, KCS entered an agreement to merge with Canadian Pacific Railroad.

Link: KCS at Wikipedia

Rails are hauled in long segments by specially-customized, articulated cars. There's enough rail being carried to redo a few miles of track. Caboose 904094 was on the end to serve as a shoving platform.

Surprisingly, ribbon rail segments are flexible enough to bend as the train negotiates curves. While being carried the rails are mounted on rollers so they can slide as the bending relatively lengthens or shortens them.

Links: rail train, dealing with curves

Starting in the 2010s, CSX extended many of its trains, with some nearing 3 miles in length. To reduce the stress on couplers, CSX has been placing a locomotive in the middle of these longer trains. They are called Distributed Power Units (DPUs).

Sunsets arrive sooner in autumn, but commuters follow the same schedule.

Maps show a stream beyond the curve at mp 13.7, but after you slog through the lowlands near it, you'll find a small piped culvert that's so overgrown with brush and vines, it can't be captured by a photo. A visit is not worth the effort.

The concrete slab in the foreground was probably a signal stand in a former life. The S signpost marks one measured mile from milepost 13 back at MARC's Dorsey Station.

Here's a rear view closeup of the S signpost. It looks to be a custom job: it's welded to an old piece of rail. At upper left is where the pavement of Ohio/Oak Avenues ends.

Fran Giacoma responded with a description:

"Per the B&O RR Roadway and Track Standards this is a 'Speed Test Sign' to be used at points where the engine speeds are to be checked. They would be placed a mile apart so an engineer could check the accuracy of the locomotive speedometer (if it had one and worked). Sort of like a 'begin measured mile' and 'end measured mile' signs seen on highways and other railroads."

CSX may be delaying ballast cleaning due to the dusty development paralleling Dorsey Run Road. Note the rusty appearance of the stone of the near track. Yes, that needs to be cleaned off periodically.

Wikipedia describes why:

"Over time, ballast becomes worn, and loses its angularity, becoming rounded. This hinders the tessellation of pieces of ballast with one another, and thus reduces its effectiveness. Fine pieces of granite, like sand, are also created by attrition, known simply as 'fines'. Combined with water in the ballast, these fines stick together, making the ballast like a lump of concrete. This hinders both track drainage and the flexibility of the ballast to constrain the track as it moves under traffic."

Directly across the tracks from the S signpost was a nice surprise: a mile marker that likely dates from the branch's original construction in 1835. It says this spot is 14 miles from Baltimore and 26 from Washington, DC. This marker is no longer extant.