Metropolitan Subdivision

Montgomery County is the most populous county in the state of Maryland. As of the 2020 census, the county's population was 1,062,061, increasing by 9.3% from 2010. The county seat and largest municipality is Rockville, although the census-designated place of Germantown is the most populous place within the county. Montgomery County, which adjoins Washington, D.C., is part of the Washington–Arlington–Alexandria, DC–VA–MD–WV metropolitan statistical area, which in turn forms part of the Baltimore–Washington combined statistical area. Most of the county's residents live in unincorporated locales, of which the most urban are Silver Spring and Bethesda, although the incorporated cities of Rockville and Gaithersburg are also large population centers, as are many smaller but significant places.

The Maryland General Assembly is the state legislature of the U.S. state of Maryland that convenes within the State House in Annapolis. It is a bicameral body: the upper chamber, the Maryland Senate, has 47 representatives and the lower chamber, the Maryland House of Delegates, has 141 representatives. Members of both houses serve four-year terms. Each house elects its own officers, judges the qualifications and election of its own members, establishes rules for the conduct of its business, and may punish or expel its own members.

The Metropolitan Railroad was a 19th-century Maryland corporation that proposed to build a railroad line from Washington, D.C., to the vicinity of Frederick, Maryland, where it would connect with the Baltimore and Ohio Railroad (B&O), and continue to Hagerstown. The company was organized by businessmen from Washington and Montgomery County, Maryland, and was chartered by the Maryland General Assembly in 1853. It conducted some initial land surveys, but had difficulty raising funds and went bankrupt in 1863. The B&O subsequently constructed a rail line on a similar route, and opened its Metropolitan Branch in 1873.

Frederick is a city in and the county seat of Frederick County, Maryland, United States. It is part of the Washington–Baltimore combined statistical area. It is located at an important crossroads at the intersection of a major north–south Native American trail and east–west routes to the Chesapeake Bay, both at Baltimore and what became Washington, D.C. and across the Appalachian mountains to the Ohio River watershed. It is a part of the Washington-Arlington-Alexandria, DC-VA-MD-WV Metropolitan Statistical Area, which is part of a greater Washington-Baltimore-Arlington, DC-MD-VA-WV-PA Combined Statistical Area.

Hagerstown is a city in and the county seat of Washington County, Maryland, United States. The population of Hagerstown city proper at the 2020 census was 43,527, and the population of the Hagerstown metropolitan area was 293,844. Hagerstown ranks as Maryland's sixth-largest incorporated city and is the largest city in the Panhandle.

Point of Rocks is an unincorporated community and census-designated place (CDP) in Frederick County, Maryland, United States. As of the 2010 census it had a population of 1,466. It is named for the striking rock formation on the adjacent Catoctin Mountain, which was formed by the Potomac River cutting through the ridge in a water gap, a typical formation in the Appalachian Mountains. The formation is not visible from the town and can only be seen from boats on the river, or from the southern bank of the river in Virginia.

A passenger train is a train used to transport people along a railroad line. These trains may consist of unpowered passenger railroad cars hauled by one or more locomotives, or may be self-propelled; self propelled passenger trains are known as multiple units or railcars. Passenger trains stop at stations or depots, where passengers may board and disembark. In most cases, passenger trains operate on a fixed schedule and have priority over freight trains.

A freight train, also called a goods train or cargo train, is a railway train that is used to carry cargo, as opposed to passengers. Freight trains are made up of one or more locomotives which provide propulsion, along with one or more railroad cars which carry freight. A wide variety of cargos are carried on trains, but the low friction inherent to rail transport means that freight trains are especially suited to carrying bulk and heavy loads over longer distances.

Gaithersburg, officially the City of Gaithersburg, is a city in Montgomery County, Maryland, United States. At the time of the 2020 U.S. Census, Gaithersburg had a population of 69,657, making it the ninth-largest location in the state. Gaithersburg is located to the northwest of Washington, and is considered a suburb and a primary city within the Washington–Arlington–Alexandria, DC–VA–MD–WV Metropolitan Statistical Area. Gaithersburg was incorporated as a town in 1878 and as a city in 1968.

Ephraim Francis Baldwin was an American architect, best known for his work for the Baltimore and Ohio Railroad and for the Roman Catholic Church.

On February 16, 1996, a MARC commuter train collided with Amtrak's Capitol Limited passenger train in Silver Spring, Maryland, United States, killing three crew and eight passengers on the MARC train; a further eleven passengers on the same train and fifteen passengers and crew on the Capitol Limited were injured. Total damage was estimated at $7.5 million.

A railway signal is a visual display device that conveys instructions or provides warning of instructions regarding the driver’s authority to proceed. The driver interprets the signal's indication and acts accordingly. Typically, a signal might inform the driver of the speed at which the train may safely proceed or it may instruct the driver to stop.

Dickerson is an Unincorporated community in Montgomery County, Maryland. It is on Maryland Route 28, between Sugarloaf Mountain and the Potomac River. It is a community near the town of Poolesville, Maryland. Dickerson is 61.5 square miles (159 km2).

Derwood is an unincorporated area and census-designated place in east-central Montgomery County, Maryland, United States. It lays just north of Rockville, southeast of Gaithersburg, southwest of Olney, and northwest of the greater Silver Spring area. Derwood was originally "Deer Park" and was then "Deer Wood" before getting its current name.

In railway signalling, an interlocking is an arrangement of signal apparatus that prevents conflicting movements through an arrangement of tracks such as junctions or crossings. The signalling appliances and tracks are sometimes collectively referred to as an interlocking plant. An interlocking is designed so that it is impossible to display a signal to proceed unless the route to be used is proven safe.

Iron is a chemical element with symbol Fe and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, just ahead of oxygen, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust, being mainly deposited by meteorites in its metallic state, with its ores also being found there.

A girder bridge is a bridge that uses girders as the means of supporting its deck. The two most common types of modern steel girder bridges are plate and box.

The Monocacy River is a free-flowing left tributary to the Potomac River, which empties into the Atlantic Ocean via the Chesapeake Bay. The river is 58.5 miles (94.1 km) long, with a drainage area of about 970 square miles (2,500 km2). It is the largest Maryland tributary to the Potomac.

Wood is a structural tissue found in the stems and roots of trees and other woody plants. It is an organic material – a natural composite of cellulose fibers that are strong in tension and embedded in a matrix of lignin that resists compression. Wood is sometimes defined as only the secondary xylem in the stems of trees, or it is defined more broadly to include the same type of tissue elsewhere such as in the roots of trees or shrubs. In a living tree it performs a support function, enabling woody plants to grow large or to stand up by themselves. It also conveys water and nutrients between the leaves, other growing tissues, and the roots. Wood may also refer to other plant materials with comparable properties, and to material engineered from wood, or woodchips or fiber.

A trestle bridge is a bridge composed of a number of short spans supported by closely spaced frames. A trestle is a rigid frame used as a support, historically a tripod used to support a stool or a pair of isosceles triangles joined at their apices by a plank or beam such as the support structure for a trestle table. Each supporting frame is a bent. A trestle differs from a viaduct in that viaducts have towers that support much longer spans and typically have a higher elevation.

A viaduct is a specific type of bridge that consists of a series of arches, piers or columns supporting a long elevated railway or road. Typically a viaduct connects two points of roughly equal elevation, allowing direct overpass across a wide valley, road, river, or other low-lying terrain features and obstacles. The term viaduct is derived from the Latin via meaning "road", and ducere meaning "to lead". It is a 19th-century derivation from an analogy with ancient Roman aqueducts. Like the Roman aqueducts, many early viaducts comprised a series of arches of roughly equal length.

Little Seneca Creek is an 14.0-mile-long (22.5 km) stream in Montgomery County, Maryland, roughly 18 miles (29 km) northwest of Washington, D.C.

Steel is an alloy of iron and carbon with improved strength and fracture resistance compared to other forms of iron. Many other elements may be present or added. Stainless steels that are corrosion- and oxidation-resistant typically need an additional 11% chromium. Because of its high tensile strength and low cost, steel is used in buildings, infrastructure, tools, ships, trains, cars, bicycles, machines, electrical appliances, and weapons.

Concrete is a composite material composed of fine and coarse aggregate bonded together with a fluid cement that hardens (cures) over time. Concrete is the second-most-used substance in the world after water, and is the most widely used building material. Its usage worldwide, ton for ton, is twice that of steel, wood, plastics, and aluminium combined. Globally, the ready-mix concrete industry, the largest segment of the concrete market, is projected to exceed $600 billion in revenue by 2025. This widespread use results in a number of environmental impacts. Most notably, the production process for cement produces large volumes of greenhouse gas emissions, leading to net 8% of global emissions. Other environmental concerns include widespread illegal sand mining, impacts on the surrounding environment such as increased surface runoff or urban heat island effect, and potential public health implications from toxic ingredients. Significant research and development is being done to try to reduce the emissions or make concrete a source of carbon sequestration, and increase recycled and secondary raw materials content into the mix to achieve a circular economy. Concrete is expected to be a key material for structures resilient to climate disasters, as well as a solution to mitigate the pollution of other industries, capturing wastes such as coal fly ash or bauxite tailings and residue.