Potomac River Bridge is a 1 7 mile 2 7 Km Two lane Continuous Truss Bridge

outubro 15, 2022 Postar um comentário

Bridges in Virginia

the John Andrew Twigg Bridge carries Route 3 across the Piankatank River, linking Mathews and Middlesex counties
Source: Virginia Department of Transportation (VDOT), John Andrew Twigg Bridge

Native Americans presumably placed logs and aligned rocks to facilitate crossing streams without getting wet, but they constructed no bridges. English colonists were reluctant to invest in building bridges as well. The technology was not a challenge for crossing small streams, but bridges required substantial investment of labor. In the 1600's, the trees needed for bridge-building materials were readily available but labor was scarce.

The first bridge-like structure built by the English colonists was a 200-foot wharf extending from the shoreline at Jamestown into the shipping channel of the James River. The first bridge was built in 1611. It crossed over Back River at Frigett (Frigate) Landing, permitting the colonists to get to the mainland from Jamestown Island.

sketch of the first bridge constructed at Jamestown in 1611
Source: National Archives, The First Three Bridges Built in Virginia

It was a beam bridge comparable in design to most modern highway bridges, where the bridge's deck sits on top of heavy beams strong enough to support the weight. Starting in the 1800's, new designs would use a variety of trusses and cables to distribute compression and tension in order to support heavier, longer spans with fewer support piers between the abutments at either end of a bridge.

the first bridge was constructed at Jamestown in 1611, to get across Back River from the island to the mainland
Source: Federal Highway Administration, 1611 First Bridge (painting by Carl Rakeman)

Colonists were required to contribute their labor, unpaid, for maintaining roads and bridges. A 1705 law recognized that unskilled labor conscripted from local residents could not construct all the needed bridges. The law declared that if a bridge which required hiring skilled workers was located within two counties, then they would split the construction costs based on the percentage of residents being taxed ("tithables") in each county. The General Assembly also could authorize charging tolls on the most expensive bridges, so travelers would help fund the project.¹

the road to the former capital of Williamsburg required crossing the Mattaponi and Pamunkey rivers by ferry
Source: David Rumsey Historical Map Collection, Map of Virginia (by Rev. James Madison, 1807)

covered bridges have been replaced by structures which can handle more, and heavier, vehicles
Source: Virginia Department of Transportation, Little Reed Island Creek

the Orange and Alexandria Railroad bridge over Bull Run was destroyed early in the Civil War
Source: Library of Congress, View on Bull Run, crossing of Orange and Alexandria railroad

the Union side rebuilt the Orange and Alexandria Railroad bridge over Bull Run
Source: Library of Congress, Railroad bridge across Bull Run. O. & A. R.R., R. R. (i.e. Railroad) bridge across Bull Run. O. & A. R.R., and U.S. Military Railroad Bridge, Bull Run, Va. Orange and Alexandria R.R.

Today, a wide range of highway, rail, and pedestrian bridges provide connections across valleys and rivers. Keeping bridges in a "state of good repair" is a major component of the operations and maintenance budget of the Virginia Department of Transportation, plus the cities and two counties (Arlington and Henrico) which retain ownership of their local roads.

Few bridges built in the 1800's have survived; most have been replaced because they became structurally unsafe or were too light/narrow to handle modern traffic. Even the "historic" covered bridges have been modified by restoration and repairs. The roof on Humpback Bridge was replaced by the Virginia Department of Transportation in 2013, but the "old" roof dated back only to the 1970's. The entire Meems Bottom Covered Bridge was rebuilt after being torched by vandals in 1976.²

the Humpback Bridge is the only Virginia bridge designated as a National Historic Landmark
Source: Virginia Department of Transportation, Humpback Bridge

A vast number of railroad bridges have been required because trains do not go up or down slopes easily. Tracks were laid out to minimize grades, with bridges built to cross low spots and occasionally tunnels to avoid high spots so locomotives could pull more cars with heavier loads.

Horses and wagons had the same problem until World War II, and historic roads closely followed topographic features to minimize the number of horses needed to haul a load. Ferries carried people and vehicles across rivers. Operating costs were higher, since a ferry operator needed to be paid, but ferries required far less initial investment than bridges. Since the advent of modern vehicles after 1910, nearly all ferries have been replaced with bridges to minimize delays.

the only bridge to cross the York River, the George P. Coleman Memorial Bridge, swings open to allow ships to pass between Yorktown and Gloucester Point
Source: Wikipedia, George P. Coleman Memorial Bridge

In Hampton Roads, tunnels have been constructed as a part of the major crossings rather than bridges, to minimize the risk of an enemy destroying a structure and creating a dam of debris that blocked US Navy ships from reaching key facilities.

a tanker hit the Benjamin Harrison Memorial Bridge in 1977, demonstrating the risk of a damaged bridge blocking the shipping channel
Source: Virginia Department of Transportation, Benjamin Harrison Memorial Bridge

Bridge components were built near each shoreline, since those structures are far less expensive, but tunnels go underneath the major shipping channels.

construction of the new High Rise Bridge over the Elizabeth River (May 11, 2018)
High Rise Bridge over the Elizabeth River (May 11, 2018)
Source: Virginia Department of Transportation, High Rise Bridge

construction of the new High Rise Bridge over the Elizabeth River (January 31, 2019)
Source: Virginia Department of Transportation, High Rise Bridge

Modern engineers consider environmental as well as construction costs before decisionmakers choose between constructing an embankment/causeway, tunnel, or bridge. However, politics remains a key a factor in allocating funding and prioritizing construction or replacement of bridges.

The tallest highway bridge in Virginia, 250 feet over Grassy Creek in Buchanan County, was constructed near Breaks Interstate Park on the Virginia-Kentucky border. Prior to its completion, the "Smart Road" bridge built in 2001 over Wilson Creek near at Blacksburg was the highest highway bridge in Virginia. That was far less than the height of the tallest building in the state, the Westin Virginia Beach Town Center. Inn 2020, Dominion Energy completed the tallest structures in Virginia, two offshore wind towers. Each blade of the 6 MW turbines was 253 feet long, on towers that rose 620 feet from sea level.³

the Smart Road bridge over Wilson Creek in Montgomery County is now the second-highest highway bridge in Virginia
Source: Ben Townsend, Ellett Valley Smart Road bridge

The two 1,700-feet long spans of the US 460 bridge are part of the Corridor Q 460 Connector in the Appalachian Development Highway System (ADHS). The $100 million bridge was built in 2011-2015, but no funding was committed for the connecting roads. Kentucky built its portion of the connector road by 2020, but Virginia had only carved out the roadbed for its future connecting highway. After the state obtained $300 million in Federal funds, a downsized road was planned for completion in 2021. The planned four-lane connector was reduced just two lanes, with climbing lanes on hills.

The two spans finally opened to traffic on November 16, 2020. That was five years after they were completed. Drivers coming into Virginia had to make a hard right turn to get to Route 80, since the rest of Corridor Q to Grundy had not been built. Drivers headed west into Kentucky could use the upgraded Route 460 from the state line to near Elkhorn City.

the tallest highway bridge in Virginia was completed between 2011-2015, using Federal funds for the Appalachian Development Highway System
Source: Virginia Department of Transportation, Route 460 Connector, Buchanan County, Virginia

The tallest bridge in Virginia was a visual monument of the political desire to improve transportation in the Appalachian region, and also to Virginia's over-optimistic approach to starting highway projects. The SmartScale prioritization process mandated by the General Assembly in 2014 eliminated the potential of another "bridge to nowhere," by requiring a commitment of full funding before construction began for all projects that were approved by the Commonwealth Transportation Board. Fewer projects could be started under the SmartScale approach, but no longer would one be left incomplete and unusable.

the highest bridge in Virginia was completed before the state built its part of the Corridor Q 460 Connector
Source: ESRI, ArcGIS Online

the bridge over Grassy Creek sat unused (except by local trespassers) for over five years
Source: Virginia Department of Transportation, Route 460 over Grassy Creek (#13)

The Virginia Department of Transportation chose to schedule rehabilitation of the deck of the bridge over Grassy Creek 28 years after completion, reflecting a more-comprehensive planning approach for the life cycle of the state's bridges. The Virginia Secretary of Transportation who inherited the Grassy Creek debacle in 2013 was responsible for implementing the SmartScale approach, and made the planning/budgeting process more integrated and logical. He was puzzled by his predecessor's decision to build the bridge before getting funding for the connecting roads, asking at one point "why would they start there?"

The cantilevered bridge was logistically challenging to construct, in an isolated area with few local workers. It was unrealistic to haul prefabricated segments over the Appalachian roads, so a concrete plant was built at the site to supply the material needed for 84 cast-in-place segments on each bridge. When Roads & Bridges chose it as the #1 bridge project in 2013, the magazine noted:⁴

Height is a relative measure. You might think the tallest bridge in Virginia would tower over its surroundings. Actually, it is just level with the mountains around it.

between 2015-2021, the connecting road to the bridge over Grassy Creek remained unfinished
Source: ESRI, ArcGIS Online

The tallest railroad bridge in Virginia crosses Copper Creek in Scott County. The Carolina, Clinchfield and Ohio (CC&O) Railway built a structure 167 feet high, parallel to a much-lower bridge constructed by the South Atlantic and Ohio (SA&O) Railway in 1891. The height of the Clinchfield bridge reflected the priority of that railroad to build a high-quality line that minimized grade, including 55 tunnels in order for heavy trains to carry Kentucky/Virginia coal to Spartanburg, South Carolina.⁵

Both bridges are still in use. CSX owns the former Carolina, Clinchfield and Ohio (CC&O) Railway bridge and Norfolk Southern owns the lower structure built by the South Atlantic and Ohio (SA&O) Railway.⁵

the tallest railroad bridge in Virginia, 167 feet high, was built by the Carolina, Clinchfield and Ohio (CC&O) Railway in 1908 and is now part of the CSX railroad
Source: cmh2315fl, Copper Creek Viaduct (Scott County, Virginia)

the tallest railroad bridge in Virginia crosses Copper Creek in Scott County (note lower bridge in foreground)
Source: cmh2315fl, Copper Creek Viaduct (Scott County, Virginia)

the low bridge built in 1891 and the 167-feet high bridge built in 1908 are still in use
Source: ESRI, ArcGIS Online

Virginia has roughly 70 swinging bridges, with over 20 in Lee County. Of the 14 in Scott County, 11 are still accessible for public use. Most swinging bridges are maintained by the Virginia Department of Transportation. Many were built to provide access across streams at low-water fords, allowing pedestrians to stay dry and allowing some connectivity during times of high water.

Only one swinging bridge crosses the James River. That structure at Buchanan uses some piers constructed in 1851 for the Buchanan Turnpike Company's Toll Bridge, which was built the same year that the James River & Kanawha Canal reached Buchanan. That covered bridge was burned during the Civil War. The replacement washed away in 1877, after which the Richmond and Alleghany Railroad rebuilt it as a toll-free structure. After a new highway bridge was built downstream in 1938, the 366-foot long swinging bridge was constructed.

In 2020, the Virginia Department of Transportation proposed to eliminate the two state-maintained swinging bridges over the Robinson River at Criglersville in Madison County. Neither bridge connected to a public paths or hiking trail, so the opportunity for grant funding was limited and the priority for using maintenance funds for the swinging bridges was low. Complete restoration was required, and the state estimated each bridge would require $1.5-$2.5 million. Dismantlement and demolition would cost $100,000 for each bridge.

The bridge over the Robinson River, built in 1948 parallel to the Lindsay Lane low-water bridge, was closed in October, 2020. Local support for the "Pottery" bridge, built in 1987, helped keep that one open after deck boards were replaced. The Virginia Department of Transportation estimated the repairs would enable keeping the bridge open for another 1-2 years. The citizen-led initiative to save the swinging bridges assumed VDOT would donate the bridges, and the landowners who controlled the right-of-way to them would allow public access.⁶

Source: Virginia's Swinging Bridges

the Virginia Department of Transportation closed the swinging bridge over the Robinson River at Lindsay Lane in 2020
Source: Virginia Department of Transportation, Criglersville Swinging Pedestrian Bridges (October 27, 2020)

The longest pedestrian swinging bridge in North America, stretching 725 feet across the Russell Fork gorge, will be constructed by 2021 over the Virginia-Kentucky border at Breaks Interstate Park. The bridge will link the park to the Pine Mountain Trail, which extends 120 miles south to Cumberland Gap. The Virginia Coalfield Economic Development Authority funded over half of the costs of the swinging bridge in order to enhance business activity stimulated by tourism.⁷

Efforts to preserve old bridges extend beyond just the covered bridges in Virginia. The Clarkton Bridge over the Staunton River, built in 1902, was documented by the Historic American Engineering Record as a representative example of a pin-connected steel Camelback truss. The bridge was closed to traffic in 1998, rather than upgraded to support modern vehicles.

the Clarkton bridge, a pin-connected steel Camelback truss, connected Halifax and Charlotte counties starting in 1902
Source: Library of Congress, Clarkton Bridge, Spanning Staunton River at State Route 620, Clarkton, Halifax County, VA

It was scheduled for demolition, but local advocates convinced the state to preserve it as a pedestrian-only bridge. Incorporating it into the Tobacco Heritage Trail was considered.

the 1902 Clarkton Bridge was converted for pedestrian use in 2005, and finally demolished in 2018
Source: Virginia Department of Transportation, Clarkton Bridge and Clarkton Bridge

In 2015, after a decade of recreational use, bridge inspectors declared the Clarkton Bridge was no longer safe for even pedestrians. Cost of repair was estimated at over $7 million, while demolition was estimated to cost only $1 million. The Clarkton Bridge was demolished in 2018.⁸

Clarkton Bridge was in rural Southside, crossing the Staunton (Roanoke) River
Source: ESRI, ArcGIS Online

The Virginia Department of Transportation closed the Waterloo Bridge over the Rappahannock River in January, 2014 because of safety concerns. The wrought iron bridge, with wooden deck, was first erected in 1878 to connect Culpeper and Fauquier counties. The 680 vehicles/day could no longer use the bridge on Route 613.

The Piedmont Environmental Council led the charge to get the Virginia Department of Transportation to repair, rather than replace, the oldest remaining Pratt through truss bridge in the state. A local resident agreed to donate $1 million, but Fauquier and Culpeper counties declined to match it.

Local, persistent efforts to preserve the 366-foot long, single-lane bridge finally paid off. In 2020 the state awarded a $3.7 million contract using state funds to remove, repair, and reinstall the components of the Waterloo Bridge, so it could once again carry cars and light trucks across the river. Traffic had averaged 630 vehicles per day before the bridge was closed.

In an eight-minute lift in April, 2020, a 550-ton crane hoisted the 30-ton bridge to a staging area on the shoreline. In November, after restoration, the Virginia Department of Transportation reinstalled it. However, the $1 million donor had died in September, so he never saw the project get completed.

The first cars crossed the bridge again in February, 2021. New six-inch-thick timbers for the bridge deck altered the experience of crossing the bridge, as noted by one driver in his pickup:⁹

The thing I notice is it doesn't rattle...

Waterloo Bridge, crossing the Rappahannock River, dates back to 1878
Source: Virginia Department of Transportation, Waterloo Bridge

Waterloo Bridge has a wooden deck
Source: Virginia Department of Transportation, Waterloo Bridge

Various designs for bridges were used after the Civil War. Superstructure shapes align tension and compression with different techniques, and reflect the different strengths/weaknesses of woods, metals, and concretes. Trusses transfer stress from the superstructure to the abutments and piers which support the structure:¹⁰

Tensile forces have a pulling effect, and failure is characterized by fracturing or tearing. In compression, on the other hand, failure occurs by buckling or crushing.

the last remaining rainbow arch highway bridge in Virginia carries US 1 across Stoney Creek in Dinwiddie County
Source: Virginia Transportation Research Council, A Management Plan for Historic Bridges in Virginia: The 2017 Update (p.106)

Albert Fink patented a distinctive W-shaped truss design in 1854. One of only two Fink truss bridges still remaining was built by the Norfolk & Western Railroad west of Lynchburg. It was moved in 1985 to Riverside Park in Lynchburg, to serve as an overlook as well as an historic exhibit. That structure is recorded as a National Historic Civil Engineering Landmark, though it has been moved from its original location.

Most truss bridges built with an iron or steel framework have been replaced by concrete structures. The US 301 bridge across the Rappahannock River, connecting Port Royal in Caroline County with Port Conway in King George County with a metal truss over the main navigation channel, was replaced in 1980.¹¹

the truss on the US 301 bridge over the Rappahannock River was eliminated in the 1980 replacement
Source: Bridge over the Rappahannock River at Port Royal, Virginia

the last remaining Fink truss bridge in Virginia is now in Riverside Park in Lynchburg
Source: Kipp Teague, Fink Truss Bridge in Riverside Park, Lynchburg, Virginia

The Varina-Enon bridge over the James River uses cables stretching diagonally from the main towers to the bridge superstructure to hold up the bridge deck for I-295. The deck was constructed from prefabricated concrete panels with a post-tensioning system. Each panel had a "tendon" of high-strength steel strands inside a duct, and the strands were pulled tight before the duct was filled with grout. The "post-tensioning" makes the concrete stronger by putting it under compression.

high-strength steel strands are pulled tight, then grouted in place to create "tendons" that put tension on concrete panels
Source: Virginia Department of Transportation, Route 460 over Grassy Creek (#13)

The Varina-Enon bridge was only the second major highway bridge (after the replacement bridge for the Sunshine Skyway in Florida) to use a concrete cable-stayed bridge design.

the Varina-Enon Bridge, completed in 1990, was the second major concrete cable-stayed highway bridge built in the United States
Source: Virginia Department of Transportation, Varina Enon Bridge over the James River. 89-5312-5 (1989)

the cables on the Varina-Enon Bridge make it a distinctive, easy-to-remember structure
Source: Virginia Department of Transportation, DSC00934

The innovative design of the high bridge eliminated any need for a drawbridge to allow ships to go back and forth to the Richmond Marine Terminal, upstream of the structure. The bridge was solid enough to withstand a tornado on 1993 that overturned trucks on the roadway. However, inspectors discovered in 2007 that a tendon had corroded and broken; multiple ducts with incomplete and/or low-quality grout had to be repaired. A 30-year maintenance plan developed in 2018 had an estimated cost of $150 million for the bridge, demonstrating that costs for maintenance over the life cycle of a bridge can exceed initial construction costs.¹²

tendons on the Varina-Enon Bridge required repair in 2007, 17 years after construction
Source: Virginia Department of Transportation, Varina Enon Bridge over the James River. 89-5312-5 (1989)

the Virginia Department of Transportation monitors the condition of bridges and culverts, to plan maintenance/replacement
Source: Virginia Department of Transportation, Bridges and Culverts

The Virginia Department of Transportation (VDOT) plans to replace rather than continue to repair the Benjamin Harrison Bridge before 2040. The state may get two additional decades of use beyond the anticipated 50-year service life span of the 1966 bridge by spending $78 million between 2018-2039. It will cost another $182 million (in 2018 dollars) to build a replacement structure. Funding might be obtained in a public-private partnership.

The Benjamin Harrison Bridge was repaired after a collision with the SS Marine Floridian tanker in 1977, but the trusses are still connected with rivets. The design provides almost no redundancy in case of a fracture of a critical structural component; the bridge could collapse without warning. The Virginia Department of Transportation publicized in 2018 that the replacement will not include a tower-driven vertical lift, or any drawbridge. A much-taller structure will be required to eliminate the maintenance and operational costs of bridge openings:¹³

As this movable bridge approaches 70 years old, it should be programmed for replacement with a fixed span bridge (non-movable). At this age the maintenance costs will accelerate, and the return on this investment will diminish with each year, as it will have reached the point where replacement will provide the best life-cycle investment. Furthermore, a fixed-span structure would reduce future maintenance and operations costs and risks for decades into the future.

the tanker ship Marine Floridian struck the Benjamin Harrison Memorial Bridge on February 24, 1977
Source: Virginia Department of Transportation, Benjamin Harrison Memorial Bridge

the Benjamin Harrison Memorial Bridge required 20 months of repairs
Source: Virginia Department of Transportation, Benjamin Harrison Memorial Bridge

The oldest Bowstring Truss Bridge in Virginia, and perhaps the oldest metal bridge in the state, is currently at the Ironto Rest Stop on I-81 between Roanoke and Blacksburg.

Bedford County ordered six bridges using the tubular arch truss design after a flood in 1877. The 55' long bridge was made from wrought iron, with rivets used to connect the tubular and trussed suspenders rather than the bolts and nuts/treaded connections for the rest of the structure. The Bowstring Truss Bridge was moved from Stony Creek to Roaring Fork, also in Bedford County, in the 1930's. It was disassembled again and reinstalled at the Ironto Rest Stop in 1977.

The bridge was added to the Virginia Landmarks Register in 2008, and to the National Register of Historic Places five years later. Moving the bridge did not disqualify it from listing on the historical registers:¹⁴

The boundaries for the Bowstring Truss Bridge are defined by the overall footprint of the bridge itself as erected at its current site. The boundaries do not include the modern (1977) concrete abutments that support it nor do they include any portions of the surrounding I-81 Ironto Rest Area since the significance of the structure is embodied and expressed solely in its engineering design regardless of location, setting, or feeling.

the Bowstring Truss Bridge retains its historical significance, even though it has been moved from Bedford County to the Ironto Rest Area in Montgomery County
Source: cmh2315fl on Flickr, Bowstring Truss Bridge

One of the most unusual bridges in Virginia was the Aqueduct Bridge constructed for the Alexandria Canal. Alexandria was a port city, and a rival of Georgetown. Both were located within the District of Columbia when the US Congress chartered the Alexandra Canal Company on May 26, 1830. Eight stone piers supported a wooden trough filled with water. That bridge, plus a seven-mile canal dug parallel to the Potomac River to Alexandria, allowed boats on the Chesapeake and Ohio (C&O) Canal to float to Alexandria with coal, grain, timber, and other freight.

the Aqueduct Bridge allowed boats to float, over the Potomac River, from the C&O Canal in Georgetown to Alexandria
Source: Architect of the Capitol, This Georgetown Bridge Was For Boats

The far western edge of the Aqueduct Bridge became part of Virginia in 1847, when the Federal government returned ("retroceded") Virginia's portion of the District of Columbia. During the Civil War the trough was covered with wooden planks so troops and wagons could use the bridge to cross the Potomac River. The trough was re-filled with water in 1866, but a second level was added in 1868 to provide a toll highway and footpath.

The Federal government purchased the structure in 1886, and replaced the original wooden "boat bridge" with an iron truss bridge for traditional pedestrian and wheeled vehicle traffic. In 1904, the Great Falls and Old Dominion Railroad widened the superstructure to support a trolley line across the bridge. After construction of the Key Bridge in 1923, the Aqueduct Bridge was closed.

The iron superstructure was removed in 1933. Seven of the eight stone piers were blasted away in 1962 so boaters would have fewer obstructions. The end of the bridge in Georgetown and the base of one pier near the Virginia shoreline have been left standing as historic remnants.¹⁵

the Aqueduct Bridge was completely within the District of Columbia until retrocession in 1847
Source: Library of Congress, Chart of the head of navigation of the Potomac River shewing the route of the Alexandria Canal (1841)

The constraints of railroads limited where bridges could be constructed. Train wheels do not grip rails the way car tires grip asphalt, so railroad engineers alter topography to minimize any grade. No railroad bridge was ever constructed across the James River downstream of Richmond. Such a bridge could have been constructed with a drawbridge rather than a high center so ships could always navigate past the structure, but Norfolk and then Newport News developed as independent shipping terminals at the end of competing railroad lines. There was no business incentive to build a railroad bridge across the river.

The construction of the New York, Philadelphia and Norfolk Railroad to the southern tip of the Eastern Shore in 1884 left a 26-mile gap between the new town of Cape Charles and the railroads that terminated in Norfolk. There was never enough traffic to justify even planning a railroad bridge across the mouth of the Chesapeake Bay. Instead, the railroad created a "car float," and used barges to transport freight between wharves at Cape Charles and Little Creek.

The car float ended permanently in 2018 when the Bay Coast Railroad ceased operating and the 49 miles of track between Cape Charles and Hallwood were abandoned. The barge that transported freight cars across the Chesapeake Bay was sold, but a remnant of an earlier barge was retained. The Captain Edward Richardson/Nandua had carried the rail cars from 1949-1981, when it sank in the Cape Charles harbor. The pilot house was retrieved and repurposed as the railroad office at the yard in Cape Charles.¹⁶

Getting a railroad bridge over the Potomac River at Washington, DC was more of a political than a technical challenge. The Baltimore and Ohio (B&O) Railroad negotiated a special arrangement with the Federal government at the start of the Civil War, and gained exclusive rights to haul rail cars across the Long Bridge. However, the Pennsylvania Railroad obtained the monopoly in 1870.

Rather than lose access to the traffic between Virginia and the northern states, the Baltimore and Ohio Railroad started a car ferry across the Potomac River. It barged railroad cars from Shepherd's Landing at Marbury Point in the District of Columbia to Alexandria from 1874-1906,. When the various railroads serving Alexandria reached an agreement for sharing use of the new Long Bridge and interchanging cars at Potomac Yard, the inefficient car float ended.

However, during World War II an "Emergency Bridge" was constructed between Shepherd's Landing at Marbury Point and Montgomery Street in Alexandria. The bridge allowed Baltimore and Ohio Railroad and the Pennsylvania Railroad trains to use a second crossing over the Potomac River, in addition to Long Bridge. The Emergency Bridge was removed in 1945, as the war in Europe ended and traffic declined.¹⁷

the Baltimore and Ohio Railroad had to operate a "car float" to barge freight cars across the Potomac River between 1874-1906
Source: Library of Congress, Map of Alexandria County, Virginia for the Virginia Title Cos

railroad drawbridges stay in the "up" position except when trains cross, in contrast to highway bridges
Source: Virginia Department of Transportation, Gilmerton Bridge

According to the 2019 statistics in the National Bridge Inventory, there were 13,933 highway bridges in Virginia in 2019. The bridges carrying the most traffic in Virginia each day are at the end of on I-64 near Bowers Hill in the City of Chesapeake. The braided ramp carrying two lanes of I-64 westbound towards I-464 carry 300,000 vehicles/day, on average.

The National Bridge Inventory also documents the number of highway bridges still in use, based on the time period of construction:¹⁸
built between 1800-1899: 17
built between 1900-1909: 21
built between 1910-1919: 61
built between 1920-1929: 253
built between 1930-1939: 1,639
built between 1940-1949: 495
built between 1950-1959: 1,118
built between 1960-1969: 2,604
built between 1970-1979: 2,320
built between 1980-1989: 1,600
built between 1990-1999: 1,721
built between 2000-2009: 1,224
built between 2010-2019: 860

number of still-remaining bridges that were built in a particular decade, after 1800's
Source: Federal Highway Administration, National Bridge Inventory

By 2020, so many metal truss bridges had been removed/replaced that Preservation Virginia included then in its list of "2020 Virginia's Most Endangered Historic Places." There were approximately 620 metal truss bridges in 1975, but by 2020 only 5% of them remained. The historic preservation organization stated that metal truss bridges were:¹⁹

...a key element of the state's distinctive landscapes that can bolster tourism and provide an increasingly unique visual experience that connects people to their journey, the roadways, and the rivers and creeks they cross in the rural landscape.

the 1882 Aden Road bridge was rehabilitated and reinstalled in Prince William County
Source: Virginia Department of Transportation, One-lane bridge on Aden Road in Nokesville and second image (by Trevor Wrayton)

Covered Bridges in Virginia

Ferries in Virginia

Hampton Roads Bridges and Tunnels

Highways in Virginia

Modern Deals to Rebuild Bridges Crossing the Potomac River

Oldest Bridges in Virginia

Railroads in Virginia

Transportation Tunnels in Virginia

Woodrow Wilson Bridge

the new Woodrow Wilson Bridge
Source: Virginia Department of Transportation, Woodrow Wilson Bridge

Maryland owns most of the American Legion Bridge over the Potomac River
Source: Virginia Department of Transportation (VDOT), I-495 Washington DC

all of the Virginia Department of Transportation (VDOT) bridges and other infrastructure must be maintained and ultimately replaced
Source: Virginia Department of Transportation (VDOT), Bridges and Culverts Map

References

1. "A History Of Roads In Virginia 'The Most Convenient Wayes'," Virginia Department of Transportation, 2006, pp.4-6, http://www.virginiadot.org/about/resources/historyofrds.pdf; American Wooden Bridges, American Society of Civil Engineers, 1976, https://www.google.com/books/edition/_/FiBSAAAAMAAJ (last checked December 2, 2019)
2. "Humpback Bridge restoration," Virginia Department of Transportation, https://www.youtube.com/watch?v=sbkIiHCeSw4; "Historic Meems Bottom Covered Bridge," Virginia Tourism Corporation, https://www.virginia.org/listings/outdoorsandsports/historicmeemsbottomcoveredbridge/(last checked December 1, 2019)
3. "Smart Road Bridge over Wilson Creek," PCL Construction, https://www.pcl.com/Projects-that-Inspire/Pages/Smart-Road-Bridge-over-Wilson-Creek.aspx; "Wind turbines taller than the state's tallest building make energy off Virginia Beach coast," The Virginian-Pilot, October 9, 2020, https://www.pilotonline.com/news/environment/vp-nw-offshore-wind-pilot-project-20201009-wk6zhu4b2fbjlm2jvpuyulux64-story.html; "Virginia's wind-powered future: Second offshore turbine now towering over Atlantic," The Virginian-Pilot, June 29, 2020, https://www.pilotonline.com/business/consumer/dp-nw-dominion-wind-20200629-xolzfld7m5hpbgywcd4v62b6me-story.html; (last checked October 11, 2020)
4. "Tallest bridge in Virginia may finally open to traffic next year," WYMT, May 24, 2019, https://www.wymt.com/content/news/Tallest-bridge-in-Virginia-may-finally-open-to-traffic-next-year-510372791.html; "Virginia and Kentucky's Beautiful Bridge to Nowhere," Governing, April 24, 2020, https://www.governing.com/community/Virginia-and-Kentuckys-Beautiful-Bridge-to-Nowhere.html; "Next year, Virginia's $100 million bridge to nowhere will finally connect to a road," Virginia Mercury, May 19, 2019, https://www.virginiamercury.com/2019/05/19/next-year-virginias-100m-bridge-to-nowhere-will-finally-connect-to-a-road/; "Route 460 over Grassy Creek (#13)," Statewide Special Structures, Virginia Department of Transportation, http://www.p3virginia.org/wp-content/uploads/2019/09/13_460-Connector-Bridge.pdf; "2013 Top 10 Bridges - No. 1," Roads and Bridges, November 1, 2013, https://www.roadsbridges.com/2013-top-10-bridges-no-1; "Virginia's tallest bridges open to traffic in Buchanan County," Bluefield Daily Telegraph, November 16, 2020, https://www.bdtonline.com/news/virginias-tallest-bridges-open-to-traffic-in-buchanan-county/article_298536ea-284d-11eb-a6e7-37c268793cd1.html (last checked November 18, 2020)
5. "The Copper Creek Railroad Trestles," Historical Marker Database, https://www.hmdb.org/m.asp?m=36106 (last checked May 8, 2020)
6. "Virginia's Swinging Bridges," Virginia Tourism Corporation, https://blog.virginia.org/2014/10/virginias-swinging-bridges/; "The Swinging Bridges of Scott County," Scott County, https://www.explorescottcountyva.org/explore/the-swinging-bridges-of-scott-county/; "Buchanan Swinging Bridge," Virginia Tourism Corporation, https://www.virginia.org/Listings/HistoricSites/BuchananSwingingBridge/; "180-0028 Buchanan Historic District," National Register of Historic Resources Registration Form, December 8, 1998, Virginia Department of Historic Resources, https://www.dhr.virginia.gov/wp-content/uploads/2019/02/180-0028_Buchanan_HD_1999_Final_Nomination.pdf; "Foot bridges in jeopardy?," Madison Eagle, September 24, 2020, https://dailyprogress.com/community/madisonnews/news/foot-bridges-in-jeopardy/article_19e47494-2393-11eb-a48c-7fff347f77bf.html; "Madison Co. Pedestrian Bridge Is Closed," Virginia Department of Transportation, October 7, 2020, http://www.virginiadot.org/newsroom/culpeper/2020/madison-co-pedestrian-bridge-is-closed10-07-2020.asp; "Discussion Heats Up On The Bridges Of Madison County," Maddrapp.com, October 13, 2020, https://madrapp.com/discussion-heats-up-on-the-bridges-of-madison-county-p681-174.htm; "Criglersville Bridges Still Swinging – For Now," MappRapp.com, October 28, 2020, https://madrapp.com/criglersville-bridges-still-swinging-%E2%80%93-for-now-p736-174.htm; "Bridge plan progress," Madison Eagle, March 8, 2021, https://dailyprogress.com/community/madisonnews/news/bridge-plan-progress/article_83e8e858-7c7f-11eb-b94e-f3d6cc307a6e.html (last checked March 11, 2021)
7. "Breaks receives funding for bridge over Russell Fork to connect Virginia, Kentucky border; expected to be the longest pedestrian swinging bridge in North America," Bristol Herald Courier, December 18, 2019, https://www.heraldcourier.com/news/local/breaks-receives-funding-for-bridge-over-russell-fork-to-connect/article_83ca7d2a-21b6-11ea-8131-83d34a536523.html; "Pine Mountain Trail," US Forest Service, https://www.fs.usda.gov/recarea/gwj/recreation/hiking/recarea/?recid=78548&actid=50 (last checked December 20, 2019)
8. "Clarkton Bridge, Spanning Staunton River at State Route 620, Clarkton, Halifax County, VA," Historic American Engineering Record, Library of Congress, https://loc.gov/pictures/item/va1741/; Clarkton Bridge Alliance, https://www.clarktonbridge.com/; "Clarkton Bridge's days numbered as demolition work to begin," The Gazette-Virginian, August 29, 2018, http://www.yourgv.com/news/local_news/clarkton-bridge-s-days-numbered-as-demolition-work-to-begin/article_a384960a-aaf7-11e8-aab7-3f3c688e723f.html; "End of the Road," South Boston News & Record, August 27, 2018, http://www.sovanow.com/index.php?/news/article/end_of_the_road1/ (last checked May 4, 2020)
9. "Coming Soon: Waterloo Bridge, Culpeper Co./Fauquier Co.," Virginia Department of Transportation, http://www.virginiadot.org/projects/culpeper/waterloo.asp; "Waterloo Bridge contract for $3.6 million awarded," FauquierNOW, January 15, 2020, https://www.fauquiernow.com/fauquier_news/article/fauquier-waterloo-bridge-contract-for-3.6-million-awarded-2020; "Save Waterloo Bridge!" Piedmont Environmental Council, https://www.pecva.org/our-mission/transportation/995-save-the-waterloo-bridge; "Maryland firm chosen to rebuild Waterloo Bridge," Fauquier Times, January 26, 2020, https://www.fauquier.com/news/maryland-firm-chosen-to-rebuild-waterloo-bridge/article_a169c05a-3c93-11ea-872d-c7efa9edb048.html; "Historic Waterloo Bridge swiftly lifted from river," FauquierNOW, April 29, 2020, https://www.fauquiernow.com/fauquier_news/article/fauquier-historic-waterloo-bridge-swiftly-lifted-from-river-2020; "Restored Waterloo Bridge truss flies back into place," FauquierNOW, November 5, 2020, https://www.fauquiernow.com/fauquier_news/article/fauquier-restored-waterloo-bridge-truss-back-in-place-11-2020; "First vehicles in 7 years cross the Waterloo Bridge," FauquierNOW, February 23, 2021, https://www.fauquiernow.com/fauquier_news/article/fauquier-first-vehicles-in-7-years-cross-the-waterloo-bridge-2-2021 (last checked February 23, 2021)
10. Ann B. Miller, Kenneth M. Clark, Matthew C. Grimes, "Final Report: A Survey of Masonry and Concrete Arch Bridges in Virginia," Virginia Transportation Research Council, February 2000, p.9, http://www.virginiadot.org/vtrc/main/online_reports/pdf/00-r11.pdf (last checked May 7, 2020)
11. "Riverside Park Bridge," Bridgehunter, https://bridgehunter.com/va/lynchburg-city/riverside-park/; "Raritan River Fink Through-Truss Bridge," Historic American Engineering Record HAER No. NJ-18, National Park Service, http://lcweb2.loc.gov/master/pnp/habshaer/nj/nj0100/nj0143/data/nj0143data.pdf; "Fink Through Truss Bridge," American Society of Civil Engineers, https://www.asce.org/project/fink-through-truss-bridge/; "Fink Deck Truss Bridge," Historic Bridges, https://historicbridges.org/bridges/browser/?bridgebrowser=virginia/fink/; Ann B. Miller, Kenneth M. Clark, "Final Report: Survey of Metal Truss Bridges in Virginia," Virginia Transportation Research Council, August 1997, p.12, http://www.virginiadot.org/vtrc/main/online_reports/pdf/98-r3.pdf (last checked August 18, 2020)
12. "Varina-Enon Bridge: I-295 over James River (#14)," Statewide Special Structures, Virginia Department of Transportation, http://www.p3virginia.org/wp-content/uploads/2019/09/14_Varina-Enon-Bridge.pdf; "Evolution of Cable-Stayed Bridge Technology," Structure Magazine, October 2008, p.10, https://www.structuremag.org/wp-content/uploads/2014/08/C-HistoricStructures-Pate-Oct081.pdf; "I-295 Varina-Enon Bridge," Figg, https://www.figgbridge.com/i-295-varina-enon-bridge; "Varina-Enon Bridge," John A. Weeks III, https://www.johnweeks.com/cablestay/pages/csb20.html (last checked April 28, 2020)
13. "Benjamin Harrison Bridge: Route 156 over James River (#1)," Statewide Special Structures, Virginia Department of Transportation, http://www.p3virginia.org/wp-content/uploads/2019/10/1_Benjamin-Harrison-Bridge-UPDATED_v2.pdf; "Marine Accident Report: U.S. Tankship SS Marine Floridian Collision With Benjamin Harrison Memorial Bridge, Hopewell, Virginia, February 24, 1977," National Transportation Safety Board, January 26, 1978, https://trid.trb.org/view.aspx?id=388078 (last checked April 28, 2020)
14. "Bowstring Truss Bridge," National Register of Historic Places Registration Form, Virginia Department of Historic Resources, November 9, 2012, https://www.dhr.virginia.gov/VLR_to_transfer/PDFNoms/060-5066_Bowstring_Truss_Bridge_2008_NR_FINAL.pdf; "Built In 1878, The Bowstring Truss Bridge In Montgomery County Is The Oldest Metal Bridge In Virginia," Only In Your State, February 26, 2020, https://www.onlyinyourstate.com/virginia/bowstring-truss-bridge-1878-va/ (last checked March 15, 2020)
15. "Alexandria Canal," Office of Historic Alexandria, https://www.alexandriava.gov/uploadedFiles/historic/info/history/HistoryOfTheAlexandriaCanalBrochure.pdf; "This Georgetown Bridge Was For Boats," Architect of the Capitol, June 25, 2016, https://architectofthecapital.org/posts/2016/5/30/aquaduct-bridge; "Aqueduct Bridge (2nd)," BridgeHunter, https://bridgehunter.com/dc/washington/bh50187/; "Aqueduct Bridge (3rd)," BridgeHunter, https://bridgehunter.com/dc/washington/bh50190/ (last checked March 30, 2020)
16. "Virginia Shore looks to rails-to-trails as railroad seeks to abandon tracks," Salisbury Daily Times, July 2, 2019, https://www.delmarvanow.com/story/news/2019/07/02/va-shore-looks-rails-trails-railroad-seeks-abandon-tracks/1616241001/; "Sell-off of Railroad Assets Shrouded in Secrecy," Eastern Shore Post, December 20, 2019, https://www.easternshorepost.com/2018/12/20/sell-off-of-railroad-assets-shrouded-in-secrecy/; "Help Us Preserve And Restore Our Town's Railroad History At The Cape Charles Museum," Cape Charles Museum and Railroad Center, https://capecharlesmuseum.org/railroad-acquisition (last checked March 31, 2020)
17. Jay Roberts, "The East Alexandria Railroad," Jaybird's Jottings blog, November 17, 2016, https://jay.typepad.com/william_jay/2016/11/the-east-alexandria-railroad.html (last checked March 31, 2020)
18. "Download NBI ASCII files," National Bridge Inventory, Federal Highway Administration, https://www.fhwa.dot.gov/bridge/nbi/ascii.cfm (last checked May 4, 2020)
19. "2020 Virginia's Most Endangered Historic Places," Preservation Virginia, 2020, https://preservationvirginia.org/wp-content/uploads/2020/05/Virginias-Most-Endangered-Historic-Places-Report-2020.pdf; "Historic truss bridge in Culpeper County named among Virginia's most endangered historic places," Culpeper Times, May 20, 2020, https://www.insidenova.com/culpeper/historic-truss-bridge-in-culpeper-county-named-among-virginias-most-endangered-historic-places/article_6688f41c-9ad8-11ea-9f73-5b05747b34c5.html (last checked May 20, 2020)

drawbridge at Great Bridge, completed in 2004
Source: US Army Corps of Engineers, Great Bridge, Bridge (080115-A-5177B-025)

bridge across the New River at Radford in 1949
Source: National Archives, New River Bridge, Radford, Virginia

1912 bridge over Gales Run on Chancellorsville Road (replaced with concrete bridge)
Source: National Archives, Washed Out Wooden Bridge, Virginia

From Feet to Space: Transportation in Virginia
Virginia Places

gerhardbantiong1987.blogspot.com

Source: http://www.virginiaplaces.org/transportation/bridges.html

Gerhard Bantiong1987