Bollman Truss Railroad Bridge

Infobox Bridge
bridge_name = Bollman Suspension and Trussed Bridge


caption = Bollman Bridge with Savage Mill tower in background, 1970
official_name =
carries =
crosses = Little Patuxent River
locale = Savage, Maryland
maint =
id =
designer = Wendel Bollmancite book
last = Jackson
first = Donald C.
authorlink =
coauthors =
title = Great American Bridges and Dams
publisher = Wiley
date = 1988
location =
pages = pp.121-122
url =
doi =
id =
isbn = 0-471-14385-5]
design = Bollman Truss
material = cast and wrought Iron
spans = 2
pierswater = 1
mainspan = 2 x convert|80|ft
length = convert|160|ft
width =
height =
load =
clearance =
below =
traffic =
begin =
complete = 1869
open =
closed =
toll =
map_cue =
map_

map_text =
map_width =
coordinates =
lat =
long = Infobox_nrhp | name =Bollman Suspension and Trussed Bridge
nrhp_type = nhl


caption =
location= Savage, Maryland
locmapin = Maryland
lat_degrees = 39
lat_minutes = 8
lat_seconds = 5
lat_direction = N
long_degrees = 76
long_minutes = 49
long_seconds = 31
long_direction = W
locmapin = Maryland
area =
built =1869
architect= Bollman, Wendal
architecture= Other
added = October 18, 1972
governing_body = Howard County, Maryland
refnum=72000582cite web|url=http://www.nr.nps.gov/|title=National Register Information System|date=2007-01-23|work=National Register of Historic Places|publisher=National Park Service]

The Bollman Truss Railroad Bridge at Savage, Maryland is the sole surviving example of a revolutionary design in the history of American bridge engineering. The 160 foot (48.8 m) double-span truss bridge is one of the oldest standing iron railroad bridges in the United States. It was the first successful all-metal bridge design to be adopted and consistently used on a railroad. The type was named for its inventor, Wendel Bollman, a self-educated Baltimore engineer.

History

The bridge was built for an unknown location on the main line of the Baltimore and Ohio Railroad in 1852, and was moved to its present location, spanning the Little Patuxent River on the spur to the Savage Mill, in 1887. This spur line dates to around 1840 and originally crossed the river on a stone arch bridge; however, due to alterations to the mill in the 1880s and topographical restrictions, a replacement bridge was needed. The bridge remained in service until the mill closed in 1947; switching crews used additional cars in order to avoid crossing the bridge with locomotives, and thus there was never a need for a more substantial structure.

It was the first successful all-metal bridge design to be adopted and consistently used on a railroad. The design employs wrought iron tension members and cast iron compression members. It was an improvement over wooden structures, as the independent structural units lessened the possibility of structural failure. Patented on January 6, 1852 [patent|US|8624|Suspension bridge] [cite web
url= http://www.google.com/patents?id=DdlIAAAAEBAJ&dq=8624&jtp=1#PPP1,M1
title= CONSTRUCTION OF BRIDGES
accessdate= 2008-09-01
last= Bollman
first= Wendel
date= 1852-01-06
publisher= Google] , the company built about a hundred of these bridges through 1873. Their durability and ease of assembly greatly facilitated expansion of American railroads in this period. Bollman's Wells Creek Bridge has also survived, but it employs a different type of truss system.

Restoration

The bridge was restored by Wallace, Montgomery & Associates, LLP for the Howard County Department of Recreation and Parks in 1983, and more recently underwent additional preservation work and was rededicated on September 16, 2000. Today it receives regular maintenance as part of Savage Park. In 1966, under a new program of the American Society of Civil Engineers, it was designated the first ever Historic Civil Engineering Landmark. [Historic plaque placed by the ASCE near the north end of the bridge. Observed April 27, 2007.] The bridge was listed on the National Register of Historic Places on December 18, 1972, and was designated a National Historic Landmark on February 16, 2000. Nearby Bollman Bridge Elementary School takes its name from the historic bridge.

References

External links

* [http://users.erols.com/rmayes/savage.html Color images of the Bollman Bridge after preservation work]
* [http://tps.cr.nps.gov/nhl/detail.cfm?ResourceId=957811596&ResourceType=Structure National Historic Landmark information]
* [http://www.nr.nps.gov/Red%20Books/72000582.red.pdf National Register information]
* [http://www.asce.org/history/brdg_bollman.html American Society of Civil Engineers - Bollman Truss Bridge]
*
* [http://www.co.ho.md.us/RAP/RAP_HoCoParksSavage.htm Savage Park]
* [http://www.du.edu/~jcalvert/tech/bolltrus.htm History and analysis of the Bollman truss]
* [http://www.marylandhistoricaltrust.net/nr/NRDetail.aspx?HDID=101&FROM=NRNHLList.aspx Bollman Suspension Truss Bridge, Howard County] , including photo in 1985, at Maryland Historical Trust
* [http://hdl.loc.gov/loc.pnp/hhh.md0583 Baltimore & Ohio Railroad, Bollman Truss Bridge, Spanning Little Patuxent River, Savage, Howard County, MD: 7 drawings, 17 photos, 6 data pages and 3 photo captioin pages] , at Historic American Building Survey