There are several pedestrian-only bridges at Canalside, Buffalo. They pass over the end of the Erie Canal, a portion of which has been paved over with a skating rink. When I was there, one of these bridges was closed due to construction and I couldn’t figure out how to get to another one. I did walk over two others of these pedestrian bridges – one over the paved portion and one over the water portion.
As I continue to explore the question “What is a Bridge?” I find that there is a structural, or form, perspective and a more philosophical, or function, perspective. In asking if the building in Chambersburg pictured above is a bridge, I earlier came to the conclusion that it is. That answer required searching beyond two standard dictionary definitions both of which required that the structure carry a path or roadway to qualify as a bridge. The Encyclopedia Britannica did not have that qualification and so I embraced their definition as I felt that this Chambersburg building and the backyards and buildings I discuss in Millvale should be called bridges. Structurally, these may be bridges, but philosophically are they bridges? Does a bridge need to allow movement across it to fulfill the purpose of a bridge?
Up to this point, I’ve been primarily focused on Merriam-Webster’s definition of bridge as a structure found in the built environment. There are many other definitions and types of bridges under their entry for “bridge,” starting with a time, place, or means of connection or transition. Other examples of “bridges” include the bridge of a nose, the bridge of a violin and other string instruments, the passage of music called a bridge that links two sections of the piece, a dental bridge, and a ship’s bridge. For each of these examples, the function of connection or transition seems to be the crucial part that makes them bridges.
In Buffalo, I also questioned the different between a structural bridge and a philosophical bridge. I proposed then that an overpass may be structurally a bridge, but philosophically if the primary purpose of the structure is to pass over instead of to connect then it is not a bridge.
Putting these ideas together, there is a difference between a structural bridge and the concept of a bridge. The Chambersburg and Millvale examples are structurally bridges, I believe, but their main purpose is to expand the buildable area. They are not intended to create connection and therefore they are not bridges.
In Chambersburg, PA, a historic town along the Lincoln Highway, the question of what is a bridge comes up again. This time, the specific iteration is: “Is a building a bridge?”
This question is a continuation of the one inspired by Millvale. When I shared my thoughts on the building/bridge and backyard/bridge in that town, I focused on the fact that those bridges were hidden from sight and are likely an important factor contributing to the town’s flooding issues.
The structure in Chambersburg, on the other hand, sits in plain view. To tackle this question, I think it is time to return to the formal definition of a bridge. I looked up a definition of a bridge for the first Pittsburgh edition of this series and seemed to accept that definition at face value. I returned to a definition of a bridge in the second Chicago definition to help define what a viaduct is. I again did not question the definition of bridge. Perhaps it is time to change that?
Merriam-Webster defines bridge as a structure carrying a pathway or roadway over a depression or obstacle.
The Oxford English Dictionary defines bridge as a structure forming or carrying a road, path, or (in later use) a railroad, etc., which spans a body of water, a roadway, a valley, or some other obstacle or gap, and allows a person or vehicle to pass unimpeded over or across it.
Both of these definitions avoid the interaction of buildings and bridges.
My first encounter with buildings on bridges was Pulteney Bridge in Bath, UK (photo of photo below). I was 13. It would be over a decade before I would start intentionally walking bridges. At that time, I declared, “That is one of the coolest bridges I’ve ever been on. There are shops on both sides of the road. You can’t tell you’re on a bridge.” (Notice the echoes of my later musings on the “bridges” of Chicago.)
The next most memorable building/bridge encounter was in Istanbul. The Galata Bridge is a 2-decker bridge with the lower deck full of restaurants with open seating facing the Bosphorus.
While both of these bridges also carry multi-modal roadways and therefore meet the two dictionary definitions of a bridge, they suggest the possibility of a broader definition of bridge.
As I did with viaducts, I next turned to “How to Read Bridges” by Edward Denison and Ian Stewart. Interestingly, they do not provide a definition for a bridge. They discuss bridge types – if the Chambersburg building is a bridge, it would be a beam bridge. They also discuss bridge uses. “Bridges are designed to satisfy a wide range of different uses from the obvious, such as vehicle, railroad, cycles, and pedestrian traffic, to the more obscure, such as carrying water. Many are even designed to cater to multiple uses.” (68) While they hint at “more obscure” uses, their chapter on uses goes on to talk specifically about pedestrian, water, vehicular, rail, and military uses. Buildings are missing from that list. However, their case studies do include Bath’s Pulteney Bridge and Florence’s Ponte Vecchio, which also includes buildings featuring shops and apartments on the bridge.
The Encyclopedia Britannica (Britannica.com) has the broadest definition of a bridge that I’ve encountered so far: Bridge, structure that spans horizontally between supports, whose function is to carry vertical loads. The prototypical bridge is quite simple – two supports holding up a beam – yet the engineering problems that must be overcome even in this simple form are inherent in every bridge: the supports must be strong enough to hold the structure up, and the span between supports must be strong enough to carry the loads.
By that criteria, the building/bridge in Chambersburg meets the definition of a bridge as it is a horizontal structure “whose function is to carry vertical loads.”
Moreover, this criteria suggests a broader interpretation of my framing question than I intended. “Is a building a bridge?” was intended to ask if a building built over a stream is considered a bridge. However, I wasn’t that specific in my wording and reading Britannica’s description of a bridge, it sounds like any building floor that is not the equivalent of concrete poured on the ground would count as a bridge. . . .Supports, beams, arches, piers, and cantilevers are all elements used in both bridges and buildings. . . .And so, the answer to the unintended broader question of “is a building a bridge?” may in fact be “yes.”
While there absolutely are structural similarities between buildings and bridges, I am not comfortable with a definition of bridge so broad that it includes all multi-story buildings and perhaps even some single-story ones. Perhaps a common distinguishing element between a building and a bridge is that bridges are designed to allow the free passage of air underneath the horizontal structure. That would make my working definition of a bridge: a structure that spans horizontally between supports, whose function is to carry vertical loads and that allows unobstructed passage of elements, objects, or animals, etc., underneath.
By this version of a definition of bridge, the building in Chambersburg is a bridge, the backyards and buildings in Millvale are likely bridges (assuming the stream has unobstructed passage below them all), but Heth’s Run Bridge while it was buried was not a bridge.
Millvale, PA, sits tucked in a valley that spills out into the Allegheny River at the far end of Pittsburgh’s 40th Street Bridge. Like all the valleys in this region, it formed over time by a stream cutting into the bed of the Allegheny Plateau. But when PennDOT announced the indefinite closure of two of Millvale’s bridges, I struggled to pinpoint their location. One of the two streets appeared to be nowhere near the streambed.
Then, in 2024, while I was primarily home-bound due to Long COVID and my mom sometimes took me along on her errands to help me get out of the house, she wanted to stop at a shop in Millvale. I thought I would sit in the car and wait for her, but as she was looking for a parking space, I noticed a barrier across one of the roads we passed with a sign that appeared to say “Bridge Closed.”
I investigated the closure while my mom went on her errand. Sure enough, on what looked like a street, just like all the other streets around, were jersey barriers marked with “Bridge Closed” signs (photo above). This street/bridge was the Lincoln Avenue Bridge that PennDOT had closed a year before. The only indication that this was a bridge was the “Bridge Closed” sign and the bridge weight limit sign on the right side of the bridge. A block over, Fremont Street had a similar barrier with “Bridge Closed” next to a bridge weight limit sign. Again, looking around from this bridge, it made perfect sense to me why I was unable to pinpoint its location on the map. (photos below)
While standing on the Liberty Avenue Bridge, it struck me if this road was a bridge, then what are the buildings and back yards on either side of the bridge in the direction of the pathway of Girty’s Run? Is the bowling alley a bridge? Is the back lawn of the adjacent houses a bridge? Do the people who live and play in these spaces know that they are on bridges?
I asked similar questions in Chicago as the ground shook beneath my feet with the passing of trucks and buses and as I walked over expansion joints. However, there wasn’t a river running underneath the Chicago ground-bridges. Those “bridges” enabled a variety of activities to happen while stacked one above the other as a solution to work with the density of the city.
In Millvale, the presence of bridges hidden in plain sight bothered me. I’ve heard over the years that Millvale has lots of trouble with flooding, in a region where flooding is common. That hearsay has left the impression that Millvale’s flooding is worse than average for the area. The municipal website includes directions for what to do when you hear the town siren give off flood warnings, which seems to support my impression. When I saw how much of the stream was buried under “bridges” made of roads, buildings, and backyards, it instantly made sense that flooding would be a major problem here.
Over my years of bridge-walking, I have come to see that intent is a part of the definition of what a bridge is. Most bridges seem to have the intent of connecting two (or more) points. However, in Buffalo, I encountered a bridge that the number one intent seems to be passing over an area. Millvale illustrates a third, vital component. The intent seems to go beyond just connecting two points (and passing over something, in this case, a stream). The intent here seems to include a demonstration that humans best nature . . . a demonstration that doesn’t appear to be working in this particular town.
Walking around downtown Buffalo, I encountered several murals. They were all placed where the built environment would have otherwise created a drab or unpleasant experience. Three were on the sides of buildings bordered by parking lots. One was along both sides of the tunnel created by Seneca One, a 1970s tower built over Main Street. The mural along Main Street was particularly appealing. Usually walking along a road that passes underneath a building is a dark and dingy experience. This mural brightened up the space and created a distraction for the whole block. As Main Street is one of the possible pedestrian connections to the Canalside waterfront area, placing a mural here was a great decision to help make the approach more palatable. There are plenty more unpleasant places to pass before reaching the water.
Three years ago, Pittsburgh’s Fern Hollow Bridge collapsed on a cold and icy morning. Since then, I have periodically checked in on the status of the new bridge, the fallout from the collapse including the Mayor’s new Commission on Infrastructure Asset Reporting and Investment, and the condition of other bridges, particularly those closed for safety reasons since the Fern Hollow Bridge collapsed.
At my last check-in one year ago, the National Transportation Safety Board’s investigation was still on-going with the latest update on their website a year old. The investigation wrapped up shortly after and the NTSB’s final report was issued in March 2024 (WTAE, March 22, 2024). Unsurprisingly, the report found that the City’s failure to act on the maintenance and repair recommendations from years of inspections led to the structural failure of the bridge. Specifically:
On Friday, January 28, 2022, about 6:37 a.m. eastern standard time, the Fern Hollow Bridge, which carried Forbes Avenue over the north side of Frick Park in Pittsburgh, Allegheny County, Pennsylvania, experienced a structural failure. As a result, the 447-foot-long bridge fell about 100 feet into the park below. The collapse began when the transverse tie plate on the southwest bridge leg failed due to extensive corrosion and section loss. The corrosion and section loss resulted from clogged drains that caused water to run down bridge legs and accumulate along with debris at the bottom of the legs, which prevented the development of a protective rust layer or patina. Although repeated maintenance and repair recommendations were documented in many inspection reports, the City of Pittsburgh failed to act on them, leading to the deterioration of the fracture-critical transverse tie plate and the structural failure of the bridge.
NTSB: Collapse of the Fern Hollow Bridge
Below are the news updates on the Fern Hollow Bridge and other bridge maintenance and replacement efforts in Pittsburgh and Allegheny County.
Historic Pittsburgh Bridge Disasters
According to Bob Regan’s 2006 book “The Bridges of Pittsburgh,” Pittsburgh is no stranger to bridge disasters:
Map of bridges discussed in the Bridge Collapse series:
Additional Resources:
Both PennDOT and the Federal Highway Administration have interactive maps of bridges for the state and country respective, and their inspection statuses. Pittsburgh now has the static Comprehensive Bridge Asset Management Program Report of the 147 bridges owned by the City of Pittsburgh.
Bridges in Pittsburgh with community engagement pages for pending rehabilitation or replacement projects:
Previous Fern Hollow Bridge Posts:
My day job for the last decade is working with zoning ordinances. *Yawn,* right? Except I find it surprisingly intriguing. For example, when I visited Grove City in 2022, I was in the middle of writing new model sign regulations for zoning. The puzzle pieces for this effort included incorporating Supreme Court rulings on the constitutionality of sign regulations and making the regulations easier to understand and follow.1 So signs were already on my mind when I encountered Grove City’s parking sculptures and my brain exploded.
Besides the century-old battle between planners and billboard companies, the most difficult thing about sign regulations is the definition of sign. Art cannot be regulated by zoning, but signs can. However, there is a lot of grey between art and sign. Grove City exemplifies that grey area.
Grove City has a series of outdoor sculptures that incorporate directional signage for public parking areas. Based on a strict interpretation of Pittsburgh’s definition of sign (which interpretation frequently got me into arguments with my boss when I was zoning staff for Pittsburgh), the minute any component of a piece of artwork contains a sign, the whole piece of art becomes a sign (see Pittsburgh’s Zoning Ordinance Section 919.01.C.1). The phrase “or any structure designed to carry the above visual information” supports my interpretation that Grove City’s parking sculptures would not be permitted in Pittsburgh because they would not comply with the sign regulations.
Fortunately, Grove City’s zoning ordinance measures a sign only on the “separate individual letters, words, or graphic elements on the background” (see Grove City Zoning Ordinance Section 702, page 72 of 84 in the PDF). As the structure doesn’t count in the calculation of sign area in Grove City, I can now understand how parking sign sculptures could be created without violating their own ordinance.
If you are a frequent visitor to urbantraipsing, you know I don’t typically take selfies. However, I did with the first parking sculpture I encountered in Grove City to provide a sense of scale. These are substantial structures. I am standing in the selfie…and, for those who don’t know me in person, I am 6 feet tall.
I bought my first car in 2021. It ended up having a lot of problems. The first time I tried to drive to Erie, it started shaking like it was going to spontaneously break apart into a million pieces, just like a cartoon. Instead, it went into limp home mode and I turned around at the next exit, which was the middle of nowhere. After several repairs and a period of no further incidents, the following year I was ready to try again. But first, I tested the car to see if it could handle Rt. 79.
I knew of Grove City as an exit about halfway to Erie and as the closest outlet mall to Pittsburgh. I decided to aim for the actual Borough of Grove City1 as a destination to explore while testing my car’s ability to handle the speed limit and hills of Rt. 79. Naturally, since I arrived safely and knew nothing about the town, I set out to walk the bridges.
A town of 2.7 square miles and less than 8,000 residents, Grove City has several bridges over Wolf Creek and elsewhere. Unfortunately, the town’s premier pedestrian bridge, Rainbow Bridge (pictured above), was closed due to construction activities in the area. I discovered a second, unmapped pedestrian bridge over a small tributary to Wolf Creek, which I crossed only to see a sign on the other side claiming the bridge was not a throughway and directing people to use the sidewalks on the street to reach Grove City College’s main campus.
While the bridges themselves were structurally uninteresting, except for the Rainbow Bridge, I visited a throughout cross-section of town in walking them….which is the point of my bridge walking habit. My path took me through the college campus, the now less prominent industrial area, the large homes built for the boss class of the industries, the small homes built for the industrial workers, and the business district, both the car oriented portion and the historic portion. There are several bridgeless neighborhoods that I did not visit, but even without them, I learned a lot about the town in a short space of time.
Bridge accidents is a common theme this year. The most significant was the collapse of Baltimore’s Francis Scott Key Bridge in March 2024 after being struck by a malfunctioning container ship. However, other accidents happened to bridges in the Pittsburgh area. Weeks after Baltimore’s bridge collapse, the Sewickley Bridge, a few miles downriver from Pittsburgh, closed for a day after being struck by runaway barges (WTAE, April 14, 2024). Then, in August, a dump truck struck an unused railroad bridge in Pittsburgh. The road underneath closed temporarily while the obsolete and now damaged bridge was removed. The adjacent, active railroad bridge remains. (WTAE, August 16, 2024)
Meanwhile, Pittsburgh continues to preemptively close bridges or restrict traffic to reduce the chances of another bridge collapse. The most recent of these is the full closure of Panther Hollow Bridge announced October 19, 2024, with immediate effect. It is called a temporary closure while the City of Pittsburgh figures out what it needs to do for the bridge. (Mayor’s Press Release, October 19, 2024) Other recent “temporary closures” of Pittsburgh bridges have turned into sporadic periods of closure and opening (Swindell Bridge) or a years-long closure while funding is found and repairs are implemented (Charles Anderson Bridge).
Another common restriction we are seeing in Pittsburgh bridges is sidewalk closures while vehicular traffic remains unaffected. Pittsburgh’s South Negley Avenue bridge is one of the bridges in town that is poised as a pending disaster. In acknowledging the structural issues of this bridge, the west sidewalk was closed in 2022. However, I noticed that by July 2023, the barriers on that sidewalk were pushed aside and it wasn’t clear if that was an official move or if pedestrians had taken matters into their own hands. Then, in June 2024, first the eastern sidewalk was closed with a temporary protected pedestrian pathway installed in the car lane (Mayor’s Press Release, June 6, 2024) and then, a week later, the western sidewalk was again closed (Mayor’s Press Release, June 17, 2024). Why this “safety” measure is helpful is beyond me as this bridge has been earmarked for replacement for years pending funding and access issues. Also, the Smithfield Street Bridge sidewalk always has rusted out holes showing the river flowing below that eventually get patched without closing the sidewalk.
Bridges are a vital connectors that enable us to move around as we live our lives. Frequently, we don’t even realize there’s a bridge there…at least not until there’s a bridge disaster. Over the last few years, there have been several bridge disasters, some due to accidents, like the collapse of Baltimore’s Francis Scott Key Bridge in March 2024 after being struck by a malfunctioning container ship, and some due to deferred maintenance, like the collapse of Pittsburgh’s Fern Hollow Bridge on an icy, cold morning in January 2022.
We have seen recently that when there is motivation, the missing links caused by bridge disasters can be repaired in record time. Pittsburgh’s Fern Hollow Bridge was completely rebuilt and opened to traffic 11 months after collapsing, instead of the usual multi-year process to design and build a new bridge. In Philadelphia, when an elevated section of I-95 collapsed after an accident in 2023, the repaired section reopened to traffic 12 days later, compared to 26 days for a similar situation in Oakland, CA. (PBS News, June 23, 2023)
Despite President Biden’s repeated request to Congress to expedite funds to replace Baltimore’s Francis Scott Key Bridge, Republicans in Congress are possibly motivated to delay so that President-elect Trump will get the credit for rebuilding this crucial transportation link. (Fox News Baltimore, November 8, 2024; WCBM, November 8, 2024) Unfortunately, Trump does not have a good track record for funding bridges.
It can be easy to overlook during the buzz of election season that there is often a delay between when a law is signed or a policy adopted and when the effects of that law or policy are felt. Bridges encapsulate that well. The memorable moments are when a bridge closes or collapses (typically viewed negatively) and when a bridge reopens (typically viewed positively). The moment when funds are allocated, the moment enabling a bridge to reopen at a later date, is not often remembered.
For example, it was front page news when the new Greenfield Bridge reopened in 2017, when Trump was President, but the funding that constructed the bridge was allocated when Obama was President. Similarly, the Charles Anderson Bridge has been closed to traffic for most of President Biden’s term in office, to the annoyance of many, but that is also when the funds were found to rehabilitate the bridge expanding the life of this historic bridge by decades. However, the reopening is projected to be in 2026, in the middle of Trump’s second term as President.
Assuming two years as the average time from funding to reopening on bridge reconstruction and rehabilitation projects, I pulled the Federal Highway Administration’s numbers for bridge construction and rehabilitation in Pittsburgh that would have been funded under the leadership of Presidents George W. Bush, Barack Obama, and Donald Trump. (FHWA InfoBridge) Given the delay between funding and completion, it is too early to measure the impact of funding under President Joseph Biden’s leadership.
Bush: 36 bridges total = 4.5 bridges per year
Obama: 76 bridges total = 9.5 bridges per year
Trump: 9 bridges total = 2.25 bridges per year
Bridge maintenance and repair rarely happens without support from federal funding. When the bipartisan infrastructure bill passed under President Biden’s leadership runs out of funds, or those funds get diverted to Project 2025, I am skeptical that new funding for bridges will be found under the leadership of President-elect Trump. Therefore, I expect more bridge disasters or, at the very least, more indefinite bridge closures in the coming years.
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