Would the Golden Gate Bridge have been able to support a BART train?

[homersimpson101]

If Marin County in the San Francisco Bay Area didn't back out of the original BART (Bay Area Rapid Transit) plan, would the Golden Gate Bridge have been able to support a BART train? And was one of the reasons why BART uses wide trains and broad gauge track was because they didn't want the wind to blow off the trains from the Golden Gate Bridge?

 

[JamesWhitcombRiley]

How BART on the Golden Gate Bridge Died: A New History seems a pretty even-handed history, which the writer says has come up a lot in the last few years on SFGate (the once Xam/Chron). The wind is mentioned but not in relation to the wide design.

 

[Willbridge]

If Marin County in the San Francisco Bay Area didn't back out of the original BART (Bay Area Rapid Transit) plan, would the Golden Gate Bridge have been able to support a BART train? And was one of the reasons why BART uses wide trains and broad gauge track was because they didn't want the wind to blow off the trains from the Golden Gate Bridge?

I donnn't know about the wind, but during the planning for the vote there were people saying that it could not support a train. After the vote someone found an old guy Back East who had worked with the engineering firm that designed the bridge and they had assumed that a rail deck could be added. This is just recollection on my part from reading SF newspaper articles from time to time, but it makes sense because when the bridge was designed there already was the extensive SP/NWP commute service on the north side of the Golden Gate.

The broad gauge was just one of many unique features adopted by BART. We can guess at the reasons for each element and there were official reasons, but overall, it seemed to have odd features for the sake of novelty. A test track near Concord was built in 1964 "...for many contemplated new items of transit equipment." The entire 75-mile system was due to open by 1972.

 

[GDRRiley]

If Marin County in the San Francisco Bay Area didn't back out of the original BART (Bay Area Rapid Transit) plan, would the Golden Gate Bridge have been able to support a BART train? And was one of the reasons why BART uses wide trains and broad gauge track was because they didn't want the wind to blow off the trains from the Golden Gate Bridge?

Yes it could have until they reinforced the bridge for earthquakes decades later.
Wayback Machine

Golden Gate Bridge Authority refused to let it happen and some really questionable things to try and prove that.

But behind the scenes, plans for BART over the Golden Gate Bridge didn’t sit well with some, said Louise Nelson Dyble, author of “Paying the Toll: Local Power, Regional Politics, and the Golden Gate Bridge.” Bridge district officials didn’t like the idea of having BART on its span, potentially cutting into its toll base. It shopped around for an engineer who would say trains on the span would not work, she said.

“Those who led the board were very much opposed to having BART cross the bridge,” said Dyble, an assistant professor of history at Michigan Technological University.

They hired Clifford Paine, one of bridge designer Joseph Strauss’ engineers, to assess the feasibility of BART on the span. He concluded it would not work, saying the added weight would stress cables and cause the span to sag enough to be in violation of Navy clearance regulations.

Later, an engineering board of review was commissioned to review all the studies and it also announced rail was not feasible, but Dyble noted the bridge district paid for the panel’s expenses and fees.

Did Marin lose out on BART?

 

[Bonser]

Yes it could have until they reinforced the bridge for earthquakes decades later.
Wayback Machine

Golden Gate Bridge Authority refused to let it happen and some really questionable things to try and prove that.

Did Marin lose out on BART?

I always thought that Marin Co. voted it down because of both the cost and the fear that BART would put a damper on their exclusivity. And it's my recollection that the BART proposal involved digging tunnels, not using the bridge.

 

[George Harris]

I always thought that Marin Co. voted it down because of both the cost and the fear that BART would put a damper on their exclusivity. And it's my recollection that the BART proposal involved digging tunnels, not using the bridge.

Depth of channel primarily and questions about seismic activity to a lesser extent caused the tunnel idea to die a quick death as being completely impractical. Several BART oddities were due to an attempt to "reinvent the wheel" by many of those involved early in the design process. The wide gauge and 1,000 volt third rail were among them. Was told by some that had been involved early on that the wide gauge was due to consideration of wind and sway of span if tracks were built across the Golden Gate, and that adding tracks under the roadway was in the initial plans for BART. Many of the post WW2 rail transit systems, BART among them, had "maybe someday" extensions on their early planning maps. (Most of WMATA's have been built.) (After the first Shinkansen derailment in an earthquake, studies determined and a design developed for an upside down "L" shaped bracket to be applied to the wheelsets that would catch on the rail to keep the train from deviating very far off the track. This is a far less costly method of dealing with the realities of seismic activity.)

 

[JamesWhitcombRiley]

Depth of channel primarily and questions about seismic activity to a lesser extent caused the tunnel idea to die a quick death as being completely impractical. Several BART oddities were due to an attempt to "reinvent the wheel" by many of those involved early in the design process. The wide gauge and 1,000 volt third rail were among them. Was told by some that had been involved early on that the wide gauge was due to consideration of wind and sway of span if tracks were built across the Golden Gate, and that adding tracks under the roadway was in the initial plans for BART. Many of the post WW2 rail transit systems, BART among them, had "maybe someday" extensions on their early planning maps. (Most of WMATA's have been built.) (After the first Shinkansen derailment in an earthquake, studies determined and a design developed for an upside down "L" shaped bracket to be applied to the wheelsets that would catch on the rail to keep the train from deviating very far off the track. This is a far less costly method of dealing with the realities of seismic activity.)

The Golden Gate at its deepest is 377 feet. I suppose the idea was to cross inland from that!

 

[west point]

IMO not trying to put BART on the Golden Gate bridge was probably wise. A suspension bridge is certainly very flexible. A few years ago the bridge decking was replaced with a much lighter set of panels. Very careful planning had to be done as each panel had to be replaced with a corresponding panel some distance away to keep the suspension in balance. There was no start at one end and go to other end. That same variation by BART trains could not be mitigated.

 

[George Harris]

There already is a suspension bridge with rail transit tracks on it. It is the Tsing Ma bridge in Hong Kong, connecting the Kowloon Peninsula with Lantau Island as part of the access to the Chek Lap Kok airport. (Anyone who has ever flown into and out of Hong Kong's Kai Tak airport will appreciate the need for the new one.) It has six lanes on its upper deck and two transit tracks on the lower deck, plus other roadways. Per Wikipedia, it is 135 feet wide, not sure whether that is deck width or between suspension cables, but I suspect the latter. The main span is 4,518 feet and it has a main channel clearance of 174 feet. The tracks are the airport link transit line, standard gauge with 1.5 kV DC, overhead wire. I would suspect the trains are longer and heavier than anything on BART.

There are highly complex rail movement joints on both ends of the suspension component of the bridge to allow for movement of the spans both under traffic and in typhoon weather conditions.

For comparison, again looking at Wikipedia, the Golden Gate Bridge has a main span of 4,200 feet and a clearance of 220 feet above water. Wiki says width of 90 feet. That is definitely not roadway deck width. The roadway is six lanes, and the lanes are narrow, I suspect 10 feet as that was the standard lane width at the time the bridge was built.

 

[west point]

It may be also that the Tacoma Narrows bridge (galloping Gertie ) might have been in the minds of some engineers. The Hong Kong bridge was built in mind of transit support design Golden Gate was not.

 

[MARC Rider]

The Ben Franklin Bridge, Philadelphia to Camden has had a subway train running on it since at least the 1930s. Currently, it's the PATCO Lindenwold Line.

 

[railiner]

The Brooklyn, Willamsburgh, and Manhattan Bridges in NYC all had rapid transit trains on their suspension spans. The latter two still do…
The San Francisco -Oakland Bay Bridge had interurban trains at one time, too.

 

[jis]

It may be also that the Tacoma Narrows bridge (galloping Gertie ) might have been in the minds of some engineers. The Hong Kong bridge was built in mind of transit support design Golden Gate was not.

Galloping Gertie was due to an aerodynamic effect in high wind. How is putting a train on a bridge going to cause the aerodynamics of the bridge deck to change?

Incidentally, the deck design of Whitestone and Throg's Neck Bridges in New York was changed and the decks modified as a result of what was learned from the Tacoma Narrows Bridge failure. So if necessary decks can be modified to address such issues several years after the bridge is built originally.

 

[Just-Thinking-51]

No particular knowledge here, but it really sounds like people were looking for an excuse not to build an extension over the bridge.

Politicians here in NY and elsewhere will study things to death. Had one a few years back saying we need a study to consolidate all the previous studies. So he could understand the issues better before commenting on a project. Double talk at its best.

 

[Bonser]

No particular knowledge here, but it really sounds like people were looking for an excuse not to build an extension over the bridge.

Politicians here in NY and elsewhere will study things to death. Had one a few years back saying we need a study to consolidate all the previous studies. So he could understand the issues better before commenting on a project. Double talk at its best.

But that's to prevent things like the Tacoma bridge disaster.

 

[jis]

But that's to prevent things like the Tacoma bridge disaster.

I am not sure that studying the same thing 15 times will help any politician either understand the issues or make informed decisions about anything compared to studying it 5 times or 10 times, consolidated or not. There are other more pressing issues that drive such decisions in a typical politician's mind

 

[trainman74]

IMO not trying to put BART on the Golden Gate bridge was probably wise. A suspension bridge is certainly very flexible. A few years ago the bridge decking was replaced with a much lighter set of panels. Very careful planning had to be done as each panel had to be replaced with a corresponding panel some distance away to keep the suspension in balance. There was no start at one end and go to other end. That same variation by BART trains could not be mitigated.

Over the bridge's lifetime, I'm sure there have been countless cases of one end of the bridge momentarily having a lot more weight on it than the other end (particularly since trucks are allowed on the bridge), so I don't see why trains would inherently be a problem.

 

[Anderson]

The Golden Gate at its deepest is 377 feet. I suppose the idea was to cross inland from that!

Either side could theoretically work. It's just the strait itself that's stupidly deep.

 

[George Harris]

No particular knowledge here, but it really sounds like people were looking for an excuse not to build an extension over the bridge.

Politicians here in NY and elsewhere will study things to death. Had one a few years back saying we need a study to consolidate all the previous studies. So he could understand the issues better before commenting on a project. Double talk at its best.

But that's to prevent things like the Tacoma bridge disaster.

Many times studies, particularly restudies, if not for the purpose of "hey world, we really are doing something" are for the purpose of killing the project using the "death by a 1,000 cuts" method.

As to having any relation to the Tacoma bridge collapse, a lot of this was what I call second level ignorance. That is, it is not what you don't know that hurts you so much as it is, you don't know there are things there that you should have known. There were two or three primary factors that led to the Tacoma bridge failure. First, slenderness ratio. That is length of suspended section divided by width between cables. Since this was a two lane bridge, this value was far higher than any previously built suspension bridge, which even if not shorter, had considerably wider spaces between outside cables. Second, the use of plate girders instead of trusses as stiffeners under the deck. This resulted in a much larger area for wind pressure. The "or three" is because the strait resulted unusual wind patterns, so it could have been that the wind alone would have been sufficient to give the bridge the "galloping Girtie" moniker, even if the stiffeners had been trusses.

It is highly doubtful that any study would have picked up on all these, if any of these, given the knowledge of the time.

 

[George Harris]

Either side could theoretically work. It's just the strait itself that's stupidly deep.
View attachment 35016

Looking at your map of the deep areas, any tunnel that would avoid the excessively deep areas would likely be twice as long as the shortest route across the strait. Probably better profile, but significantly more expensive due to length alone.
The location and shape of the hole is exactly what you get when an earthfill dam is overtopped. When that happens a gully at the point of overtopping develops and as it erodes the difference between water elevation and low point of the outflow point increases, thus increasing the rate of flow, this process ongoing until the lake is empty. This process is very rapid and results in downstream water flows far in excess of the worst natural flooding. Think the Johnstown PA flood of where the dam of the lake 14 miles upstream overtopped and the lake drained in a matter of a few hours, sending what was reported as a 40 feet high wall of water into the town. That from a lake reported to be 60 feet deep, maximum. At the Golden Gate we see the result of the lake covering most of what is now the Central Valley overtopping the gap. How long did it take? I have no idea, but probably a lot less time than that is commonly extrapolated. I would suspect a few years to a few decades at the most. Remember, what we have here is a relatively narrow ridge, and once overtopped, the volume of water available to flow would be huge and increasing until the lake was empty. This is completely unlike the condition at Niagra Falls which is going over the edge of a plateau with a relatively shallow depth of flow.

 

[cirdan]

I am not sure that studying the same thing 15 times will help any politician either understand the issues or make informed decisions about anything compared to studying it 5 times or 10 times, consolidated or not. There are other more pressing issues that drive such decisions in a typical politician's mind

The summary needs to be written by somebody who can insert the required level of bias. The politician can then make an objective and impartial decision based on that. If the bias inserted turns out to be insufficient to produce the necessary result, a new summary is commissioned.

 

[Willbridge]

No particular knowledge here, but it really sounds like people were looking for an excuse not to build an extension over the bridge.

Politicians here in NY and elsewhere will study things to death. Had one a few years back saying we need a study to consolidate all the previous studies. So he could understand the issues better before commenting on a project. Double talk at its best.

The Golden Gate bridge district which was an independent authority was looking for a way to protect its toll revenues. Their studies recommended against, BART District's study said it was feasible. A consequence of their opposition was their need to offer an alternative. which became their bus and ferry system [which I think was a good idea].

I wasn't around when the two bridges were built and my dad is gone now so I can't ask him, but for some reason the Trans-Bay Bridge is run by Caltrans and the Golden Gate Bridge is run by the authority. The history of it suggests that it had to do with financing. And as mentioned above, the Trans-Bay carried suburban and interurban trains of the Key System and the Sacramento Northern.

https://en.wikipedia.org/wiki/Golden_Gate_Bridge#Gallery
Same Bay, completely different history:

 

[desertflyer]

I currently sit on the Golden Gate Bridge Pedestrian and Bicycle Advisory Committee. It's really interesting to hear the history of the bridge, how it was funded, and how that all factors into the way the bridge district operates today, a lot of which you've all already discussed in the thread.

From what I can tell, the district has really no incentive to ever work with another agency to link service across the gate. It complicate things as far as bridge management is concerned. You wouldn't believe how many conversations we have just trying to determine who has jurisdiction in the spots around the bridge itself and whether or not something falls into the bridge district, Caltrans, or one of the National Parks. It makes even the smallest things complicated when it comes to projects and improvements. These entities don't work as closely together or as proactively as you might expect.

Right now, in addition to the constant earthquake retrofitting, most resources are going into the suicide deterrent net, which is slated to be completed pretty soon. They've also been investing a lot in lowering the load on the bridge to reduce fatigue and maintenance as the bridge ages. Two things have done in that regard is replace the bridge deck with lighter material and replace the slats along the sidewalk to reduce wind resistance, as storms and wind worsens across the gate with the impacts of climate change.

Something that's kind of interesting is that replacing the slats with the narrower ones has cause two unexpected consequences. The wind on the west side bicycle path is now significantly worse, to the point of being dangerous. It has also caused the bridge to hit a resonant frequency on windy days causing an ominous loud hum that can be heard for miles around. There is now a plan moving forward to install small aluminum clips that will act as disruptors to reduce the amount of noise without negating the span's wind drag improvements. A good way to spend an additional $450k!

All this is to say that the district is mostly in a maintenance mindset now, and I wouldn't expect that to change. Long gone are the days of proposing BART or even a second road deck - something that was deemed feasible by the district in the 1960s once BART across the span was already nixed.


Knowing how the bridge is managed today, I can imagine that they are glad they didn't more forward with either BART or the second deck due to the wear and wind issues it would cause as the wind worsens and the bridge ages. However, the lack of frequent, high quality transit between SF and the north bay has caused quite the ripple effect. In SF, Geary Blvd would probably have subway rail service instead of the BRT-lite transit it has today, Marin and Sonoma County would be more connected to the city, and transit riders would have a lot more mobility.

Sorry for the rant.

 

[John Santos]

[...]

Knowing how the bridge is managed today, I can imagine that they are glad they didn't more forward with either BART or the second deck due to the wear and wind issues it would cause as the wind worsens and the bridge ages. However, the lack of frequent, high quality transit between SF and the north bay has caused quite the ripple effect. In SF, Geary Blvd would probably have subway rail service instead of the BRT-lite transit it has today, Marin and Sonoma County would be more connected to the city, and transit riders would have a lot more mobility.

Sorry for the rant.

I've taken the Muni to the Sausalito ferry to catch the bus to Muir Woods and/or Mill Valley a handful of times over the last several decades. It was a fun trip if you are not in a rush, but would probably be way too slow and infrequent for commuters.

 

[BCL]

Where to start? The issue with BART was supposedly the novel aluminum shells, which were extremely light. Not sure about bridges, but they have several viaduct sections from Richmond to Berkeley as well as from Oakland to Fremont. There were worries about the wind possibly knocking over cars where it was about 35 feet down.

People were allowed to walk on the roadway during thr 50th anniversary of the Golden Gate Bridge. They didn’t carefully balance the weight, but at one point the roadway was noticeably flattened, when it typically is arched.

As for suspension bridges with rail, the Oakland-San Francisco Bay Bridge had Key System trains going through both spans. It did use the lower deck though, which had sway bracing the same as the cantilever section.