[HN Gopher] Cycling: Why Tunnels are Better than Bridges (2014)
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Cycling: Why Tunnels are Better than Bridges (2014)
Author : pmontra
Score : 96 points
Date : 2022-06-26 06:13 UTC (16 hours ago)
(HTM) web link (www.notechmagazine.com)
(TXT) w3m dump (www.notechmagazine.com)
| pacifika wrote:
| If we would keep the tunnels smelling less like urine, I would
| agree more
| bagels wrote:
| It's amazing how well bike/pedestrian bridges and underpasses
| so effectively capture urine.
| 11235813213455 wrote:
| what a waste of a resource useful for the soil / grass /
| plants
| Graffur wrote:
| As a kid I had to cycle through one of these. There was always
| anti-social behaviour around them.
| iostream24 wrote:
| Not the sort of tunnels I was thinking about, obviously. Mountain
| tunnels for cars often have no room for pedestrians or
| maintenance workers let alone cyclists, and basically zone-limit
| cyclists.
| AlbertCory wrote:
| In America, we'd call that an underpass, not a tunnel, as others
| are pointed out.
|
| Actual tunnels in America are scary as shit to cycle through. The
| "sidewalk" is maybe 24 inches wide, and the cars are 6 inches
| from you. There is no shoulder to ride in.
|
| Whereas bridges tend to have normal width sidewalks, like in his
| picture.
| anttiharju wrote:
| > A possible disadvantage is low social safety. It is important
| that cyclists can see out of a tunnel before they enter it. There
| should be no turns within the tunnel, no-where for a potential
| mugger to hide. Obviously tunnels should also be well lit.
|
| I feel like this is something that's often neglected.
|
| Just recently here in Finland there was a case where a cyclist
| died because a roadblock made of concrete was brought to the
| middle of a dark tunnel.
|
| The goal was to block cars from using the tunnel, but for the
| summer the tunnel's lights were turned off. The cyclist hit the
| roadblock at a relatively high speed, was basically launched
| forward and pretty much immediately died on impact to the ground.
|
| Now of course maybe the cyclist shouldn't have been going that
| fast, but the decision to bring a roadblock to the middle of a
| dark tunnel is also questionable. Maybe two roadblocks at each
| end (where there is natural light)?
|
| I feel tunnels are much more dangerous than bridges. They're dark
| and the downhills leading to them encourage high speeds.
|
| Link to the news article: (in Finnish)
| https://yle.fi/uutiset/3-12456122
|
| Google translate seems to do well on the article: https://yle-
| fi.translate.goog/uutiset/3-12456122?_x_tr_sl=fi...
|
| Although maybe concrete piglet/pig should be just "concrete
| roadblock"
|
| edits: added the news articles
| usrusr wrote:
| Was just about to write something similar, just without the
| bloody evidence: the "no turns!" part should be right at the
| start where benefits of inertia-assisted climbing is
| advertised, because that all turns into the opposite when there
| are turns that force inhertia loss (or, more likely: some in-
| between of inertia loss and risk taking).
| jaclaz wrote:
| In theory (but not always in practice) the steepness of the
| road accessing the underpass should be within the limits
| stated for the type of road (so - again in theory - not too
| steep).
|
| A good example of how NOT to design an underpass (very steep
| AND curve in the middle), this is Florence (Italy):
|
| https://www.google.it/maps/@43.7754979,11.2351912,3a,75y,53..
| ..
|
| But they did put on a sign to prevent pedestrians to access
| it, so the mugglers won't go hiding there ;).
| anttiharju wrote:
| At first glance that underpass didn't seem that steep, but
| then I went to look for the underpass which I feel is super
| steep, I realized, maybe it's just difficult to get a good
| sense of the steepness from streetview.
|
| Here's one I've gone through and feel is a rather dangerous
| one: https://maps.app.goo.gl/pU36XG6J89QL2nqJA
|
| The view is from top of the underpass, but if you look to
| the back left you can see there's a downhill and then a
| really sharp 90deg turn which might lead to really
| dangerous situations due to poor visibility and high speed.
| jaclaz wrote:
| Yes, streetview does not convey the actual situation, in
| person it is steep (though I have seen steeper ones).
|
| That underpass is just after a bridge (over the river) so
| they couldn't make it less steep by making the ramp
| longer, but the cyclists (those that know the area) can
| turn on the right right before the ramp and use the
| "normal" roads/streets, someone that isn't already
| familiar with it is taken by surprise.
|
| This view from a bit further renders a little better the
| situation:
|
| https://www.google.it/maps/@43.7752485,11.2348264,3a,75y,
| 22....
| usrusr wrote:
| Some more thoughts about the risk taking: that inevitably
| happens to everyone, even the least reckless. Magnitudes
| certainly differ, but it's always far from gone. Because when
| cycling, the brain unavoidably enters a state that would be
| called hypermiling if it happened while driving. The bad
| thing about stopping or slowing down isn't so much the time
| lost, it's the exertion required to get going again. And that
| logic does not just happen on the conscious level, it's much
| deeper. You'll hate applying the brakes even if, on the
| conscious level, exertion is the only goal of the ride
| because you're not going anywhere but doing a workout.
| "Stopping leads to exertion, don't stop" must be some preset
| circuit in our brains that has been there since before
| bipedalism. It's certainly also noticeable when driving (we
| hate the red light even when not in a hurry at all) but it's
| much stronger when the exertion isn't just a gentle touch
| with the right foot.
|
| Back to that straight tunnel from the picture: something like
| that is extremely rare, because bike roads are rarely built
| completely separate from other roads and when they are not
| separate, the descent/ascent parts inevitably get folded into
| wherever they fit.
| _ph_ wrote:
| Admittedly, bike lighting is a solved problem by now, one
| shouldn't bike where you cannot see. There is always the risk
| of an obstacle you wouldn't expect, could be even an injured
| person blocking the way.
|
| But of course, this doesn't justify any of those ridiculus and
| dangerous artificial blocks. Just clearly marking the bike
| paths with color should be good enough. If an car ever is
| caught there, well, rip apart the drivers license. Or just
| leave it to the bicyclists :p I have seen too many of those
| blockages myself, they are dangerous and often enough I cannot
| pass them with my bicycle.
| matsemann wrote:
| Yeah, destroying pedestrian and cycle infrastructure to keep
| cars out is a pet peeve of mine. It's often dangerous, makes
| the path inaccessible, and just plain ugly.
|
| Like the "concrete pigs" you mention. Often not marked
| properly, and cyclists have to slow down to a crawl to pass.
| Often 90% of the road is blocked with a boom barrier, and
| pedestrians and cyclists all have to share the remaining part
| to squeeze through. That only increases conflict. Also pretty
| hard for bigger cargo bikes, wheelchairs etc to pass. During
| winter, the booms are opened for the snow plow and then closed.
| Which means that as a cyclist I still have to cycle around on
| the un-plowed part...
|
| It's insane the lengths one has to go to avoid cars destroying
| everything.
|
| Edit: An example pic https://imgur.com/a/FmDd5Ve Nice wide
| road, have to close it off with a boom because of cars.
| Pedestrians and cyclists have to pass on the icy parts...
| throwaway0a5e wrote:
| Some drunk mistakes the bike path for their turn and the
| municipal planner shows up to work on Monday with an inbox
| that's been blown up by a million Karens screeching about
| "gotta keep cars out"
|
| So he goes through the catalog of typical off the shelf
| solutions that exist in his trade, selects a reasonable one
| and has it installed. 6mo later his inbox gets blown up by
| the same million Karens screeching about how the barrier made
| the bike path suck.
|
| A large subset of the public is made up of people that don't
| understand that everything is tradeoffs and think they can
| have their cake and eat it too. And because these people
| can't wrap their minds around the tradeoffs it's impossible
| to have the adult dialog regarding which tradeoffs they
| dislike least that needs to be had if the least worst
| solution is to be reached. There's no winning when dealing
| with this kind of customer base unless you creatively define
| "winning" to exclude customer satisfaction. But when you do
| that you get other failure modes. You can sometimes money
| your way around the problems but that's just a constant
| factor improvement on something that's exponentially crap.
| [deleted]
| null_object wrote:
| At the end of this article (translated from Swedish) are a
| whole bunch of deadly obstacles placed in the way of cyclists
| "for their own safety": https://bicycling-
| se.translate.goog/blogg/bilhindren-som-dod...
| matsemann wrote:
| Yeah, those pictures are quite crazy. I follow him on
| Twitter and saw the thread asking for examples, I think he
| got hundreds of images!
| checkurprivlege wrote:
| worst are the iron chains hanging 30 cms over the ground
| bagels wrote:
| Just yesterday I had such a conflict. Someone thought one of
| these narrow openings was a good be place to stop for dog
| defacation.
| FastMonkey wrote:
| Tunnels are also significantly more expensive, which is why
| they're so rare. With a tunnel, you generally have significant
| earthworks, possibly a permanent groundwater issue (you may
| have essentially created a boat that you do not want to float),
| and you still have to build a bridge capable of carrying
| whatever traffic the bikes are bypassing. A bicycle bridge is
| just the bicycle bridge, a relatively light structure, easy to
| construct and maintain.
| benj111 wrote:
| >Now of course maybe the cyclist shouldn't have been going that
| fast
|
| Now replace cyclist with motorist.
|
| Would it be in anyway acceptable for someone to plonk an
| unmarked concrete block in the middle of an unlit road?
| usrusr wrote:
| That never happens to motorists because the roads are rarely
| designed by people who don't drive. For cycling, that's not
| often false than true, unless you consider people who know
| how to ride a bike because they did it as a child as falling
| into the "true" bin, or people who never ride outside some
| vacation resort, and never faster than 10 mph.
| Gordonjcp wrote:
| > Would it be in anyway acceptable for someone to plonk an
| unmarked concrete block in the middle of an unlit road?
|
| You mean like the "traffic calming measures" most urban roads
| have, to slow down cars?
| occz wrote:
| Traffic calming measures, unless implemented entirely
| incorrectly, are not unmarked. To have them unmarked would
| defeat the purpose, which is to indicate that the driver of
| the vehicle attempting to navigate the street must slow
| down. It is not in the interest of those living on a street
| with traffic calming measures to have drivers cross the
| traffic calming measure at a high speed.
| bagels wrote:
| Narrow or winding roads, or roads with no central marker
| are calming techniques often unaccompanied by signage
| Gordonjcp wrote:
| Okay, but many of those traffic calming measures are a
| big concrete block in the middle of the road.
| anttiharju wrote:
| Probably no.
|
| But there is a guideline that you should only go at the speed
| from which you can stop from within the visible part of the
| road.
| usrusr wrote:
| And yet roads are full of highly visible warning signs
| whereverr there is a turn that might not be safe at
| slightly beyond general maximum speed in some weather
| conditions.
| anttiharju wrote:
| I'm not sure I've seen weather condition specific warning
| signs, apart from the speed limits being lowered for the
| winter season by swapping the signs themselves.
|
| Can you link to an example?
| seszett wrote:
| They're pretty common in some places. The E17/A22
| entering France for example has these overhead signs[0]
| that go from 110 in good conditions down to 70 in very
| bad conditions or even 50 if there's congestion. There
| are also similar signs in Belgium but they're more rarely
| adjusted depending on weather, it's usually just
| according to traffic.
|
| [0] https://maps.app.goo.gl/pbCArbN5yraJZFBw9
| devilbunny wrote:
| I can't seem to find a link, but I know there is a fog-
| prone Interstate zone in eastern Tennessee (probably
| I-81, might be I-40) with variable speed limit signs not
| terribly different from those on UK smart motorways.
|
| Hungary has an elegant, low-tech solution. Broad white
| stripes are painted ~100 m apart on the shoulder of the
| road. Fixed signs indicate the allowed speed - if you can
| see three, it's 130, two is 110, one is 80 (or something
| like that - it's been a few years).
| solar-ice wrote:
| The UK's "smart motorways" project does this.
| https://en.wikipedia.org/wiki/Smart_motorway
|
| Actually turns out they're a terrible idea, tbh.
| silvestrov wrote:
| Dark underpasses can be avoided by splitting the "bridge" into
| multiple smaller bridges.
|
| Example of a "6 lane" split into 6 smaller bridges:
| https://goo.gl/maps/V84SqmbjkASapyxQA
|
| This allows for a lot of light and no overhead lights are
| needed.
|
| (my gut tells me this design was used to improve
| maintainability: you cannot completely close the bridge or
| highway as the city is too dependent. But they could get away
| with closing 1-of-5 bridges for some time).
| Symbiote wrote:
| Five of the six bridges carry railway lines.
|
| I think the design is more likely because the tracks are very
| close to a station, so they're spaced widely to allow for the
| platforms.
| silvestrov wrote:
| The station is very small and cheaply built, so it might
| have been cheaper to make two tracks on one bridge and then
| have the "people platform" on each side of the tracks
| instead of between.
|
| Just like this place: https://goo.gl/maps/gwfGxdxDs4sbpF2S7
|
| Or this with a station on a curve:
| https://goo.gl/maps/Eo5fZK5E8kYoFAuW8
| jpcapdevila wrote:
| > "Tunnels offer protection from wind and rain."
|
| Not sure about this one. Back home in Guadalajara Mexico a lot of
| tunnels get flooded during rain season. I'm talking about 6ft of
| water.
|
| To be fair, even streets turn into rivers / pools.
| codeangler wrote:
| This article is right for a single scenario: the long straight
| away in and out of a fair weather, well drained path/road/bikeway
|
| As others have mentioned adding a turn before or after the
| underpass increases risk. A number of them (person to person,
| hidden obstruction, unsafe traction spots: ice, damp silt, etc)
|
| A pedestrian bridge has recently been replaced in town (boulder,
| co) And I miss the bridge each day I commute. The pedestrian
| underpass has poor visibility (compared to the bridge that was
| there) and the above stated risks. While snow/ rain/ice would
| build up at times, it would clear out days sooner than the
| underpasses along my four mile commute.
|
| But I was shouting to the wind to keep the bridge, as part of the
| financing for pedestrians underpasses in town is funded by
| fed/state/local flood mdigiation dollars.
| _ph_ wrote:
| Yes, as bicycles/pedestrians are not as tall as trucks, the
| underpasses can be lower with all resulting benefits. So yes, the
| bikes probably should go under the cars. Doesn't mean however,
| that the cars couldn't go over a raised bridge. Or even just
| split the difference. Have the underpass go down like 1.5m and
| then raise the road above that.
| jaclaz wrote:
| The article is actually about underpasses, which are not
| "tunnels" but rather a bridge (or overpass) built on the "other"
| road.
|
| Such "tunnels" are normally very short and straight, so I cannot
| understand the reference to turns in the article, a "real" tunnel
| is several tens of meters, more often hundreds or thousands
| meters long and very likely is not straight, though I doubt that
| they are the preferred hideout for mugglers aiming at cyclists.
| nstom wrote:
| Based on his name and the picture in the article, I assume the
| author is Dutch. We don't have the distinction between
| underpasses and tunnels in our language and just call
| everything 'tunnel'. It may have to do with the country being
| so flat that there are no mountains to tunnel through.
|
| I can only think of a single real bicycle/pedestrian tunnel,
| which is the Maastunnel in Rotterdam. Incidentally it is also
| one of the oldest tunnels in the country. It was recently
| renovated and is actually really pleasant to cycle through,
| because motorised traffic uses a separate tunnel tube.
|
| As for turns in underpasses, at complex junctions or
| infrastructural elements it may be tempting to just make a
| small bend so that the underpass is cheaper to build or easier
| to fit in to the environment. Take these crossroads for
| example: https://goo.gl/maps/21Yqj89WwyiiuZfD9. If you look
| closely you will see a bicycle tunnel going underneath from the
| southwest to the northeast. This important connection for the
| residents southwest of the shopping center is relatively long
| and has a slight bend. This makes it feel dark and unsafe to
| the people who use it.
|
| A better design can be found at this roundabout:
| https://goo.gl/maps/TXuFjXj85huufc7m6. Because the middle
| section is open, all of the individual underpasses are short
| and there is a lot of daylight, making cycling there safer and
| more pleasant.
| jaclaz wrote:
| Yep, I understand that now.
|
| Here in Italy (where we have lots of mountains and conversely
| tunnels) the distiction between tunnel and underpass (or
| overpass) is neat, we also have (though not extremely common)
| distinctions betweeen different kinds of tunnels (Galleria):
| Beldin wrote:
| Overpass is called "viaduct" in Dutch, though a multi-lane
| overpass is often colloquially called a tunnel. We do have
| tunnel-like structures for what technically are overpasses,
| eg.: bike path next to a river; major multilane road crosses
| river+bikepath; resulting structure for bike path is a tunnel
| (Dommeltunneltje in Eindhoven), though doesn't go
| underground.
| LittlePeter wrote:
| There is "onderdoorgang", which shows similar images as in
| the OP: https://www.google.com/search?q=onderdoorgang
|
| But I don't think I ever used this word... I'd say tunnel I
| guess.
| rmbyrro wrote:
| Clarification: this is valid, useful criticism, not at all
| pendantry.
|
| Usage of the "tunnels" word got me confused through the first
| half of the article, until it showed a photo of an underpassage
| in the Netherlands.
| owisd wrote:
| The difference Network Rail (the UK's rail infrastructure body)
| used to distinguish between a tunnel and a bridge was that if
| it was over 20m long it was a tunnel, but then someone came up
| with the bright idea to redefine a tunnel as over 30m long, so
| everything in the 20-30m range would cost less to maintain
| because bridge engineers were cheaper than tunnel engineers.
| anttiharju wrote:
| Yeah, underpass is a much more appropriate name.
|
| Now that you mention it, it does seem strange that the article
| doesn't mention turns before/after tunnels as those tend to
| lead to risk taking (going too fast into the underpass that you
| can't see into).
|
| At least in Finland the underpasses used by cyclists are also
| used by pedestrians, so the underpasses being used as mugging
| spots is conceivable, although I've never heard about it
| happening.
| Someone wrote:
| I think it's more about perceived safety than about actual
| risks.
|
| A design that is safe, but makes "the people" think it is
| dangerous is a failed design, as fewer people would use it.
| emn13 wrote:
| I live near a mixed use cycle+pedestrian underpass under a
| railroad that has curves into and out of it. It's mildy
| terrifying in a way that's surely by design. I don't know
| how safe it actually is, but it _is_ used very heavily -
| because it's by far the shortest path connecting most
| routes on the opposite sides of the train track, which
| trumps virtually all other concerns in day to day traffic,
| especially for pedestrians and cyclists.
|
| And hey, there's no car traffic, so accidents are likely to
| be at least a little milder, though hitting one of those
| stone pillars is perhaps not much better.
| bobthepanda wrote:
| Actual tunnels are usually pretty awful for cyclists,
| pedestrians and motorcyclists since they tend to be hot and
| full of exhaust fumes.
| sofixa wrote:
| Not if the tunnel is cycle and pedestrian only, like the Sint
| Anna tunnel under the Scheldt in Antwerp.
| robinson7d wrote:
| Totally, and this seems to be exactly the type of tunnel
| that the article's author is discussing, evidenced by the
| second point they make:
|
| > Tunnels have a smaller height difference than bridges.
| Only need clearance for the height of a cyclist, not for
| trucks or trains plus electric lines.
| bobthepanda wrote:
| Note the phrasing of "actual tunnel", which is meant to
| agree with this in the comment chain
|
| > The article is actually about underpasses, which are
| not "tunnels" but rather a bridge (or overpass) built on
| the "other" road.
| Gualdrapo wrote:
| And (at least here in Bogota) they are pretty good places for
| burglars to hide, surprise and attack cyclists.
| AlecSchueler wrote:
| Any tunnel I've been in has been fine. Motorcycles can't
| enter, they have to go on the road, not the cycle lane.
| Smaller "scooters" can be admitted but there is plenty of
| active ventilation to deal with that.
|
| In the case of the Maas Tunnel in Rotterdam there is a second
| tunnel for combustion vehicles. Pedestrians have a tunnel of
| their own below the cycle tunnel.
| agsnu wrote:
| I immediately thought of the Rotherhithe tunnel in London.
| While pedestrians and cyclists can use it, it's grim - see
| this video for example of someone walking it
| https://www.youtube.com/watch?v=hjAHzZa_pc8
|
| Clearly for crossing any lengthy stretch of water, a bridge
| is much preferable to a tunnel.
| AlecSchueler wrote:
| You're basing that position of the case of one badly
| designed bridge though. Try some underwater cycling
| tunnels in the Netherlands. The Benelux tunnel is a joy
| to use.
| vinay427 wrote:
| I think they meant tunnels in general that affect people
| not in cars, including motorcyclists, because of their lack
| of a loosely airtight or climate-controlled environment. As
| opposed to a tunnel specifically for bicyclists and
| motorcyclists, which is also how I read it at first.
| seszett wrote:
| The Kennedytunnel in Antwerp is two-level with a bike
| tunnel on top of the (very crowded) motorway, and it does
| smell of fumes in spite of the ventilation.
|
| The large detours of the bike path at both ends of the
| tunnel are also a bit annoying as they significantly
| increase the distance you have to cycle. The alternative
| with elevators like in the Sint Annatunnel isn't really
| better though, because there you just have to wait for a
| long time for the elevator.
|
| I much prefer bridges but where I've used bike bridges
| (like in Nantes) they were very low with little clearance
| above water. Even in Lille they're just a few meters, maybe
| ten meters at most, above water, so they're easy to climb
| without a large detour.
|
| I wouldn't take the Pont de Chevire on a bike for
| example...
| em-bee wrote:
| this is a summary for a more detailed article here:
| http://www.aviewfromthecyclepath.com/2014/08/why-tunnels-are...
| trompetenaccoun wrote:
| >no-where for a potential mugger to hide
|
| Or maybe the opposite: Design cities to give muggers even more
| spaces to hide. Maybe then the people looking the other way will
| finally notice that there are major cultural/political issues in
| the societies where muggings are commonplace. I've yet to hear
| about Japanese tunnels being engineered specifically to reduce
| muggings.
| sriram_malhar wrote:
| Underpasses are terrible for coastal cities that receive a lot of
| rain. I am thinking in particular of places like Mumbai in the
| monsoons, where the water accumulates much faster than you can
| pump it out (enough to keep it dry-ish at all times). There is
| also the problem of where to pump it to, esp. if the tide's up
| and all the drainage is already full.
| analog31 wrote:
| In my locale, there's been extensive construction of bike
| infrastructure. There's some kind of grand plan, but it makes
| sense that provisions for bikes are added when they're going to
| rebuild everything: The road, crosswalks, sewers, etc. And
| there's no space left in town where they're not trying to cram
| everything together.
|
| So the choices of bridges or tunnels tends to be one of what will
| actually fit. There's one giant road intersection where there are
| two bridges and a tunnel.
|
| The tunnel fits entirely within the footprint of the road above
| it, which is 6 lanes and carries heavy trucking. Its cost was
| probably absorbed by the overall project cost and need to support
| those 6 lanes throughout. The bridges can be much lighter, since
| they really only need to support themselves, but need extra space
| at the two ends for the ramps. One of these ramps displaced a
| house that was there.
|
| In the town where my son attends college, there's a bike path
| along a river, that regularly gets flooded when the river rises.
| But that was by design -- space for the bike path also doubles as
| a flood control measure, as is true of a lot of park space that's
| built along rivers.
| michaelcampbell wrote:
| > Tunnels have a smaller height difference than bridges. Only
| need clearance for the height of a cyclist, not for trucks or
| trains plus electric lines.
|
| Well, sure. Tunnels built _FOR BICYCLES ONLY_ will have this
| advantage. A bridge build FOR BICYCLES ONLY would have similar
| small height requirements so this seems kind of moot.
|
| Seems that the rest of the ideas are mostly based on the same
| one; smaller inclines/declines. The "work first, then coast" is
| not, of course.
| rakoo wrote:
| No, a bridge needs to go over the road that is used by trucks,
| even if the bridge is bicycles-only
| michaelcampbell wrote:
| That is a good point, but I was thinking of it in terms of 2
| roads are going to cross and rather than make an intersection
| you have the choice of a bridge or a tunnel. On that road,
| the same trucks/bicycles/etc will use it regardless of your
| choice, so the tunnel can't be any less "height aware" than
| the bridge.
| fdupress wrote:
| Wait... A bridge built for bicycles only to go over still needs
| cars and lorries and other large things going under it.
|
| A bridge built for bicycles only to go under is nice, and means
| not even having to deal with a slope. (But might be more costly
| than a bicycle tunnel.)
| michaelcampbell wrote:
| I was speaking to the requirements of the bridge's height
| requirements, not the ones of the road it goes over, but
| point taken.
| sk8terboi wrote:
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