> 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.
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).
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):
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.
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 90° turn which might lead to really dangerous situations due to poor visibility and high speed.
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:
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.
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.
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.
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.
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.
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).
I wasn't even referring to signs that are only applicable in specific weather conditions, just pointing out the absurd amount of handholding drivers tend to get. Some drunk chump might run straight into the trees? Add more reflective chevrons. Someone still crashed? Add flashing LEDs.
And yes, German signage certainly does weather dependency, speed limits with "Zusatzzeichen 1052-36" are quite frequent (I think it's put up everywhere the surface doesn't drain as good as it should, e.g. if surface angle changes slightly from the ground setting after construction)
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.
Cycling infrastructure designed by people who don't cycle is far too common.
A favourite example I have to deal with often is when the path has to narrow, so they put up signs telling all cyclists to dismount. I pass through a few of these often, and whenever a cyclist obeys the sign it creates immediate congestion because pushing a bike is slow and takes up more space. Then you get a cascade effect of pedestrians stepping into car traffic to avoid the bottleneck.
Another is rumble strips to slow down bikes at pedestrian crossings. It doesn't slow anyone enough to prevent incident, and tends to give pedestrians an illusion of priority so they stop looking for bikes in the path. Not to mention being uncomfortable enough to discourage using the bike path at all, and shaking lights out of position.
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.
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...
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.
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).
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.
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.
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.
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.
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.
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.
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.
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 Cheviré on a bike for example...
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.
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.
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.
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.
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):
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.
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.
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.
As a Mumbaikar living in the Netherlands (where OP appears to be), you're right - such underpasses will be a terrible idea in the monsoon season for Mumbai-like places.
However for the Netherlands, rain is much more evenly distributed across the year and even "heavy" rain days are much lesser than the amount of rain a tropical city like Mumbai gets - which is why it's unlikely to be a major issue in the NL.
(Side note I don't think there are pumps at every underpass if at all, perhaps only if the underground drains/sewers overflow. Also NL maintains high sea walls/dykes partly out of necessity so there likely will be place to pump it here.)
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.
> 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.
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.
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.)
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.
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.
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.
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.
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.
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[ 4.9 ms ] story [ 94.7 ms ] threadI 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
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 ;).
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 90° turn which might lead to really dangerous situations due to poor visibility and high speed.
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....
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.
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?
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.
Can you link to an example?
[0] https://maps.app.goo.gl/pbCArbN5yraJZFBw9
Actually turns out they're a terrible idea, tbh.
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).
And yes, German signage certainly does weather dependency, speed limits with "Zusatzzeichen 1052-36" are quite frequent (I think it's put up everywhere the surface doesn't drain as good as it should, e.g. if surface angle changes slightly from the ground setting after construction)
A favourite example I have to deal with often is when the path has to narrow, so they put up signs telling all cyclists to dismount. I pass through a few of these often, and whenever a cyclist obeys the sign it creates immediate congestion because pushing a bike is slow and takes up more space. Then you get a cascade effect of pedestrians stepping into car traffic to avoid the bottleneck.
Another is rumble strips to slow down bikes at pedestrian crossings. It doesn't slow anyone enough to prevent incident, and tends to give pedestrians an illusion of priority so they stop looking for bikes in the path. Not to mention being uncomfortable enough to discourage using the bike path at all, and shaking lights out of position.
Do you by chance mean those things on the ground with the raised dots/grooves? [1]
Those are actually for helping the blind navigate it. If it is something different JUST to slow bikes though... That just makes me go WTF.
[1] https://cdn.w600.comps.canstockphoto.com/man-walking-on-yell...
You mean like the "traffic calming measures" most urban roads have, to slow down cars?
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...
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.
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).
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.
Just like this place: https://goo.gl/maps/gwfGxdxDs4sbpF2S7
Or this with a station on a curve: https://goo.gl/maps/Eo5fZK5E8kYoFAuW8
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.
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.
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.
A design that is safe, but makes “the people” think it is dangerous is a failed design, as fewer people would use it.
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.
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.
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 Cheviré on a bike for example...
Clearly for crossing any lengthy stretch of water, a bridge is much preferable to a tunnel.
> 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.
> The article is actually about underpasses, which are not "tunnels" but rather a bridge (or overpass) built on the "other" road.
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.
But I don't think I ever used this word... I'd say tunnel I guess.
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):
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.
However for the Netherlands, rain is much more evenly distributed across the year and even "heavy" rain days are much lesser than the amount of rain a tropical city like Mumbai gets - which is why it's unlikely to be a major issue in the NL.
(Side note I don't think there are pumps at every underpass if at all, perhaps only if the underground drains/sewers overflow. Also NL maintains high sea walls/dykes partly out of necessity so there likely will be place to pump it here.)
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.
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.
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.)
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.
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.
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.
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.