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I know you guys are traffic engineers and not bridge engineers but does this look more or less ok? I imagine the cycle track was a more recent upgrade, which explains why the bridge structure isn't centered under the car part. Or should everything shift over to the left and leave the right side over-hanging more? But do the general proportions look more or less believable? It's 2 18-20m spans, so pretty small bridge. I imagine it was 3 lane but then they took out one of the lanes for a cycle track. Baronjutter fucked around with this message at 21:27 on Jul 27, 2014 |
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Jul 27, 2014 20:11
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If this is for the US, then you seem to have accidentally added too many bicycle and ped lanes.
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Jul 28, 2014 00:19
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Volmarias posted:If this is for the US, then you seem to have accidentally added too many bicycle and ped lanes. No the number is fine, he just made them more than half again as large as 'necessary', especially the bike lane.
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Jul 28, 2014 00:50
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They're all narrower than the rest of the network, it's a bit of a bottle-neck actually! The sidewalks are only about 1.5m wide, which is pretty narrow for a city sidewalk (all the sidewalks here seem to vary between about 3m and 5m+). If the cycle track was any narrower there'd be no room to pass safely, it's two-way traffic.
Baronjutter fucked around with this message at 01:05 on Jul 28, 2014 |
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Jul 28, 2014 00:53
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Baronjutter posted:I know you guys are traffic engineers and not bridge engineers but does this look more or less ok? A few comments: - 2.5 m construction height is quite a lot for a 20 m span bridge, - Steel girder bridges like this are very susceptible to fatique issues, - I wouldnt recommend the overhangs on the side of the bridge, it would be better to add a support beam from the end of the overhang to the main girders, or just add another girder, - Have you considered prestressed concrete girders? If you have over 2.5 meter of construction height available, I'm fairly sure this would be the most viable option. Also, I just read that this bridge is going over train tracks. In that case i would most definitely recommend concrete. Steel bridges require a lot of maintenance, and if you have to shut down rail traffic every time you do maintenance to the underside of the bridge, the economic costs would rise pretty fast. Dutch Engineer fucked around with this message at 09:27 on Jul 28, 2014 |
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Jul 28, 2014 08:40
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Dutch Engineer posted:A few comments: So it would look more or less the same but instead of steel beams there would be fatter concrete beams? For two 20m spans carrying a 13m road with only 2 car lanes what would the general cross section look like? How many beams and approx what height/width for each beam?
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Jul 28, 2014 15:37
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I saw this in Atlantic City, NJ, and it struck me as...useless. https://www.youtube.com/watch?v=DPLO08S8Ec8 The only explanation I can think is the road was "recently" converted to a one way street, and they forgot to remove the light. But why leave it up?
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Jul 28, 2014 16:21
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Maybe so they can reverse the road direction for hurricane evacuations.
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Jul 28, 2014 16:35
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It should just always be red to further tell the visually impaired that it's a one way street. Hollly poo poo I see so many people going down our one way streets here. They're big wide 3-4 lane deals with tons of signs and generally every street going east/west is a one way. The curbs even give you hints you're not supposed to turn the wrong way onto them. Even with heavy traffic coming towards them, almost every week I see someone turn down one of them. So many different reactions. Some flip out and start dangerously driving backwards hoping to do a little 3-point turn at the intersection they came from. Some just stop and panic, I've seen a lot of ladies just cover their face and have a little panic attack as the wall of cars comes towards them. Some even just put their hazard lights on while they sit there. Others manage to do a quick u-turn since it's 3-4 lanes so tons of room. The proudest ones are the ones who just drive down the entire block the wrong way, either not noticing or thinking it's the best option. Generally people clear the lane for them but they certainly get honked the gently caress out. I don't know how the city can make it more clear that they are one-way streets.
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Jul 28, 2014 16:42
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Baronjutter posted:So it would look more or less the same but instead of steel beams there would be fatter concrete beams? For two 20m spans carrying a 13m road with only 2 car lanes what would the general cross section look like? How many beams and approx what height/width for each beam? Here's what I'd do:  Prestressed concrete hollow box girders over the full width of the bridge, approx 1 meter high with a 150 mm layer of highly reinforced conrete op top of it. Use a seamless connection to fix the deck to the foundation to save on maintenance costs. It really doesn't matter a lot that there are only 2 car lanes. Suppose a car or truck accidentally swerves on the bike lane? The bridge deck has to be able to resist the loads of that truck, or else it collapses on the train tracks, along with the truck. And the moment your city decides they want to use the ped and bike lanes as car lanes instead, you're already prepared for it. Yes, that will happen.
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Jul 28, 2014 18:35
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Communist Zombie posted:No the number is fine, he just made them more than half again as large as 'necessary', especially the bike lane. Oh? In the Netherlands, bike lanes must be a minimum of 1.8m wide. In most parts of the UK (though not apparently London based on what I saw there), it's 1.5m. That looks like a two-way bike lane, so 3m - 4m is about right. http://www.camcycle.org.uk/resources/cyclelanewidths/ http://bicycledutch.wordpress.com/2011/04/07/state-of-the-art-bikeway-design-or-is-it/ Properly designed bike lanes should allow cyclists to pass each other while remaining in the lane. E: Dutch Engineer posted:It really doesn't matter a lot that there are only 2 car lanes. Suppose a car or truck accidentally swerves on the bike lane? The bridge deck has to be able to resist the loads of that truck, or else it collapses on the train tracks, along with the truck. That's why you have concrete separators for bike lanes.  Well, in an ideal world.Dutch Engineer posted:And the moment your city decides they want to use the ped and bike lanes as car lanes instead, you're already prepared for it. Yes, that will happen. Does this happen in this day and age? I thought most cities were shifting towards more bike infrastructure, not less. Well, I heard of it happening in a very big, major route bridge in Vancouver, where they dedicated one lane to cyclists for about two weeks after opening the bridge, then just turned it over to cars (leaving cyclists to have to ride on a narrow sidewalk with nothing but a low handrail separating them from a 50m drop), but that was 15 years ago, and on a huge arterial, not a little 25m span. Lead out in cuffs fucked around with this message at 18:43 on Jul 28, 2014 |
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Jul 28, 2014 18:37
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Dutch Engineer posted:And the moment your city decides they want to use the ped and bike lanes as car lanes instead, you're already prepared for it. Yes, that will happen. Is this actually a problem in the netherlands? Bike infra seems growing and sacred there, almost part of the national identity. I can't even imagine a lovely painted-on bike lane being scrapped in north america, let alone a fully separated cycle track with a curb and everything.
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Jul 28, 2014 18:47
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Baronjutter posted:Is this actually a problem in the netherlands? Bike infra seems growing and sacred there, almost part of the national identity. I can't even imagine a lovely painted-on bike lane being scrapped in north america, let alone a fully separated cycle track with a curb and everything. It's not that they'll scrap the bike and ped lanes entirely, but more often that they will rearrange the lanes in different layouts when doing road renovation. It's best to anticipate this in the design phase of the project, instead of having to reinforce or replace the bridge afterwards. Then again, my projects mainly concern infrastructure in historic city centres, so this may or may not apply to you.
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Jul 28, 2014 19:03
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They could for example add car lanes to the bridge, and build a separate lightweight bike and ped bridge next to it if they want to increase capacity.
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Jul 28, 2014 19:07
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Dutch Engineer posted:It's not that they'll scrap the bike and ped lanes entirely, but more often that they will rearrange the lanes in different layouts when doing road renovation. It's best to anticipate this in the design phase of the project, instead of having to reinforce or replace the bridge afterwards. Right, so more temporary re-jiggering during construction or upkeep, or like entropist said, expanding both networks by 'twinning' the bridge with a dedicated cycle bridge or something. I'm imagining this bridge is a bit old though, maybe from the 70's or so. When did precast beams gain popularity and when did those hollow tube/box things you posted gain popularity? Here's what I have now, based on an actual diagram of a 30m span. My deck is about twice as thick as it should be but I'm making this all out of mostly 1/8" birch so it will have to do. I'd also love to make the concrete beams more I-beam shaped but I don't have the tooling for that. Hope this will do, I've certainly see bridges like this where their beams are just rectangular deals.  My main question now is if I need those metal supporty things in between the beams. I've seen some bridges that have them, some that don't. Some look like mine, some look like mine but upsidedown. Some are just metal beams, some are concrete. What should I put in between the beams (if anything) and what should there be at the joint? Also would this need "bridge shoes" or could it all just sit on the supports/abutment ? Baronjutter fucked around with this message at 19:22 on Jul 28, 2014 |
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Jul 28, 2014 19:13
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Baronjutter posted:Right, so more temporary re-jiggering during construction or upkeep, or like entropist said, expanding both networks by 'twinning' the bridge with a dedicated cycle bridge or something. I'm imagining this bridge is a bit old though, maybe from the 70's or so. When did precast beams gain popularity and when did those hollow tube/box things you posted gain popularity? "Twinning" is relatively expensive. Suppose the original bridge has a 80 year lifespan, and it gets twinned when it's 60 years old. Then when the original bridge had reached the end of it's lifespan, the cycle bridge is only 20 years old, but the odds that it will be replaced as well are pretty high, since bridge replacements nearly always mean that the road layout will change as well. The first bridge made of prestressed concrete in the Netherlands was built somewhere in the 1950's I think, but they got popular after 1965 when the new concrete design regulations were published.
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Jul 28, 2014 19:34
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Entropist posted:They could for example add car lanes to the bridge, and build a separate lightweight bike and ped bridge next to it if they want to increase capacity. Out of curiosity, how do the costs weigh up between adding bike lanes to an existing multi-lane bridge (by widening it), versus constructing a new, dedicated bicycle/ped bridge? Say a bridge like this or this.
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Jul 28, 2014 20:23
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I've seen them add wider sidewalks just hanging off the sides of bridges before, but I've also seen them add poo poo UNDER the bridge. Ped/Bike paths weigh basically nothing compared to the needs of a car deck handling heavy trucks and such so I seems like you can just sort of tack them on or hang them off the existing bridge without too much trouble.
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Jul 28, 2014 20:59
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Baronjutter posted:Right, so more temporary re-jiggering during construction or upkeep, or like entropist said, expanding both networks by 'twinning' the bridge with a dedicated cycle bridge or something. I'm imagining this bridge is a bit old though, maybe from the 70's or so. When did precast beams gain popularity and when did those hollow tube/box things you posted gain popularity? Most roads, and therefore also bridges here in Denmark, would be something like | ped | bike | 2-lane car | bike | ped|. Dual bike lanes, on the same side of the road, like the one you're proposing also occur, but they're relatively rare. They're most common when there's not a lot of space, and in that case we'd probably also only have one sidewalk. Is there any particular reason your setup is like this?
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Jul 28, 2014 21:31
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Because the connecting cycle track is on that side of the road. The rest of the road is like that. Sidewalk, lane lane, buffer, 2-way cycle track, sidewalk. Something like this    I don't know how common this arrangement is outside of NL or exactly what the advantages/disadvantages are vs having single-direction bike lanes flanking the road. Maybe Dutch Engineer can weigh in? Baronjutter fucked around with this message at 21:40 on Jul 28, 2014 |
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Jul 28, 2014 21:36
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I guess there's two situations where you mainly see them in the Netherlands. Firstly, when there's a canal on the other side with no space there to add a bike path, as in your second and third picture. And secondly, when it's a rural road where you don't really need frequent access to both sides of the road, and it is cheaper to just build a path on one side. Actually in your first picture there is a bike lane on the other side for local access, as well as the bike path. This might be done as an upgrade for a road which used to have only bike lanes, but there's no space to build separated bike paths on each side.
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Jul 28, 2014 22:06
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Here's how I'd design it: Those are precast concrete beams, and they're more than strong enough, even without cross-bracing. You'd probably be fine with a shallower section, or a bunch of box beams like Dutch engineer said. I would avoid putting the bike and ped lanes on a higher level than the motorized lanes, since it complicates drainage and staging.
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Jul 28, 2014 22:49
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Entropist posted:I guess there's two situations where you mainly see them in the Netherlands. Firstly, when there's a canal on the other side with no space there to add a bike path, as in your second and third picture. And secondly, when it's a rural road where you don't really need frequent access to both sides of the road, and it is cheaper to just build a path on one side. Yeah, this is my take on it as well. In a city it quickly converts a lot of right turns into road crossings, but it's economical, both in terms of money and space, to have both directions in the same side. I can't tell for sure from your pictures, but it looks like there's also just one sidewalk. I can't think of many situations where you'd have split side walks and but joined bike lanes, but I'm sure they exist here as well.
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Jul 28, 2014 23:05
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Kameh posted:I saw this in Atlantic City, NJ, and it struck me as...useless. There are no pedestrian signals. That lone signal head is for peds so that they know which direction has right of way. Intersection in question. Varance fucked around with this message at 00:22 on Jul 29, 2014 |
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Jul 29, 2014 00:20
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This is more urban planning than road engineering but the plan has a couple of neat road cross sections in the proposed designs. You can read about the whole project overview here: https://urbanmelbourne.info/policy/2014/07/29/fishermans-bend-strategic-framework-plan-released It is a large ex-industrial area which is to be converted into high and medium density commercial and residential over the next 40 years with a lot of proposed and approved towers already in the four new precincts. The area is across the river from the Docklands which has just reached the halfway point of redevelopment with another 15 years to finish up, which then connects to the CBD (Central Business District) across the stupidly-not-sunk-raillines that seperate the two now. http://www.mpa.vic.gov.au/fishermansbendsfp Anyway, a couple of the street cross sections, they plan one large Boulevard type road as the central spine by widening the road by 6 meters and running trams on a dedicated grass strip clearway and then two other types of streets, with 30 and 22 meter widths and small side pedestrian priority side streets of 12 meters: Boulevards:  30m streets:  22 & 12 meters:  For the PT, Parks and Bike Routes see the link at the top of the post, they have some maps lifted from the plans, but below I've put the new streets map, contuning a grid based layout for new streets to subdivide current larger blocks that are currently warehouses or factories. 
drunkill fucked around with this message at 11:41 on Jul 29, 2014 |
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Jul 29, 2014 11:38
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A lot of those streets seem a bit wide, but I guess you need to be wide if you're including all that stuff.
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Jul 29, 2014 16:33
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Central Melbourne is known for it's wide streets (30 meters of roadspace) which greatly benefited the city over time in regards to trams and leafy green streets and is why the city is seen as very European. Wide streets in this new area are wanted because there will be 100-200m towers along some of the areas so wide streets allows more sunlight in. Plus because Fishermans Bend is surrounded to the north and west by the river there isn't too much traffic passing through the area (apart from the Westgate Freeway) so having it as a heavily pedestrianised and bike used precinct is another goal. You can see the current area in google maps here: https://www.google.com.au/maps/@-37.8282529,144.9315852,1691m/data=!3m1!1e3?hl=en And a map from 1945 of the airfield and war-related factories in the area, a precinct has been named Wirraway after one of the WW2 fighterplanes built in the area: http://www.lib.unimelb.edu.au/collections/maps/historical/1945melb/l_sheets/848b4a.jpg drunkill fucked around with this message at 18:20 on Jul 29, 2014 |
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Jul 29, 2014 18:03
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Baronjutter posted:Because the connecting cycle track is on that side of the road. The rest of the road is like that. Sidewalk, lane lane, buffer, 2-way cycle track, sidewalk. They did two-way cycle tracks in downtown Vancouver (example). While it's nice to have the separated facility, having it two way on one side of the street seriously complicated the intersection design, and makes it a bit tricky to get on and off the cycle track in a lot of places. Plus the lanes are actually really narrow for two-way cycle traffic (some of which can be going quite fast). Two-way bike lanes are a hacky solution for when there isn't enough space. drunkill posted:This is more urban planning than road engineering but the plan has a couple of neat road cross sections in the proposed designs.  2m bike lanes? Set on the outside of parking with a buffer rather than right in the door zone?  Baronjutter posted:A lot of those streets seem a bit wide, but I guess you need to be wide if you're including all that stuff. The actual roadway is really narrow -- about 1/4 the width of the "street" or less. For comparison, Berlin.
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Jul 29, 2014 18:35
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If 2-lane bike paths aren't ideal I'll eliminate them. For some reason I thought they were more ideal in certain situations and that they'd make intersections more simple since there's only 1 crossing rather than 2. If you need to access a building on the other side you'd just convert to a pedestrian and cross over like normal. I guess the 2-lane paths work better as sort of "bike highways" out in the burbs or even inter-city.
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Jul 29, 2014 18:59
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Hey guys, remember that one road I pointed out a few weeks ago that was blocked by a retention pond? Yeah, we're going to complete that within the next 10 years as part of an upcoming transportation referendum. Estimated cost of $8.42 million for a less than a mile of 2 lane road because we have to fill in that loving retention pond. A similar project twice the length will only cost $2.19 million. 
Varance fucked around with this message at 02:05 on Jul 30, 2014 |
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Jul 30, 2014 01:58
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Varance posted:Hey guys, remember that one road I pointed out a few weeks ago that was blocked by a retention pond? Yeah, we're going to complete that within the next 10 years as part of an upcoming transportation referendum. How exactly did that get hosed up? If the road was planned why didn't the city already own the right of way?
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Jul 30, 2014 02:02
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Baronjutter posted:How exactly did that get hosed up? If the road was planned why didn't the city already own the right of way? Back in 1999, traffic in Brandon wasn't bollocked, so the council rubberstamped that particular development without requiring the road be built despite not fitting the transportation master plan for the area... and then the developer added the lake as a modification to the master plan under the pretense of improving drainage, with the added bonus of deterring county attempts to build a through road in their new subdivision. In other words, the developer snuck it in after everyone had their say and a chance to stop it. -------- Anyway, here's a draft of the proposal in video format. It's a bit long-winded, to say the least. Varance fucked around with this message at 02:24 on Jul 30, 2014 |
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Jul 30, 2014 02:08
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These are my favorite bits of New Tampa/Lutz/Wesley Chapel development road fuckery. Guess why they happened. https://www.google.com/maps/@28.1711252,-82.3197923,418m/data=!3m1!1e3  https://www.google.com/maps/@28.1712864,-82.4378953,418m/data=!3m1!1e3
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Jul 30, 2014 02:24
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That would be the county line between Hillsborough and Pasco. Can't have heathens from the neighboring county in our neighborhood. No sir! Actually, Pasco lives in its own little bubble and doesn't listen to what Hillsborough has to say unless there's money at stake. Here's another video of what we're trying to do. Might want to skip ahead to the 4 minute mark, though. https://www.youtube.com/watch?v=iWOmYreJfuo Varance fucked around with this message at 02:35 on Jul 30, 2014 |
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Jul 30, 2014 02:25
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http://usa.streetsblog.org/2014/07/28/fhwa-to-engineers-go-ahead-and-use-city-friendly-street-designs/ Well that's a bit of good news.
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Jul 30, 2014 20:59
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Baronjutter posted:http://usa.streetsblog.org/2014/07/28/fhwa-to-engineers-go-ahead-and-use-city-friendly-street-designs/ That is good. I don't know how our local FHWA office will react, though - they are pretty inconsistent and can be almost despotic at times.
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Jul 30, 2014 23:14
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The future is now! UK to allow driverless cars on public roads in January. Sounds like cool stuff!
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Aug 5, 2014 15:30
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Silver Falcon posted:The future is now! I wonder how many driverless cars will have to enter the traffic stream before there's a significant shift in driver characteristics. The accident rate should reduce almost linearly with the number of automated cars, but I think that congestion would increase somewhat (driverless cars tend to be much less aggressive), before eventually dropping off when human drivers become a minority. Any thoughts?
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Aug 7, 2014 00:53
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As long as these cars doing exactly under the speed limit keep right (or left in this case) they're ok by me!
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Aug 7, 2014 01:34
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I wonder if particularly poor quality streets would need to be repaved and restriped to accommodate driverless cars. That's going to be a lot of road fixing.
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