OpenGeofiction
MAWANAROO VIADUCT AND other MARAPURA FREEWAYS - HIGHWAY ENGINEERING?
Posted by indyroads on 23 April 2016 in English.I cannot figure out the ramp design and left exit arrangement of this viaduct skyway. the ramps cross over themselves to the left-handed driver direction prior to coming to intersecting roads, and these ramps cross over each other which seems like an engineering nightmare. In order to allow for these ramps the viaducts would have to be extremely high to allow for two levels of crossing ramps and then a boulevard beneath that. I am also wondering what the purpose of the tandem boulevard along this corridor. Was this designed this way just because it looks cool or because it has some actual functionality. — http://opengeofiction.net/#map=17/18.77812/88.97672
When it comes to freeways/motorways. left exits should be avioded at all times. only in rare situations would a left exit be an option. Additionally the Spaghetti Maze ( http://opengeofiction.net/#map=17/18.81450/88.97951 ) interchange at A-1 and A-9 has been modified to have a ramp for free flow on to every side street rather than terminating some ramps to a traffic signal as the interchange was originally designed. all of these ramps could in practice cause driver confusion and also creates an engineering nightmare for civil engineers. Again it seems like a bit of creative overkill if you ask me.
Thirdly there are a TON of very closely spaced freeways here as well. some spaced less than one mile from each other. Again just wondering about the need for that many closely spaced freeways.
Discussion
Comment from histor on 23 April 2016 at 18:58
[http://opengeofiction.net/#map=17/18.77812/88.97672] Why not change the direction of road no. 1 and so avoid the diagonal crossings.
And the second example - indeed a nightmare.
Comment from indyroads on 23 April 2016 at 19:29
I still think this makes for a lot of very closely spaced intersections here, which instead of relieving congestion would actually cause more. Not sure how this could be designed for optimum performance, but the design doesnt seem feasable.
With regard to the nightmare intersection, that will need a rework.
Comment from histor on 23 April 2016 at 21:33
I changed your first Marapura-monster.
Comment from Maxwell Black on 23 April 2016 at 21:42
Actually, your in and out ramps are swapped. They should be similar to this: http://i483.photobucket.com/albums/rr194/Rings_of_Saturn/Open%20GeoFiction/Screen%20shot%202016-04-23%20at%2010.20.59%20PM.jpg~original
As for the Bream Bight FWay / Marapura St. intersection, it is, indeed a bit messy and the angles of curves are a bit too tight. Maybe you should try a variation of a trumpet interchange? https://en.wikipedia.org/wiki/Interchange_(road)#Trumpet_interchange
Also, as some said, usually entrances and exits of the same direction of traffic are not placed close together as this created a phenomenon called weaving in traffic pattern which are a source of accidents. This being said, regulations are different from country to country and it has varied over time (i.e. in the last 70 years). Close entrances/exits should be avoided but I see it as perfectly fine for recreating an older area of town, for example.
Comment from isleño on 23 April 2016 at 21:49
I don’t know enough about highway engineering to offer thoughts on the interchanges and stuff, but I definitely agree that the proliferation of motorways throughout Marapura District is a bit overwhelming. I don’t want to delete people’s hard work — so maybe we can keep the details, but just downgrade some of the routes to ‘trunk’ and ‘primary’ status, to reduce the visual overload?
Indy, you’ve given some really good advice on roads in the past. If you think you might be willing to create a wiki page for “OGF: Making realistic roadways,” with simple illustrations to visually show the most basic points of road design and the most common mistakes you find in OGF, I think it might be useful for a lot of people. (Teach a man to fish, yada yada…) Anyway, something to think about, if you’re interested.
Comment from histor on 23 April 2016 at 22:13
As Maxwell Black shows on his graphic - the exits go to the right (to 99 %), if you drive on the right side. Never I have seen exits with diagonal self crossing to the left side. This too is more expensif and dangerous as the normal design.
I changed now the exits 3, 4 and 5. The great labyrinth at exit 6 may be a work, what is to do after thinking about a more optimal solution. And as isleño write - the “Beltway” can be downgraded to an primary road or trunk road and the Santa Rosa connection too.
Comment from Ernestpkirby on 24 April 2016 at 00:27
In Freedemia the only time I use left exits is when there’s more space in between the sides of an elevated freeway (large median-like space between) than on each side of the freeway to save space, and in general that’s for a long stretch of road. Unionway 7 in Quentinsburgh is the only real good example of that, though. I don’t think that left exits when done correctly are always horrible, but when people drive on the right, it’s usually not the best idea unless its a rare spot where its actually simpler.
Comment from histor on 25 April 2016 at 06:05
Monster # 6 is downgraded. Indeed, why a complicat junction with a trunk road, when this trunk-road is only a short piece between primary-roads
Comment from joschi81 on 25 April 2016 at 09:15
Even with the reductions already made, the freeway density in Marapura is much to high in my point of view. Why does freeway A1 have to cross the city so close to the center? And why is there even an additional freeway along the harborfront? Ok, some cities did such “quirks” even in reality, but to be honest: The quality of life must be very, very bad in Marapura! Ok, that’s my opinion. And of course there might be people who like car-oriented cities…
Comment from histor on 25 April 2016 at 12:40
Too I deleted this “main”-railway line west of Marapura-station with a curve of only 150 m
Comment from wangi on 25 April 2016 at 13:30
Using edit summaries in collaborative & open areas is much appreciated - helps everyone else keep up with changes and understand edits.
Comment from wangi on 25 April 2016 at 13:52
Indyroads, on the original Mawanaroo Boulevard question - yeah, over provisioned. In reality i think this would see the Mawanaroo Freeway merged with Mawanaroo Boulevard after Central Street, as a trunk or primary route. At grade, no parallel elevated section. It would continue past 24th Street to Ferry Way.
Likewise get rid of Santa Rosa Freeway and Harbor Extension.
The high speed rail tunnel once it hits land could also be more more realistic by routing it to the existing rail right-of-way along the harbour front as soon as possible, and bringing it above ground / into a cutting sooner.
Comment from indyroads on 25 April 2016 at 14:13
WOW!!! this looks awesome. That is a much better design for the whole thing. I love it.
Comment from indyroads on 26 April 2016 at 18:02
Since it is an at grade boulevard it will lose its A-1 designation south of Cntral, It willjust be denoted as route 1 south of that point to maintain route continuity. The A-201 bypass will serve as a better alternative for through traffic at this point.
Also downgrading A-401 to an express highway also makes sense as the traffic volumes would not have justified a full freeway/motorway along that route.
Comment from Sarepava on 27 April 2016 at 19:26
I think the high-speed tunnel is fine actually. If you look at the Euro Tunnel it stays underground for a good few miles on the UK side, and also if there harbour is active imagine the disruption of taking land and building the line. There is also an established city here which would make land acquisition difficult and expensive - no cost saving not to tunnel this way. And it means the trains can accelerate to full speed without having noise restrictions in residential areas.
I did think the tunnel would need either a ventilation and service shaft in the middle, or else an air pumping station on one side. You would have had a shaft or two dug on land to get the TBMs in and out, and presumably there is a central service tunnel leading to emergency stairs, so there would in all probability be a building where it hits land on the Gobras side.
Comment from wangi on 30 April 2016 at 01:23
Thanks for that Sarepava, totally understand that reasoning. And agree on need for infrastructure for ventilation and portals.
Depending on the legal setting… The commercial side of land permits for tunnelling under 100s of residential properties vs 1 or 2 complacent commercial undertakings agreeing - well, one is easier?
Tunnel under the railway ROW, portal still coming out ~ 7th Street?