9-line access access management access point accessibility ADA air quality alignment amenity antiplanner atlanta BART benchmark BID bike Blogs boston branded bus corridors brookings brt bus Bus Rapid Transit BYU capacity car pool car pool lane cars central link Centrality certification commuter rail condo congestion congestion pricing connections consistency coverage crossings CRT cycling DART dedicated dedicated right of way density denver depreciation developers development economics efficiency Envision Utah equity eugene exclusive extension FAQ favela Federal Funding Flex Bus florida free fare zone freeways frequent network frontrunner frontunner Gallivan garden cities gas prices geotagging goat Google grade-separation Granary District growth headway heavy rail hedonic High Speed Rail history housing housing affordability housing bubble housing prices HOV income infill innovative intersections intensity ITS junk science LA land use Land Value Economics LEED legacy city light rail linear park location LRT lyft M/ART malls mapping maps metrics metro MetroRail missoula mixed mixed traffic mixed-traffic mobile mode choice Mode Share multi-family MXD neighborhood networks news NIMBY office online op-ed open letter Operations parking parking meters peak travel pedestrian environment phasing Photomorphing planning Portland property property values Provo proximity quality_transit rail railvolution rant rapid rapid transit RDA real estate redevelopment reliability research retail Ridership ridesharing right of way roadway network ROW salt lake city san diego schedule schedule span seattle separated service branding shuttle silver line single family SLC SLC transit master plan slums smartphone snow sprawl standing stop spacing streetcar streetscape streetscaping subdivision Sugarhouse Sugarhouse Streetcar Tacoma taxi technology tenure termini time-separation TOD townhouse traffic signal tram transit transit agency transit networks transit oriented development Transit Planning transponder transportation travel time TRAX trip planning trolley tunnel uber university of utah urban design urban land UTA UTA 2 Go Trip Planner utah Utah County Utah Transit Authority value vmt walking distance web welfare transit Westside Connector WFRC wheelchairs zoning

Tuesday, February 12, 2013

Hex City II

SimCity hex-grid traffic plan.

The blue and green streets are one-way streets in the direction indicated. The red and orange are two-way streets, with a wrinkle--on the orange roads, the you drive on the left, rather than on the right (with a visual barrier between, to prevent confusing drivers).

The result of this complicated pattern is that every single turn you make on the network is a 'safe' turning movement that does not require crossing traffic, so there is no-need for stop-signs or traffic lights, only terminating turn-pockets onto and off of roads. Consequently, you can go pretty much as fast as you like.

The turning rule is:  You never cross traffic. So you can go left from green onto yellow, and from blue onto yellow. The rule ought to have been 'rights onto red, lefts onto yellow'.

Travel in the NW-->SE direction(blue, green paths) is fast direct. But travel in the NE-->SW is a pain (gray path), because every other road you have to take a 'red' street, and wind up going about 50% more distance. I think the lack of streetlights would be worth it, but not sure. The plan would be most suitable for a city where most of the travel is in one direction, such as a mountain valley. 

I can't see retrofitting an existing city, but it would make a novel subdivision plat, or the  traffic plan for a tabula rasa city like Brasilia or Masdar.

 For local streets, connecting these main-streets, you can do pretty much what you want, with some limited exceptions: The turn pockets have to be oriented toward the direction of flow,  so as not to generate temptation to 'cross' in front of traffic, on red or yellow streets:

  • practical problems: will ignore drunk drivers, but how about people who aren't spatially inclined? I could imagine getting lost *extremely* easily. 
    I don't propose to make this real in the least--it's a bad idea in a multitude of ways. It's a traffic network for SimCity, or for Traffic Simulation software. If you are working with a 'omnipotent' traffic allocator, which knows the whole network (and never gets lost) it just chooses the most direct route for each residential cell and the nearest employment cell.

    A system like this would drive most people nuts. They would have to constantly be aware of where they are because if they miss a turn, its much more costly, timewise, to correct it than on a square grid.
    Most places don't actually HAVE grids, or ones of analogous scale. Grids are more the exception than the rule, actually. Phoenix has one due to it's near-total lack of geography (rivers, mountains, valleys, etc).