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< h1 > < a class = "header" href = "#how-ab-street-works" id = "how-ab-street-works" > How A/B Street works< / a > < / h1 >
< p > The overview:< / p >
< ol >
< li > A detailed map of Seattle is built from
< a href = "https://www.openstreetmap.org/about" > OpenStreetMap (OSM)< / a > < / li >
< li > A realistic set of daily trips by car, bike, foot, and bus are simulated< / li >
< li > You make small changes to roads and intersections< / li >
< li > You explore how these changes affect the trips< / li >
< / ol >
< p > Details below. Many limitations are mentioned; improvements are ongoing. I'll
add pictures to explain better when I get time.< / p >
<!-- ts -->
< ul >
< li > < a href = "#how-ab-street-works" > How A/B Street works< / a >
< ul >
< li > < a href = "#driving" > Driving< / a > < / li >
< li > < a href = "#parking" > Parking< / a > < / li >
< li > < a href = "#biking" > Biking< / a > < / li >
< li > < a href = "#walking" > Walking< / a > < / li >
< li > < a href = "#transit" > Transit< / a > < / li >
< li > < a href = "#intersections" > Intersections< / a > < / li >
< li > < a href = "#people-and-trips" > People and trips< / a > < / li >
< li > < a href = "#map-edits" > Map edits< / a > < / li >
< / ul >
< / li >
< / ul >
<!-- Added by: dabreegster, at: Mon Jun 8 12:17:13 PDT 2020 -->
<!-- te -->
< h2 > < a class = "header" href = "#driving" id = "driving" > Driving< / a > < / h2 >
< ul >
< li > Movement: no acceleration, go the full speed limit of the road unless there's
a slower vehicle in front< / li >
< li > Lanes
< ul >
< li > No over-taking or lane-changing in the middle of a road, only at
intersections< / li >
< li > Strange choice of lanes -- the least full at the time of arrival< / li >
< li > Narrow two-way neighborhood roads where, in practice, only one car at a time
can go are currently full two-way roads< / li >
< / ul >
< / li >
< li > Routing is based on fastest time assuming no traffic
< ul >
< li > No rerouting if the driver encounters a traffic jam< / li >
< / ul >
< / li >
< / ul >
< h2 > < a class = "header" href = "#parking" id = "parking" > Parking< / a > < / h2 >
< ul >
< li > Types
< ul >
< li > On-street: parallel parking lanes from
< a href = "http://data-seattlecitygis.opendata.arcgis.com/datasets/blockface" > GeoData blockface dataset< / a >
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and < a href = "side_projects/parking_mapper.html" > manually mapped< / a > < / li >
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< li > Off-street: most buildings have at least a few parking spots in a driveway
or carport
< ul >
< li > Currently experimenting in the downtown map: set the number of available
spots based on number of cars seeded at midnight< / li >
< / ul >
< / li >
< li > Parking lots: the number of spots is inferred< / li >
< / ul >
< / li >
< li > Restrictions
< ul >
< li > All spots are public except for the few spots associated with each building< / li >
< li > No time restrictions or modeling of payment< / li >
< / ul >
< / li >
< li > How cars park
< ul >
< li > Drivers won't look for parking until they first reach their destination
building. Then they'll drive to the nearest open parking spot (magically
knowing what spots are open, even if they're a few blocks away). If somebody
else has taken the spot when they arrive, they'll try again.< / li >
< li > Once a driver finds an open spot, they'll take 10-15 seconds to park. They
block the road behind them in the meantime. There are no conflicts between
pedestrians and cars when using a driveway. Cars won't make left turns into
or out of driveways.< / li >
< / ul >
< / li >
< li > Some parking along the boundary of the map is " blackholed" , meaning it's
impossible to actually reach it. Nobody will use these spots.< / li >
< / ul >
< h2 > < a class = "header" href = "#biking" id = "biking" > Biking< / a > < / h2 >
< ul >
< li > Choice of lane
< ul >
< li > Multi-use trails like the Burke Gilman and separated cycle-tracks like the
one along Broadway are currently missing< / li >
< li > Cyclists won't use an empty parking lane< / li >
< li > On roads without a bike lane, cyclists currently won't stick to the
rightmost lane< / li >
< li > No over-taking yet, so cars can get stuck behind a bike even if there's a
passing lane< / li >
< / ul >
< / li >
< li > Elevation change isn't factored into route choice or speed yet; pretend
everybody has an e-bike< / li >
< li > Beginning or ending a cycling trip takes 30-45 seconds. Locking up at bike
racks with limited capacity isn't modeled; in practice, it's always easy in
Seattle to find a place to lock up.< / li >
< / ul >
< h2 > < a class = "header" href = "#walking" id = "walking" > Walking< / a > < / h2 >
< ul >
< li > Not using sidewalk and crosswalk data from OSM yet< / li >
< li > No jay-walking, even on empty residential streets< / li >
< li > Pedestrians can't use roads without sidewalks at all
< ul >
< li > When a road only has a sidewalk on one side, driveways will cross the road< / li >
< / ul >
< / li >
< li > Pedestrians can " ghost" through each other; crowds of people can grow to any
size< / li >
< / ul >
< h2 > < a class = "header" href = "#transit" id = "transit" > Transit< / a > < / h2 >
< ul >
< li > The modeling of buses is extremely simple and buggy; I'll work on this soon< / li >
< li > No light rail yet< / li >
< / ul >
< h2 > < a class = "header" href = "#intersections" id = "intersections" > Intersections< / a > < / h2 >
< ul >
< li > Conflicting movements are coarse: a second vehicle won't start a conflicting
turn, even if the first vehicle is physically out of the way but still
partially in the intersection< / li >
< li > Most of the time, vehicles won't " block the box" -- if there's no room in the
target lane, a vehicle won't start turning and risk getting stuck in the
intersection< / li >
< li > Traffic signals
< ul >
< li > Only fixed timers; no actuated signals or
< a href = "https://www.seattle.gov/transportation/projects-and-programs/programs/technology-program/mercer-scoot" > centralized control< / a >
yet< / li >
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< li > The timing and stages are automatically guessed, except some intersections
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are
< a href = "https://docs.google.com/document/d/1Od_7WvBVYsvpY4etRI0sKmYmZnwXMAXcJxVmm8Iwdcg/edit?usp=sharing" > manually mapped< / a > < / li >
< li > No pedestrian beg buttons; walk signals always come on< / li >
< li > The signal doesn't change for rush hour or weekday/weekend traffic; there's
one pattern all day< / li >
< / ul >
< / li >
< li > Turn restrictions from OSM are applied
< ul >
< li > Per lane (left turn only from leftmost lane), entire roads, multiple
intersections< / li >
< / ul >
< / li >
< / ul >
< h2 > < a class = "header" href = "#people-and-trips" id = "people-and-trips" > People and trips< / a > < / h2 >
< ul >
< li > A " synthetic population" of ~700,000 people come from
< a href = "https://www.psrc.org/activity-based-travel-model-soundcast" > PSRC's Soundcast model< / a >
< ul >
< li > Soundcast uses census, land-use, vehicle counts, and commuter surveys. The
current data is from 2014.< / li >
< li > All driving trips are currently single-occupancy; no car-pooling or
ridesharing< / li >
< li > Parked cars are initially placed at midnight based on the number of trips
between buildings< / li >
< / ul >
< / li >
< li > Each person's schedule never changes
< ul >
< li > Your changes to the map won't yet convince somebody to take a bus or walk
instead of drive< / li >
< / ul >
< / li >
< / ul >
< h2 > < a class = "header" href = "#map-edits" id = "map-edits" > Map edits< / a > < / h2 >
< ul >
< li > Types of edits
< ul >
< li > Change types of lanes. Sometimes this is unrealistic based on actual road
width, but data for this is unavailable.< / li >
< li > Reversing direction of lanes< / li >
< li > Changing stop signs< / li >
< li > Changing traffic signal timing< / li >
< li > Closing roads and intersections for construction, forcing rerouting< / li >
< / ul >
< / li >
< li > Disconnecting the map
< ul >
< li > Generally you can't close sidewalks or make changes to make buildings
unreachable< / li >
< li > You shouldn't be able to make bus stops unreachable, but currently this is
buggy< / li >
< / ul >
< / li >
< / ul >
< / main >
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