mirror of
https://github.com/a-b-street/abstreet.git
synced 2024-11-24 09:24:26 +03:00
326 lines
20 KiB
HTML
326 lines
20 KiB
HTML
<!DOCTYPE HTML>
|
|
<html lang="en" class="sidebar-visible no-js light">
|
|
<head>
|
|
<!-- Book generated using mdBook -->
|
|
<meta charset="UTF-8">
|
|
<title>Gridlock - A/B Street</title>
|
|
|
|
|
|
<meta content="text/html; charset=utf-8" http-equiv="Content-Type">
|
|
<meta name="description" content="">
|
|
<meta name="viewport" content="width=device-width, initial-scale=1">
|
|
<meta name="theme-color" content="#ffffff" />
|
|
|
|
<link rel="shortcut icon" href="../favicon.png">
|
|
<link rel="stylesheet" href="../css/variables.css">
|
|
<link rel="stylesheet" href="../css/general.css">
|
|
<link rel="stylesheet" href="../css/chrome.css">
|
|
<link rel="stylesheet" href="../css/print.css" media="print">
|
|
|
|
<!-- Fonts -->
|
|
<link rel="stylesheet" href="../FontAwesome/css/font-awesome.css">
|
|
<link href="https://fonts.googleapis.com/css?family=Open+Sans:300italic,400italic,600italic,700italic,800italic,400,300,600,700,800" rel="stylesheet" type="text/css">
|
|
<link href="https://fonts.googleapis.com/css?family=Source+Code+Pro:500" rel="stylesheet" type="text/css">
|
|
|
|
<!-- Highlight.js Stylesheets -->
|
|
<link rel="stylesheet" href="../highlight.css">
|
|
<link rel="stylesheet" href="../tomorrow-night.css">
|
|
<link rel="stylesheet" href="../ayu-highlight.css">
|
|
|
|
<!-- Custom theme stylesheets -->
|
|
|
|
|
|
|
|
</head>
|
|
<body>
|
|
<!-- Provide site root to javascript -->
|
|
<script type="text/javascript">
|
|
var path_to_root = "../";
|
|
var default_theme = window.matchMedia("(prefers-color-scheme: dark)").matches ? "light" : "light";
|
|
</script>
|
|
|
|
<!-- Work around some values being stored in localStorage wrapped in quotes -->
|
|
<script type="text/javascript">
|
|
try {
|
|
var theme = localStorage.getItem('mdbook-theme');
|
|
var sidebar = localStorage.getItem('mdbook-sidebar');
|
|
|
|
if (theme.startsWith('"') && theme.endsWith('"')) {
|
|
localStorage.setItem('mdbook-theme', theme.slice(1, theme.length - 1));
|
|
}
|
|
|
|
if (sidebar.startsWith('"') && sidebar.endsWith('"')) {
|
|
localStorage.setItem('mdbook-sidebar', sidebar.slice(1, sidebar.length - 1));
|
|
}
|
|
} catch (e) { }
|
|
</script>
|
|
|
|
<!-- Set the theme before any content is loaded, prevents flash -->
|
|
<script type="text/javascript">
|
|
var theme;
|
|
try { theme = localStorage.getItem('mdbook-theme'); } catch(e) { }
|
|
if (theme === null || theme === undefined) { theme = default_theme; }
|
|
var html = document.querySelector('html');
|
|
html.classList.remove('no-js')
|
|
html.classList.remove('light')
|
|
html.classList.add(theme);
|
|
html.classList.add('js');
|
|
</script>
|
|
|
|
<!-- Hide / unhide sidebar before it is displayed -->
|
|
<script type="text/javascript">
|
|
var html = document.querySelector('html');
|
|
var sidebar = 'hidden';
|
|
if (document.body.clientWidth >= 1080) {
|
|
try { sidebar = localStorage.getItem('mdbook-sidebar'); } catch(e) { }
|
|
sidebar = sidebar || 'visible';
|
|
}
|
|
html.classList.remove('sidebar-visible');
|
|
html.classList.add("sidebar-" + sidebar);
|
|
</script>
|
|
|
|
<nav id="sidebar" class="sidebar" aria-label="Table of contents">
|
|
<div class="sidebar-scrollbox">
|
|
<ol class="chapter"><li class="chapter-item expanded "><a href="../index.html"><strong aria-hidden="true">1.</strong> Overview</a></li><li class="chapter-item expanded "><a href="../howto/index.html"><strong aria-hidden="true">2.</strong> Instructions</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../howto/map_parking.html"><strong aria-hidden="true">2.1.</strong> How to map on-street parking</a></li><li class="chapter-item expanded "><a href="../howto/new_city.html"><strong aria-hidden="true">2.2.</strong> Importing a new city</a></li></ol></li><li class="chapter-item expanded "><a href="../how_it_works.html"><strong aria-hidden="true">3.</strong> How it works</a></li><li class="chapter-item expanded "><a href="../case_studies/index.html"><strong aria-hidden="true">4.</strong> Case studies</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../case_studies/lake_wash.html"><strong aria-hidden="true">4.1.</strong> Lake Washington Blvd Stay Healthy Street</a></li><li class="chapter-item expanded "><a href="../case_studies/west_seattle.html"><strong aria-hidden="true">4.2.</strong> West Seattle mitigations</a></li><li class="spacer"></li></ol></li><li class="chapter-item expanded "><a href="../dev/index.html"><strong aria-hidden="true">5.</strong> Developer guide</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../dev/misc_tricks.html"><strong aria-hidden="true">5.1.</strong> Misc developer tricks</a></li><li class="chapter-item expanded "><a href="../dev/api.html"><strong aria-hidden="true">5.2.</strong> API</a></li><li class="chapter-item expanded "><a href="../dev/testing.html"><strong aria-hidden="true">5.3.</strong> Testing</a></li></ol></li><li class="chapter-item expanded "><a href="../map/index.html"><strong aria-hidden="true">6.</strong> Map model</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../map/importing/index.html"><strong aria-hidden="true">6.1.</strong> Importing</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../map/importing/convert_osm.html"><strong aria-hidden="true">6.1.1.</strong> convert_osm</a></li><li class="chapter-item expanded "><a href="../map/importing/geometry.html"><strong aria-hidden="true">6.1.2.</strong> Road/intersection geometry</a></li><li class="chapter-item expanded "><a href="../map/importing/rest.html"><strong aria-hidden="true">6.1.3.</strong> The rest</a></li></ol></li><li class="chapter-item expanded "><a href="../map/edits.html"><strong aria-hidden="true">6.2.</strong> Live edits</a></li><li class="chapter-item expanded "><a href="../map/misc.html"><strong aria-hidden="true">6.3.</strong> Misc</a></li></ol></li><li class="chapter-item expanded "><a href="../trafficsim/index.html"><strong aria-hidden="true">7.</strong> Traffic simulation</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../trafficsim/discrete_event.html"><strong aria-hidden="true">7.1.</strong> Discrete event simulation</a></li><li class="chapter-item expanded "><a href="../trafficsim/travel_demand.html"><strong aria-hidden="true">7.2.</strong> Travel demand</a></li><li class="chapter-item expanded "><a href="../trafficsim/gridlock.html" class="active"><strong aria-hidden="true">7.3.</strong> Gridlock</a></li><li class="chapter-item expanded "><a href="../trafficsim/trips.html"><strong aria-hidden="true">7.4.</strong> Multi-modal trips</a></li><li class="chapter-item expanded "><a href="../trafficsim/live_edits.html"><strong aria-hidden="true">7.5.</strong> Live edits</a></li><li class="spacer"></li></ol></li><li class="chapter-item expanded "><a href="../project/index.html"><strong aria-hidden="true">8.</strong> Project</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../project/roadmap.html"><strong aria-hidden="true">8.1.</strong> Roadmap</a></li><li class="chapter-item expanded "><a href="../project/motivations.html"><strong aria-hidden="true">8.2.</strong> Motivations</a></li><li class="chapter-item expanded "><a href="../project/history/index.html"><strong aria-hidden="true">8.3.</strong> History</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../project/history/backstory.html"><strong aria-hidden="true">8.3.1.</strong> Backstory</a></li><li class="chapter-item expanded "><a href="../project/history/year1.html"><strong aria-hidden="true">8.3.2.</strong> Year 1</a></li><li class="chapter-item expanded "><a href="../project/history/year2.html"><strong aria-hidden="true">8.3.3.</strong> Year 2</a></li><li class="chapter-item expanded "><a href="../project/history/year3.html"><strong aria-hidden="true">8.3.4.</strong> Year 3</a></li></ol></li><li class="chapter-item expanded "><a href="../project/CHANGELOG.html"><strong aria-hidden="true">8.4.</strong> Full CHANGELOG</a></li><li class="chapter-item expanded "><a href="../project/references.html"><strong aria-hidden="true">8.5.</strong> References</a></li></ol></li></ol>
|
|
</div>
|
|
<div id="sidebar-resize-handle" class="sidebar-resize-handle"></div>
|
|
</nav>
|
|
|
|
<div id="page-wrapper" class="page-wrapper">
|
|
|
|
<div class="page">
|
|
|
|
<div id="menu-bar-hover-placeholder"></div>
|
|
<div id="menu-bar" class="menu-bar sticky bordered">
|
|
<div class="left-buttons">
|
|
<button id="sidebar-toggle" class="icon-button" type="button" title="Toggle Table of Contents" aria-label="Toggle Table of Contents" aria-controls="sidebar">
|
|
<i class="fa fa-bars"></i>
|
|
</button>
|
|
<button id="theme-toggle" class="icon-button" type="button" title="Change theme" aria-label="Change theme" aria-haspopup="true" aria-expanded="false" aria-controls="theme-list">
|
|
<i class="fa fa-paint-brush"></i>
|
|
</button>
|
|
<ul id="theme-list" class="theme-popup" aria-label="Themes" role="menu">
|
|
<li role="none"><button role="menuitem" class="theme" id="light">Light (default)</button></li>
|
|
<li role="none"><button role="menuitem" class="theme" id="rust">Rust</button></li>
|
|
<li role="none"><button role="menuitem" class="theme" id="coal">Coal</button></li>
|
|
<li role="none"><button role="menuitem" class="theme" id="navy">Navy</button></li>
|
|
<li role="none"><button role="menuitem" class="theme" id="ayu">Ayu</button></li>
|
|
</ul>
|
|
|
|
<button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
|
|
<i class="fa fa-search"></i>
|
|
</button>
|
|
|
|
</div>
|
|
|
|
<h1 class="menu-title">A/B Street</h1>
|
|
|
|
<div class="right-buttons">
|
|
<a href="../print.html" title="Print this book" aria-label="Print this book">
|
|
<i id="print-button" class="fa fa-print"></i>
|
|
</a>
|
|
|
|
</div>
|
|
</div>
|
|
|
|
|
|
<div id="search-wrapper" class="hidden">
|
|
<form id="searchbar-outer" class="searchbar-outer">
|
|
<input type="search" name="search" id="searchbar" name="searchbar" placeholder="Search this book ..." aria-controls="searchresults-outer" aria-describedby="searchresults-header">
|
|
</form>
|
|
<div id="searchresults-outer" class="searchresults-outer hidden">
|
|
<div id="searchresults-header" class="searchresults-header"></div>
|
|
<ul id="searchresults">
|
|
</ul>
|
|
</div>
|
|
</div>
|
|
|
|
|
|
<!-- Apply ARIA attributes after the sidebar and the sidebar toggle button are added to the DOM -->
|
|
<script type="text/javascript">
|
|
document.getElementById('sidebar-toggle').setAttribute('aria-expanded', sidebar === 'visible');
|
|
document.getElementById('sidebar').setAttribute('aria-hidden', sidebar !== 'visible');
|
|
Array.from(document.querySelectorAll('#sidebar a')).forEach(function(link) {
|
|
link.setAttribute('tabIndex', sidebar === 'visible' ? 0 : -1);
|
|
});
|
|
</script>
|
|
|
|
<div id="content" class="content">
|
|
<main>
|
|
<h1><a class="header" href="#gridlock" id="gridlock">Gridlock</a></h1>
|
|
<p>Here "gridlock" refers to the general problem of trips getting permanently
|
|
stuck, preventing the full simulation from completing. Most of the work is
|
|
tracked <a href="https://github.com/dabreegster/abstreet/issues/114">here</a>.</p>
|
|
<p>My general approach right now to get a map working is to cancel some percent of
|
|
all trips, look for individual problems, fix them, and repeat. Once the full day
|
|
works, cancel less trips. It's easier to isolate the root cause of problems when
|
|
there are less of them erupting simultaneously.</p>
|
|
<p>The general lesson is: you can't code your way around all edge cases. The data
|
|
in OSM often needs manual fixes. It's often useful to spend coding effort on
|
|
tools to detect and fix OSM problems.</p>
|
|
<h2><a class="header" href="#problems" id="problems">Problems</a></h2>
|
|
<p>The choices in the movement model matter. Some gridlock is inherent to any
|
|
system with queueing and conflicting turns. But in reality, people wiggle around
|
|
partly blocked turns. And some of this comes from the treatment of the
|
|
front/back of vehicles.</p>
|
|
<ul>
|
|
<li>Short roads in OSM causing very weird geometry</li>
|
|
<li>Intersection geometry being too large, requiring too much time to cross</li>
|
|
<li>Unrealistic traffic patterns caused by everyone trying to park in one big
|
|
garage (downtown) or take some alley (the UW soundcast issue)</li>
|
|
<li>Too many people try to take an unprotected left turn (often at a stop sign)</li>
|
|
<li>Bad individual traffic signals, usually at 5- or 6-ways</li>
|
|
<li>Groups of traffic signals logically acting as a single intersection</li>
|
|
<li>Separate traffic signals along a corridor being unsynchronized</li>
|
|
<li>Vehicles performing illegal sequences of turns</li>
|
|
<li>Vehicles are stuck with their plan and not reacting to traffic by changing
|
|
route</li>
|
|
<li>Real traffic would result in a gridlock without a deliberate actions to avoid
|
|
it. Such actions range from individual decisions of drivers to police manually
|
|
controlling traffic. Intelligent avoidance of gridlock is not simulated and is
|
|
extremely hard to simulate.</li>
|
|
<li>Vehicles will wait in lane filled with already waiting vehicles, even if there
|
|
is a completely empty lane allowing travel in desired direction. It makes
|
|
easier for entire lane between crossings to fill, contributing to gridlocks.
|
|
Note that while this and other clearly stupid behaviors are clearly
|
|
unrealistic, it is not trivial to implement more realistic and more efficient
|
|
decisions.</li>
|
|
<li>Issues caused by the unrealistic
|
|
<a href="https://github.com/dabreegster/abstreet/blob/master/docs/articles/trafficsim/article.md#lane-changing">lane-changing model</a>
|
|
<ul>
|
|
<li>Two turns that go to the same lane (one going "straight", the other often a
|
|
lane-change) conflict. The conflict is coarse, at the granularity of the
|
|
entire intersection. So if vehicles are piled up in two lanes trying to
|
|
merge into one, then one group is likely to go through as expected, but the
|
|
second group will wait for the first to completely clear the intersection.
|
|
Until then, it looks like a conflicting turn is being done.</li>
|
|
</ul>
|
|
</li>
|
|
</ul>
|
|
<h2><a class="header" href="#solutions" id="solutions">Solutions</a></h2>
|
|
<p>Divide into implemented or not.</p>
|
|
<ul>
|
|
<li>Synchronizing pairs of signals</li>
|
|
<li>Uber-turns
|
|
<ul>
|
|
<li>for interpreting OSM turn restrictions</li>
|
|
<li>for synchronizing a group of signals</li>
|
|
<li>for locking turn sequences
|
|
<ul>
|
|
<li>Once a vehicle starts an uber-turn, prevent others from starting
|
|
conflicting turns on nearby intersections. Until groups of traffic signals
|
|
are configured as one, this is necessary to prevent somebody from making
|
|
it halfway through a sequence then getting blocked.</li>
|
|
</ul>
|
|
</li>
|
|
</ul>
|
|
</li>
|
|
<li>Cycle detector</li>
|
|
<li>block-the-box protection
|
|
<ul>
|
|
<li>the manual list of overrides</li>
|
|
<li>likely shouldn't apply during uber-turns</li>
|
|
<li>is it always fine to block the box at degenerate intersections?</li>
|
|
</ul>
|
|
</li>
|
|
<li>hacks to allow conflicting turns at really broken intersections</li>
|
|
<li>manually timing signals</li>
|
|
<li>penalties for lane choice to make lane usage realistic</li>
|
|
</ul>
|
|
<h3><a class="header" href="#not-implemented" id="not-implemented">Not implemented</a></h3>
|
|
<ul>
|
|
<li>Dynamic rerouting</li>
|
|
<li>Allow multiple vehicles through intersection at once if there is enough space
|
|
on lane where given vehicle is going. Currrently vehicles travel through
|
|
crossings one by one (or, with <code>--disable_block_the_box</code> enabled - will enter
|
|
crossing even if leaving it will be impossible).</li>
|
|
<li>Last resort: if someone's waiting on a turn >5m, just go.</li>
|
|
<li>Uber-turns
|
|
<ul>
|
|
<li>Group both stop sign and traffic signal intersections when looking for
|
|
uber-turns. Even a single traffic signal surrounded by tiny roads with stop
|
|
signs is causing problems.</li>
|
|
</ul>
|
|
</li>
|
|
</ul>
|
|
<h2><a class="header" href="#fixing-data-used-in-simulation" id="fixing-data-used-in-simulation">Fixing data used in simulation</a></h2>
|
|
<p>Give more examples of changesets.</p>
|
|
<ul>
|
|
<li>upstreaming turn restrictions into OSM to prevent invalid U-turns and other
|
|
crazy movements
|
|
<ul>
|
|
<li>ex: <a href="https://www.openstreetmap.org/changeset/87945050">https://www.openstreetmap.org/changeset/87945050</a></li>
|
|
</ul>
|
|
</li>
|
|
<li>upstreaming lane count fixes into OSM to improve geometry</li>
|
|
</ul>
|
|
|
|
</main>
|
|
|
|
<nav class="nav-wrapper" aria-label="Page navigation">
|
|
<!-- Mobile navigation buttons -->
|
|
|
|
<a rel="prev" href="../trafficsim/travel_demand.html" class="mobile-nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left">
|
|
<i class="fa fa-angle-left"></i>
|
|
</a>
|
|
|
|
|
|
|
|
<a rel="next" href="../trafficsim/trips.html" class="mobile-nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
|
|
<i class="fa fa-angle-right"></i>
|
|
</a>
|
|
|
|
|
|
<div style="clear: both"></div>
|
|
</nav>
|
|
</div>
|
|
</div>
|
|
|
|
<nav class="nav-wide-wrapper" aria-label="Page navigation">
|
|
|
|
<a rel="prev" href="../trafficsim/travel_demand.html" class="nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left">
|
|
<i class="fa fa-angle-left"></i>
|
|
</a>
|
|
|
|
|
|
|
|
<a rel="next" href="../trafficsim/trips.html" class="nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
|
|
<i class="fa fa-angle-right"></i>
|
|
</a>
|
|
|
|
</nav>
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<script type="text/javascript">
|
|
window.playpen_copyable = true;
|
|
</script>
|
|
|
|
|
|
|
|
|
|
|
|
<script src="../elasticlunr.min.js" type="text/javascript" charset="utf-8"></script>
|
|
<script src="../mark.min.js" type="text/javascript" charset="utf-8"></script>
|
|
<script src="../searcher.js" type="text/javascript" charset="utf-8"></script>
|
|
|
|
|
|
<script src="../clipboard.min.js" type="text/javascript" charset="utf-8"></script>
|
|
<script src="../highlight.js" type="text/javascript" charset="utf-8"></script>
|
|
<script src="../book.js" type="text/javascript" charset="utf-8"></script>
|
|
|
|
<!-- Custom JS scripts -->
|
|
|
|
|
|
|
|
|
|
</body>
|
|
</html>
|