science

Isochrone map

Isochrone map is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Isochrone map rather than just read about it. In short: An isochrone map in geography and urban planning is a map that depicts the area accessible from a point within a certain time threshold. An isochrone (iso = equal, chrone = time) is defined as "a line drawn on a map connecting points at which something occurs or arrives at the same time".

Key takeaways

Isochrone map belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Isochrone map to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Isochrone map from memory before moving on to harder problems.

Reference excerpt

An isochrone map in geography and urban planning is a map that depicts the area accessible from a point within a certain time threshold. An isochrone (iso = equal, chrone = time) is defined as "a line drawn on a map connecting points at which something occurs or arrives at the same time". In hydrology and transportation planning isochrone maps are commonly used to depict areas of equal travel time. The term is also used in cardiology as a tool to visually detect abnormalities using body surface distribution.

History

Early examples of Isochrone maps include the Galton's Isochronic Postal Charts and Isochronic Passage Charts of 1881 and 1882, Bartholomew's Isochronic Distance Map and Chart first published 1889, and Albrecht Penck's Isochronenkarte first published 1887. Where as Galton and the Bartholomews published maps depicting the days or weeks it took to travel long distances, Albrecht further developed the idea to not only depict long distances and world travel but also smaller areas. Penck also created a series of maps that only depict the travel times of a certain transportation mode, for example rail transport. Isochrone maps are commonly used in the UK in connection with development control. Isochrones are currently typically computed by via generating shortest-path trees on network graphs, and then generating a convex hull around the accessible nodes. Increases in computation, data storage, and improvements in algorithms have facilitated the rapid generation of isochrones. Recent techniques in visualization include linking travel times to network edges to show the paths accessible from a point rather than show the area accessible from a point.

Usage

Hydrology Isochrone and related maps are used to show the time taken for runoff water within a drainage basin to reach a lake, reservoir or outlet, assuming constant and uniform effective rainfall. An early example of this method was demonstrated by Clark in 1945.

Transport planning Isochrone maps have been used in transportation planning since at least 1887. Isochrone maps in the context of transport planning are essentially maps of accessibility where travel time is used as the cost metric. Isochrone maps can be created for different modes of transportation, e.g. foot, bicycle, motor vehicle. Put simply, the output of an isochrone map for transport will show how far (in distance) is reachable from a start point, including the parameter of time. Such maps for private motor transport were widely used in a 1972 study into airport accessibility in Hampshire, South East England. At that time, their use was disadvantaged by being time-consuming to create.

A related concept is the isodapane map, where the contours represent transportation cost instead of transportation time.

General public Journey time websites have been built using mapping technologies and open data. Isochrones can be used by house hunters wishing to evaluate residential areas. An isochrone map of the London Underground network was made available in 2007.

Services and applications Several digital tools exist which can generate isochrone maps. openstreetmap-based solutions:

CommuteTimeMap – Build and visualize isochrones worldwide. Geoapify Isochrone API – API service to build isochrones for drive, truck, bicycle, walk and transit modes. Worldwide. GraphHopper – can be used to calculate a detailed time information for every point within a certain time or distance reach. GRASS v.net.iso module instaGIS Iso4App – Public Transport Isochrone maps (Isochrones based on GTFS data) Mapbox Isochrone API (interactive Mapbox example) Mapumental OpenRouteService Isochrones Service – uses OSM data and map, shows isochrones worldwide (no source code available) OpenTripPlanner – a development branch has work on an Analytics Extension, which currently provides isochrones based on the OSM network and GTFS data (source code available) OSRM Isochrone – Generate drivetime isochrones from OSM using OSRM. pgRouting – The creation of journey time isochrones to airports in Finland has been explained using the GIS software QGIS and pgRouting (an extension of PostGIS). pysochrone is a Python script and simple web interface for computing and displaying isochrones from an OGR-supported data source (e.g. PostGIS) Reachability Analysis – An application (built using WhereOS and OSM data) which calculates reachability (isochrone) from given set of addresses. Safe Routes to School Mapping Toolkit – working to create travel distance/time web app for pedestrians and bicyclists using OSM data (source code available) TargomoAPI – Travel times, Routing, Points of Interests, Isochrones – developer tools to build state-of-the-art geospatial analytics applications, enhance location search, and personalize user experience. (Interactive Demo) TravelTime API Uses some OSM Data and has a free isochrone generator tool using public transport, cycling, walking, driving and combined bike and train. Available as a plugin for QGIS and ArcGIS. Valhalla isochrone service Walkscore Travel Time API – uses GTFS and OSM data for maps of Seattle, San Francisco, and Washington DC. Built on the open source Graphserver library. (no source) WNYC Transit Time – public transit isochrones for NYC Stadia Maps Isochrone API (tutorial with an interactive JSFiddle) GTFS-based solutions:

Mapnificent Proprietary data solutions:

Google Maps API PedCatch

See also Daily urban system Public transport timetable Traffic congestion map Transit map Walking distance measure

References

External links

Further Exploration #9: Isochrone Maps (Travel Time Maps) Travel time between American counties: 1880 and 1900

Illustrations

Worked examples

Example 1 — a first encounter with Isochrone map

Start with the simplest possible case. Write down what Isochrone map claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Isochrone map before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Isochrone map ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Isochrone map

In research: Isochrone map appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Isochrone map in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Isochrone map is common in secondary-school and first-year university syllabi. It links to neighbouring topics Cardiology, Hydrology models, Thematic maps, so understanding it makes those chapters shorter.
In everyday life: Look for Isochrone map outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Isochrone map in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Isochrone map means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Isochrone map out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Isochrone map in simple terms?

Why does Isochrone map matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Isochrone map?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Isochrone map.