PTV Visum Creating Scaled Network From Scratch

8/12/2019 PTV Visum Creating Scaled Network From Scratch

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PTV AG Sep-12 Page 1/5

Often seen: A small network, created to test some functionality, to make aquick estimation or to contribute to a larger network. How to set it up smartand effectively?

This article describes a way to create a stable fundament for any network, fast and

suitable for every place in the world.

1.First of all after starting Visum, consider to use or to set up the project file directories,or create a standard set to be used and adapted from now on.

2.Secondly, think about the traffic systems your model needs. Visum defines by default B

(bus), C (car) and W (Walk). Defining additional ones now, means being able to use them

already in the next step.

NETWORK FROM THE SRATCH

CREATING A CORRECTLY SCALED


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PTV Visum: Tips & Tricks


3.Consider to set up some of the link types. Maybe your organization does use a

standard set saved as NET file.

4.Now think about the e.g. city you are going to model. Its Wikipedia site lists its

geographic coordinates for sure. How to read these? For example Amsterdam is denoted

as 52 22 N, 4 53 O, which means almost 52 and a half degree above the equator(note: use as Y coordinate) and almost 5 degrees east of Greenwich (as X coordinate).

5.In PTV Visum, choose Network -> Network parameters -> Spatial reference system ->

From file -> click the button "..." -> Geographic Coordinate Systems -> World ->

WGS1984.prj. Click OK to leave all dialogs.

6.Now add one node: Choose the "Insert mode" (button "+" in the window "Network"),click on the "Nodes" button below it, click somewhere in the network editor and add itscoordinates: X=4.9 Y=52.4. Click OK to leave the dialog.


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7.Leave the Insert mode and enter the Edit mode again (arrow button in the Network

window). Press the F3 key to search your node and zoom into it. The status bar will report

the coordinates of your cursor in degrees, the scale can be ignored now.

8.Now enter the Insert mode again and choose Backgrounds: In the dialog "Create

background " choose "Internet maps" and check the option regarding the OSM license.Click OK to confirm your settings. Visum will load a OSM map as background file,

depending on your zoom showing half of the world, Europe or even some part of the

Netherlands. Important: the wanted city is already contained.

9.Now you can zoom to get closer and repeat the procedure to load additional

background maps showing more detail, if needed.

Map tile (c)OpenStreetMapcontributors,CC-BY-SA

10.Once you are satisfied with your zoom level, remove all loaded maps. Why? These

maps have been adapted to the WGS1984 map datum, but the projection used to displaythem onto your screen is like viewing through a standing cylinder ("standing" on the

equator).
http://www.openstreetmap.org/http://www.openstreetmap.org/http://www.openstreetmap.org/http://creativecommons.org/licenses/by-sa/2.0/http://creativecommons.org/licenses/by-sa/2.0/http://creativecommons.org/licenses/by-sa/2.0/http://creativecommons.org/licenses/by-sa/2.0/http://www.openstreetmap.org/


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This means: a city like Amsterdam halfway between the equator and the North Pole looks

somewhat distorted, because you are looking onto it from a 53 degree angle.

Map

Tile (c)OpenStreetMapcontributors,CC-BY-SA

The solution:

11.We will transform the node's coordinates to another spatial reference system,

preferable to a local metric system. You don't know what system might by common for

your city? No problem, Wikipedia's page regarding the metric UTM system offers

worldwide defined zones. From there choose the zone for your city. Note UTM usesrectangular zones for military purposes, but you only need the 6 degree wide strip's

number. For example Amsterdam is within the zone "31U", you only need the "31", in

Visum denoted as "31N", "N" for the northern hemisphere.

12.Choose in PTV Visum:

Network -> Network parameters -> Spatial reference system -> click the button

"GCS_WGS_1984" -> Projected Coordinate Systems -> Utm -> Wgs 1984 -> WGS 1984

UTM Zone 31N.prj


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13.Now repeat the procedure to load background maps again. Their projection meets our

needs perfectly, as "we are looking from above".

Map tile (c)OpenStreetMapcontributors,CC-BY-SA

14.Consider removing the only just created node or moving it.

15.Once adding additional nodes, their coordinates will match metric values.

16.Once adding links, their link lengths will be realistic. The same for all tsys dependent

link run times.

17.Once adding line routes and time profiles, they will use these lengths and run times

and this eases modeling headways or even a realistic time table.

PTV Visum Creating Scaled Network From Scratch

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