Calculating Visibilty atop Riga's Freedom Monument using GRASS 6.4.1.

  What would I see if I placed a camera atop of Riga's Freedom Monument?  Using GRASS 6.4.1. I used as an input the coordinates of 56.57 and 24.647 and I listed the height of the viewer at 42 meters, the height of the monument.  I used the default range of 100000 meters and the results are shown above.  It seems to me that most of the country would be visible?  Notice that the thin lines, which are either railroads or roads that I added as shapefiles to the map, have no images around them.  Perhaps these roads and railways are at lower elevations?  At any rate, I cannot understand the results and perhaps I did something wrong, but it was interesting to do this experiment.  Notice that for one of the pictures, I choose one with trolleybus and tram wires!  The results indicate as follows:  If I was standing atop of the Freedom Monument and if no buildings blocked my view and I was able to see the flat surface of the earth, I would see most of the yellow areas extensively into the interior and I would see higher elevations (in red) in the distance (over 150 meters high).  I would also see the island area across the water.  Of course, the buildings in Riga would block my view because this calculation was based on natural elevations only and did not take into effect the height of surrounding buildings.  The white areas would be hidden because they are low or because they are behind a high elevation area.

Latvia Carve Stream Map Using GRASS 6.4.1.

In the map below, I used GRASS 6.4.1 and its' Hydrology program to create the attached map.  Instead of using existing streams as an input, I used Latvian Railways.  Roads are also shown on the map.  I believe that the bright yellow areas appearing near railroads are those areas that are in danger of flooding in a strong storm.  I do not work in this field and I am just experimenting with the software.  No decisions should be made using this map.  The software is a great learning tool

Tramway Null(0)

Calculating Visibility from Riga, Latvia

In the map above, I used GRASS 6.4.1 to calculate visibility from the ocean near Riga.  I used coordiates 24.10, 57.07 in the projection and I set the range to 5 X 10 (6) Meters.  The result is based on the elevation file and shows a thin line of red dots along the shoreline and on a neighboring island.  This theoretically means that an observer standing at the point that the road runs perpendicular to the Ocean will find visibility to the shoreline and the ocean, but not much on shore.  This is only an experiment and I am not sure of the results; there may be an error here.

In my choice of x,y coordinate, I picked one at random and I am not sure if it is in the City of Riga and the height of the elevation of the observer is 1.5 meters or the height of a person  A more interesting perspective would be a calculation from a point of interest, such as the top of the railroad bridge near 13 Janvara iela or other point.  If someone has a nice point of interest to calculate visibility from Riga, I will nead the x, y coordinate and the height in meters.

Example:  Freedom Monument, 42 Meters High, 56" 57,  24"4.

Regards,
Tramway Null(0)

Latvia Grass 6.4.1 Experiment using Elevation Files

The map below was produced using GRASS 6.4.1 in which I added shapefiles for Latvian elevation and railroads.  These shapefiles are on the web.  The thin lines are Latvian railway lines.  In this first attemp, I tried to use the hydrology program to "carve channels" using the railroad vector file as the source of the streams.  So far, I was not able to get a positive result.  Is it possible that Latvian railways are all on the surface or embankment?  If time permits, I will experiement later,  In working with data from a country or location which is different from your source maps, it is important to first bring in your first file, shape or otherwise to a blank map, and then use the "o" option to set the projection to the area where the map is.  Even though this map is in my New York directory, by bringing in the first file from Latvia, and setting the code to option "O", my coordinates are now for Latvia.  More to follow later.

Why are Riga Tramway Trolley Poles so Long?

  In another blog, an observer posted the above question.  Viewing the wonderful "Riga Latvia Tramway Route 4 Video" posted earlier, I was able to see many scenes with the overhead.  I am not an overhead expert, but here are some of my oberservations:

1.  When a two way streetcar crossed a trolleybus line, the overhead hardware appears to be that of one trolleybus lane crossing another trolleybus lane at right angles.  Or in other words, the two tramway wires, one let us say going south and one going north join to what looks like a 180 degree trolleybus crossing.  This means for one of the tram wires will be significantly out of place and needs a long pole.  See  "Observed in Riga Diagram".  Riga  has a number of trolleybus lines.  In order to avoid complex tram-trolleybus overhead hardwire at crossings, see top right diagram, a simple trolleybus crossing is used where one of the tram wires is significantly shifted. In a two way tram and trolleybus crossing, instead of having four pieces of complicated overhead you only need two.
2. I believe that trams that have pantographs need more complicated overhead where there is a trolleybus crossing.  This is avoided using trolley pole technology. Where there is trackwork, I see that the overhead in Riga is shifted significantly.

These are my guesses only, I do not work in this field.

Tramway Null(0)
The picture to the right is a traditional trolleybus crossing.  In Riga, this appears to be adopted for a tram - trolleybus crossing using one piece of equipment.

More Riga Trolleys

   In this short video, you will see some shots that concentrate on the area around the Centraltirgus area of Rigas.  You will see more streetcar equipment types and a commuter train that goes over the railroad bridge that you saw in the first video posted on Riga.  You will get to see that mysterious underpass that looks like a subway station entrance.  Riga hoped to build a Metro system but was not successful.  Perhaps the underpass was a demonstation of what a future Riga subway station would look like.  The city looks different in the rain and you will get to see at least the Centraltirgus (Central Market) area from a different angle.