The Bridge.

 

bridge1.gif (1868 bytes)
This is a diagram of a typical bridge with the following elements:
  • The main, or center, road length and width. If you enter a road width of zero then only one side of the bridge will be drawn. This type of structure, having only one side, can be used to make quite different objects - a cross or scaffolding are good examples.
  • The altitude of each end of the bridge.
  • One road section is placed at each side of the bridge. If you specify a length of zero for the end roads those roads will not be drawn.

This shows the Texture options.
You can choose textures for both sides of the road, the road surface, and for underneath. If your type of structure doesn't need to use a road texture (like in a scaffolding structure) check on the appropriate box.

 

How to make a bridge:
Before you start to draw make sure of your lengths and start playing with the Horizontal and Vertical scale spinners to get the best scale. Choose GRID 0 and you'll get a horizontal and a vertical line which is the center of the bridge. Any point above the horizontal line will be positive and any point below it will be negative. This enables you to draw lines that are situated below the road. The position of the point on the screen is shown in meters and feet. If your bridge is 200 meters long try to use a scale that will give you the nearest point to get 100 and -100 meters on each side of the screen. The center of your screen is also the center of the whole bridge. Use the same method to obtain the optimum vertical scale.

bridge2.gif (1886 bytes) Now we are going to build a bridge.

The length of the road is 200 meters and its width is 10 meters. We also have 3 connected points to add. The height of the structure is 8 meters and the altitude of the bridge over the ground is 6 meters.

  1. Set the Road length to 200.
  2. Set the Road width to 10.
  3. End 1 and End 2 are zero.
  4. Set the Altitude 1 and Altitude 2 spinners to 6.
The best Horizontal scale value I can get is 0.4. Place your mouse on each side of the screen to test this value. The best Vertical scale value I can get is 0.1.
bridge3.gif (1146 bytes)

This shows the numerical sequence of the points in my drawing. So now we are ready to start.

Press the Add/modify button to activate this function.

Place your mouse on the left side of the screen until you get a reading of -100 and 0 meters. Click the LEFT mouse button to add the first point.

Place your mouse on the right side of the screen until you get a reading of 100 and 0 meters. Click the LEFT mouse button to add point number 2.

A line will now be drawn from point 1 to 2 on the screen.

The grid will show Row 001 and Row 002 with the following values:
Connector = N , Color = 00, Lights N, and Lines will show a red square.

If you want to use a blue line from point 1 to 2 on the screen then press the Draw Blue switch. Now click on the GRID panel, row number 2, where the Lines column is. A blue box will appear in this cell and the line will be redrawn in blue.

Continue to design the bridge. Add points 3, 4, 5, 6, 7 and 8. Point 8 goes right over and is in the same position as point 1.

We now have to draw points 9 to 10 which means starting a new point. To start a new series of points click on the Start new point button, then click on the screen where point 9 should be. Then add point 10 and stop.

Row number 9 on the grid will say 009n. The n flag tells you that this is a new start point.

Now add points 11-12, 13-14, 15-16 and 17-18 using the same method.

We now have to connect points 4, 5 and 6. To connect a point just select your point on the grid control and click on the column CONNECT.
So click on rows 4, 5 and 6 on the Connect column. The flag will change from N(o) to Y(es) or viceversa.