The 4th topic

4.2.2.2. Use the model viewer for general inspection, the dimensions of its parts getting and answer questions in the exercise. 

4.2.2.3. Use the three-dimensional objects of the bridge for general inspection, and see information about its drawings components in the exercise. 

You can open the drawing by the link and move the Zoom window for a better drawing overview.

4.2.2.4. Carefully consider the model and its drawing.

Pay attention to the location of the model's projections and how the dimensions are applied to each projection—this describes the procedure for producing the model.

Remember that each projection must have at least two dimensions - otherwise, the projection is considered needless.

4.2.2.5. Choose one model and overview it. Choose the most informative projection of the model - this projection is the main one, a front view. 

Then, I will draw three projections of the model. 

Do not forget about the axes of symmetry - they help you understand and read the drawing better.

Could you put the dimensions in the drawing order shown in the sample? 

Could you imagine the order of making the model using the applied dimensions? This is a good way to check the correctness of the drawing's design.