What you are asking is not supported by the control. However, you could try to create a custom style that would bind the thickness of the sparkline to the current value of the position in which it is above. This link
will bring you to the documentation on the visual structure of the control.
This is not an easy thing to accomplish, but you can learn more about the ControlTemplate here
. Also, go to the overview documentation and learn more on how the RadTimeBar functions and what it is designed for by going here
What I can recommend doing is using a different control to visualize the multiple sparklines. RadGridView is designed for this type of data presentation, you can find a demonstration of it in action here
. Go through the examples by clicking on the "Next Example" button.