Susan,
For number lines, which are a way of representing spatially the relationships between numbers, a tactile graphic (or raised line drawing) is best.
Since both we and the Guidelines for Technical Material exist in the real world, where tactile graphics can be prohibitively expensive and time-consuming, tactile graphics are NOT THE ONLY way to transcribe a number line. We could use line mode to "draw" number lines with braille cells, as long as we're careful to use the appropriate indicators (arrow mode, line modes, numeric indicators, etc.) so that the braille reader is alterted when something represents a line to be "traced" and not a symbols-sequence to be "read." Nonetheless, it is BETTER TO DRAW number lines 99% of the time, including your examples.
Does that address your concern?
–Kyle