Determining width of paths

I have an image, like the one below that has different paths. I want to be able to detect the thin parts of these paths and highlight them. What is the best way to go about this?

Just an idea that might work. Let original image be $I_0$. Erode just enough to remove the thin lines, then dilate back to obtain $I_1$. Afterwards, obtain the difference of the $I_0$ and $I_1$.

StackExchange Computer Science Q#33080, answer score: 6