Now select the path of the biggest road using the Selection Tool (black arrow). Go to the Appearance palette, now notice at the top the word 'Path' is mentioned. Add the different strokes as shown in the images above. This time you need to stack 3 different strokes on top of each other, starting with the bottom one of 20 pt black, then 16 pt white and lastly 1 pt black dashed. To create the dashes, click on the word stroke to evoke the Stroke panel, check the option Dashed Line and enter 6 pt for dash and 8 pt for gap. Now select the other big road and apply the following strokes: 15 pt black, 12 pt white and 1 pt grey dashed, using 3 pt dash and 5 pt gap.