One Way Streets are dependent on how you draw the polyline. If the direction of the one way street is from west to east, you have to draw the polyline from west to east. If you accidently drew the polyline in the opposite direction, fear not, simply reverse the polyline by using the Select objects tool > right-click on polyline > Reverse polyline.
Once you have drawn the polyline, go into the line object property (Select objects tool > double click polyline) then select the Routing tab to Check the One Way option.
To visualize one way streets on the map, go into the Properties tab and check Polyline has direction.
This causes arrowheads to appear on the polyline.
