While setting up your cross-section, you can use centerline locking to more easily trace an underlying satellite aerial image. This is especially helpful if you don't know your existing lane widths for a given street. Centerline locking allows you to lock the lane edge offset for one lane line at a time. This is helpful since it allows you to add lanes or update lane widths on one side of your cross-section.
Turn on the underlying aerial and turn down opacity to 50%.
Create your street and set up the correct number and type of lanes.
Update the street's offset so that the sketched centerline matches the underlying aerial centerline.
Lock the centerline in the cross-section.
Update other cross-section widths until the sketched plan matches the underlying aerial.
1. Turn on the "Satellite" base map using the Map style picker.
2. Turn the Opacity level to 50% so that you can see the underlying aerial.
3. Click on the street to create the default cross-section. Update the "Offset" until the centerline of the cross-section matches the underlying aerial.
4. Lock the centerline offset in place by clicking the "Lock" icon in the cross-section.
5. You can now set the width of each lane, starting from the centerline and working your way towards the outside edges of the street. As you configure each lane, make sure the lane lines in your sketch are lined up with the ones in the underlying aerial imagery.
The "Ruler" tool can be helpful to measure lane widths on the underlying aerial.
Open the Ruler tool by clicking on it in the tool menu or pressing "R".
Click once on one lane edge. Drag your mouse until you've reached the other lane edge. You will see the measured distance at the bottom of the screen: