How to make roads on a plane?

With the edge loop tool? subdivide? or how else could I make these roads on a plane in Blender?

P.s. a flat plane

First, you look if you can upsize image. If not, clean what’s available leaving just runways/roads. Bring into vector drawing app at hands, trace bitmap. Bring resulting svg into Bleder, correct converted from curves mesh according to your initial image, fill in voids. Use Inset on ngons, Loop Tools addon to spread out vertices. A bit of manual work and there you have it:

Wow so Blender will trace it automatically?

Edit: wouldn’t it be ngons then? Which won’t work in Unity

Blender does not trace anything yet - Inkscape does have tool to trace bitmaps resulting into svg file of vector outlines; blender can import svg as curves which if set to 2D do some skinning. Result is awfully terrible from the ‘proper’ geometry point of view. To correct this takes select all vertices and delete - limited dissolve to convert into ‘proper’ n-gons (which will be triangulated again behind the scenes if you export them, btw). What gets easier while mesh is n-gons is to fill in needed spots, assign textures, materials.

If you would need parts of the mesh to be quads you’d probably do this manually: use knife, J-key, GridFill tools or fiddle assigning real thickness and Remesh mod in Block mode.

Edit: You might be told that tris are bad, n-gons even worse and so on. This concerns only modeling process where any math operation (think modifiers) tend to work fine on quads and stop on 3 or n>4 corner faces.
Rendering process ( think -game rendering) uses different paradigm - triangle is prime element you could approximate any imaginable surface.
When you export final mesh from Blender triangulation is either done automatically or you have checkbox on export panel. Any n-gons you have not spotted for some reason will be triangulated.

You could also try a very very light displacement modifier, But it will require a whole lot of geometry, subdivide the plane MANY times, APPLY the displace modifier using the texture / image of your roads / airfield, then do a decimate modifier to remove most of the unneeded stuff, unfortunately this can lead to issues with non cardinal roads.

this may not be what you are looking for but it is a very fast easy way to make basic roads quickly.

a. Create a curve and bevel with a road shaped profile?
b. Create a curve and portion of a road then use an Array modifier with a Curve modifier to shape it?

An InkScape SVG could be used to create an image texture for the ground plane.

Yea, i know my handwriting is bad… " Inkscape does have tool to trace bitmaps resulting into svg file of vector outlines". Post #4.
Thank you for understanding.