Time to call in the Dirt Squad and make that grey tarmac look worn and weathered. Having added white lines I then used a mixture of weathering powders and very dilute brown and grey paints to add dirt to the tarmac surfaces.
Unless a road and pavement are newly laid then the tarmac will weather as it oxidises from that fresh black colour to a muted grey. Add to that the passage of vehicles and the weather and you get an added bonus of dirt on the tarmac. Given the passage of vehicles and the effect of rain much of this dirt accumulates around the kerb edge.
I'd say the Dirt Squad have done a great job!