Slight improvement to road graphics

[jamespetts]

I have noticed that some of the road graphics have stray cyan pixels for some reason: I have removed these using the Gimp, and the fixed graphics are below:

[jamespetts]

I have realised that I have forgotten to apply this to the concrete elevated road. Now done:

[kierongreen]

Excellent - fortunately this is one of the elevated ways that I won't be redrawing!