When I use curve modifier with array modifier to make a road this happens:
tutorial I work with:
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On your file you didn't create any Curve modifier, so nothing happens. Put the Curve modifier below the Array modifier. You'll see that your object is completely swollen. That's because you have somehow played with the vertices radius as you can see in the 3D view T panel if you select the curve, switch to Edit mode and select all. Bring this value back to 1.
Just to expand on @moonboots' answer, because I've been confused by it myself, in the past.
Every vertex on a curve has a radius; in the illustration below, the leftmost vertex has a radius of 3, the rightmost 0.5.
NOTE: you must apply scale and rotation with CTRL + A to the curve and also to the object, take into account that the result can vary according to the size of the object and the acute angle of the curves
You can follow the configuration that I have in my image so that it fits your model