NL guy here.

So a centre marking tells me it’s an 80 km/h road, and the side markings, together with the trees off to the side, aim to optically narrow the road, making drivers more conscious of their speed. This is part of the Dutch universally applied standards of traffic calming.

If there were only markings on the side, usually a little inwards from the roadside, it’d be a 60 km/h road. This would be even more pronounced if the space outside of those lines had red asphalt. In such a case, it’s sometimes allowed, or even expected, for cyclists to cycle in the main roadway.