Ok, in that case I wouldn't tag as highway=construction because navigation software will treat the road as closed and  unusable. You could map the affected road as being one-way alternating, and map a separate footpath with highway=construction. However you should consider how long the works are going to last. I read somewhere that road works that will last less than 3 months should not be mapped, and started doing same. I don't think there's a hard rule around this, but the main factor for me is that some navigation apps might not update their OSM data for months, which can have the effect of the app avoiding a road that has since re-opened. In this case since its basically a layout change and not a closure, there will probably be little/no impact on routing choices for navigation apps so it's probably OK to map it here IMO.