The short section between the Zurich interchange with the A7, and exit 15 for Zurich is designated as the A31 and is built to motorway standards. The next 7 km continues as a 4-lane expressway, until the road narrows to just a normal 2-lane road for the next 3 km while it passes over an elevated section through Harlingen. This section from Zurich to Harlingen is designated as the N31, but retains the motorway-style grade separated intersections. For the next 18 km, until exit 22 for Marssum, the road is once again designated the A31 and is built to motorway standards. This section of the A31 bypasses the towns of Franeker and Dronrijp. At exit 22 one has to take this exit to follow the N31 while continuing over the exit, the road reverts to an expressway and continues as the N383 into Leeuwarden. The remaining 35 km of the N31, until it meets exit 30 of the A7, is once again an expressway. Of this last section, the first 13 km around Leeuwarden is a just a 2-lane road with at-grade intersections and utilises traffic signals and roundabouts, while the final section opens out into 4-lanes with grade separated intersections. The widening of this last section to four lanes, was completed in 2008.
History
Harlingen-Port was supposed to be an exchanging point for mainly passengers, already in 1845-64, and so, supposed to be connected by three railwayjunctions. One of these was planned alongside the 'Afsluitdijk'. Besides that, Harlingen was connected by road to the E-10 highway running from Barcelone to St.Petersbourg. In the opinion of the NL government, Harlingen-Port was/is doomed to be insulated but, Harlingens' and Friesland/Gronings isolation was decided politically and not on a geographical basis. The industry and transport connection of Friesland-Groningen provinces was also politically determined not to develop. The 're-numbering' of the E10 Highway onto 'N31' was determined with the political decision, to de-generate important Hinterland-connections out from Harlingen-Port. The highway was built without escape lanes, like the 'n31' connection Leeuwarden onto Drachten.... and therefore more dangerous, because of no entrance to emergency 112 vehicles in case of accidents. The real highways in NL and Northern NL are named 'A-highways' like A7, A1, A2. The railway along The Afsluitdijk was also planned along the trajectory of the now realized 4-lanes Motorway 'N31' Harlingen-Zurch-'Afsluitdijk.' The Railway along this enclosure-dike was discerned after WW II in 1940 to 1945, of cause by the decision, to electrify the railjoncton Statal Railway no. A - Arnhem.
