Why Does Every French Service Area Smell Like A Pissoire?

We have now been venturing to France and beyond for nigh on three decades with much useage of their wonderful Autoroute system This includes the familiar Aires which seem to be spaced every 20kms and which offer plenty of parking, lots of picnic tables and benches and always toilets.  Many of them also lift your spirits with stunning views of the French countryside.  

However, the other constant that they also provide is an overwhelming whiff of stale urine which seems to drift through the air (or Aire) regardless of where you park. I have been trying to establish the reason for this and can only assume an intense need for truckers to relieve themselves the instant they come to a halt and jump out of their cabs?

We managed to get on an earlier boat last night, The Spirit of France and it was amazingly quiet.  Linda used some of this month's pension to upgrade us to Club Class and you can see from the attached photo just how busy it was!  We had the exclusive service of the Club Steward for the whole of the voyage and we were never able to establish if he was pleased to see us or totally arsed that only two people had elected for the Club experience.

The crossing with P&O was superb and within 40 minutes of leaving the ship, we were getting ready for bed at Aire de Rely having grabbed the last available parking place.  We had completed 337 miles at an average of 22mpg, the latter revealing that I perhaps need to be a tad lighter with the right foot.

We are overnighting tonight at Camping le Felsberg in Saint-Avold but more about that with my next update.