that maybe true but according to most when you mention BSL, its Basel,CH that comes to mind and not say Mulhouse,Fr . then again its alot closer to Basel then Mulhouse

I highly doubt most folks who work 1` way or another for an airline will have any idea that BSL isnt in CH but is physically in FR, just as some wont know that GVA has a Swiss and a French section

Pre EU, the Basel SBB station had an SNCF area (tracks were numbered 30+), you had to do passport control to enter. Was that section in FRANCE?

It was still there pre-Schengen. The section was technically in France. The same with the DB part of the Basel Badischer Bahnhof.

But that station was not physically connected to SBB.

Was in Basel in September and the SNCF part of the station was cut off from the rest of the SBB station, but this is(was?) because the whole station is under renovation. To enter or exit the SNCF portion, you have to pass through a customs post which was unstaffed when I was there. I guess there are now ID checks at the customs post, if non-Swiss cannot enter Switzerland.

Some trains from Basel SCNF have their first stop at Basel St Johann which is still in Switzerland. How did that work if you passed into French customs territory once you got on the train?

What about all those trams and buses which cross the borders? Basel tram 10 and bus 55 start in Switzerland, then cross the border to France / Germany respectively then go back to Switzerland again, and you hardly notice unless you are following the route on your GPS in real time :D

There are so many tiny roads and paths crossing the Swiss borders, I struggle to see how these were patrolled before Schengen, which was not that long ago. Were they all barricaded or policed and what is happening now?

In normal times there are SBB trains going through the Badischer Bahnhof, but because SBB runs the local S-Bahns instead of DB to Lörrach and further. These trains stop at a couple of stops before they cross the border though. I've taken them a few times.

You cannot cross the border into Switzerland from France unless you have a Swiss passport or a work permit allowing you to cross into Switzerland for your essential work. In addition, those coming from France will have to have an Attestation de déplacement dérogatoire, signed, dated and timed each day for each journey to and from work ... plus their French ID.

And little tracks etc can be closed by barriers (firmly embedded) or nasty things that will rip your tyres to shreds ... not to mention official police cameras.

If you are not going for essential work, or are returning as a national to your country to live (and go into quarantine) the Swiss border is closed to you. Switzerland may not be shouting from the rooftops, but has plenty of COVID-19 problems within its borders. Tourism is CLOSED for the moment, and probably for several months at least to come.

Schengen basically codified what was already common anyway. I have never in my life shown a passport at a Swiss (or French or German) land border. The only time I have ever been stopped at the Swiss border was when a border guard needed to explain to me that my trailer needed the highway sticker too.

Nothing that will stop a pedestrian or cyclist though. The border has never been very firm in that area.

I have. It happened several years ago as I was driving from Konstanz(Germany) to Kreuzlingen and was stopped by the Swiss border guard.

Military police are now actively patrolling the border. Though the odd pedestrian or cyclist will probably find their way through if they really try.

About 10(?) years ago I took the overnight train from Basel SNCF to Paris, the first stop was St. Louis and then Mulhouse (the train was relatively "deep" in France), after departing Mulhouse a group of customs agents (at 2 am) were doing their "thing":p. Shouldn't this have been done at Basel SNCF? Do they do customs checks on the RER between Orsay and Champ de Mars:rolleyes:--my point is that my train was well into French territory.

I think they've got the right to effect controls anywhere they want at any time they want. It happened to me a couple of times on the Luxembourg train, and also by car well inside the French border having crossed from Germany. There is nothing pleasant about these people, mostly they appear to be thugs in a uniform.

I've even been checked by the Swiss version on a domestic train from Zürich to Basel. I'd been listening to music so it took me a minute to understand that they asked me where I was traveling. The officer decided to switch to French just before getting a stern Geography lesson from me of the greater Basel area in Swiss-German. He jumped as though I'd just bitten him.

If this were on a NON-STOP train the only place you could be going to is BASEL!:D--(From your post I assume it wasn't a Lyria headed on to Paris.)