Like Budapest, London is two cities, split by a river. OK, they don't have separate names. But just try getting from one side to the other at the moment.

Within London, once you get downstream of Tower Bridge, there are three options: two tunnels and one ferry. And there was a fire near one end of the main tunnel this morning. Consequently, there were Problems.

Of course, this was the day I had to drop L, L8, JA and a friend at London City Airport.

I'd looked up the RAC's recommended route – go via the Woolwich ferry, takes half an hour. Mind you, it reckoned the actual crossing takes zero time (which I suppose it does, if you're talking driving time).

So we allowed plenty of time. First choice en route – go via Blackheath (where lots of the bodies from the great Black Death plagues are buried, apparently) or Greenwich? Well, the latter's usually better as the road across Blackheath can have problems, so let's go that way.

Oops. All the traffic that couldn't get across the main tunnel is trying to get 'upstream' from there to the other tunnel one way, while all the traffic that thinks the other tunnel is too congested (which it doubtless was, it's less than half the capacity of the main one) and is going 'downstream' and is running into the tailbacks of traffic that can't get through the main tunnel.

We wanted the ferry, further downstream. After taking half an hour to get from Catford to Greenwich – something that should take about five minutes – and seeing that the main road from there was solid, it was time to skirt Greenwich Park and get onto Blackheath.

Oooh! No problems. And it stayed that way until near the roundabout onto the ferry. Normally there are two boats… today of all days, there was only one. An hour's delay said the signs.

So I parked L's car in a very naughty place by the terminal building (double yellow lines, half on a pavement, but not actually blocking anything and out of sight of the main roads) and we all went across as foot passengers carrying nine pieces of luggage between us.

There's a bus that goes from North Woolwich to the airport. In fact, we could see several of them. All stuck in the jams on that side. By this point, we're over an hour into the journey and are there are under twenty minutes to check-in.

Fortunately, one of the people at the bus stop knew the number for a local mincab firm. A call on my mobile and one soon arrived… to the annoyance of a police towing vehicle which didn't like it driving on the wrong side of the road – safely, as everything coming the other way was stuck solid trying to get onto the ferry or past the stuff that wanted…

They all got in, and drove off. I went back across the ferry, where by this point, the queue to get into the queue for the northbound ferry stretched about ten times further, and was getting longer and longer in all three directions: east, south and west. It looked like a hour's wait to get into the 'hour's wait' holding car park.

I was very glad to see the car still there sans ticket or clamp and took it back to L's… where there was a message saying 'made it'. Phew. (London City Airport's very good for things like this – the check-in times are much closer to flight times and there are far fewer people there than for any of the other London airports.)

So if you're thinking of taking a bus or car or anything other than a train across the river today, don't bother.