Following on from our @merseyshpping Twitter-bot which helps us (and anyone else) get a better feel for the traffic on the River Mersey, we decided to take it another step along.

Knowing what ships are coming and going is lovely, but when you live and work just a few minutes walk from the Liverpool Cruise Terminal, what is even better is catching one of the ships just as they arrive or leave.

To see if this was possible we built @pier_head. It’s another little bot, but rather than watch the AIS data for current river traffic, it takes the cruise terminal schedule and tweets a couple of alerts to give you half-an-hour and quarter-of-an-hour’s notice of a ship either arriving or departing.

We worked with ScraperWiki to pull together the data source, from the Cruise Liverpool website, which they made available as an iCal feed so that it might be useful for other people to add to their calendar as well as feeding the Twitter-bot.

Sadly this showed how fragile unofficial data sources are and also how much the actual arrival and departure times are compared to the published schedule. Ship captains get to make the final call, based on river conditions rather than a strict adherance to a clock.

So for now we’ve parked this, until we can find a better way to predict the ships movements.