The Shannon traffic figures for the early part of the year need to be treated with caution. As at other times of the year, the figures show only vessels that passed through locks (and Portumna Bridge), so boats out on the lakes, or on the river between locks, will not be recorded. So the traffic figures don’t tell us the total amount of traffic; their main use is in showing trends from year to year.
The figures for the early months have a further disadvantage. Numbers of passages are low anyway and a single event — especially a weather event like floods, ice or gales — can have a major effect on winter and spring traffic, whereas the effect might be much smaller on the figures for the whole year.
I am grateful to Waterways Ireland for supplying the figures. I have them for each counting point, but won’t give all that detail here.
January 2012: 35
February 2012: 59
March 2012: 642
April 2012: 3316
Total: 4052
To put that in context, here are the figures from 2002 onwards:
| Year | J | F | M | A | YTD | 5YMA |
| 2002 | 10 | 6 | 1331 | 3528 | 4875 | |
| 2003 | 10 | 35 | 644 | 5515 | 6204 | 5157.4 |
| 2004 | 60 | 52 | 424 | 4768 | 5304 | 5524.6 |
| 2005 | 13 | 54 | 2162 | 3123 | 5352 | 5848.6 |
| 2006 | 37 | 55 | 591 | 5205 | 5888 | 5423.4 |
| 2007 | 42 | 85 | 698 | 5670 | 6495 | 5358.2 |
| 2008 | 28 | 44 | 1377 | 2629 | 4078 | 4991.0 |
| 2009 | 42 | 82 | 563 | 4291 | 4978 | 4849.6 |
| 2010 | 30 | 45 | 495 | 2946 | 3516 | 4363.o |
| 2011 | 48 | 66 | 512 | 4555 | 5181 | |
| 2012 | 35 | 59 | 642 | 3316 | 4062 |
The YTD column is Year To Date; 5YMA is a five-year moving average, which might remove some of the distortion caused by one-off events like ice and floods. I still wouldn’t read too much into four months’ figures, but the general trend is downwards.
Irish waterways history 