The RMT accepted a 4.75% paydeal in February which then magically wasn't enough in June. In my book that's a fantastic deal given most of us won't be seeing any payrise at all this year and will consider ourselves lucky if we have a job left at the end of 2012.
Basically it's just opportunism. The union just sees a chance to try & grab more cash for their members by betting that the govt won't want the Olympic headlines to be about traffic chaos.
It's self-serving, greedy and gives unions a bad name. They are hardly the only group of people whom are going to be working that bit harder of the Olympic period. There are loads of others who will including thousands upon thousands of unpaid volunteers who want the country to be highlighted in a positive way.