Turning Left in a left turn lane

A lot of drivers just don't indicate full stop.

yep, check behind, signal, approach turn, check nearside mirror, proceed if clear - all muscle memory/natural to do.

No surprise left hooks happen like this when the first step or two aren't done. Its very telling what kind of self centred mindset some have when they can't even imagine why they might want to signal. Makes you wonder what else is missing from their skill set.

"There is no mention of "use your indicator" or signal etc in the law. It specifies only a general indication"

Incorrect, the law specifically says you must use "a direction indicator........or give the appropriate hand signal".

Those wands have made that junction more dangerous. Any time I drove that road before they put in the wands, I would indicate that I was turning left, and I would move as far left as possible so that bikes couldn't come up my inside. You can't do that anymore. If I'm on the bike, when I approach a junction with stopped traffic, I prepare to stop or take avoiding action. I just don't trust other road users to do what they're supposed to do, and on a bike you come off second best.

I don't know if it's a legal requirement to indicate when in a left turn lane or if by following the only legally allowed path (turning left) means that you aren't altering course (this is something that a court would have to decide), but indicating wouldn't have prevented the collision. What would have prevented this collision was either the driver checking his mirrors before pulling off or the cyclist noticing that the car was moving in the left turn lane and slowing/stopping even if not legally required to(on the basis that it's better to be alive than right). When I was learning to drive, my instructor stressed that all an indicator definitely means is that the bulb isn't blown. You can't rely on them being used correctly.

has signalled an intention to turn to the left and there is a reasonable expectation that the vehicle in which the driver has signalled an intention to turn to the left 

Where is there a reference to using an indicator? How does one indicate straight on?

You are intending to change direction, but are you intending to alter course? It's the latter that requires indication. As I said, a court would have to decide if turning left while in a left turn only lane is altering course.

In the junction in question, there is an arrow about 25-30m before the junction which says the left lane is left turn only, but the road layout does not suggest that it is a left turn only lane and, afaik this arrow is the only signage indicating that it is a left turn only lane. There has been no point up to this where the motorist was required to indicate in order to enter that lane as the lane split from one lane into two. This creates an ambiguity in the intended course of travel, meaning that a motorist should (although I don't know if they must) indicate that they are turning. Looking at a different junction layout, if you take someone going from Ellis Quay to Blackhall Place, a person has already indicated to move into the left turn lane, and in that instance there isn't any ambiguity in their intended direction of travel. They are not, in my opinion, altering course and an indicator should not be required (although I personally would use one as I feel it makes my intentions clearer). A court would have to decide if my interpretation is correct.

The junction has been recently changed to this traffic flow, and, in my opinion, they have done an awful job. Where there is a cycle lane that goes straight, it should not go to the left of a left turn only lane, and whatever about a shared lane which allows cyclists to take command position and control the lane, putting a segregated cycle lane down the left forces a conflict situation which the cyclist cannot easily mitigate.

The last time I went through that junction it was still a left/straight lane. If I was approaching that junction and the light was red/going red and I was going to be in the first 1/2 cars at the light, I would indicate and pull right over to the left. If there were cyclists coming up that I could see, then I would hang back a little to let them go past me before pulling in behind them.

If traffic was moving, and there were cyclists there, I would assume they were going straight, and depending on exact position and relative speeds, I would either go in front of them if I was well clear, or let them go first if I wasn't going to be well clear. And by well clear, I don't mean barely missing hitting them, I mean plenty of space so that they were not in any danger of being hit by me (or hitting me as I slowed).

so a left turn lane with a bike lane which goes straight? As in right across it?

jesus christ, well done to whoever designed that.

what's next, how about putting straight bike lane here for instance?

https://www.google.ie/maps/@53.4049389,-6.2653751,3a,75y,348.78h,62.85t/data=!3m6!1e1!3m4!1sGtTI4gT-zJoWmxuQZkGCGA!2e0!7i16384!8i8192

Or do people here expect drivers to signal left on the above as well?

Correct on the design - this is something a lot of Drivers will not be aware of (and usually results in "use the bike lane our road tax paid for" or other such nonsense - where a lot of the time the design is so poor its safer to not use them... but thats a digression!)

That junction - why wouldn't you be signalling left? On approach I'd signal left to enter the lane and would keep the indicator on - that way any pedestrians waiting to cross and everyone else knows - BUT even if you argue that the junction shows more clearly to peds what is going on - it is more hassle to cancel the signal that do nothing and cancel after you turn.

Unless there is some new tax on using indicators, I don't see what the arguments against are?

I don't even understand that question tbh.

The difference arises when there's a risk of taking out a cyclist (or pedestrian) when you turn to the left.

Using your indicator means they get some advance warning of your intentions.

Honestly, what's so difficult to understand about that?

That junction has two traffic light signals for cars. One for left turn, and one for straight on.

They need to add a third for cyclists, which can be green for straight on when the car light is red for turn left, and Green for turn left in sync with the car light.

They won't be in conflict with left turning traffic if they obey the traffic lights.

That's akin to saying cyclists going straight through a set of lights are in direct conflict with crossing traffic.