Red line Luas - a bad example of on street running trams?

monument

I'm branching this off from one of the Metro North is in doubt threads.

On street trams have a bad rep on this board, mainly because the city centre section of the red line Luas. But with this thread what I'm trying to ask or question is.... is the line an abnormally bad example of on-street running?

Think about it, starting from St James's Hospital it grinds to a halt around the grounds of the hospital, then it interacts with a massive 11 major routes...

[St James's]
- St James's Street
(Bow Lane West)
(shared running on part of Steven's Lane)
- St John's Road West
[Heuston]
(access to/from Heuston)
- Wolfe Tone Quay
(Temple Street West {to/from Arbour Hill})
[Museum]
(access to/from museum)
(access from Hendrick Place)
- Blackhall Place
(John Street North)
- Queen Street
(Smithfield)
[Smithfield]
(Bow Street / Lincoln Lane)
- Church Street
[Four Courts]
(Greek Street / Chancery Place)
(St Michan's Street / Ormond Square)
(Arann Street East)
- Capel Street
(access from Lower Jervis Lane)
(access from Wolfe Tone Street)
- Jervis Street
[Jervis]
(shared running on Upper Abbey Street)
- O'Connell Street
[Abbey Street]
(Marbrough Street)
- Bersford Place & Gardiner Street
(bus interaction at Store Street)
- Amiens Street

...I've mark the crossing in bold where (I think... and I'm open to correction...) the Luas does not have priority, does not always have priority, where trams are often slowed as priority isn't given to it fast enough, or where traffic often blocks the tram etc.

There's also cases where, at smaller junctions, trams are often slowed where the right of ways could possibly be extinguished (my suggestions in italics) without affecting traffic or access too much compared to the benefit of less delays and generally speeding up the city centre section.

But my main question is, wouldn't other tram lines into/across the city have far less interaction with major routes, and there for have more priority and faster running?

On a side point, not to blame the designers, but the limits they were given, the line was badly designed. First aren't Smithfield and the Four Courts stops far too close, or would it have made much of a difference due to other factors anyway?

Secondly, in respective of how footpaths were rather poorly or not at all provided when they could have easily been at construction (both sides of Smithfield are prime examples).

markpb

I'm guessing that there are two problems here. The first is the lack of political will to give Luas more priority over cars. The second is due to limitations in the traffic control system. I know roughly how Scats works but it seems to be very inflexible.

The Luas rolls up and actives the signal, the light remains stopped until the end of a fixed time period has passed, Luas rolls through, lights return to normal. Unless there's a stop before the junction, the Luas should be able to signal on the approach, not at the junction. And unless there's a massive backlog of traffic that the control centre are manually trying to clear, the Luas should never have to wait more than a few seconds for a clear signal.

A very simple example is on the green line just before Harcourt stop (Charlotte way, Harcourt st, Hatch st junction). A more flexible traffic system would allow trams from the city to signal the lights from a block away, stop the traffic in time, tram rolls through without stopping or slowing down much and as soon as it's passed, the traffic can continue. Obviously it's a little more difficult for trams travelling into the city but the driver should be able to signal the lights as he closes the doors, not (as I presume it is) from the head of the junction.

Traffic

Luas has full priority at the following junctions:

- St John's Road West
- Wolfe Tone Quay
- Queen Street
- Church Street
- Capel Street
- Jervis Street

A more flexible traffic system would allow trams from the city to signal the lights from a block away, stop the traffic in time, tram rolls through without stopping or slowing down much and as soon as it's passed, the traffic can continue.

Thats exactly how it works. The trams dont signal but are picked up by detectors along the track

murphaph

Given the disruption that occured during construction, they should have gone the whole hog and dug a cut and cover trench from Heuston to Connolly. They had to do all the messy utility diversion stuff anyway!

HonalD

Traffic wrote: »

Luas has full priority at the following junctions:

- St John's Road West
- Wolfe Tone Quay
- Queen Street
- Church Street
- Capel Street
- Jervis Street



Thats exactly how it works. The trams dont signal but are picked up by detectors along the track

Mmmmmmmmmm sounds like the lady protests too much - Traffic, if this is true, it's not a very good "full priority" system me thinks?!?!

Slice

What is the speed restrictions for on-street Luas? It strikes me as quite slow in comparison to other tram networks

monument

Traffic wrote: »

Luas has full priority at the following junctions:

- St John's Road West
- Wolfe Tone Quay
- Queen Street
- Church Street
- Capel Street
- Jervis Street

I'm not sure what "full priority" is in this case is, I live off Parkgate Street and often see the Luas stopped at Wolfe Tone Quay for 30-60 seconds.

And I regularly see it stopped or slowed notably at most of the others.

On thing I have noticed a good few times is trams coming from both directions to a junction where one is just crossing and the second is just coming to the junction but is stopped on its side. The motor traffic is allowed to pass again just for a few mins while the tram is left waiting there.

markpb

Traffic wrote: »

Thats exactly how it works. The trams dont signal but are picked up by detectors along the track

I won't argue cause obviously you know best but a document published about the Luas a few years ago said that at certain junctions the driver starts a Request To Signal process on the tram when it reaches the head of the junction. This is the same as driving over a circuit on the road and tells Scats to give the Luas green time at the end of the current cycle.

Whether or not it's the case, at a lot of junctions where the Luas approaches without stopping, it has to sit and wait for the cycle. Given that it only takes a few seconds for the Luas to pass, there's an argument for inserting a Luas phase into the middle of the cycle if the traffic control system can handle that.

Slice wrote: »

What is the speed restrictions for on-street Luas? It strikes me as quite slow in comparison to other tram networks

I think it's 20kph for safety reasons. DCC are quite afraid (and apparently have evidence to back them up) of pedestrians walking in front of Luas trams, especially at junctions so all the on-street sections have incredibly low limits.

Victor

There are, I think 3 different levels of priority. It was discussed recently but best explained in Michael Phillip's letter, which nobody seems to have copied.

http://www.boards.ie/vbulletin/showthread.php?t=2055315321&highlight=priority

Carawaystick

markpb wrote: »

I think it's 20kph for safety reasons. DCC are quite afraid (and apparently have evidence to back them up) of pedestrians walking in front of Luas trams, especially at junctions so all the on-street sections have incredibly low limits.

Pedestrians have the right of way over vehicles when they are crossing at a junction unless it is a pedestrian crossing or within 15m of a crossing. There are a few of these on Harcourt st and near Greek st and Ormond square and Charles st west on the red line. and also where 3 ends of store street meet when the trams served Busárus and Connolly

Slice

How can a Luas possible be any more dangerous than a car? People are used to them by now. The on-street maximum speed strikes me as way too slow and when it's tied into all that stopping and starting it has to do at junctions it makes for a very slow journey altogether.

Ham'nd'egger

Slice wrote: »

How can a Luas possible be any more dangerous than a car? People are used to them by now. The on-street maximum speed strikes me as way too slow and when it's tied into all that stopping and starting it has to do at junctions it makes for a very slow journey altogether.

Basic laws of Physics make a Luas tram far more dangerous; a Luas tram has far more transfer of energy in the event of a collision due to it's huge mass (weight) compared to a car or bus; the driver also has less ability to brake it to halt in minimal time using the same principles. It also has noof crumple/impact zones to absorb a crash when compared to a car

markpb

Slice wrote: »

How can a Luas possible be any more dangerous than a car? People are used to them by now. The on-street maximum speed strikes me as way too slow and when it's tied into all that stopping and starting it has to do at junctions it makes for a very slow journey altogether.

I'd imagine the low speed limit is for good PR, like we saw last year 'safest tram system in the world, only one fatality in four years'. The media in this country would like nothing more than a good crash so they could give out about the Luas shambolic safety records, blah blah blah.

trellheim

In a potential crash, a car has a possibility [ not always mind you ] of swerving to avoid a collision. A Luas can only brake. Steel Wheel on Steel Rail is a low friction coefficient

Slice

Basic laws of Physics make a Luas tram far more dangerous

That's only if basic laws of common sense desert you

monument

There's nothing basic about "common sense". It's one of the most strange and complex human inventions.