Dandenong line capacity boost undersold

On the weekend I was chatting about the Dandenong skyrail proposal to rellies at their house near Hughesdale station. They are keeping an open mind; they are not immediately under the rail line, and they can see the obvious benefit from getting the level crossings removed quickly, but are concerned about some aspects, which it sounds like are not being adequately explained.

For instance: condition and maintenance of any parkland created by the elevated rail. The Level Crossing Removal Authority (LXRA) seems to be forming the view that they would fund at least ten years of maintenance.

And of course after media attention last week a lot of local chatter is about the future need to expand the line to four tracks. (Three tracks isn’t nearly as useful as four.)

It’s worth noting that the skyrail project, along with other measures, buy a lot of extra capacity for the line.

How much? I’ve been trying to work it out, but official information is really scarce. The official figure thrown around is 42%, but this doesn’t seem to take into account all the upgrades.

Currently

Looking at what might well be the busiest hour, inbound AM peak 7:31-8:30am at Caulfield, there are 15 Metro services and 2 V/Line services scheduled, or 17 trains per hour in all.

The current signalling allows for a train every 3 minutes, or 20 trains per hour. The widely used practice is to use 80% of the theoretical capacity (to allow for short delays), which means the line is using just over its practical capacity. No wonder delays so easily occur.

Each train’s desired load standard is 798 (133 per carriage), but seat modifications currently underway are meant to increase that to 900 (150 per carriage). Remember, this is NOT a capacity figure.

New signalling

Firstly, the signalling (with conventional technology) to allow a train every 144 seconds (eg 25 trains per hour), in line with a long term plan that was kicked-off with the Westall upgrade project some years ago.

Staying within the 80% of theoretical capacity (so it runs more smoothly than now) therefore gives you 20 trains per hour — 18 Metro and 2 V/Line.

Why not high-capacity (in-cab) signalling? They want to prove it first on the Sandringham South Morang line — not unreasonable given the complexities of shared running between Metro, V/Line and freight. What they are saying is that any upgrades in the mean time will be future compatible with in-cab signalling.

Removing the crossings

Secondly, you couldn’t just do the signalling upgrade without removing the crossings, because it would lock up the road system across the south-eastern suburbs, delaying motorists, pedestrians, cyclists and bus users alike. So grade separation helps unlock that track capacity.

High capacity trains

The third major point is the trains to run on the line. The new High Capacity Metro Trains (HCMTs) will run on the Dandenong line in the next few years. As detailed in this extensive post from last year, they’ll start as 7 car sets with a load standard of 1100 people (157 per car).

This is achieved by having continuous usable space and, I expect, fewer seats. Hopefully a balance will be found between carrying capacity and ensuring those travelling the longest distances can get a seat.

Later on, when the Metro rail tunnel opens, the plan is for the HCMTs to expand to 10 car sets — a load standard of 1570. (Crush load around 2000.)

Longer trains obviously involves extending platforms — something not possible in the City Loop, but included in the Metro rail tunnel and the rebuilt skyrail stations. It will also obviously be necessary on all the other stations out to Cranbourne and Pakenham, as well as Sunbury (as the rail tunnel will connect them).

Put it all together – what do you get?

Somewhere in the mix would need to be duplication of the Cranbourne line, and flying junctions (overpasses) at Dandenong so trains don’t get delayed waiting for each other there.

So, pulling together all the various upgrade figures (which have been gleaned from various government information — it doesn’t seem to all be in one place anywhere), what do we get?

The government often quotes a 42% capacity boost. As I understand it, that figure includes the level crossing removals and new trains, but excludes the metro rail tunnel. I’m trying to find out how precisely they get that figure, but taking the tunnel into account, it woefully undersells the true capacity boost anyway.

Perhaps these numbers don’t exactly tally with the official ones, but 28,000 per hour is huge. That’s about the equivalent of 12 lanes of traffic. Behold, the power of mass transit!

From trying to explain some of this to my relatives, it’s clear to me that the government/LXRA hasn’t communicated this point very well (if at all).

With all these upgrades, a huge amount of extra capacity is provided, much higher than the quoted 42%, putting off the need for extra tracks for many years.

How long will this last? Well, that depends on the future growth along the corridor, obviously. Capacity can grow even further with high-capacity in-cab signalling, provided it’s okay to have all trains (including V/Line) run at a consistent speed. That should allow enough trains to provide a line out to Rowville.

Hopefully I haven’t messed up these figures. And this is not to say that planning shouldn’t happen now for future track expansion.

But if basically you’re more than doubling peak capacity by 2026 when the metro tunnel opens, that’ll take a while to fill up again.

• Submissions to the Dandenong Skyrail project close TODAY at 5pm. If you have any thoughts, even just a few words, good or bad, put them in.