Sensational-Adelaide.com

This is what I do with my spare time.

Here's my take on Britannia Roundabout if it were to be made into an intersection on the cheap, so:
- No overpasses
- No property acquisitions
- No decades long legal battles with parklands fanatics over every blade of grass

Enjoy.

That's hardly what I'd call poorly thought out! That layout you've drawn up I hadn't thought of myself. As neat as it looks in drawing, how would you coordinate the traffic signals on the two halves to prevent large queues building up in the middle?

Cheers AG. The signal sequence would be... fun to do. It's going to be a long cycle no matter what you do. That's why I've put in the right turn restrictions for any route that could be easily done by bypassing this intersection, shortening the cycle at least a bit.

That being said, the intersections of Regency, Muller and Hampstead Roads before they were realigned were an example of a dog-leg well sequenced.
Here's a very very quick mock up of what could be done. Obviously there's room for improvement and there would need to be a different sequence for different parts of the day.

yeah I dont think there would be a better idea.

How do you do that AtD? Looks like a professional plan

I used Adobe Illustrator.

And I agree, I don't know if there'd actually be any increased throughput with an intersection over a roundabout. A third lane could be added to the roundabout to increase throughput. However, I think the biggest issue with Britannia is safety (especially pedestrian access) and not so much traffic. It's something open for debate. *shrug*

AtD, how would you rate your design from a cyclists perspective?

Wayno wrote:AtD, how would you rate your design from a cyclists perspective?

No worse than the average intersection and much better than what's currently there.

I reworked your bus lanes, as there is enough space for the changes.
Makes it easier for buses from Dequetteville Terrace to get to Kensington road and Fullarton Road.

Good thinking. It'd require a "B" light phase to the signal sequence. With a detector loop it could be slotted in almost 'on demand' so there's minimal delay for buses.

Wayno: Do you have any ideas re: bikes?

AtD wrote:Wayno: Do you have any ideas re: bikes?

Maybe only allow them to cross as pedestrians? or use the bus lanes and get priority? certainly could do with some bike lines in the parklands thereabouts...

My first reaction is that this is quite a good plan, and very well thought out. Compared with my own plan for a fully signalized roundabout (that I devised for a uni assignment a few years ago) it would probably cost more, but only slightly more. And it does require the removal of some trees (so some people will oppose it for that) but you've done well minimizing that by keeping within the existing boundaries. It is slightly more restrictive (I don't have the turning traffic volumes to hand so I can't immediately tell whether that's a problem) but your plan does have one huge advantage: it is far more pedestrian friendly.

However I do have one suggestion for improvement, because there's a lot of left turning traffic from Fullarton Road S in the morning peak (despite its scarcity at other times) and some buses from Kensington Road to Dequetteville Terrace are stuck in the wrong lane. Therefore I suggest having a second left turn lane instead of the Fullarton Road S bus lane, then putting the bus lane on the extreme left on the section between Kensington Road and Dequetteville Terrace, with a B light at the end. That bus lane would not normally be used, but could be a tremendous advantage for buses from Kensington Road stuck in the wrong lane, or for buses from Fullarton Road when the traffic to Wakefield Road is free flowing but the traffic to Dequetteville Terrace isn't.

Only just found this thread - and I'm very impressed AtD! Well done. Also well done to the others who've taken a good plan and improved on it. I look forward to seeing your next "poorly thought out idea"!

I just had another thought about this. What if you cut off the access road from Fullarton Road (north) to Wakefield Road (but leaving the access road in the opposite direction in place) and converted the approach lanes of Fullarton Road (north) at Kensington Road such that the left lane serves traffic going straight and turning left and the right lane serves traffic turning right. It would improve traffic flow turning left into Wakefield Road from Fullarton Road (south) and Kensington Road as the left turn signal could remain green indefinitely until a pedestrian activates the pedestrian crossing across Wakefield Road.

perhaps underground the pedestrian & bike crossings - would not cost too much! and removes a big element of risk from the equation. We also tend to bang-on about how councils don't collaborate to enable easy bike access into the city - this could be a good first step... i realise this cross-road undergound intersection solution is not ideal (esp for bikes - you'd almost need underground traffic lights!) but at least it'll get us talking. Another reason for undergrounding is to enable easier access to the "newly invigorated vic park" which is not too far distant...

Interesting, but as a cyclist - I don't think I'd particularly enjoy having a steep gradient to enter and exit an underground tunnel. For pedestrians, I think an overpass would be better. If only that it's less likely to attract the seedy people after dark.

Bang on about councils not collaborating on easy bike access to the city. Bike lanes tend to disappear just before you get to the CBD (I'm looking at you Payneham Rd/Magill Rd/North Tce, Kent Town)

Wayno wrote:perhaps underground the pedestrian & bike crossings - would not cost too much! and removes a big element of risk from the equation. We also tend to bang-on about how councils don't collaborate to enable easy bike access into the city - this could be a good first step...

Britannia-undergound-peds.JPG

i realise this cross-road undergound intersection solution is not ideal (esp for bikes - you'd almost need underground traffic lights!) but at least it'll get us talking. Another reason for undergrounding is to enable easier access to the "newly invigorated vic park" which is not too far distant...