So I went to the drop in session on the Blackwood roundabout upgrade held by DPTI Transport last night. The project team rep told me that 4 traffic lanes on each of the 4 roads was a non-negotiable starting point for the design. Given this, there is very little room for any changes to the concept design. There can be no concessions to pedestrians except at the church, and no concessions to cyclist safety.
Because the project team is a traffic team at DPTI, their objectives are maximising cars/hour at peak hours, and making the roundabout easier and safer to navigate for car drivers. They are building what they know, and questions about anything else just got shrugs.
Answers I got to questions include: It is not safe to have pedestrians near to roundabouts, so pedestrians will have to go down the road and press the beg-buttons to cross. It is not safe to make provision for cyclists on roundabouts, so there are none. I was advised to ‘take the lane’ if I wanted to cycle through it, i.e. get in the middle of a lane as if I was a car.
When I mentioned overseas roundabout designs that cater for pedestrians and cyclists, I was told that 4 traffic lanes at each exit means there is no room for such things. I mentioned research showing that neighbourhoods which introduce pedestrian and cycling friendly measures see an upturn in business takings. More shrugs.
I asked about the modelling that necessitated 17 car lanes, and I was told that I would not be allowed access to the modelling and wouldn’t understand it in any case. But I was assured that 17 car lanes are definitely needed, the queues would be huge otherwise.
So it's all about car flow rates and making it easier for drivers to not stuff up driving round it. As far as the project team are concerned there is little value in talking about pedestrians or cyclists because the car requirements are non-negotiable and there isn't any space left.
And therefore increase the traffic down Laffers Rd (past a school) and Sheoak Rd (past a pre-school and another school) so that cars get onto James Rd for priority at the roundabout.
But the same already happens, in reverse: traffic which should be using James Road, instead "rat runs" across to Main Road and Old Belair Road.
I used to live in Glenalta, and the quickest way down the hill (by car) should have been a left turn onto Upper Sturt Road and then go down James Road. But during peak hour I didn't, because James Road traffic was always banked up at the Old Belair Road intersection. So instead I would do a rather dangerous right turn onto Main Road, drive past Belair Primary, and then on down Old Belair Road. (EDIT: So my experience was the opposite of Matt S, who found James Rd worked better!)
I agree though that a roundabout would replace one bad situation with another. A better fix would be a traffic light at the James / Old Belair Road intersection. That way the traffic light would sort it out, so that neither route has an excessive delay.
I also agree a rounabout is an awful soluton. I live 100m from Sheoak / Old Belair intersection and am generally held up by those trying to avoid James road and turn right from sheoak (again what Henry describes in reverse).
A friend suggested an alternative rounabout near Belair Fine Wine may work better. Embrace cars using the sheoak route, and less backing up of traffic on steep and winding roads. I hope this is atleast considered and modelled as a potential solution.