Below is a visualisation of the proposed Milton Road / Elizabeth Way junction as part of the City Deal bus priority.
You will notice how the straight-on Milton Road traffic has to give way to the right-turning bicycle traffic – reducing capacity. This is the same problem for left-turning Milton Road traffic going towards Elizabeth Way, they have to give way to bicycle traffic going straight on. Or, in reality, force riders to stop at the edge, or merge vehicularly, to make the turn.
The capacity of this junction is halved because of this. And the simulation has given no time for people walking across the junction, so the actual capacity would be lower. It may give buses priority, but it significantly reduces car capacity. And the buses are delayed too.
What could you do instead? Well, you could build a protected junction.
In the second video, you have a separate bicycle / pedestrian phase. After the southern arm is stopped, all the bicycle lights (and pedestrian lights) are given a green light, and bicycles rotate around the junction safely. There are no buses or heavy goods vehicles trying to squash them. This traffic is given a green light before the Milton Road southbound arm is given green, meaning that people on bicycles are given a green light.
Also, this junction links Highworth Avenue into the bicycle network, and allows people from the avenue to turn right into Milton Road safely and in one movement.
Importantly, there are no advanced stop lines, no advanced cycle traffic lights. Everything is safe, more space is given to queuing traffic, and more time is given for moving traffic.
This second junction design has double – yes double – the car traffic capacity. It can also move more people on bicycles than the proposed design. And most importantly, the additional delays to buses are measured in seconds rather than minutes.
The original proposal comes from the Greater Cambridge City Deal Milton and Histon Roads bus priority draft options report. See http://www.gccitydeal.co.uk/citydeal/download/downloads/id/15/draft_options_report.pdf