Firstly, we should recognise that detecting a signal (i.e. rider diversion) will be challenging given the inherent variation in counts between days. This variation can be attributable to weather, seasons and day of week. However, there is also an inherent variation (“noise”) above and beyound these (theoretically) predictable factors. Observed changes in rider demand that can be attributed to the project will need to be very substantial to exceed this inherent variation. In other words, the “signal” will need to significantly exceed the “noise”.
Second, I assume the automatic counters on Kurilpa and Goodwill Bridges are operational and that data can be obtained, either directly from DPW or indirectly via Pentagon Systems. Note that the pedestrian counters on these bridges cannot be trusted.
Third, our site rationale is based on two principles:
Establish a screenline along Margaret St to establish whether total rider demand has changed; this screenline is defined by Grey St, South Bank, Bicentennial Bikeway (existing automatic counter) and George St (north of Margaret St).
If there is substantial diversion away from the Bicentennial Bikeway near Queen’s Wharf we would expect riders approaching the CBD from the west to divert up the Herschel St ramp or between Adelaide and Queen Streets, and those from the south to use Gardens Point Road (BUT can riders actually get CBD access this way given Lamington Dr/Alice St is one-way sbnd?). Another option may be for riders to turn right from Goodwill Bridge and ride around the Botanical Gardens to Edward St, but is this likely?
Finally, it is assumed (as per the Queen’s Wharf website) that William St in the vicinity of the project will be closed entirely for the duration of the construction, and that George St will only facilitate southbound movements. It seems possible some riders will travel northbound along the footpath, although given pedestrian volumes this movement will presumably be low.
There are presumably two main rider demands along this section of Bicentennial Bikeway:
Riders travelling to/from the CBD or South Brisbane (via Goodwill Bridge) for commuting, and
Riders riding for recreation (presumably many doing so as part of the “river loop”).
The first of this group will presumably divert up the ramps (Henschel St, Ann St) or Gardens Point Rd to the CBD, or else cross the river at Kurilpa Bridge or Victoria Bridge and use South Bank or Grey St to travel farther south. This group would be counted both at the ramps and on Grey St or South Bank. Options for recreation riders are presumably much wider, but would presumably still largely consist of diverting up the ramps and through the CBD or across to South Bank.
What we cannot be sure of is what proportion of riders, and at what times of day, are using the QW section of the bikeway to access the CBD and what proportion are riding through. The intercept surveys should provide insight into these proportions.
As shown below, the sites either form a screenline (parallel to Margaret St) or are at locations likely to experience an increase in demand as riders divert (i.e. Henschel St, Ann St, Gardens Point Rd).
I suggest the most compelling sites are likely to be George St, the two ramps from the west (Henschel St and Ann St), and Gardens Point Rd and possibly the path around the botanical gardens to the east of Goodwill Bridge. The South Bank sites feel likely to be more marginal (particularly Grey St) and the site on the bikeway itself is superflous if, as one would hope, we can rely upon the automatic counter at this site.