Recently a lot of discussions have been occurring on how AT decides whether to place a Transit Lane vs a Bus Lane, I decided the investigate and this is what I found.
According to the AT Code of Practice on the matter, the following flowchart is used
So for a route to qualify for a Bus Lane it has to
- Be either a Frequent Transit Network route or have 15bph.
- Have a Level of Service lower than C
- Then under a corridor productivity assessment be recommended as a Bus Lane which can be seen from the below example for Dominion Rd.
The productivity is calucated as follows:
Corridor productivity of the route is defined as the movement of people through a corridor by lane per hour. Corridor productivity is calculated by multiplying the number of person trips with travel speed, expressed as an average by lane for the corridor. As such, the higher the number of person trips accommodated by lane per hour, or the higher the corridor productivity, then the more efficiently the route is operating. Austroads have suggested a benchmark value of 38,000 person-km /hour per lane be used to reflect favourable corridor productivity or efficiency of a corridor. In practise, a corridor productivity of 75% of this benchmark or higher, is desirable on arterials. This Austroads value is derived from the productivity pertaining to a single lane carrying 900 vehicles/hour with an average travel speed of 35 km/h, which is representative of LOS B, and reflects a high level of productivity or efficiency for the route. Applying an average occupancy of 1.2 to 1.3 per vehicle, results in the 38,000 person-km/hour per lane value adopted in the assessment. By way of comparison, 20 buses travelling at the same average speed, with occupancies of 55 passengers per bus, surpasses this productivity benchmark, and demonstrates the significant potential buses have in exponentially increasing productivity along a corridor. Another way of describing this is to note that the efficiency of a bus lane with 20 well-occupied buses will always be greater than the alternative of allowing that lane to be filled with traffic. As an example, Dominion Road currently carries 34 buses in the morning peak hour. With the addition of a further 6 buses, the bus lane on Dominion Road will have the potential to operate at a productivity or efficiency, of double the 38,000 person-km/hour per lane benchmark. To achieve the same productivity without the bus lane, there would effectively need to be two additional general lanes added to the Dominion Road cross-section.
Taxis are also allowed to use Transit Lanes regardless of passenger or not:
Taxis are permitted to travel on T2 or T3 lanes, whether or not there are an appropriate number of people on board, on the basis of the vehicle being a passenger service vehicle. This however does not apply to bus lanes.
However, the big weakness, especially with Transit Lanes, is the non-compliance as they are much harder to enforce. If we are to stick with T3 lanes for major Bus Lanes we really need to get better on this.
Another weakness is also, for example, take Manukau Rd is extra congestion is caused by cars merging in/out of the Transit Lanes to try to overtake buses.
It would also be interesting to see a recent Corridor Productivity Assessment for Manukau & Onewa Rds
So what do you think of the AT Code of Practice standards on the issue?