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Wednesday, 30 July 2014

Ferry Connections: Part 2 - Interchanges

A ferry operation can be viewed as a system made up of infrastructure elements (fleet and terminals), its customers, staff and a timetable. It is an open system, heavily influenced by the maritime environment, Government policy and regulation, the operation of other modes of transport and many other factors.  

Few aspects of this system are as important as ferry terminals, especially interchanges where passengers transfer from one line to another, or to or from another mode. In a harsh maritime environment, there can be a preoccupation with engineering issues and perhaps less attention on efficient ingress and egress of passengers or how the terminal fits with the overall network plan. 

Eagle Street Ferry Terminal Brisbane
The reliability of the network and the convenience of transfers between boats is largely a function of interchange design and how well it matches the vessel fleet.

Where an interchange is well designed, passengers can disembark and board quickly. If this happens, and the design of the fleet is compatible with the terminal design, there will only be a small variation in boarding time between a light loading and a heavy loading. This in turn helps ensure scheduled connections are met.  

To achieve this happy situation, there are two main requirements of the interchange:
  • capacity to deploy multiple, wide gangways. A single, narrow gangway only allows one passenger at a time to board or disembark. It takes one minute for 50 passengers to board via a single narrow gangway, and longer if there are passengers with strollers or special needs. If 100 are disembarking and 100 are boarding, then the boarding process takes four minutes or more. This is an unacceptably long dwell, not including the time needed to plank/ remove the gangway and tie lines. The solution is to provide for two wide gangways at all high demand wharves, which enable four to six passengers to board simultaneously.
  • keeping disembarking and boarding passengers separate at high demand terminals. If the wharf pontoon is too small, the crowd of passengers waiting to board interferes with the egress of disembarking passengers. Passengers transferring between vessels also need to be accommodated efficiently.
Each interchange must be an appropriate adaptation to the particular location and circumstances of its location. A "one size fits all" approach to designing wharf upgrades is doomed to failure.   

In last week's post, a network plan for Sydney Ferries was outlined with six locations where dual berthing wharf facilities are needed. It is not enough to simply say "this wharf needs to be dual berthing". There must be a visualisation of how these interchanges will work in practice, taking into account the proposed timetable and the implications for vessel and passenger movements. The goal should be to make sure dwell time is minimised and passengers can move safely and quickly between vessels.

At the outset, it should be noted that a classical 'four way' interchange that you might expect in a rail network, where two lines intersect at a four platform station and trains in both directions on both lines arrive at the same time, is not something you would want to replicate in the Sydney Ferry network, outside of Circular Quay. The cost of infrastructure to support this would be significant and not necessary unless transfers in all directions are imperative.

Some less grandiose models are suggested here.

1. Corner Connection

Network requirement:  two lines intersect at a terminal; transfers are required in some, but not all directions. Cremorne Point is an example of a corner connection in the proposed Sydney Ferry network described in the previous post. In this case, transfers from Barangaroo and Rose Bay in the direction of Mosman (and return) need to be possible, but it is not necessary for there to be transfers in the direction of Circular Quay. This means the Mosman to Circular Quay vessel can depart ahead of the other three.
Terminal design solution: required transfers can be supported, without conflicts, with a double length dual berth pontoon. The following diagrams show the order of vessels berthing and departing. Note that the connecting 225 bus arrives first allowing passengers to transfer to Circular Quay, Rose Bay and Barangaroo and departs last with passengers disembarking the ferries. In this case, a single ramp is shown, but separate ramps for boarding and disembarking passengers could be provided if needed.


2. T Connection

Network requirements: A T connection occurs where a wharf is the terminus of one line and an intermediate stop on another. An example is Rose Bay, assuming it is the terminus of a Ring Line connecting the Eastern Suburbs with the North Shore and Barangaroo, as well as an intermediate stop in both directions for the Watsons Bay line. In a situation like this, it is preferable to minimise the dwell for vessels on the Watsons Bay line to avoid inconveniencing passengers who have not completed their journey. There is scope, however, for a layover for the Ring Line as Rose Bay is the terminus. 
Terminal design solution: In this T connection, the inbound and outbound Watsons Bay vessels berth simultaneously at Rose Bay. As the vessel from Barangaroo is also in a layover at the same time, three berths are required. The simplest way to accommodate this is to use a double sided pontoon which is perpendicular to the shoreline and long enough to allow the Barangaroo vessel to berth "in the corner". 

These examples of terminal design show the importance of long term planning in the design of the network and timetable. Unless this is done, the supporting infrastructure may not meet future requirements.The Swiss Federal Railways develops its timetable 20 years in advance. This creates a sufficient lead time for infrastructure improvements to be put in place and minimises reworking and waste.  

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