With congestion one of the most pressing issues facing the global transportation system, SPI feels that its ability to offer low-cost decentralized solutions to the ferry and freight industries that provides one its greatest values.
The following article from The Placemaking Institute offers insight into the decentralized model:
“Evidence underlines that the emergence of hub-and-spoke networks is a transitional form of network development rationalizing limited volumes through a limited number of routes. When traffic becomes sufficient, direct point-to-point services tend to be established as they better reflect the preference of users.”
“Metro areas that have integrated their rail transit into a decentralized network structure are found to enjoy higher riding habit, higher service productivity, and better cost-effectiveness than metro areas with other network structures or modal combinations.”
Transit is moving from its traditional centralized hub-and-spoke model to one that follows the point-to-point (no centralized hub) model, where multiple “nodes” are distributed around a city (examples: Providence, Seattle, Tallahassee, Orlando, Atlanta).
In input/output economic parlance, they are disaggregating clusters by increasingly expanding and diversifying their operations to locations where their investments will be most profitable. Cities that are remodeling their public transit network but are sticking to the hub-and-spoke model are creating X number of hubs throughout the city; thus these hubs are becoming, in effect, nodes (example: Los Angeles).
Advantage of point-to-point system:
It minimizes connections and travel time (the more that passengers use it, the more intuitive it becomes) and increases accessibility (and greater accessibility is good).
Advantage of hub-and-spoke system:
They are simple; new ones can be created easily; scheduling is convenient for passengers since there are few routes, with frequent service, so they may find the network more intuitive. An example of technology that obviates this advantage: The Chicago Transit Authority’s Bus Tracker.
Disadvantages of hub-and-spoke system:
Because the model is centralized, day-to-day operations may be relatively inflexible. Changes at the hub, or even in a single route, could have unexpected consequences throughout the network.
Route scheduling is complicated for the network operator. Scarce resources must be used carefully to avoid starving the hub, and traffic analysis and precise timing are required to keep the hub operating efficiently.
The hub constitutes a bottleneck in the network. Total capacity of the network is limited by the hub’s capacity. Delays at the hub can result in delays throughout the network. Delays at a spoke can also affect the network.
People must pass through the hub before reaching their destination, requiring longer journeys than direct point-to-point trips. This is often desirable for freight, which can benefit from sorting and consolidating operations at the hub, but not for people.
In a spoke-hub network the hub is likely to be a single point of failure.
Filtering people through a hub or a series of hubs is wasteful and inefficient compared to the direct point-to-point model, which can reduce transport emissions and operational costs?
US Intracoastal Shipping Network (ISN)
|041||E-041||Port of New York||NY|
|042||E-042||Port of Tacoma||NY|
|062||E-062||Havre de Grace||MD|
|124||G-017||Port St Joe||FL|
|180||W-036||South San Francisco||CA|
|183||W-039||Half Moon Bay||CA|
Washington State Ferry System
The Washington State Ferry System (WSF) transports 23 million passengers a year – roughly 6 million of which are passengers without vehicles.
WSF uses 9 ferries to service 20 destinations operating at an average speed of 5 mph. Due to the high cost of building traditional ferry terminals, they remain limited in number relative to the vast area WSF serves. This leads to a hub and spoke routing system which is highly inefficient and results in the type of congestion and pollution like that seen in Seattle. (see RED lines below).
Decentralization via Seaphantoms
One method to counter this hub and spoke model would be for the WSF to expand its fleet to include Seaphantoms, thus providing commuters with better service in terms of lost personal time, additional departure times and destinations closer to their workplace. (see BLUE lines above).
In addition to the significant savings in capital and operating costs per ferry per passenger, the community would benefit from substantially reduced pollution and congestion as well.
With the current total cost of a traditional 2,000 passenger/144 vehicle ferry nearing the $180 million mark, a better option might be to acquire 60 $3 million Seaphantom SP54s for the same amount, giving the operator much more flexibility in terms of departure times and destinations while simultaneously lowering fuel costs and other operating expenses for walk-ons.
The cycle time of an average ferry with a transit distance of eleven miles, the cycle time for that vessel running at the customary 5.5mph is 2hrs plus another hour of load-on time resulting in a three hour cycle. Assuming a conservative cycle time for Seaphantom 54s running at 60mph to be 40 minutes, SPI can operate five cycles in the time the traditional ferry finishes one.
LOGISTICAL INNOVATIONS : SP54 Equivalence
Using the above chart, a ratio of five cycles to one would afford the opportunity to use only 20 Seaphantom SP54s to transport the same number of passengers as one 2,000 passenger ferry in the same amount of time. With a cost of $3 million each, the 20 phantoms would result in a total capital cost of $60 million or one third the cost of the $180 million ferry.
LOGISTICAL INNOVATIONS : SP72 Equivalence
Using the above chart again, a ratio of five cycles to one would afford the opportunity to use only 8 Seaphantom SP72s to transport the same number of passengers as one 2,000 passenger ferry in the same amount of time. With a cost of $7 million each, the 20 phantoms would result in a total capital cost of $56 million or one third the cost of the $180 million ferry.
Additional Cost Savings
With Seaphantoms handling commuters, the size and cost of the remaining auto ferries could be reduced as well, lowering WSF’s capital and operating costs still further.