Critical Mass

Dynamic car sharing is uniquely distinguished from static or casual ride sharing by its ad-hoc nature (see Definition of Dynamic Ridesharing). It is based on the principle that travel is inherently spontaneous and that some users will only rideshare if a service can be availed of at short notice and a broad number locations. The vision for dynamic ridesharing is that by offering flexible ridesharing it can become almost ubiquitous, and function as a general transport utility.

If dynamic ridesharing can break free of niche scenarios, then it will enjoy networks effects and economies of scale. It seems likely, however, that consumers will give the benefit of the doubt to a new service such as ridesharing only three times. If they do not have a good experience within the first three attempts, they will not return. Herein lies the ‘critical mass’ issue that faces ridesharing generally and dynamic ridesharing particularly.

In order for each new ridesharing route to cross this critical mass chasm, more than half of the new drivers and new passengers must receive a match within their first three attempts, or the popularity of the route will decay and ride sharing will fail. For the dynamic ridesharing vision to succeed in a region, the majority of routes must cross the critical mass chasm.

In static ride sharing schemes, critical mass has a low threshold. Critical mass is achievable since the driver and rider probably know each other, or share a community, so the supply and demand are matched before each passenger attempts to avail of the service.

In casual ridesharing ("casual carpooling") critical mass is achievable because matching occurs at a bottle-neck ‘port’ where much of the traffic is traveling to the same destination. The active locations seem to have grown organically – initially by drivers "stealing" riders from transit. Riders are waiting (for a bus, say) anyway; the initial drivers will always succeed in finding a rider.

In dynamic ridesharing the driver and passenger do not know each other, and there may be no single focal point for traffic traveling to the same destination. For a dynamic ridesharing route to cross the critical mass chasm the ‘chicken and egg’ scenario is that:

- There must be a sufficient number of drivers offering seats, to enough destinations, at enough times that are of interest to passenger. Without a significant number of drivers offering seats to many destinations and at many times, then it is probable that when new passengers request their first ride, they cannot be offered a seat.

- There must be sufficient passengers demanding seats to destination that are offered by drivers. If sufficient passenger demands are not available, the drivers will see little point in taking the trouble to offer their seats to share.

Note: No-one (that we know of) has calculated, for the various road networks and travel patterns, what the absolute number or proportions of drivers and passengers must be to achieve critical mass. (Kirshner attempted to do so with simulations that could show, for various densities – in time and space – and rider-driver proportions, what fraction of riders and drivers would be successfully matched. See Ride Now!)

A number of ‘pump priming’ solutions have been suggested or attempted to bridge the critical mass chasm:

- Emulate a casual ridesharing service by focusing promotion efforts on a single route where significant incentives (for example, a car pool lane, or demand for parking) exists. In a concerted campaign bring the route to critical mass, as if a conventional casual ridesharing site. Leverage the flexibility offered by dynamic ridesharing to expand the service from this single route to include similar high demand routes, according to demand. This approach has been tried and failed at least twice before for a variety of reasons. The predominant learning being that to execute a concerted campaign requires the cooperation of institutions that controlled the incentive (car pool lane, or parking), and/or controlled communication with the community of users.

- Offer sufficient subsidies to compel sufficient numbers of drivers to register and offer their empty seats for long enough for the passengers community to build up. Offer passengers sufficient subsidies to continue to request rides while the driver community builds up. This is the approach currently intended for Mapflow’s pilot in Dublin, Ireland. It is accepted that subsidizing 100 drivers is unlikely to achieve a critical mass that will be sustained.

- Employ professional drivers (taxi, shuttle buses) to provide an initial dynamic transport service, for as long as it takes to build up passenger numbers. Then encourage private drivers to offer these passengers their empty seats.

- Launch and promote an ‘early adopter’ product that provides some stand-alone value to the consumer driver, which may or may not be related to ride sharing. Evangelize the vision of dynamic ridesharing in terms that will encourage grassroots supporters to establish their own ridesharing community, enabled by the dynamic features of the driver product.

- [others?]

Like static or casual ridesharing, an adoption process/campaign could be devised to bring one or two pilot routes into to existence and perhaps to critical mass. To be worthwhile, the total cost of that adoption process must be less than the value delivered by the ridesharing operation, once it is up and running. Additionally, to deliver the promise represented in the vision for dynamic ridesharing, many new routes must come into existence and achieve critical mass on their own. Therefore, a successful dynamic ridesharing product will include an adoption mechanism that universally overcomes the critical mass chasm that is inherent in the ridesharing market.

Inhibitor: lack of a well known, tried and tested mechanism that, for a given territory, brings on-line sufficient drivers and passengers before the interest of either is lost.