  The technology-enabled ride-pooling (RP) is designed as an on-demand feeder
service to connect remote areas to transit terminals (or activity centers). We
propose the so-called ``hold-dispatch'' operation strategy, which imposes a
target number of shared rides (termed the ride-pooling size) for each vehicle
to enhance RP's transportation efficiency. Analytical models are formulated at
the planning level to estimate the costs of the RP operator and the patrons.
Accordingly, the design problem is constructed to minimize the total system
cost concerning the system layout (i.e., in terms of service zone
partitioning), resource deployment (i.e., fleet size), and operational decision
(i.e., ride-pooling size). The proposed models admit spatial heterogeneity
arising from the non-uniformity of demand distributions and service locations,
and can furnish heterogeneous designs. Closed-form formulas for the optimal
zoning and fleet size are developed, which unveil fundamental insights
regarding the impacts of key operating factors (e.g., demand density and
distance to the terminal). Extensive numerical experiments demonstrate (i) the
effectiveness of heterogeneous service designs and (ii) the advantage of the
proposed RP service with hold-dispatch strategy over alternative designs
studied in the literature, i.e., RP with a ``quick-dispatch'' strategy and
flexible-route transit, in a wide range of operating scenarios. These findings
can assist transportation network companies and transit agencies in
successfully integrating RP and transit services.
