  Meal delivery services provided by platforms with integrated delivery systems
are becoming increasingly popular. This paper adopts a rolling horizon approach
to solve the meal delivery routing problem (MDRP). To improve delivery
efficiency in scenarios with high delivery demand, multiple orders are allowed
to be combined into one bundle with orders from different restaurants.
Following this strategy, an optimization-based four-stage heuristic algorithm
is developed to generate an optimal routing plan at each decision point. The
algorithm first generates bundles according to orders' spatial and temporal
distribution. Secondly, we find feasible bundle pairs. Then, routes for
delivering any single bundle or multiple bundles are optimized, respectively.
Finally, the routes are assigned to available couriers. In computational
experiments using instances from open datasets, the system's performance is
evaluated in respect of average click-to-door time and ready-to-pickup time. We
demonstrate that this algorithm can effectively process real-time information
and assign optimal routes to the couriers. By comparing the proposed method
with existing the-state-of-the-art algorithms, the results indicate that our
method can generate solutions with higher service quality and shorter distance.
