Transporting pupils to and from schools is a complex and
expensive logistics problem for many public school districts, especially in
rural areas where travel distances are longer. In many regions of the world,
students ride public transit to school, but public school districts in the US
and Canada generally provide transportation in dedicated school buses. Each bus
typically makes a sequence of trips each morning and each afternoon, where each
trip serves a separate school, usually with staggered start times for different
school levels (elementary school, intermediate school, high school). This
research explores whether the successful business logistics practice of mixed
loading can be applied to school bus transportation. Mixed load school bus
trips carry students for more than one school at the same time, and amixed load
routing policy reduces the number of stops to pick up and drop off students,
but it adds travel distance at the end of a trip to visit multiple schools. We
first provide a general strategic analysis using continuous approximation
modeling to assess the conditions under which mixed loading is likely to be
beneficial. Then we present a discrete algorithm for finding mixed load bus
trips. Results for benchmark data sets explore the tradeoffs between minimizing
the number of buses used and minimizing the travel distance. We also present a
case study for a Missouri school district to illustrate the application of the
models in practice. Results show that mixed load bus routing can be beneficial
when students are sparsely distributed, when a large percentage of bus stops
are shared by students of different schools, and when schools are closer together.
No comments:
Post a Comment