VEHICLE CAPACITY AND UTILISATION
Vehicle capability is one of the factors
that constrain the set of transportation options available for personal
transportation. The capacity for carrying passengers and cargo is of particular
interest when energy consumption is considered, because the use of more
efficient vehicles may be limited for trips with higher load requirements.
VEHICLE ROUTING
The vehicle routing problem (VRP) is a combinatorial
optimization and integer programming problem. It generalises the well-known
travelling salesman problem (TSP). It first appeared in a paper in which first
algorithmic approach was written and was applied to petrol deliveries. Often,
the context is that of delivering goods located at a central depot to customers
who have placed orders for such goods. The objective of the VRP is to minimize
the total route cost
Determining the optimal solution to VRP is
NP-hard, so the size of problems that can be solved, optimally, using
mathematical programming or combinatorial optimization may be limited.
Therefore, commercial solvers tend to use heuristics due to the size &
frequency of real world VRPs they need to solve.
Sometimes it is impossible to satisfy all
of a customer's demands and in such cases solvers may reduce some customers'
demands or leave some customers unserved. To deal with these situations a
priority variable for each customer can be introduced or associated penalties
for the partial or lack of service for each customer given
The objective
function
The objective function of a VRP can be very
different depending on the particular application of the result but a few of
the more common objectives are:
- · Minimize the global transportation cost based on the global distance travelled as well as the fixed costs associated with the used vehicles and drivers
- · Minimize the number of vehicles needed to serve all customers
- · Least variation in travel time and vehicle load
- · Minimize penalties for low quality service
1.) Vehicle Routing Problem with Pickup and Delivery
(VRPPD)-A number of goods need to be moved from
certain pickup locations to other delivery locations. The goal is to find
optimal routes for a fleet of vehicles to visit the pickup and drop-off
locations.
2.) Vehicle Routing Problem with LIFO: Similar to the VRPPD, except an additional restriction is placed
on the loading of the vehicles: at any delivery location, the item being
delivered must be the item most recently picked up. This scheme reduces the
loading and unloading times at delivery locations because there is no need to
temporarily unload items other than the ones that should be dropped off.
3.) Vehicle Routing Problem with Time Windows (VRPTW): The delivery locations have time windows within which the
deliveries (or visits) must be made.
4.) Capacitated Vehicle Routing Problem: CVRP or CVRPTW. The vehicles have limited carrying capacity of the
goods that must be delivered.
5.) Vehicle Routing Problem with Multiple Trips (VRPMT): The vehicles can do more than one route.
6.) Open Vehicle Routing Problem (OVRP): Vehicles are not required to return to the depot.
Several software vendors have built
software products to solve the various VRP problems. Numerous articles are
available for more detail on their research and results.
Although VRP is related to the Job Shop
Scheduling Problem, the two problems are typically solved using different
techniques.
Approaches to the vehicle routing
problem
There are three main different approaches
to modelling the VRP
1. Vehicle flow formulations—this uses
integer variables associated with each arc that count the number of times that
the edge is traversed by a vehicle. It is generally used for basic VRPs. This
is good for cases where the solution cost can be expressed as the sum of any
costs associated with the arcs. However it can't be used to handle many
practical applications.
2. Commodity flow formulations—additional
integer variables are associated with the arcs or edges which represent the
flow of commodities along the paths travelled by the vehicles. This has only
recently been used to find an exact solution.
3. Set partitioning problem —these have an
exponential number of binary variables which are each associated with a
different feasible circuit. The VRP is then instead formulated as a set
partitioning problem which asks what is the collection of circuits with minimum
cost that satisfy the VRP constraints. This allows for very general route
costs.
TRANSPORT SAFETY AND SECURITY
Public transportation poses a higher risk
of safety and security since there happen to be more passengers in one car. The
problem becomes worse in developing countries, because of the lack of suitable
and integrated approaches.
This perception is used as a base to
develop an improvement agenda for the particular context of developing
countries. The rank of importance for each factor is analysed by applying the
factor analysis. Analysis shows that the user is the most important party
involved. The understanding and awareness of the user (including the driver) is
the most important variable to improve the condition.
Three aspects of an improvement agenda are
proposed based on the perception data, namely technology, management, and institution. This agenda is clarified
by a set of action plans incorporating the responsible parties and a time
frame. The action plan is divided into three terms to define a clear goal for
each step. The short-term action focuses on the hardware and on preparing
further steps, whereas the medium-term action focuses on developing and
improving the standard of safety and security. The long-term action focuses on
advancing safety and security practices. The effectiveness of this agenda and
action plan rests upon a set of assumptions, such as the degree of seriousness
from the authoritative institution, fair distribution of information, the
availability of reasonable resources, and coordinated and collaborative action
from all parties involved reaching the objective.
Public transportation provides a mobility
service to the user, as well as producing a wide impact on the system.
Consequently, it should be operated in such a way as to achieve an efficient
and effective transportation system. To achieve this, there is a need to
measure the quality of service as a way to evaluate its performance.
Safety from crime: Staff/police presence;
lighting; visible monitoring; layout; identified help points;
Safety from accidents: Presence/visibility
of supports; avoidance/visibility of hazards; active safeguarding by staff;
Perceptions of security: Conspicuousness of
safety measures; press relations.
LOAD PLANNING & ROUTE OPTIMIZATION & FLEET MANAGEMENT SYSTEM
Delivery vehicles are limited by their
load/capacity such as:
- 1. Number of boxes that can fit into the vehicle.
- 2. Weight of orders that can be loaded on the vehicle.
- 3. Volume of orders that can fit into the vehicle.
- 4. Number of pallets that can be loaded onto the vehicle.
Vehicle load planning, routing and
scheduling are critical decisions in a Transportation cycle. Effective load
planning can help Transporters reduce fuel usage, improve vehicle safety and
speed.
The Load planning module offers the
transporter a comparison between order volume and vehicle resources available.
A plan gets created based on best recommended combination and the transporter
chooses most optimised plan for delivery. A completely automated load planning
& route planning function in the TMS helps control the expenses, prevent
delivery delays and avoid cumbersome co-ordination with customer and drivers.
Fleet management is
the management of:
- · Commercial motor vehicles such as cars ,
- · vans , trucks, specialist vehicles (such as mobile construction machinery), and trailers
- · Private vehicles used for work purposes
- · Aviation machinery such as aircraft
- · Ships
- · Rail, cars.
Fleet (vehicle) management can include a
range of functions, such as vehicle financing, vehicle maintenance, vehicle
telematics (tracking and diagnostics), driver management, speed management,
fuel management and health and safety management. Fleet Management is a
function which allows companies which rely on transportation in business to
remove or minimize the risks associated with vehicle investment, improving efficiency,
productivity and reducing their overall transportation and staff costs. These
functions can be dealt with by either an in-house fleet-management department
or an outsourced fleet-management provider.
Principle of geo location based on the GPS
for the position determination and the GSM/GPRS or telecommunication satellites
network for the data transmission.
Mechanical
diagnostics
An advanced fleet management systems (FMS)
can connect to the vehicle's on-board computer, and gather data for the user.
Data such as mileage and fuel consumption are gathered into a global statistics
scheme.
Driver
behaviour
Highly developed fleet management and
vehicle telematics systems collect a full range of data in real-time and for
transport and fleet managers. By combining received data from the vehicle
tracking system and the on-board computer, it is possible to form a profile for
any given driver (average speed, frequency of detours, breaks, severity of manoeuvres,
choice of gears, etc.). This data can be used to highlight drivers with
dangerous habits and to suggest remedial training applicable to the issues, or
to ensure that drivers are meeting KPIs .
Management
of ships
Fleet management also refers to the management
of ships while at sea. Shipping fleet management contracts are normally given
to fleet management companies that handle aspects like crewing, maintenance,
and day-to-day operations. This gives the ship owner time to concentrate on
cargo booking.
Fleet
security and control
Recent advances in fleet management allow
for the addition of over-the-air (OTA) security and control of fleet vehicles.
Fleet Security and Control includes security of the vehicle while stopped or
not in operation and the ability to safely disable a vehicle while in
operation. This allows the fleet manager to recover stolen or rogue vehicles
while reducing the chance of lost or stolen cargo. The additional of Fleet
Security and Control to a fleet management system gives a fleet card manager
preventative measures to address cargo damage and loss.
1.
Remote vehicle disabling
systems
Remote vehicle disabling systems provide
users at remote locations the ability to prevent an engine from starting,
prevent movement of a vehicle, and to stop or slow an operating vehicle. Remote
disabling allows a dispatcher or other authorized personnel to gradually
decelerate a vehicle by downshifting, limiting the throttle capability, or
bleeding air from the braking system from a remote location. Some of these
systems provide advance notification to the driver that the vehicle disabling
is about to occur. After stopping a vehicle, some systems will lock the
vehicle's brakes or will not allow the vehicle's engine to be restarted within
a certain time-frame.
Remote disabling systems can also be
integrated into a remote panic and emergency notification system. In an
emergency, a driver can send an emergency alert by pressing a panic button on
the dashboard, or by using a key-fob panic button if the driver is within close
proximity of the truck. Then, the carrier or other approved organization can be
remotely alerted to allow a dispatcher or other authorized personnel to
evaluate the situation, communicate with the driver, and/or potentially disable
the vehicle.
Fleet replacement and lifecycle
management
The timely replacement of vehicles and
equipment is a process that requires the ability to predict asset lifecycles
based on costing information, utilization, and asset age. Organizations prefer
to use new fleet as a strategy for cost reduction where the used fleet is sold
so that a new fleet is maintained.
Funding requirements are also an issue,
because many organizations, especially government, purchase vehicles with cash.
The ad hoc nature and traditional low funding levels with cash has put many
operations in an aged fleet. This lack of adequate funding for replacement can
also result in higher maintenance costs due to aged vehicles.
