SOLFI: An Integrated Platform for Sustainable Urban Last-Mile Logistics’ Operations—Study, Design and Development

Abstract

Sustainable urban logistics has an important impact on the cities, which emphasizes the need for better management of logistics activities, including the usage of environmentally friendly transportation. The sustainability of cities, a concern that is on the agenda, is a very important topic pertaining to current political and societal issues. In this sense, although collaboration among urban logistics stakeholders on projects can be challenging, this effort pays off when there is a significant result for the sustainability of cities. This paper aims to present an Information System, named SOLFI (Sistema de Otimização para a Logística urbana com Fluxos Integrados), for planning management and control of urban logistics based on sustainability that integrates the transport of passengers and freight, using the city bus network and bicycles to perform last-mile deliveries. To develop the SOLFI solution and to ensure co-creation through a participative design approach, an agile methodology was used. In terms of results, the SOLFI integrates different agents in the movement of goods in urban centers with less polluting and small vehicles, in particular buses and bicycles. It represents a decision support system that is intended to operate in real-time, managing the entire process from the request until the load delivery to the final destination, to simplify, automate, and improve the urban logistics process. Thus, the main characteristics of SOLFI are to manage all the information required for this process in order to: (i) request quotation and acceptance management; (ii) deliver plan development to all the agents involved; (iii) manage the loads along the network; (iv) allow the tracking and control of requests along the network; and (v) enable replanning due to various possible disruptions that may occur during the process. SOLFI’s distinctive characteristic and main contribution result from the integration of all the transportation network and all agents in the same platform while considering synchronization among involved agents. The SOLFI solution allows for the reduction of traditional flows of goods, taking advantage of the availability of public passenger transport (buses) to perform the main travel distance within the city and the use of bicycles as a last-mile step. In this way, there is a reduction in the number of polluting vehicles in the city, meeting sustainability practices.

1. Introduction

The population growth that has occurred in cities has strongly contributed to the increase in passenger transport and especially to the transport of goods, which co-exist in urban space. Moreover, in recent years, there has been a greater demand for e-commerce, particularly with the changes that COVID-19 brought, and this was reflected in the urban logistics of our cities, which have become more complex as more transport circulates, with an impact on the environment, quality of life in cities and costs. In addition to the social, economic, and environmental impacts of urban logistics, there is an increasing concern over the need to decrease carbon-based fleets in cities, with a greater emphasis on reducing pollution and thus improving environmental quality.

There are several possible solutions to these concerns, entailing environmentally friendly alternative storage and transportation solutions [1]. However, despite the stakeholders being active elements in urban logistics, their interests are not always aligned, focusing on their own needs and preferences, which increases the complexity of the urban environment [2,3]. According to the same authors, transport companies/couriers focus on satisfying customers at low costs, forgetting environmental pollution; customers choose transport companies based on price and responsiveness, and the local government tries to create conditions to serve its citizens well [3]. To solve this holistic and complex problem, it is necessary to take concerted action, with the involvement of all stakeholders, to find a solution for sustainability in urban logistics that considers the sharing of logistical resources. This solution could potentially lead to fewer vehicles in urban areas, and consequently less pollution and lower prices for freight transport, with an impact on the customer. However, as previously shown in the literature, collaboration in practical urban logistics projects brings extra challenges in the planning and control of the system [4]. Developing solutions and promoting mechanisms to improve freight transport services and reduce their impacts to promote the sustainability of cities is also an important challenge for researchers [3]. Moreover, to be effective in this approach, these solutions must integrate information and communication technologies (ICT) to design the last mile and define operation strategies, improving real-time decisions based on data exploitation and dynamic analysis in real time [5]. Thus, the gap in the literature combined with the urgent need to create solutions that ensure the three pillars of sustainability—economic, social, and environmental—in cities, which tend to grow in population density, motivated the development of a solution mediated by ICT, which was named SOLFI (Sistema de Otimização para a Logística urbana com Fluxos Integrados). This research aims to contribute to sustainability in urban logistics by addressing the problem of freight distribution in the cities through the integration of flows of people and goods to ensure a more efficient and environmentally-friendly distribution process, using, whenever possible, the same transportation network. Given the importance of mediating this type of service with ICTs, this research aims to present an integrated platform for sustainable urban last-mile logistics operations, responsible for the management and control of all the activities related to a new logistics service for freight distribution within cities. The specific problem to be solved by the new services enabled by SOLFI is characterized by a huge number of small orders (in volume and weight) or requests to be delivered to a huge number of final customers (end-users or retailers), located in the inner city or clustered in various parts of the city. In traditional distribution solutions, these requests are delivered to the final customer through logistics operators directly from their distribution centers, using mostly fossil-fuel vehicles. Besides the negative impacts of the traditional distribution solution on the city’s sustainability, these logistics operators many times face challenges in optimizing delivery when balancing the requests’ due dates and the process efficiency. Furthermore, there are typically traffic constraints in the inner city creating restrictions on the type of vehicles that can be used and impacting the service efficiency and quality. The SOLFI aims to offer a new service that can be used by logistics operators as an alternative solution to the delivery of some of their delivery requests, although the service can be used by any individual that aims to send freight to the inner city. The basic idea of this new service is to have some points strategically located in the city outskirts where the logistics operators/individuals can drop off freight to be sent to the inner city. These points are serviced by a network of buses, that are used to transport the requests from there to a set of bus stops, nearly located to the request’s final destination. Upon arrival at a bus stop, the requests are collected by a last-mile operator and delivered to their final customers, through a user-friendly fleet of vehicles, constituted by a network of bicycles to perform the freight delivery from the bus stop to the requested final destination.

Traditionally, in theory and practice, the flows of people and goods in the city have been treated separately, although both entities share the same road infrastructure and influence each other. Therefore, one of the main advantages resulting from the integration of the two types of flows is a better and smarter use of available capacity. Moreover, the integration of the two types of distribution flows is quite common in long-haul distribution. However, in the first- and last-mile delivery, it is understudied and underutilized [6,7], making it an interesting research topic.

Despite the significant body of literature considering urban logistics problems combining freight and people flows, most of the contributions deal with a particular problem or issue. As an example, refs. [5,8] develops a mathematical model and an Adaptive Large Neighborhood Search algorithm for the optimization of the vehicle routing process, resulting from the integration of passengers and bus flows. Another recent contribution [7] also considers the optimization of the vehicle routing process, but in this case, considering passenger stochastic demands using a fleet of grounded and autonomous robots. Papers focusing on the development of distribution plans for the integrated urban logistics problem can also be found. See, for example [9], in which the authors present a mathematical model and an improved Variable Neighborhood Search algorithm for the combination of passenger and metro flows.

To the best of our knowledge, there is a lack of platforms to manage all the information used in the urban logistics process, integrating all the decisions involved from the request quotation until the freight delivery and also allowing all the agents involved in the process to track the request along the process. Ref. [10] conceptualizes several problems at the strategic, tactical, and operational levels to be solved when combining passenger and freight flows using rail transportation, but the focus of the paper is not the development of a platform to plan, manage and control the operations. In addition, there are several platforms in the literature to support urban logistics planning, management and control activities, namely: managing urban load distribution [11]; supporting and facilitating the business of last-mile delivery companies [12]; integrating collaborative transport between a traditional fleet and last-mile green deliveries (such as bicycles) [13]; and simulate and optimize alternative solutions for road transport [14]. However, there is a lack of integrated solutions covering the planning, management, and control along the network, from a delivery request quotation to the load delivery to the final customer, with the integration of passenger and freight flows.

Case studies that analyze the integration of flows of people and goods can also be found in the literature [15,16], but they are not integrated into the same transportation network, and the implementation and operation of these shared networks remain a big challenge [17]. The main challenge is to optimally plan, manage and control the freight movements within a logistical network while considering integration and coordination among involved stakeholders [17]. Therefore, there is a gap in terms of software related to urban logistics that integrates flows of people and goods in the same transportation network. Thus, through the conceptualization and implementation of the SOLFI system, we are contributing to the urban logistics literature by providing a solution that tackles, in an integrated way, all the decision-making planning processes and the request traceability of the processes.

The research underlying the presentation of the solution described in this article presents an integrated technological solution—SOLFI—for urban logistics combining passengers and freight flows to improve the sustainability of the cities. The following research question oriented the research: how to plan, conceptualize, and develop a platform for the operational planning, management and control of urban logistics combining passenger and freight flows? To answer the research question, an agile methodology was followed, integrating a user-centered approach in a co-creation process.

This article is structured in six sections, beginning with this introduction section. Afterwards, in Section 2, the literature review on urban logistics is explored. In Section 3, the methodology used for the development of the SOLFI is detailed, and in the next section, Section 4, the main results of this research are presented. Furthermore, in Section 5, a discussion is exposed and finally, in Section 6, the main conclusions, limitations, and further developments of this study are elucidated.

2. Literature Review

This work intends to present the development of a software for urban logistics that integrates the transport of passengers and freight, using bicycles for the delivery process from the bus stop to the end destination. This solution is aimed to improve cities’ sustainability, allowing us to solve the challenges involving different stakeholders. Therefore, the literature review is structured into two parts: sustainability in urban logistics in terms of the related concepts and challenges, and existing solutions for urban logistics.

2.1. Sustainability in Urban Logistics: Concepts and Challenges

Recently, there has been a growing demand for e-commerce, reflected in an increase in urban logistics needs in cities, offering consumers the possibility to choose a wide variety of products and compare prices, decide where to buy, communicate with sellers, and customize products through connected devices [18]. Moreover, in 2021, the demand for delivery services increased with the COVID-19 pandemic in urban areas. Although electronic transactions travel through digital networks, the purchased products must still be physically transported and delivered to consumers [18]. These operations, in particular last-mile operations, have increased due to the growth of e-commerce and direct-to-consumer strategies [19].

There are numerous definitions of urban logistics, but a common characteristic is to find efficient and effective ways to transport goods in urban areas while considering the negative effects on congestion, safety, and the environment [7,20]. Urban logistics can be considered the last element of a supply chain, embracing the deliveries to the final consumer, usually known as last-mile deliveries [21]. These last-mile deliveries focus on both household/domestic supplies, being the outcome of commercial transactions, and deliveries necessary for the daily business of enterprises operating within the city [22].

The last-mile delivery process refers to the distribution of the freight or parcels purchased by the customer, from the supplier to the customer or from the supplier to the pick-up location designated by the customer [23]. It is a critical part of the supply chain because of its high costs and customers’ increasing expectations from e-commerce and same-day delivery services [24]. Last-mile delivery services are responsible for a large part of supply chain costs, representing between 13% and 75% of the total cost [25]. In addition to cost, the last-mile delivery process has characteristics of low efficiency and high pollution [26,27,28]. Furthermore, in the whole supply process, which includes packaging, loading and unloading, transporting, sorting, and delivering tasks, the last-mile delivery is the only connection to face the customer [23], where customer satisfaction is a very important dimension that enterprises need to tackle to enhance their competitive advantages [29]. Urban deliveries assume a significant role in the functioning of cities, being a critical factor in their attractiveness, and having a direct impact on the quality of life perceived by citizens and users [30,31]. Authorities and decision-makers have so far produced uncoordinated policies and rules to tackle such matters, often resulting in minor or even counter-productive effects [32].

A city needs an efficient transport network and access to a wide range of goods, as well as resources. Due to that, the transportation function is one of the key responsibilities of any city [21]. Urban freight transport is a major challenge for transport companies as well as for local authorities, creating several problems, such as congestion, noise levels and air pollution, damaging the quality of life of citizens and the performance of stakeholders [33]. At the same time, road freight transport contributes to significant emissions and congestion [34]. Therefore, to achieve the United Nations’ sustainability goals, a sustainable and efficient road freight transport sector is mandatory [34]. The mobility of freight and passengers is facing growing challenges, such as urbanization and e-commerce escalating tendencies, the increasing complexity of the stakeholders’ scene, and the rising fragmentation of freight transport. All these modern trends have adverse impacts on congestion, safety, the environment, and quality of life in general [35].

The reduction of costs is a common interest of profit maximizers, such as shippers and carriers, and money-savers, such as consumers. In contrast, governors are interested in dealing with environmental factors, such as traffic congestion, accidents, pollutant emissions, and noise [19,36]. Stakeholders’ interests follow distinct behaviors to pursue different objectives. Moreover, the different urban logistics that stakeholders’ expectations engender present many challenges for managers, especially in the context of city users’ needs and their quality of life [21].

In summary, the reasons why the issue of urban logistics is increasingly complex and costly are: the growth of e-commerce and related delivery shattering patterns, greater customer expectations, the aspiration to increase delivery performance at lower costs, and the enhancement in city/urban sustainability and livability [37]. Urban goods transport plays a critical role in satisfying people’s needs but creates significant impacts on city sustainability. Moreover, according to [36], the environmental problems related to traffic and congestion, pollutant emissions, and noise can be solved by introducing the concept of sustainability in urban logistics.

2.2. State of the Art: Solutions for Urban Logistics

In the recent past, several alternative solutions to the traditional ones emerged to support the urban logistics process and make it more environmentally friendly. One of those solutions is related to the introduction of urban distribution infrastructures, introducing a new phase in the delivery system. A popular solution is the introduction of Urban Logistics Spaces that create an interface between deliveries and receipts, improving the management of goods’ flows [33]; additionally, consider an environmentally-friendly fleet (typically cargo bikes or electric vehicles) to perform the last distribution phase. The typology of urban distribution infrastructures can be categorized into five classes: Urban Logistics Zones; Urban Consolidation Centers; Proximity Logistics Spaces; Goods Reception Points (Points Relay and Delivery Areas); and Urban Logistics Boxes [33], and several examples of applications can be found in the literature and practice.

Solutions that combine the passenger transport service and goods delivery services, as a public transit-based logistics transport system, can also be found [38,39]. The combined system of people and freight flows has a set of passengers and parcels that need to be transported simultaneously from their origins to their destinations [33]. To be effective, these combined systems imply a strong linkage between urban freight transport, the urban mobility system as a whole, and the key stakeholders, making this integration complex and involving different aspects [40]. Several examples of integration can be found in the literature, such as the integration with a taxi service [41,42], a bus service [43], and a metro service [44].

There is a potential gain in sustainability when sharing passengers and goods in the urban network, focusing on the improvements to service time and wasted energy [45]. The emphasis is on the mobility system’s efficiency and efficacy, resulting in more feasible operations when compared to the current model where passengers and freight transport coexist as independent systems [46,47]. This type of solution can also reduce costs and increase environmental quality and social value. It can yield some travel cost reductions for passengers [39] and lower direct and generated costs for all involved stakeholders [40]. Furthermore, this integration can lead to minimizing vehicle miles travelled, traffic congestion, and pollution levels in urban areas [39], more care for environmental issues, and higher social value [40]. This solution accomplishes socially desirable transport options and is economically feasible in urban areas, as it reduces air pollution and congestion [48]. However, it must guarantee that the transportation of goods does not disturb passenger trips [39].

Information and communications technologies (ICT) can present another type of solution to overcome the challenges of sustainability and restrict the side effects of urban logistics. Furthermore, some studies reveal positive effects of emerging technologies on the three sustainability pillars: environmental, social, and economic. The role of advanced ICT and big data are highlighted for reaching the goals of sustainable development, as well as ensuring a healthy and livable environment for the city and its citizens [49].

As stated by [34], digitalization, including digitized information flows, automation, and artificial intelligence, offers many opportunities to improve efficiency, reduce costs, and enhance service levels in freight transport. Automated technologies, such as drones and robots, in urban freight transportation are an opportunity to foster more efficient systems characterized by the integration of different and complementary modes of delivery [24]. Drones can help to deliver small packages to destinations without any traffic congestion, which would otherwise delay delivery and impact the level of customer service [20]. Robots also represent an attractive solution, particularly in urban environments characterized by a considerable number of stops and relatively short delivery distances. The robots’ storerooms could be divided into different partitions so that each trip could serve more than a single customer at a time (although this functionality is not present in real-world systems) and counterweigh for their lower speeds [24].

The adoption of new technology allows for minimizing costs in the road freight transport industry [34] and throughout the urban logistics system. These technologies may improve efficiency in terms of cost savings, as well as reduce adverse environmental impacts [50].

Most measures taken by the public sector concerning urban freight transport are directed at lowering the negative social and environmental effects caused by transport activities. In this sense, decision-makers responsible for transport policies carry out various initiatives that focus on the physical infrastructure, road traffic, vehicle design, or basic logistic operations [49].

3. Materials and Methods

3.1. SOLFI Development Protocol

Given the complexity of the solutions proposed, and the variety of associated requirements, the methodology used to develop it followed an agile approach supported by co-design techniques in a user-centered design (UCD) method. The agile method, one of the most used in the development of complex solutions, represents iterative and incremental development approaches, with progress in small cycles until the final solution is reached [51]. These cycles, or short iterations, occur throughout the Software Development Life Cycle, with continuous testing [52] and feedback collection [53].

The UCD, a more traditional approach that puts users and their needs first, complements the development by ensuring stakeholder involvement at all stages of the process [54,55]. Furthermore, issues related to usability and acceptability of solutions can be overcome with UCD, since they are based on the principle of software with users in mind, focusing on a custom software product design that the user wants [53].

Most of the current trends in software development are closely related to the UCD approach with a participatory component [56]. This approach facilitates collaboration with various stakeholders (users, researchers, teamwork, designers, partners, and clients) throughout the project development (from needs assessment to content development, pilot testing, and dissemination), called participatory design, co-creation, or co-design [56,57,58,59,60,61].

Thus, based on these principles [51,55], the methodology adopted for the development of SOLFI, and depicted in Figure 1, followed several iterations in four phases: (i) planning—to understand and specify the context of use; (ii) design—to specify the user and organizational requirements; (iii) development—to produce design solutions; and (iv) testing—to evaluate the designs against requirements.

3.2. Techniques for Understanding the Problem and Collecting SOLFI Requirements

Following the protocol shown in Figure 1, the definition of SOLFI requirements was based on the use of a set of techniques, namely: brainstorming, direct observation, document analysis, interviews, and questionnaires. It should further be highlighted that a set of existing platforms were also subject to content analysis to understand the state of the art and do a benchmark.

Thus, in the initial phase, to better understand the problem and define the solution requirements, brainstorming sessions with customers and users were conducted. Simultaneously, to understand the context and scenarios related to data and/or information flows, as well as all the management of processes and possible mechanisms to deal with unforeseen situations, direct observation of organizational and logistical processes was carried out. Then, document analysis based on the study of three reports about the Characterization of Urban Logistics in Porto City by a partner was used. In this method, four data collection techniques were used (i.e., traffic counts; survey of logistics and retailers; driver surveys; and interviews with logistics agents). To complete the understanding of the problem and elicit the requirements of SOLFI solution, interviews with key stakeholders—partners in the SOLFI project (External Logistics Operator—Grupo Rangel, Public Transportation Operator—STCP, and Micro Logistics Operator—Contra-Relógio)—were conducted. The interview guides were prepared based on the information already collected and missing from the logistical study to obtain as much information as possible about the reality of the project partners.

Two types of questionnaires to know the needs/specifications of the users of this solution were developed and applied. The objective of the first was to know and collect the opinion of private customers who buy online regarding their experience of receiving the merchandise. The second one aimed to obtain the perspective of retailers and learn about their experience of receiving and/or sending merchandise. In the first questionnaire, 302 answers were obtained, and in the second, 138.

Another important component that contributed to the definition of the concept was the benchmarking on existing platforms which partially can serve the same purpose, i.e., support urban logistics. In this way,

Table 1. Research of existing platforms in the literature.

Platform	Place	References
A platform enabling the pursuit of a new paradigm of urban freight distribution management tackling the limited access to incentives for sustainable operators.	Metropolitan Areas in Italy	[11]
Decision Support System to overcome the difficulties generated by the collaborative transportation between a traditional fleet and green last-mile deliveries (adoption of bikes). Prototype platform designed to support layer for the growing business of the companies that operate in the last mile in the cities in an isolated way.	---	[13]
A decision-aided tool for simulating and optimizing alternative solutions to road transportation in a city. A platform enabling the pursuit of a new paradigm of urban freight distribution management tackling the limited access to incentives for sustainable operators. Decision Support System to overcome the difficulties generated by the collaborative transportation between a traditional fleet and green last-mile deliveries (adoption of bikes). Prototype platform designed to support layer for the growing business of the companies that operate in the last mile in the cities, in an isolated way.	---	[12]
A decision support system to simulate and optimize alternative solutions to road transportation in a city.	Grand Paris Sud	[14]

presents the platforms identified based on the literature, and

Table 2. Research of existing software on the market.

Software	Features	Type	URL
anyLogistix	- creation and management of supply chains with digital simulation. - Integration of supply chain design - optimization of the supply chain - simulations with data from the operations that allow the analysis and improvement of the network.	not only operates for logistics but also for manufacturing and retail	https://www.anylogistix.com/ (accessed on 10 December 2022)
AscendTMS	- cargo and dispatch management, vehicle management - GPS load tracking from the vehicle driver’s mobile phone, real-time display of the vehicle load rate, traffic information and handling of load complaints	- Web based	https://inmotionglobal.com/ (accessed on 10 December 2022)
OpenLMIS	- logistics management that facilitates the requisition and replenishment process in environments with few resources for healthcare products. - system automation throughout the supply chain - allows users to plan, manage, and deliver products to customers.	- open source - Web based	https://openlmis.org/ (accessed on 10 December 2022)
QuickBox	- tracking the order	- for transport and logistics companies	https://software-transportes-logistica.com/ (accessed on 10 December 2022)

presents the platforms that have been identified in the market.

4. Result: An Integrated Platform for Sustainable Urban Last-Mile Logistics’ Operations—SOLFI

This section presents the main results of this research, which culminated in the study, conceptualization, and development of an integrated platform for sustainable urban logistics operations in the last mile, called SOLFI. This application represents an intelligent decision support system that enables the management of the new freight distribution service in urban spaces, integrated with passenger transport focusing on the first and last mile. At the same time, it aims to ensure an efficient and environmentally responsible urban logistics process, through the more efficient and responsible use of the transport network and an intelligent freight management system focused on technological communication and decision-making.

In order to present the different aspects of the solution, highlighting the innovative aspects of SOLFI, this section will address the main requirements of SOLFI and its conceptual model, the architecture and technologies that defined the final solution, as well as some Graphical User Interfaces (GUI) demonstrating the application from a user point of view.

4.1. SOLFI: A Conceptual Perspective

Based on several techniques described previously, useful information to detail the Requirements Specification Document (RSD) of the SOLFI was identified. Given the complexity of the solution and the different areas of intervention, the SOLFI was organized into several modules: Administrator, Order Reception, Transport Operator, Micro logistics Operator, Client, and Store (Figure 2).

The Administrator Module represents the Backoffice where the administration of the whole SOLFI system is done.

The Order Reception Module represents a central part of the SOLFI, interacting with different actors (transport operator, micro-logistics operator, and client that represents the customer who requires the service). Thus, the main objective of this module is to manage the receipt of requests for quotations in real time and plan their delivery by drawing up a distribution plan. For this purpose, this module includes a set of functionalities to allow the quotation and registration of orders, the definition of vehicles and network, the definition of logistics operator’s schedules, and, based on the data inserted, the execution of order distribution plans using a mathematical algorithm.

The Transport Operator Module stores and manages the relevant information about the transport operator, also promoting the exchange of information and connection between the order placed in the reception module and the transport operator that will take that order to the place where the micro-logistics operator picks it up. Thus, the main functionalities that integrate this module are: the definition of vehicles and networks, the definition of schedules for the transport operator, consultation of parcel distribution plans, tracking updates, and communication of disruptions.

The Micro Logistics Operator Module is responsible for the multimodal connection which will route the order from the transport operator to the final customer via the micro-logistics operator. This module receives the check-in and check-out plan of the orders and provides the micro-logistics operator with detailed information about the transfer operation of the orders, such as, for example, collection points for the orders, expected arrival times of the vehicles with the orders, characteristics of the orders, such as weight, volume and other special requirements, delivery locations of end customers, and delivery times to end customers. On this basis, the main functionalities that this module comprises are: the definition of micro logistics operator vehicles, consultation of parcel distribution plans, tracking updates, communication of disruptions, the definition of the opening hours of the stores, and communication of disruptions by stores.

The Client Module is responsible for providing real-time information to end-users, especially to suppliers and/or customers who request the service on the status of the order in progress, promoting the traceability of the distribution process. Clients can, at any time, view the location of the order they are about to receive, with information on check-in and check-out points, the route taken, and the expected delivery time.

Finally, the Store Module is responsible for the check-in and check-out of the orders and communication of disruptions.

In general, SOLFI will provide its stakeholders with a set of functionalities.

Table 3. List of high-level requirements of the SOLFI.

Requirement Name	Description	Module
		Administrator	Order Reception	Transport Operator	Micro logistics Operator	Client	Store
Define Company	Create and change companies operating on the SOLFI platform. {Types of Companies are: Logistics Operator, Transport Operator and Micro Logistics Operator}.	X
Create and Manage Pickup Point	A pickup point is characterized by address, geographic coordinates, and opening hours.	X
Create and Manage Users	The administrator module allows to create users and change user profiles, create company users with the appropriate permissions, and manage the company’s users and profiles.	X	X	X	X
Define Vehicles	Vehicle types will be defined, essential for the generation of transport plans since the algorithm needs to know the available transport capacity.		X	X	X
Define Hubs	The definition of Hubs can be done through a form, but it should also be possible to do it directly through a map with the filling of the geographic coordinates being automated.		X	X	X
Define Segment	Allows operators to define connections between hubs. These connections, in an aggregated way, constitute a path. Logistics and transport companies must define their trip.		X	X
Define Trip	Each operator defines the trips taken. These trips are composed of a set of segments and a list of paths.		X	X
Define Schedules	Each system operator (logistics and public transport companies) must define the time for their trip or the maximum delivery time from a hub.		X	X	X
Request Order Quotation	After entering the order data, the system estimates the final quotation and, based on this, makes plans using algorithms and optimization models to transport the respective order.		X
Order Registration	To register an order, the following information is required: the address of the sender; the recipient’s address; recipient contact; package type; and length, width, height and weight of the package.		X
Consult Distribution Plans	The operator who registered the order can consult the complete distribution plan, which includes all the hubs through which the order is expected to pass (with estimated date/time of passage through the hub), all the paths that the order will take and which operator will carry it on each path. The remaining operators will only be able to consult the information of the distribution plan of an order regarding the part of the transport that will have to be carried out.		X	X	X
Consult Transport Plans	Each operator can consult the orders that it will have to transport in each vehicle, for each path segment, that is, between hubs.		X	X	X
Check-in/Check-out of Orders	Indicate the Check-in/Check-out of an order in a hub, vehicle or that has been delivered.		X	X	X		X
Disruption Communication	Every time a problem arises that affects the delivery of the order (eg., delay, traffic, accidents, breakdown), it must be possible to report a disruption. This communication should indicate the type of disruption and the expected time of delay so that the algorithms can calculate new distribution plans, alert the other operators that should transport the order later, as well as update the tracking for the customer.		X	X	X		X
Manage Schedules of Pickup Point	The pickup points must manage their opening hours. This schedule is important to produce distribution plans for orders.				X
Tracking	At any time, a customer can consult the tracking of an order. A list of places where it has been, the disruptions that may have occurred, as well as the expected delivery period of the order, must be presented.						X

presents a set of high-level requirements to support the entire management of the platform, with the administrator module being responsible for data entry and system maintenance.

Regarding the process related to the use of the system, it is described as follows. The process starts with the customer/sender making the Request Order Quotation. Based on this information, the application computes the final quotation and the distribution plan, using an appropriate algorithm, to inform the customer about the final quote and distribution plan for his/her order. The customer, after being notified by the system, decides whether to register the order or not. If the customer wishes to proceed with the order, he/she must confirm the order (CU: confirm order), and, based on this action, all the stakeholders involved in the order distribution process are notified (UC: creates a notification to send to delivery actors). These notifications include all details about the distribution plan, addressed to each of the actors involved, such as the estimated time when the order arrives at each point of the delivery process. During this procedure, the customer is also notified of the location and, therefore, the times that the order must be dropped off at the hub; the order is then checked in on the respective urban transport, notifying the micro-logistics operator that this check-in was successful.

The bus (Urban Transporter) that transports the order is responsible for communicating any disruption in the process if any unexpected event arises, such as breakdowns or traffic accidents. Then, at the stop where the order has to be unloaded, there is a micro-logistics operator to make the transfer from the bus to the environmentally-friendly vehicle. To minimize the stopping time for urban passenger transport, the micro-logistics operator performs the check-out of the order from the bus and simultaneously performs the check-in in the last-mile vehicle. When the check-in of the micro-logistics operator is carried out, a notification informing the status of the order and the estimated delivery time is sent to the final customer. Finally, at the destination address, the micro-logistics operator checks out the order from last-mile transport and the final customer confirms receipt of the order.

To support the requirements described above, the system will contain a data model, as outlined in the class diagram represented in Figure 3.

4.2. SOLFI: Architecture and Technological Perspective

From a technology perspective, the SOLFI integrates different modules (web applications and two web responsive applications) that interact with the database through a dedicated API for this purpose (Figure 4). To manage the authentication on which the project is based, there is an extra application built on the principles of Model—View—Controller (MVC) that is responsible for managing user sessions centrally. This application, Opt.Solfi.Auth, also allows administrators to manage users enrolled in the platform and their associated profile types, as well as the management of applications authorized to request access tokens to the APIs and the operators on the platform. For the optimization algorithms, a service that runs in the background on the server was created. This service includes Octave libraries that run MatLab scripts and get the output. Due to the legal provisions introduced by the new General Data Protection Regulation, the platform includes an extensive record of the activity that is carried out by each user in order to track access to personal data contained in the platform. These records are inserted into a database parallel to the main platform database. All WebAPI are programmed to ensure that these log methods are applied to your call. In addition, methods have also been created to record access to personal data in the Opt.Solfi.Auth application.

In this way, the applications included in this product are summarized as follows:

• Web applications

  -

  Opt.Solfi.OrderReception—application of reception/management of orders by External Logistics Operator

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  Opt.Solfi.NetworkSchedules—application for managing the resources of companies, as well as the network and schedules. It will be mainly used by Public Transportation Operator.

• Responsive Web Applications

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  Opt.Solfi.Distribution—application for consultation/management of distribution plans by External Logistics Operator, Public Transportation Operator and Micro Logistics Operator.

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  Opt.Solfi.Customer—application for consultation of the tracking of orders by the sender and/or receiver

• WebAPI

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  Opt.Solfi.WebApi.ResourceManagement—API used by NetworkSchedules and Distribution applications

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  Opt.Solfi.WebApi.OrderReception—API used by the OrderReception application

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  Opt.Solfi.WebApi.Customer—API used by Customer application

• Authentication and authorization server

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  Opt.Solfi.Auth—Management of Company Types, Companies, User Profiles and Users

• Service that runs the algorithms

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  Opt.Solfi.Algorithms

The SOLFI solution is mainly based on the use of .NET Framework 4.6.1 technology and is programmed in the C# language. The applications are developed in Typescript using react.js libraries in version 15. Both databases, application data and access log, are based on Data Base Management System Microsoft SQL Server 2019.

4.3. SOLFI Graphical User Interfaces

In this section, some Graphical User Interfaces (GUIs) of the SOLFI platform will be depicted to highlight some of its key functionalities. The selection of these interfaces was based on the requirements listed in Table 3.

Figure 5 shows the authentication menu where the users need to register their credentials (login and password) to access the platform (the related requirement listed in Table 3 is Create and Manage Users whose implementation is associated with various modules of the platform such as the Administrator and the Order Reception).

Figure 6, Figure 7 and Figure 8 present interfaces related to the SOLFI functionality that permits managing the distribution network by creating and/or editing: key elements. The requirements of Table 3 here illustrated are Define Hubs and Define Schedules. The modules Order Reception, Transport Operator and Micro Logistics are involved in the implementation of these requirements.

Figure 6 shows an example of a network map where external hubs (green markers), internal hubs (black markers), public transportation paths (blue lines), and micro logistics zones (shadowed areas) are highlighted. It is also possible to see the name of each hub (internal or external) near them.

The internal and external hubs can be created and managed through the map (Figure 6) or a list (Figure 7).

Figure 8 shows the schedule list. From this list, it is possible to create and edit schedules, change dates, and remove or consult the scheduled travel list. Schedules are sets of trips grouped by day type and with the same validity period. The best way to create timetables with trips in SOLFI is by using the importer, which allows the use of files in the INFOPUB, GTFS, and NETEX formats. If there are no times for intermediate crossing points of the trips, it is possible to calculate them using the option “Deduct missing transit times”.

The registration of an order (requirement Order Registration from Table 3) is accomplished through the module Order Reception. To enter an order in the system, it is necessary to fill in (Figure 9) the data concerning the sender and the recipient, select the desired date for delivery, select the external hubs where the micro logistics operator is willing to deliver the order, as well as choose the desired period for the order delivery. Additionally, it is necessary to fill in the information regarding the packaging(s) that make up the order (dimensions and weight). When clicking submit, an algorithm has been executed that checks if there is availability to transport the order. In the case of availability, the system asks for the order number and the recipient’s contact.

The transport operator and the external logistics operators may consult, for a given date, the transport plan for orders (requirement Consult Transport Plan from Table 3). It can be filtered by hub and by line. For each order, the estimated time of arrival and departure from each hub are listed, along with the line of the transport operator, as well as the operator that will transport to the external hub, between the external hub and the internal hub, and after the internal hub. In this list (Figure 10) it is also possible to create a disruption for an order or for a set of orders at the same time, as well as consult the disruptions for one or more orders.

Figure 11 shows all the orders of the day or only those that have not yet entered and left the hub. This feature allows check-in and check-out orders in a hub (requirement Check-in/Check-out of Orders in Table 3), for a selected date. On the right side, it is possible to check the bus timetable in real-time and infer the orders that will be sent on that bus, according to the expected date of entry into the hub or already in the hub and have not yet left.

Among other features, it is also possible to track the status of the order (requirement Tracking in Table 3). When entering the order code, the status and location of the order will be displayed, as illustrated in Figure 12.

The interfaces presented above are examples of the various interfaces and respective functionalities that the SOLFI platform utilizes to help the decision process, in real time, of the sustainable distribution of goods in urban centres.

4.4. Pilot Test with SOLFI and Some Qualitative Results

To present the SOLFI concept and platform and collect feedback, several actions were carried out, namely a workshop and a presentation and training session on the platform with the logistics operators’ partners—the ones that will mainly interact with the platform besides the customer that can, at any time, track the order situation.

Additionally, to validate the concept and the effectiveness of the SOLFI platform, pilot tests were carried out in a real environment in the second largest city of Portugal—Oporto, for a period of a week, from 8 to 11 November 2022. The pilot test took place as follows: each day, the external logistics operator selected a group of orders to be delivered using the SOLFI service and created mock packages based on these orders. One of the users played the role of an external hub operator and was responsible for receiving these mock packages. The external hub operator would then place the packages on the appropriate bus trip according to the generated distribution plan by the SOLFI platform. Each package was accompanied by a different user, who was responsible for getting the orders off the bus at the assigned stop, checking in at the internal hub, and delivering the package to the Micro logistics operator. The Micro logistics operator would then register in the SOLFI app that they had collected the package and then deliver it to the final destination. During the journey on the buses, the orders were accompanied by a person to ensure their protection. Thus, the entire process, from order request to order delivery, was managed through the SOLFI app and tested in a real environment with simulated orders.

Regarding the format, the pilot test followed an incremental testing approach in order to test each function separately and also together. This way, the test took place gradually, adding new features to the user workflow. At the start, users were instructed to only use the check-in and check-out features to verify the functionality of the essential tracking features. Over the course of the pilot, complementary features such as delivery time restrictions, disruptions (e.g., the cancellation of a bus) and alternative trips, and user notifications were incrementally enabled. This allowed us to gather feedback from users and stakeholders on specific feature packages and identify any issues or areas for improvement early on, enabling us to adjust before the full rollout.

The software solution used a continuous deployment pipeline, which allowed us to quickly deploy any necessary software changes and fixes to production, reducing the impact of any software bugs and allowing us to focus on the feasibility of the SOLFI project rather than the validation of the software component. In the final two days, the complete feature set was enabled, and the test users were already familiar with how to use the system, providing a close approximation of how SOLFI would function in a real-world scenario.

Through the pilot, it was possible to prove that the concept works. Although there is not significant measurable quantitative data on the use of SOLFI, the results of the tests showed that SOLFI was effective in delivering goods and satisfying customer requests on time in a simulated environment, with a reduction in the number of vehicles circulating, with the integration of flows of people and goods while using the same transportation infrastructure (bus) that operates in the urban network.

In a nutshell, and considering the present pilot test, it is possible to conclude, even if in a qualitative way, that:

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The system proved to be effective in the management of small parcel deliveries, thus being able to contribute to the reduction of transport cars entering the cities and, with this, i.e., reduce the circulation of polluting vehicles in the cities to detriment of environmentally friendly vehicles.

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The system is easy to use and does not cause any negative reaction from the user.

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From the logistics company’s point of view, the system can support real-time decisions, helping in the internal management of orders.

However, it is safeguarded that SOLFI will serve only small parcel deliveries, while the traditional service will be maintained for large orders. However, with this, more efficient and responsible use of a city’s transport network is possible through an intelligent freight management system centered on technological communication and decision-making. Following this, the main feedback given by the logistics operators was that the platform is intuitive, user-friendly, and well-organized in terms of function. Regarding users’ requirements, some possibilities that the SOLFI concept/app could respond to in future developments were raised by them:

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Include the possibility of returning the order if the customer is no longer interested in keeping it. This situation occurs when the order is sent using the cash-on-delivery option. Currently, the SOLFI platform does not address return flows.

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Use of a network of shops or network of lockers that can act as internal hubs so that the Micro logistics operator does not have to be at the internal hub at the time of the arrival of the bus to collect parcels, giving it greater flexibility in managing its delivery process.

5. Discussion

The concern over the environment was always present in the project so, in this sense, it was possible to develop an Information System that can help with the management of a sustainability-based solution for modern cities, which is called SOLFI. This solution promotes a new service for the distribution of goods in cities, focused on the first and last mile with an efficient and environmentally responsible urban logistics process, through more efficient and responsible use of the urban transport network. Thus, in general, the SOLFI represents an intelligent decision support system that allows managing the new distribution service in real-time, i.e., an intelligent freight transport management system focused on technologies, communication, and decision-making. This technological solution promotes and intermediates a new logistic service model characterized by the integration of flows of people and goods, using the same transportation infrastructure (bus) that operates in the urban network whenever possible. Compared to other solutions, namely solutions for managing urban load distribution [11]; solutions to support and facilitate the business of last-mile delivery companies [12]; solutions to integrate collaborative transport between a traditional fleet and last-mile green deliveries (such as bicycles) [13]; and solutions to simulate and optimize alternative solutions for road transport [14], our solution not only promotes a new service based on more environmentally-friendly fleets to ensure the first and last-mile delivery of some types of goods but also creates a technological tool that enhances the management of these services in any urban location. In fact, this type of solution that integrates different agents in the movement of goods in urban centers with less pollution and smaller vehicles, in particular buses and bicycles, already exists [4], but does not consider its integration into a single software platform.

Although this solution was developed in the context of a Portuguese city (the second largest city in Portugal), the procedures considered for this development are common to most cities in the world, which makes it possible to apply this solution to any city in the world operating with a similar urban transport network.

SOLFI combines the flow of people and cargo [38,39,40] using public transport (buses) [43]. This solution is composed of features that are present in systems described in the literature and intends to overcome the complexities generated by collaborative transport between a traditional fleet and last-mile green deliveries, with the adoption of bicycles [14]. This allows for the pursuit of a new paradigm of the urban distribution of goods management, facing limited access to incentives for sustainable operators [11]; supports and facilitates the growth of the business of last-mile delivery companies operating in cities [12]; and aids decision making to simulate and optimize road transport solutions in cities [14].

It should be noted that in this study the collaboration of the stakeholders involved in the project was challenging but added significant results [4], particularly in defining the requirements of the SOLFI solution. Moreover, the methodology used to develop SOLFI was very advantageous for the team, meeting some of the benefits of the agile approach; its improved communication and collaboration allowed for faster detection of flaws, reduced development costs, and allowed interactive delivery. On the other hand, the utilization of the user-centered approach allowed us to gain a better knowledge of SOLFI users.

Assuming that the deliveries would be carried out under normal conditions by a vehicle dedicated to freight transport, this would mean one or more lorries/vans making trips during the day in the city center (consuming fuel, occupying public space, and causing emissions), even considering that those deliveries would be made using optimized routes. With SOLFI, the lorry(ies)/van(s) only has(have) to transport all the freight to the outer hub on the outskirts of the city. In quantitative terms, considering that the bus journeys are regular/daily/scheduled, the scenario with SOLFI means not carrying out the aforementioned freight distribution routes, thus reducing the number of kilometers performed per day—consequently reducing fuel consumption and emissions, among other benefits. Therefore, it is expected that the use of SOLFI can contribute to the reduction of costs, such as travel costs for passengers [39], direct and generated costs for all stakeholders [40], minimize costs in the road freight transport sector and urban logistics [34], and increase environmental quality and social value [40]; in particular, minimizing kilometers travelled, congestion, and pollution levels in urban areas [39,48]. In short, this solution allows for a gain in sustainability by sharing goods and passengers in an urban network, with a focus on improving service time and energy waste [44].

6. Implications and Contributions

Our research contributes to the literature with a new platform for the planning, management, and control of urban logistics activities with the integration of freight into a passenger bus transportation network prepared to use real-time information. Thus, the users of the platform can have the support of an information and decision support system to assist with their operational decisions, as well as to manage possible disruptions and track the shipping process, from order acceptance to the final address.

With the adoption of this solution by urban centers, considerable gains are expected for society in terms of the three fundamental pillars of sustainability, i.e., environmental, economic, and social. Social sustainability, insofar as this solution can contribute to reducing the number of vehicles circulating in the cities, thus improving the quality of life of the citizens who live there, particularly within major urban centers. Several benefits can be mentioned, such as the reduction of pollution, noise and traffic congestion. Consequently, this type of shared logistics will contribute to a reduction in the costs associated with the transport of goods and promote higher efficiency rates for the bus transportation network, contributing to the pillar of economic sustainability. Finally, with a more immediate payback, a reduction of gas emissions in cities is expected by reducing the circulation of polluting vehicles, both through the sharing of goods and passenger transport and also by replacing polluting vehicles with environmentally friendly vehicles in the last mile (e.g., bicycles).

Thus, the implications for policy-makers and city planners are expected to help promote more sustainable cities, mainly in the reduction of the flow of goods with public passenger transport, and the reduction of the number of vehicles in the city, which in turn reduces the costs.

From a theoretical perspective for scholars interested in the topic, this research contributes to the increasing knowledge in an emerging priority area—sustainability through a new technology-based logistics service.

From a practical perspective, it is believed that this work could help practitioners, namely decision-makers, to streamline the decision process in the management of integrated passengers and freight. Additionally, in the long term and with indirect impact, this Information System may contribute to improving the quality of life in cities by reducing polluting vehicles and replacing them with environmentally-friendly vehicles.

7. Conclusions and Future Work

Urban logistics is a fundamental area, both for economic growth and for the social and environmental sustainability of the city. Thus, logistics activities related to transportation within cities should be managed and organized in a way that allows the minimum circulation of polluting vehicles within cities, namely by integrating, whenever possible, passenger flows and freight flows. In line with this, the presented study proposes a new urban logistics service that combines passengers and freight flows to improve the sustainability of the cities through a dedicated technological application, named SOLFI. With this solution it is possible to promote the management and articulation of services by different stakeholders. The SOLFI solution was built based on the co-participation of all partners and stakeholders in the project. The agile methodology allowed each iteration to add value. The techniques of the user-centered approach allowed us to define and adjust the requirements throughout the project.

Collaboration of urban logistics stakeholders on projects can be challenging, but this effort pays off when there is a significant reduction in vehicles and pollution in urban areas, and lower prices for goods. This integration is present in the SOLFI solution, allowing for the improvement of logistics services.

The participation of stakeholders and partners of the project was very important for the project and particularly enriched the definition of requirements.

This solution integrates different agents in the movement of goods in urban centers with less polluting and smaller vehicles, in particular buses (Public Transportation Operator) and bicycles (Micro Logistics Operator). It is a decision support system, in real time, of fleet management through models and optimization methods to simplify, automate, and improve the urban logistics process.

This solution has several benefits, namely the reduction of traditional flows of goods, taking advantage of the availability of public passenger transport, and reducing the number of polluting vehicles in the city. Thus, this results in a positive impact on urban mobility, which is a concern of the political agenda and society in general, and follows up on the commitment to promote better sustainability practices. On the other hand, it may allow the reduction of direct and indirect costs in logistics.

Despite the expected contributions, some limitations can be identified in this research. The study, in terms of requirement surveys and development scenarios, was focused on a city that may not be at all representative of other urban centers operating with different transportation networks. Thus, as a future work, in line with the objectives of this project, it is intended to test the application not only in the city where the study was conducted—where the pilot will be carried out—but also in other urban centers with different characteristics.