Electric Vehicle Routing Problem with an Enhanced Vehicle Dispatching Approach Considering Real-Life Data

Round 1

Reviewer 1 Report

In the article, the authors have addressed the very important and timely topic of optimizing the use of electric cars. A great advantage of the presented approach is the application of many constraints taking place in real conditions, for example, temperature, or topography of the terrain. The use of real (rather than random) input data during the simulation, e.g., collected from the selected region and route, would be a valuable exercise.

A few minor comments on the text:

1.      verse 292 - there is" aggressive drivers exceed speed limits...". - aggressive driving may or may not mean exceeding the speed limit. It is possible to drive aggressively without exceeding the speed limit.

2.      verse 332 - "its batteries are charged to their full capacity." - does the battery have to be charged to its full capacity? maybe in some cases, e.g., when returning to base, you can charge only the part of the battery necessary to return to base - this will save charging time.

3.      Figure 2 - the figure has poor legibility I suggest improving it. In addition, in the legend there are symbols that I can not find in the figure (e.g. "S"; "WH") - please verify this and if they are not needed they can be removed from the legend.

4.      Please check the numbers in the figure and table references in the text, e.g.:

a.      verse 442 – there is „In Fig. 1. „ – it seems to me that it should be Fig. 2,

b.      verse 480 – there is „in Fig. 3” - it seems to me that it should be Fig. 4,

c.      verse 484 – there is „by Fig. 4” – it seems to me that it should be Fig. 5,

d.      verse 754 – there is „Table 12” - it seems to me that it should be Table 7.

5.      Verses 606 -608 - what is the frequency of data updates? Are the updates done automatically or is driver intervention required for this? Is real-time information provided, e.g. in the case of sudden road blockage due to an accident (then a new road should be mapped)?

6.      verses 631 - 632 - has there been any consideration of the situation in which, for various reasons (such as illness), there must be a change of driver? In this case, is the route profile updated?

7.      In the figure references, I propose to remove the terms above and below e.g.:

a.      verse 723 Fig 8 above – (fig. 8 is bellow) - it will be better only Fig. 8,

b. verse 743 Fig. 7 bellow - (fig.7 is above) - it will be better only Fig. 7.

Author Response

Original Manuscript ID: energies-2902081

Original Article Title: Electric Vehicle Routing Problem with an enhanced vehicles dispatching approach considering real-life Data

To: MDPI Energies

Re: Response to reviewers

Dear Editor, Dear Reviewer,

We appreciate the chance to revise and resubmit our work to address the concerns provided by the reviewers.

We have uploaded our detailed response to the remarks (the response to reviewers), along with a revised manuscript that includes highlighted revisions in yellow.

Best regards,

Meryem ABID, Mohamed TABAA, and Hanaa HACHIMI

+----------------------------------------------+

In the article, the authors have addressed the very important and timely topic of optimizing the use of electric cars. A great advantage of the presented approach is the application of many constraints taking place in real conditions, for example, temperature, or topography of the terrain. The use of real (rather than random) input data during the simulation, e.g., collected from the selected region and route, would be a valuable exercise.

We thank you for taking the time to evaluate our work.

A few minor comments on the text:

• verse 292 - there is" aggressive drivers exceed speed limits...". - aggressive driving may or may not mean exceeding the speed limit. It is possible to drive aggressively without exceeding the speed limit.

We would like to express our thanks for all pertinent and constructive remarks. We agree entirely with your remark regarding aggressive driving. Various profiles of driving exist (experimented drivers who do not exceed speed limit, and other who do, beginner drivers who respect speed limitations and other who don’t) therefore, it is difficult to include all profiles. To this end, we considered only two profiles which represents the two extremities of driving behaviour: aggressive drivers and passive drivers. Please refer to verses [290-294], which we reformulated to better explain these assumptions.

• verse 332 - "its batteries are charged to their full capacity." - does the battery have to be charged to its full capacity? maybe in some cases, e.g., when returning to base, you can charge only the part of the battery necessary to return to base - this will save charging time.

In literature, there exists mainly two policies for charging: full and partial. In our model, we considered a full charging policy in which vehicles recharges fully whether at the warehouse, or -if needed- at any charging stations they visit along their route. We added a line at the beginning of the verses [330-336] to highlight the charging policy adopted.

• Figure 2 - the figure has poor legibility I suggest improving it. In addition, in the legend

there are symbols that I can not find in the figure (e.g. "S"; "WH") - please verify this and if they are not needed they can be removed from the legend.

Thank you for pointing this out. Given the dimensions of the figure, we chose to remake it in order to avoid any resolution problem. Please find the new figure inverse 408. 

• Please check the numbers in the figure and table references in the text, e.g.:

1. verse 442 – there is „In Fig. 1. „ – it seems to me that it should be Fig. 2,

Fig.1. has been changed to Fig. 3.

1. verse 480 – there is „in Fig. 3” - it seems to me that it should be Fig. 4,

Fig.3. has been changed to Fig. 4.

1. verse 484 – there is „by Fig. 4” – it seems to me that it should be Fig. 5,

Fig.4. has been changed to Fig. 5.

7. verse 754 – there is „Table 12” - it seems to me that it should be Table 7.

Table 12. has been changed to Table 7.

• Verses 606 -608 - what is the frequency of data updates? Are the updates done automatically or is driver intervention required for this? Is real-time information provided, e.g. in the case of sudden road blockage due to an accident (then a new road should be mapped)?

We appreciate your constructive feedback. We added an explanation for the data update frequency in verses [616-620]. Data is generated once for every dataset, before the first population (initial set of solutions) is produced.

• verses 631 - 632 - has there been any consideration of the situation in which, for various reasons (such as illness), there must be a change of driver? In this case, is the route profile updated?

We agree with your pertinent remark. In our model, once the driver is assigned to a vehicle (i.e. a route), it is assumed that they’re capable of carrying on the delivery operations before returning to the warehouse. In other words, we did not consider the case of driver’s change. However, we consider this to be a promising concept for our future works.

• In the figure references, I propose to remove the terms above and below e.g.:

Duly noted. Unless we inadvertently missed it, we removed all “below” and “above” terms following figures’ references.

1. verse 723 Fig 8 above – (fig. 8 is bellow) - it will be better only Fig. 8,

Thank you, we removed the term “above”.

7. verse 743 Fig. 7 bellow - (fig.7 is above) - it will be better only Fig. 7.

Thank you, we removed the term “above”.

Reviewer 2 Report

In the Abstract we can read: “While charging cost is less than the cost of fuel”. Please elaborate, does this only apply to Morocco? What amount difference comes into play here?

We can read in the Abstract: “our approach proved effective in finding the optimal solutions in a reasonable time for 5 to 15 customers datasets”. Please explain how realistic it is in a world that will transition to electric cars in a few years that we will have 5 to 15 cars on the street. If your system cannot make calculations for a realistic number of cars, what is the point of calculations for 5 to 15 road users.

In the Introduction section we can read: “and the race to score 30 the leading place in the international market, countries in the four corners of the globe 31 invested in, among other things, larger fleets to strengthen their logistics’ performance.” What literature or database supports this view?

In the Metodology section we can read: “Understandably, the more constraints we impose on the approach, the slower it be comes, which inspired our decision to split the solution into three stages.” And in the Results section we can read: “The time required to find the optimal solution for 15-customers datasets is almost 14 times the time needed for 5-customers datasets.” Can you explain what is the reason for the situation that as we read " the slower it be comes " in your approach? And what time frame do you mean exactly?

“Table 4. characteristics of the Volvo electric vehicles used for deliveries [42].” Word “characteristics “ should start from capital letter

Please clarify what the row numbered 7, 7 and 6 refers to in Table 4.

Please clarify what what means “Traffic (%)” in the Table 5. What relation allows you to calculate the percentage of traffic jams on the street?

Please explain why you used Google Colab Pro Plus in the simulation? How is this tool different from others?

We can read: “The driver profile is linked to the vehicle, which means that once a vehicle is selected, the amount of acceleration assigned to it is applied on all arcs driven by this vehicle.”  Is this acceleration given in advance, regardless of the driver's behavior on the highway?

Author Response

Original Manuscript ID: energies-2902081

Original Article Title: Electric Vehicle Routing Problem with an enhanced vehicles dispatching approach considering real-life Data

To: MDPI Energies

Re: Response to reviewers

Dear Editor, Dear Reviewer,

We thank you for taking the time to evaluate our work, and we appreciate your valuable and constructive remarks.

We have uploaded our detailed response to the remarks (the response to reviewers), along with a revised manuscript that includes highlighted revisions in yellow.

Best regards,

Meryem ABID, Mohamed TABAA, and Hanaa HACHIMI

+----------------------------------+

We thank you for taking the time to evaluate our work.

Comments and Suggestions for Authors

• In the Abstract we can read: “While charging cost is less than the cost of fuel”. Please elaborate, does this only apply to Morocco? What amount difference comes into play here?

Thank you for pointing this out. Given the rising prices of gasoline across the globe, the price of electricity is still lower than that of gasoline.

For instance, VOLVO offers two FH trucks with similar design, except that one is electric (with a battery capacity of 360 to 540 kWh) [1], and the other is Diesel-powered (with a tank capacity of 375 to 445 litres) [2]. In this example we will compare the FH electric of 360 kWh to the FH diesel of 375 litres.

In Morocco, and as of March 2024, the price of 1 kWh (during rush hours) is 1.36 MAD [3], while the price of 1 litre of Diesel is 14.06 MAD [4]. Therefore, the price for a full charge will be equal to 489.6 MAD (= 360 kWh x 1.36 MAD/kWh). On the other hand, the price for a full tank of diesel will be equal to 5272.5 MAD (= 375 litres x 14.06 MAD/litre). The equivalent of both amounts in USD will be 48.86 USD and 526.12 USD for FH electric and FH diesel, respectively. Accordingly, we can notice the vast gap between the two amounts, and therefore we can confirm that the aforementioned assumption is true for Morocco.

References

[1]        “Volvo FH Electric.” Accessed: Mar. 11, 2024. [Online]. Available: https://www.volvotrucks.com/en-en/trucks/electric/volvo-fh-electric.html

[2]        “Caractéristiques techniques du Volvo FH.” Accessed: Mar. 11, 2024. [Online]. Available: https://www.volvotrucks.fr/fr-fr/trucks/models/volvo-fh/specifications.html#accordion-8796ab295a-item-8671da7eb4

[3]        “Site web officiel de l’ONEE - Branche Electricité.” Accessed: Dec. 05, 2023. [Online]. Available: http://www.one.ma/FR/pages/interne.asp?esp=1&id1=2&id2=35&id3=10&t2=1&t3=1

[4]        “Maroc les prix du diesel, 04-mars-2024,” GlobalPetrolPrices.com. Accessed: Mar. 11, 2024. [Online]. Available: https://fr.globalpetrolprices.com/Morocco/diesel_prices/

• We can read in the Abstract: “our approach proved effective in finding the optimal solutions in a reasonable time for 5 to 15 customers datasets”. Please explain how realistic it is in a world that will transition to electric cars in a few years that we will have 5 to 15 cars on the street. If your system cannot make calculations for a realistic number of cars, what is the point of calculations for 5 to 15 road users.

Thank you for your pertinent remark.

In our model we aim to serve a set of customers using electric trucks, while considering infrastructure data and road conditions. The set of customers, along with charging stations, and the warehouse can be represented using a weighted graph where each vertex represents the route connecting two nodes. Our work aims to find the optimal path that generates the least costs possible and by cost we refer to travel time, distance, energy consumption and the number of vehicles deployed.

Given the various constraints applied, computational time increases, therefore, the number of customers served was limited to 15.

To summarize, the number 15 refers to the number of customers to be served, and not the number of vehicles using the road.

• In the Introduction section we can read: “and the race to score 30 the leading place in the international market, countries in the four corners of the globe 31 invested in, among other things, larger fleets to strengthen their logistics’ performance.” What literature or database supports this view?

The assumption regarding the expansion of logistic fleets can be deduced from the transition from the ETSP to the EVRP. For instance, the Electric Vehicle Travelling salesperson problem (ETSP) aims to serve a set of customers using one single electric vehicle. This results in multiple back and forth trips between customers and the main warehouse. This version of the routing problem is scarcely used nowadays because it requires longer delivery times. This issue gave birth to what is known as Electric Vehicle Routing Problem (EVRP), which uses several vehicles. When using more than one vehicle, customers can be served simultaneously, thus, respecting their time window (or availability).

The more vehicles a company has, the more customers can be served. However, an equilibrium must be found between the number of vehicles to use, and the number of customers, and that is to avoid excessive costs (energy, driver’s wage, rental cost of the vehicle…).

Finally, the expression “larger fleets to strengthen their logistics’ performance” refers to the break of the industrial revolutions, where acquiring larger fleets was a necessity to help reach distant countries. The use of more vehicles, of all types, helped companies expand internationally.

• In the Metodology section we can read: “Understandably, the more constraints we impose on the approach, the slower it be comes, which inspired our decision to split the solution into three stages.” And in the Results section we can read: “The time required to find the optimal solution for 15-customers datasets is almost 14 times the time needed for 5-customers datasets.” Can you explain what is the reason for the situation that as we read " the slower it be comes " in your approach? And what time frame do you mean exactly?

In our work, when we denote a model “slow”, we refer to the computational time required to generate an optimal solution. When various constraints are enforced, the model requires more execution time to converge towards a solution. Moreover, the execution time is heavily influenced by the number of customers to serve.

• “Table 4. characteristics of the Volvo electric vehicles used for deliveries [42].” Word “characteristics “ should start from capital letter

Thank you for pointing this out. We have applied the required modification.

• Please clarify what the row numbered 7, 7 and 6 refers to in Table 4.

In our model, we consider a heterogenous fleet (non-identical vehicles). Accordingly, We consider a fleet of 20 VOLVO electric vehicles, where the seven first vehicles are VOLVO FL, and the other seven vehicles are VOVLO FE, and finally, the remaining 6 vehicles are VOLVO FH.

• Please clarify what what means “Traffic (%)” in the Table 5. What relation allows you to calculate the percentage of traffic jams on the street?

In the absence of an API, we generated random data regarding traffic, amongst others, and we expressed it in percentage. For instance, 50% traffic means that the vehicle will be forced to drive at a speed of 50% of its original speed. For example, if the vehicle drives at 60 km/hr, and the traffic is of 50%, the vehicle will be driving at 30 km/hr.

• Please explain why you used Google Colab Pro Plus in the simulation? How is this tool different from others?

While other platforms rely on the machine’s (computer’s) characteristics for simulations, mainly the RAM size, Google Colab Pro Plus offers an online platform with computation units with up to 52 GB of RAM, regardless of the computer’s characteristics.

• We can read: “The driver profile is linked to the vehicle, which means that once a vehicle is selected, the amount of acceleration assigned to it is applied on all arcs driven by this vehicle.” Is this acceleration given in advance, regardless of the driver's behavior on the highway?

Since predicting the drivers’ behaviour at every moment is almost impossible, we decided to select an acceleration rate for every driver’s profile (passive and aggressive). The acceleration is certainly provided in advance (Please refer to section [638-641]) and is set as 3-4 m/s² and 1.5-2 m/s² for aggressive drivers and passive drivers, respectively.