Geographies of fuel dispensing: locational analysis and conformity of petrol filling stations (PFS) to planning standards in Ota, Nigeria

Following the observation of the indiscriminate location of petrol filling stations, this study analyzes the location pattern and conformity of the PFS to planning standards in Ota, Ogun State. A survey of petrol filling stations in Ota was conducted to achieve the twin purposes of taking inventory and documenting their geographic coordinates. A nearest neighbour analysis was used to compute the nearest neighbor index, the Z-score, and the probability (p) value in order to determine the pattern of the distributions. Buffer and proximity analysis was done in Arcmap to analyze the conformity of PFS to the planning standard. The findings revealed that there are 50 PFS located along the 15 roads in the study area, of which 72% are owned by independent marketers, 18% are owned by major marketers, and 10% are owned by the NNPC. The spatial analysis of petrol filing stations indicates that PFS were more concentrated on the major roads, in the transitional residential zones, and in the Central Business Districts. With a nearest neighbor index (Rn) value of 0.405547 (less than 1), a Z-value of −10.171697 (less than −1.96), and a p value of 0.00000, the distributional pattern of PFS revealed that the pattern was clustering. The study finds only 16% complied with the 400 m distance to the next filling station; more than two-thirds (78%) of the petrol filling stations did not meet the 15 m setback requirement; and only 10% met the 50 m distance requirement to residential buildings. Among other recommendations, the study suggests the need for more proactiveness and effectiveness from the regulatory agencies.


Introduction
Africa and Asia are homes to most of the world's fastest-growing cities.By 2050, the majority of the world's urban population will be concentrated in Asia (52%) and Africa (21%), as the urban populations of both continents are expected to triple between 2018 and 2050 (UN- Habitat, 2018).Nigeria is, without a doubt one of, if not the, most significant contributors to Africa's urbanizing profile (Adeboyejo, 2013).The phenomenal growth of the urban population in Nigeria has boosted the use of automobiles, electric dynamos, and other petroleum-consuming plants.This has contributed to the rising demand for petroleum-based products, which has been exacerbated by the appalling electricity supply in Nigeria.As a result, the numbers of petrol stations created in various parts of Nigerian cities are steadily increasing.Furthermore, the attractive price of petrol at both regulated and black-market prices has encouraged the influx of people into the petrol retailing sector, resulting in an unprecedented numbers of Petrol Filling Stations (PFS) in most Nigerian urban areas.
A petrol filling station (also known as a fueling station, gas station, or petroleum outlet) is any land, building, or equipment used for the sale or dispensing of gasoline or oil for motor vehicles or incidental thereto, and includes the entire land, building, or equipment whether the use as a petrol station is the predominant use or is only a part thereof (Ayodele, 2011).It has also been described as a location with fuel equipment and pipelines, storage containers, a service station, and building spaces for selling fuel (inflammable liquids) to customers (Nieminen, 2005).
Petroleum products are extremely combustible and frequently kept in subsurface tanks where they are sold at PFS by meter pumps.Because of the importance of retail outlet sites to people's health and safety, sufficient planning guidance and adherence to existing location criteria are required.The Nigerian Upstream Petroleum Regulatory Commission (NUPRC) of the Nigerian Federal Ministry of Petroleum Resources (FMPR) is a government body that controls the sale of petroleum products throughout Nigeria.The NUPRC, previously known as the Department of Petroleum Resources (DPR), also offers instructions and guidelines regarding how to set up and run a filling station that may sell petroleum products like Automated Gas Oil (AGO), also known as diesel, Dual Purpose Kerosene (DPK), and Premium Motor Spirit (PMS), also known as petrol.
The NUPRC is also required by law to ensure adherence to petroleum laws, guidelines and regulations in the oil and gas industry to ensure safety and prevent health risks.Depending on the gravity of the offence, the consequences for violating the NUPRC guidelines by petrol stations range from labelling that petrol station as illegal to license revocation, and when the license is revoked, dealing, packaging,, selling, or trading in petroleum or petroleum products becomes criminal.
In addition to NUPRC guidelines, the location of PFS is regulated and controlled by urban and regional planning agencies, both at the national and state levels.Despite the plethora of government agencies tasked with controlling and regulating the extraction and dispensing of fuel, Nigeria is showing laxity regarding the indiscriminate citing of oil and gas stations as well as tank farms.Evidence abounds that despite the guidelines controlling the location of PFS in Nigeria, most of them are in a disorderly and potentially hazardous manner (Afolabi et al., 2011;Jia et al., 2022;Olapeju, 2017;Ulakpa et al., 2022).
The haphazard location of PFS in Nigerian cities, particularly in undesirable locations, indicates a lack of regard for planning standards.Indiscriminate siting, insufficient size, a limited setback from the road, and inadequate distance allowance from important buildings like churches, schools, mosques and churches, are all manifestations of utter disregard for planning regulations.Regrettably, the growing number of PFS, the majority of which are badly sited and adjacent to residential structures and public places, has become a "typical" phenomenon in Nigerian cities.The situation in Ogun State is disconcerting, as the State government sealed 26 illegal buildings, including gas outlets and petrol filling stations for non-compliance with the physical planning law of the state (Olatunji, 2021) while NUPRC agents in the state also sealed 73 PFS for operating without a license (Oluchi, 2018).It is on this premise that this study examines the geographical distribution, locational analysis, and conformity of PFS to planning standards in Ota, Ogun State, Nigeria.

Literature review
The extant literature has demonstrated pressing health, safety, and environmental concerns and widespread trepidations about the adverse effects of the indiscriminate location of PFS.As a result, many authors have suggested that the location of petrol stations must be done strategically and consciously in order to reduce their impacts on both humans and their immediate surroundings (Ulakpa et al., 2022;Douti et al., 2019;Ekpenyong et al., 2019;Thomas et al., 2016).
Consequent on the foregoing, studies in the worldwide literature have directed useful effort towards the locational attributes and hazards of PFS, and as a result, there are quite a number of case studies that have been conducted on filling station location around the world, specifically to ascertain the dangers associated with filling station location.The City of Singapore case, in which Chan et al., (2007) proposed a structural model to explain both the geographic locations of Singapore's gasoline retailers and the nature of price competition between retailers and their geographic locations, sparked an interesting discussion in the literature.Surprisingly, the model's premise was that the Singapore government decides where the city's gasoline stations should be located.Hamid et al., (2009) also discussed the potential of a petrol station site based on traffic volume counts using a regression and Geographic Information System (GIS)-based spatial system.The authors emphasized, with special reference to the United States of America, that site potentiality is an important factor that influences the business success of a petrol station that relies on customer visits.
Although, there appears to be paucity of empirical literature on the area of petrol service stations in Nigeria, the pocket of studies available was focused extensively on the location of PFS.Mohammed et al. (2014) conducted a study in the Kano Metropolitan Area to assess the compliance of petrol filling stations to DPR's Physical Planning Standards.The findings revealed some unique and significant information about the noncompliance of some PFS with the standards.Njoku and Alagbe (2015) also used GIS to highlight a flagrant violation of physical planning standards in the location of a PFS in Oyo state.While they agree that petrol filling stations should be located in easily accessible areas, they were concerned about over-provision within one geographical area as well as indiscriminate locations in the state.
More recent studies (Abiola & Oyinloye, 2021;Ekpenyong et al., 2019;Jia et al., 2022;Ulakpa et al., 2022) have attested to the fact that the siting of retail petrol stations in various towns across Nigeria is drastically on the rise and there are several irregularities in its location with respect to residential settlements and other infrastructures.The location of these stations poses high risk to both the environment and human health.
Like in many other parts in Nigeria, studies on the indiscriminate location of PFS in Ogun State have received some attention in the research community (Adedeji et al., 2022;Ogunyemi et al., 2017;Okubena & Fayomi, 2018;Olapeju, 2017).It is concerning that the number of academic publications on the subject is not proportionate to the magnitude of the problem in Ogun State, particularly in Ota, the headquarters of the most populous local government in Ogun State and industrial hub of the state.

The study area
The Study area is Ota, the headquarters of Ado-Odo/Ota Local Government in Ogun State, found in the south west part of Nigeria.It lies between Longitudes 2° 53 E and 3° 15 E, and Latitudes 6° 25 N and 6° 450 N. (see Fig. 1) Ota was chosen as the study area in part because of the enormous population it has in Ogun State.For instance, according to the 1991 and 2006 Nigerian population censuses, Ado-Odo/Ota was the most populous and second-most populous local government area in Ogun State, respectively.The local government is home to 234,647 people (according to the 1991 census) and 527,242 people (according to the 2006 census).The phenomenal population growth of the study area is greatly influenced by its proximity to Lagos and its transitory location near the international border.Ota has a total land area of about 878 km 2 (about the area of San Antonio, Texas).It is connected by roads to Lagos and the Republic of Benin.The trunk "A" road Owode-Idiroko Road was built to connect Sango-Ota with the border towns of Idiroko and the Benin Republic (Cotonu).It is a two-way road that functions as both an international and an intercity transit corridor.
The choice of Ota was also premised on its economic importance to Ogun state.For instance, Ota natives and residents make a living through trading, which was made popular by the town's close proximity to both Lagos and the Benin Republic.Today, the town has become a trading hub with two international markets.Many businesses began constructed factories in Ota mainly because it was less congested than Lagos industrial estates.Thus, Ota began to develop as an industrial city, and by 1999, it had become Nigeria's third-largest industrial hub.(Salako, 1999).Today, Ota has the most industries and the largest industrial areas in Ogun State.As a result, the town was officially designated as an industrial city, and the state government began to encourage businesses to locate in and around the city.
Furthermore, the town is home to some of the nation's top industrial and business conglomerates, including Honda Manufacturing Limited and Obasanjo Farm Limited, as well as some of the country's leading educational institutions, including Bells University of Technology and Covenant University.
One important manifestation of increased population and bourgeoning economic activities in the Ota is an increase in mobility demand, which always contributes to an increase in the number of automobiles in the town and, by extension, more fuel consumption.This has in turn increased the number of petrol filling stations in different parts of the town, especially along the major the roads.The scrambling of petrol marketers for space to profit from this situation has resulted in the indiscriminate location of PFS (Ogunyemi et al., 2017).

Types of data required
The data required for this study are: (i) The number of PFS (ii) The names of the streets and neighbourhoods where they are situated; and (iii) The geographic coordinates of the filling stations.

Method of data collection
An inventory of PFS in Ota were conducted to achieve the twin purposes of documenting their geographic coordinates and other locational characteristics.An inventory is commonly understood to be a detailed list of items in a location.In the context of this study, an inventory is a list of PFS in the study area.The inventorial tool used in this study is counting, which is an observational quantitative method of research.The method does not require any interaction with human subjects.This, in turn, eliminates the possibility of the results being a misrepresentation of reality.
Based on the knowledge that PFS are usually located along the road, the inventory taking started with identifying the locations of PFS through the guidance of the Ota Street Map.After locating the PFS, their attribute data, such as names of the stations, location address, number of pumps, etc., were obtained through structured observation.Also known as systemic observation, structured observation is a method of collecting observational data using a predetermined coding scheme, which produces reliable and replicable data.The exercise generated a list of all identified PFS, which was used to calculate the number of PFS in the study area.
The coordinates of all identified PFS was obtained using handheld Global Positioning System (GPS).All GPS data were transposed into satellite imagery to create digital maps of current petrol station development and to perform buffering and proximity analysis.

Methods of data analysis
The geographic coordinates of PFS obtained from field GPS observation were combined with attribute data in an excel environment.A 2.5 m resolution Google Earth imagery of Ota from 2021 was obtained.The map-to-image geo-referencing technique was used to geo-reference the imagery after it was imported into the ArcGIS 9.3 environment.
In the ArcMap environment, the Nearest Neighbor Analysis (NNA) was performed to examine the distributional pattern of PFS in the study area, and Nearest Neighbor Index (NNI), Z-Score, and probability (p) value were computed.The method compares the actual distance between points and their closest neighbours to the distance that would be predicted by chance.
The ratio of observed to expected values is known as the nearest neighbour statistics/index, or Rn.Rn has a value between 0 (when all points are in the same place and their distances from one another are equal) and 2.14.(For a flawless, symmetrical, or uniform point pattern dispersed over an extremely large area.)The observed distance between neighbours is equal to the distance anticipated for a random distribution, which is why Rn = 1 denotes a random pattern.The nearest neighbor formula is: where Rn = the description of the distribution; đ = the mean distance between the nearest Neighbours (km); n = the number of points in the study area; A = the area under study (km 2 ).
ArcGIS was used to find statistically significant spatial clusters of high values (hot spots) and low values using the Getis-Ord Gi statistic (cold spots).For each feature in the Input Feature Class, it creates a new Output Feature Class with a z-score, p-value, and confidence level bin (Gi Bin).A high z-score and low p-value suggest a spatial clustering of high values.A low negative z-score and a small p-value suggest that low values are spatially clustered.With the z-score, the degree of clustering rises (or falls).The absence of apparent spatial clustering is seen when the z-score is close to zero.
ArcMap was used to perform buffer and proximity analyses to assess the PFS's adherence to standards (as specified by NUPRC).Several queries, including those for the distances of 15 m between the PFS edge and the road, 400 m (about 1312.34 feet), and 100 m (about 328.08 feet), between the PFS and the public building, were run to produce the desired results.

Distributional analysis of petrol filling stations
The results of the PFS inventory conducted at the time of the study showed that there were fifty (50) PFS in the study area.The names, locations, types, ownership, and types of roads located are shown in Table 1.The data in the Table was used for the analyses that follow.
In Nigeria, both the public and private sectors own petrol stations.The private sector is made up of Vol.: (0123456789) independent marketers-individual business owners or partners-or major marketers-multinational corporations.Nigeria National Petroleum Company is a government-owned company that belongs to the public sector (NNPC).Figure 2 demonstrates that independent marketers own more than two-thirds (72%) of the filling stations.Major oil marketers held less than a fifth (18%) of the oil stations in Ota, while NNPC held 10%.This finding is in concordance with similar studies (Sule et al., 2011) where it was discovered that independent marketers owned most PFS in Nigeria.
The finding is a pointer to the fact that petrol marketing is a lucrative business dominated by business owners who invest their funds to make a profit.The dominance of independent marketers in the retail sale of petroleum products benefits economic diversification because it dismantles the stranglehold of multinational corporations that had previously ruled the sector and creates employment opportunities for Nigerians in the downstream petroleum sector.
The number of pumps in each station was determined in order to assess the potential threat that these stations might pose during their operations.According to a breakdown of PFS by number of pumps, half of the identified filling stations (50%) had more than one dispensing pump (mega stations).One-fourth (28%) had three to four dispensing pumps (medium stations), while the remaining 22% had one or two dispensing pumps (mini stations).
Table 2 shows the distribution of PFS by ownership and type.The results show that 60% of the PFS owned by NNPC were mega filling stations while 20% apiece were medium and mini PFS, respectively.The major marketers had nine (9) PFS in Ota.Two thirds (66.7%) of these stations were mega stations while 11% and 22% were medium and mini stations, respectively.The independent marketers had a total of 36 (44.4%) of these PFS which were mega stations while 33.3% and 22.2% were medium and mini PFS, respectively.

Spatial analysis of petrol filling stations
The spatial frameworks on which the spatial analysis of PFS is predicated are road corridors and residential areas.The geographic distribution of PFS shows that the filling stations are not evenly distributed among the major thoroughfares and populated areas (see Table 3 and Fig. 3).
The fifty (50) identified PFS are along fifteen (15) road corridors as seen in Table 3.
The two roads with the most petrol stations are Winners-Idiroko and Iyana Iyesi, Idiroko roads.They have 6 PFS, each of which represents 12% of the total.With five (5) each, the Awolowo, Ilo Awela, and Ilogbo roads come next.There are four (4) each on Oju-ore, Ilogbo, Itele, and Ota-idiroko roads.There are three (3) on each of the Sango-Idiroko, Obasanjo, and Iyesi roads, two (2) on Oke Sunna Road, and one (1) on each on the other roads.
The breakdown of these road corridors by road types shows that 34 of the 50 identified PFS (representing 68%) are located on major roads.This reinforces the findings of similar studies conducted in Nigeria (Dogara, 2017) and Kenya (Karanja & Gathitu, 2018), which found that PFS is typically found along major roads with high traffic volumes.
The breakdown by residential zones indicates that almost half (48%) of the PFS were located in the transitional zone.This is followed by the sub-urban zone (40%) while the traditional core had the least (12%).What can be inferred from the foregoing analysis is that PFS were more concentrated in sub-urban and transitional zones while they were less visible in traditional core areas.Indeed, these findings corroborate that of Baichie and Wallimsi (2000) where it was reported that while less prevalent in town centres, filling stations are more prevalent on the town's exit side.
Further analysis shows that PFS were concentrated in the Central Business Districts (CBDs), populated residential areas and along major roads linking the commercial town of Ota and other notable cities.The distribution covered Sango Ota-Abeokuta expressway; Iju-Iyana Ota Road; Olorunda-Iju road and Toll-Gate cutting across areas such as Winners, Obasanjo farm, Joju, Olorunda, and Iyesi.

Distributional pattern of petrol filling stations
Nearest Neighbour Analysis was performed on the 50 PFS within 87,539,458.891718m of Ota to identify their distribution pattern in the study area.The results in Table 4 and Fig. 4 show that the pattern is approaching or tending towards clustered, with the nearest Neighbour index (Rn) value of 0.405547 (less than 1), a Z-value of −10.171697 (less than −1.96) and a p-value of 0.00000.Meanwhile, an ideal facility location pattern should be one of regular distribution in space rather than clustering.This pattern implies that PFS in the study area exhibits unhealthy competition, which has serious negative consequences for spatial functionality, efficiency, and aesthetics.
Hot spot analysis was then performed to determine the statistically significant hotspots and coldspots of PFS sites.Hotspot areas in the study area have a statistically significant high concentration of PFS, whereas cold-spot areas have a statistically significant low concentration of PFS.The result of the hotspot analysis as shown in Fig. 5 indicates that the locations of PFS in the study area can be distinguished by hotspot and cold-spot areas according to the degree of their clustering.The filling stations in hotspot areas are indicated with shades of red while cold-spot areas are indicated with shades of blue on the map.
It follows, therefore, that several hotspots could be identified, the majority of which are in the central business district of the study area, with the hotspots in the Sango, Toll Gate, and Oju Ore being of particular interest.These areas are characterized by traffic congestion, particularly during a fuel crisis; PFS compete with residential buildings, putting their occupants in grave danger in the event of a fire outbreak.Additionally, residents of nearby buildings are exposed to the pungent odour of hydrocarbon fuels as well as elevated levels of fuel vapour.
The cold hotspot zones include a pocket of areas in Ilogbo, Akeja, and Winners Chapel, but most are along the Obasanjo-Idiroko road, including Iyana Iyesi, Bells Junction, and Winners Junction.Exclusively commercial land use is evident along this road.As a result, residents are less likely to be affected by fire accidents caused by PFS, incidents of traffic  This study assesses the conformity of the PFS to the physical development standards by correlating some of these standards with the current locations of the PFS in the study area.This was accomplished by utilizing the buffering and proximity analysis tools included in ArcGIS 10.Although both the NUPRC and OSMPPUD have physical development standards that must be satisfied before the operators are given the all-clear to commence operations, this study considered the standards as specified by the NUPRC.The reason for this is that NUPRC standards are stricter than OSMPPUD standards.For instance, while the NUPRC recommends a setback of 15 m from the road, OSMPPUD recommends a setback of 9 m.The NUPRC requires a 400 m distance between the existing and the proposed PFS, but OSMPPUD only requires 300 m.Distances between the PFS in the study area were determined in the ArcMap environment using Nearest Buffering Operation.The result (Fig. 6) shows that a vast majority (84%) of the PFS were less than 400 m from their Neighbours.
The reason for this is not farfetched.The threat of competition forces petrol retailers to consider locations where they can gain the most market share.To minimize the distance that customers should travel, they want to be in a central location (the CBD and along major roads) for their target customers.Instinctually, all competing retailers make the same choice at the same time, which results in the PFS being clustered together and falling short of the required 400 m to the next PFS.However, the clustering of PFS is hazardous to the adjoining residents, especially during a fire outbreak from the PFS, as the fire can easily spread to the next PFS due to proximity.
According to NUPRC guidelines, the distance between the road and the PFS pump should not be less than 15 m.The proximity analysis of PFS shows that only 12 PFS (24%) meet the 15 m setback requirement while more than two third (78%) did not meet this requirement (Fig. 7).Most stations that did not comply with the 15 m setback requirement are in the Toll Gate, Sango, and Ojuore Central Business Districts.The few remaining stations in this category are located along the major roads that radiate from the CBDs toward Idiroko Road, including the Obasanjo, Iyana Iyesi, Bells Junction, and Winner's corridors.
One requirement for PFS as stated in NUPRC guidelines is that the distance between PFS and residential structures should be kept at 50 m.To create a buffer zone for residential buildings, a petrol station should be placed 50 m from all sides of the built-up areas.
The nearest residential building distances to PFS were as shown in Fig. 8.The assessment of the minimum distance of PFS from residential buildings shows that the NUPRC's requirement of 50 m between PFS and residential buildings was violated  What could be observed from the foregoing analyses is that the planning standards set up by regulatory bodies to guide the location of PFS were grossly violated.If all regulatory standards for PFS location are strictly adhered to, nearly all PFS in the study area are not eligible for town planning approval.The uncontrolled and unguided pattern of development and functionality of PFS thus points to the inefficiency of the regulatory agencies in the state.Based on previous studies (Kio-Lawson et al., 2016;Odekunle et al., 2019;Osinbajo, 2004) the arbitrary construction of PFS without conformity to the planning standard and, most often, without approval could be as result of the following: i.The inefficiency of regulatory bodies such as NUPRC and OSMPPUD ii.Lack of synergic collaboration among the regulatory bodies.
iii.Corruption undermines the effectiveness and efficiency of regulatory bodies to function efficiently.iv.Political interference in the location of PFS

Conclusion and recommendation
This study examined the location and distribution of petrol filling stations in Ota, a medium sized town in the most populous local government area of Ogun State, Nigeria.Some insidious effects of indiscriminate and defiance of planning standard in the location of filling station were identified.There is sufficient evidence in this study to conclude that PFS are not evenly distributed, but are more concentrated in CBDs, populated residential areas, and along major roads.It is also determined that most PFS in the study area flagrantly violated all applicable regulations.Based on the findings, the following recommendations are offered.
i.The NUPRC and OSMPPUD should mandate that the geographic coordinates of the proposed site be included in the application materials for PFS siting.This can assist in updating the spatial database for the PFS and checking compliance with the distance to the next PFS, public buildings, road setbacks and residential buildings.ii.By reconciling the discrepancies in the standards for the location of PFS and safety regulations between the two regulatory bodies, the NUPRC and OSMPPUD can collaborate to ensure that petroleum and gas marketers do not compromise public safety regulations in the state.The recent resolve by the Ogun State government to partner with the NUPRC to daunt the arbitrary construction of petrol stations without approval in the state is a positive step in this direction.iii.The regulatory bodies in the state, namely the NUPRC and OSMPPUD, should be more proactive in enforcing compliance orders for petroleum and gas operators in the siting of the PFS.iv.Both regulatory agencies should conduct a verification and approval auditing exercise to clamp down on PFS that were either incorrectly approved or were operating illegally without approval.Those who were incorrectly approved should be reviewed, and appropriate compliance action should be taken against them, while those who operate without approval should be penalized with an additional assessment fee, and those who deviated from the approval given to them should be made to start the process over.

Fig. 1
Fig. 1 Ota in the context of ogun state, Nigeria

Fig. 3
Fig. 3 Spatial distribution of PFS in Ota

Fig. 4
Fig. 4 Summary of nearest neighbor analysis

Fig. 5
Fig. 5 Hotspot analysis of petrol filling stations

Fig.
Fig. PFS that fail to meet the 400m distance Requirement of NUPRC

Fig. 8
Fig.8PFS that meet the required 50 m standard for residential buildings (with blue shades)

Table 4
Summary of nearest neighbour analysis