Determining transit nodes for potential transit-oriented development: Along the LRT corridor in Addis Ababa, Ethiopia

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Frontiers of Architectural Research xxx (xxxx) xxx

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Research Article

Determining transit nodes for potential transit-oriented development: Along the LRT corridor in Addis Ababa, Ethiopia Eden Atsbeha Teklemariam*, Zhongwei Shen School of Architecture and Design, Southwest Jiaotong Univeristy, Chengdu, China Received 9 September 2019; received in revised form 21 February 2020; accepted 10 March 2020

KEYWORDS Accessibility; LRT; Transit; TOD; TOD index; Addis Ababa

Abstract The aim of transit-oriented development (TOD) is to create a livable urban environment by improving the integration between land-use and transportation systems. The capital city of Ethiopia, Addis Ababa, aims to promote a sustainable transportation system by launching its first light rail transit (LRT) network to control the current pattern of increased congestion and the need for mass transport. Planning for TOD around existing transit stations helps achieve improved transit choice and encourages local economic development. Therefore, this article proposes a methodology to quantitatively measure the existing TOD in terms of a TOD index within the walkable distance of transit nodes by measuring the criteria that define TOD levels. The TOD index is calculated for areas of 22 stations on the East-West LRT line of Addis Ababa. Depending on the value of the TOD index, certain stations are identified to have a potential TOD but poor transit accessibility. With these results, the recommendation to improve TOD planning can become accurate for each station, depending on its relevant factors. Such results also help identify each station’s potential for TOD planning and its improvements toward future local developments. ª 2020 Higher Education Press Limited Company. Production and hosting by Elsevier B.V. on behalf of KeAi. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/).

1. Introduction A renewed interest in public transportation that integrates transport and land use, particularly in light rail transit

(LRT), sparks transit-oriented development (TOD). TOD promotes a livable and accessible urban environment around transit nodes. The definition of TOD focuses on the goal of creating a walkable environment and encourages

* Corresponding author. E-mail address: [email protected] (E.A. Teklemariam). Peer review under responsibility of Southeast University. https://doi.org/10.1016/j.foar.2020.03.005 2095-2635/ª 2020 Higher Education Press Limited Company. Production and hosting by Elsevier B.V. on behalf of KeAi. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Please cite this article as: Teklemariam, E.A., Shen, Z., Determining transit nodes for potential transit-oriented development: Along the LRT corridor in Addis Ababa, Ethiopia, Frontiers of Architectural Research, https://doi.org/10.1016/j.foar.2020.03.005

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2 the use of cycling, walking, and public transport, both of which can be achieved by developing high-density mixed land use around transit nodes (Cervero, 2004; Dittmar and Poticha, 2004; Parker et al., 2002; Schlossberg and Brown, 2004). The benefits of TOD include increased access to public transportation and hence to additional opportunities, walkable environment utilization, increased transit ridership, low air pollution and greenhouse gas emission, improved access to jobs, and healthy lifestyles. TOD has direct and indirect benefits. The primary benefits are those that can accrue to transit agency, such as increased ridership and revenue, neighborhood revitalization, economic gain through joint development (D), and transit (T). The indirect benefits of TOD are congestion relief, land conservation, reduced road expenditure, and improved safety for pedestrians and cyclists (Cervero, 2004). Most investments in infrastructure within Addis Ababa are often made without understanding its existing conditions. This situation clearly emphasizes that planning for TOD should be preceded by a quantitative understanding of the current circumstance, which, in turn, requires measuring the current TOD level. Therefore, measuring the potentials for TOD reveals the importance of conceptualizing accessibility and improving transit nodes. The evaluation of a successful TOD must express the existing TOD of an area in terms of the TOD index (Evans et al., 2007). Evaluations of transit nodes can benefit from lessons learned from previous projects, as such evaluations have been successfully implemented in the USA, Europe, Singapore, and Hong Kong. However, regarding various evaluation studies and experiences, the establishment of a successful TOD depends on the involvement of public and private sectors. Moreover, essential local elements must also be considered because one cannot merely copy experiences as to how politics, economic conditions, and regional cultures differ from places where TOD is successfully established. The implementation of TOD around the major transit stations in Addis Ababa has failed due to specific reasons. Therefore, this paper presents an approach to measure the TOD level of areas and to identify the reasons for high or low scores. GIS and spatial multiple criteria analysis (SMCA) are used to measure TOD levels. Section 2 reviews past studies on TOD assessment around transit stations. Section 3 presents a study area analysis and the data collection method. Section 4 introduces the specific techniques for measuring TOD. Section 5 elaborates the results on the basis of a case study on Addis Ababa. Section 6 provides the summary of the findings and recommendations made for improvements. Finally, Section 7 concludes.

2. Literature review Various definitions of TOD have surfaced over the years based on different viewpoints and perspectives. Different case studies have presented how TOD is planned at regional, urban, and local scales. Others have focused on planning and financial issues (Cervero et al., 2002), TOD and employment (Belzer et al., 2011), TOD and property value (Park et al., 2016), TOD and affordability (Bostic

E.A. Teklemariam, Z. Shen et al., 2018), and density and mixed use and TOD (Cascetta and Pagliara, 2008). However, measurements to identify the existing TOD level of areas are not found. Thus, Atkinson-Palombo and Kuby (2011) attempted to assess the existing condition of TOD and understand the heterogeneity of the built environment before implementation becomes essential to enhance the success of transit nodes. Renne (2009) emphasized the measurement of an existing built environment according to its density and transit ridership. The author also suggested that an increase in property value improves a TOD project. In the current study, the working definition focuses on measuring the existing built environment of the surrounding transit node. Bernick and Cervero (1997) focused on measuring the built environment and highlighted the role of density, diversity, and design in the success of TOD. Later interests emerge to include destination accessibility, distance to transit, and demand management (Ewing and Cervero, 2010). Similarly, Schlossberg and Brown (2004) paid attention to the physical characteristics of a transit station and TOD as an integrated approach to transportation and land-use planning. Despite all the advantages and attractiveness of TOD, its concept suffers from the lack of spatially explicit measurement tools that directly deliver spatial analyses and visual capabilities, which quantify the TOD level index. Therefore, different defined measurements employed by different authors can lead to various comparable outcomes. Moreover, the measurements of TOD levels around transit nodes need a proper framework when public investments are made in infrastructure. Renne and Wells (2005) highlighted that plans for TOD without measuring the existing TOD levels of areas fail in achieving sustainable transit nodes and lack coordination between land use. Similarly, Cervero (2004) stated that most studies evaluate transit nodes on the basis of the ridership and effect of land values while neglecting other aspects. Researchers have made discussions beyond the integration of land use, transportation, and built environment. Thomas and Bertolini (2014, 2015) identified critical factors to successfully implement the TOD policy. However, they focused on the measurements of existing transit stations to identify the critical needs that are effective for TOD plans. Although many studies have measured TOD around transit stations, one of the most recurring approaches is to develop a station TOD index, where all study area (East-West [E-W] line in Addis Ababa) stations are grouped into ranks depending on the characteristics of a place. Evans and Pratt (2007) proposed the TOD index that is a quantified expression of the TOD level of an area. Renne and Wells (2005) elaborated the most important factors for successful TOD. They investigated 56 existing indicators under five categories of travel behavior, economy, environmental built, and social diversity. These factors surveyed transport and other professionals and came up with 10 indicators for evaluating TOD. These indicators are transit ridership, density, quality of streetscape, quantity of mixed-use structure, pedestrian safety, increase in property value, increase in tax revenue, public perception, number of mode connections at transit stations, and parking. Evans et al. (2007) suggested developing a TOD index as a potential device for considering the degree to which a

Please cite this article as: Teklemariam, E.A., Shen, Z., Determining transit nodes for potential transit-oriented development: Along the LRT corridor in Addis Ababa, Ethiopia, Frontiers of Architectural Research, https://doi.org/10.1016/j.foar.2020.03.005

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LRT corridor in Addis Ababa, Ethiopia

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particular project is intrinsically oriented toward transit. ITDP (2014) showed similar studies on quantifying TOD by using the TOD scoring system within walking distance. They focused on scoring a new development depending on the principles of walking, cycling, connecting, mixing, densifying, compacting, and shifting. Similarly, Papa and Bertolini (2015) quantified TOD at the city level by measuring the TOD degree for an urban area, as an extent to which urban development is concentrated along the rail corridors in the city.

3. Data collection The E-W LRT line of Addis Ababa, the capital city of Ethiopia, is selected as the study area. Addis Ababa is known as the home to the Africa Union and the diplomatic capital of Africa. Thus, the city government aims to stimulate a sustainable transport system and believes that TOD can be an appropriate strategy to achieve sustainable development. The city is the central economic zone of Ethiopia that covers 527 m2 and includes 10 districts (subcities), as seen in Fig. 1. The policy vision of Addis Ababa centers on creating additional housing and employment with a sustainable transport system. To do so, the city-regional government launched the first LRT system on September 20, 2015 and is planning to establish the bus rapid transit. Hence, knowing which of the areas in the region require transit connectivity is an advantage. Realizing this benefit, the city-regional government proposes two linear lines in the major corridor of the city, namely, E-W and NeS lines (Fig. 2). The E-W line is 17 km long and connects Ayat neighborhood to

Fig. 1

Torhailoch, passing through the main centers of the city, Megenagna, Meskel Square, Leghar, and Mexico Square. The NeS line with a total length of 16.9 km passes through Merkato, Lideta, Leghar, Meskel Square, and Gotera connecting Menelik II Square to Kality. The full extent of the railway network is 31 km and comprises 39 stations. The data used in this research are collected from government departments and field surveys. The secondary data include land use, road networks, public transport networks, and population. Furthermore, spatial data analysis using ArcGIS and SMCA are employed to assess the TOD index. To present the methodology for developing the TOD index, this study covers 22 existing stations of the E-W LRT line.

4. Methodology Evaluating TOD by using an index requires measuring the factors that influence transit developments around transit stations. These factors are related to the urban development around transit nodes and the transit system. These factors are also identified as spatial and non-spatial and have various scales depending on the existing conditions of different transit areas. Due to various perceptions of the concept, different authors have emphasized TOD measurement in various ways. Bernick and Cervero (1997) focused on the measurement of a built environment, explicitly measuring density, diversity, and design to successfully approach TOD. Kamruzzaman et al. (2014) conducted the same analysis of the existing built environment that can ease facilitation for TOD planning. Cervero and Bosselmann (1998) emphasized visual simulation

Addis Ababa city map.

Please cite this article as: Teklemariam, E.A., Shen, Z., Determining transit nodes for potential transit-oriented development: Along the LRT corridor in Addis Ababa, Ethiopia, Frontiers of Architectural Research, https://doi.org/10.1016/j.foar.2020.03.005

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E.A. Teklemariam, Z. Shen

Fig. 2

Addis Ababa LRT map.

techniques, believing that such techniques convey a comprehensive array of environmental choices. In the present study, the concept of the TOD index developed by Evans et al. (2007) is used to measure spatial criteria and create an index to reflect existing TOD levels. For measuring TOD around transit nodes, demarcating the analysis area in which TOD can be measured is important. Calthorpe (1993) elaborated that the concept of TOD is built within a typically comfortable walking distance from a station. No fixed rule to the distance exists, and the typical comfortable walking distance ranges from 400 m to 800 m. To measure the TOD level of a station area by using an index, a 10-min walking distance of 800 m radius is developed (Schlossberg, 2007), which is relevant to the TOD planning of Addis Ababa. Once the TOD study area is demarcated, the variables that outline the SMCA for the TOD index are specified. Thus, when such an index is computed for each station area, recommendations can be made on how to improve TOD around stations.

4.1. Identification of indicators As mentioned in the literature, measuring the TOD levels of areas means measuring the various indicators that define the characteristics of TOD. These indicators are density, land-use diversity, urban design, and distance to transit

(proximity), all of which are crucial for TOD. High urban densities are essential for TOD because of the effective use of land values around transit nodes. High density development near stations also makes transits convenient and encourages ridership. Similarly, the diverse use of activities creates a balanced and consistent flow of ridership throughout the day. Proximity reduces regional congestion and pollution and creates healthy walkable neighborhoods. Design also plays a significant role in creating user-friendly environments by encouraging pedestrians and bike users. The utilization capacities of public spaces and parking facilities are fundamental indicators for TOD. Having public spaces/green areas for TOD is essential as people come together and enjoy their neighborhood. Providing optimum parking spaces for cars and bicycles is also important. On the basis of the above discussion, the indicators are subsequently divided into measurable indicators, as presented in Table 1. This list of indicators must fulfill the aim of TOD measurement. After calculating all indicators, SMCA is adopted to compute the TOD index. GIS-based SMCA can be used to assess multiple spatial indicators (Beukes et al., 2011). To bring all spatial indicators into comparable units, the maximum standardization method is used, where the maximum indicator achieves value is 1, and the minimum is 0. The indicators have a directly proportional relationship

Please cite this article as: Teklemariam, E.A., Shen, Z., Determining transit nodes for potential transit-oriented development: Along the LRT corridor in Addis Ababa, Ethiopia, Frontiers of Architectural Research, https://doi.org/10.1016/j.foar.2020.03.005

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LRT corridor in Addis Ababa, Ethiopia Table 1

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Indicators and measurement variables of TOD.

Criterion

Indicator

How dense are the transit stations? Land-use diversity Destination to accessibility Distance to transit

-

-

Design

-

Population density Commercial density Land-use mix Land-use mixedness

People per m2 Commercial/job per m2 Mix percentage Mixed-use index

Pedestrian path Intersection density

Walkable distance to reach stations Number of intersections Urban design principles: parking, open spaces, and design elements

Parking utilization Open areas, green spaces

with the TOD index. Therefore, high values positively contribute to the TOD index value.

4.2. Calculation of indicators 4.2.1. Density 4.2.1.1. Population density. The first indicator is population density, which measures the proportion of residents within each service area of 800 m. The 2017 population census is used to identify the population density of districts. By computing the population of a district with its respective area, the population density data per district are analyzed as follows in Formula 1. PD Z NPOA

ð1Þ

where PD Z Population density, NP Z District population, A Z District area. PA Z PDOSA

ð2Þ

where PA Z Buffer area population, PD Z Population density, SAZ Buffer area coverage, TOD area Z 2.01 m2. After finding the number of populations within each 800 m, population density is calculated. The population of each resident is used to approximate the number of populations that falls into the buffer. Pd Z PROSA

Reference, Index

ð3Þ

where Pd Z Population density of the buffer area, PA Z Population residence area, SAZ Buffer area coverage. Each house unit holds five persons (according to Addis Ababa’s standard and regulation). 4.2.1.2. Commercial density. Similarly, commercial density is calculated using the same method of calculating the population density. First, the quantity of a retail building is counted within a service area. The building footprint data are used to approximate proportion.

land uses and is widely measured using an entropy method. A high entropy value indicates high land-use diversity within an area. The formula used to calculate this index is the equation employed by Frank et al. (2006), depending on the actual data availability. The land-use types considered for this indicator are pure residential, mixed residential, commercial, administration, service, religious place, and open space. Fig. 3 shows the existing land use of a single station. Land  use mix Z  A = ðlnðNÞÞ

ð5Þ

where Area Z (b1/a)*ln (b1/a) þ (b2/a))ln (b2/a) þ (b3/a)) ln (b3/a) þ (b4/a))ln (b4/a) þ (b5/a))ln (b5/a). 5 P ðbi =aÞ  lnðbi =aÞ; where A Z Total Therefore, A Z iZ1

m2 of all five land uses presented within the 800 m catchment area, b1 Z Area Residential; b2 Z Area Commercial; b3 Z Area Service; b4 Z Area Administration; b5 Z Area Open space; b6 Z Area Religious. 4.2.3. Destination accessibility 4.2.3.1. Land-use mixedness. Land-use mixedness is used to assess destination accessibility, which indicates the easiness to access places within short trips. Land-use mixedness is also different from land-use diversity. It measures the mixedness of residential land use with other land uses. Non-work trips can be made on foot if the residential land use is sufficiently mixed with other landuse types. Zhang and Guindon (2006) revealed that land-use mixedness can be computed using the following equation: MlðiÞ Z

X  X  ðLr þ Lo Þ Lo O j

ð6Þ

j

where CD Z Commercial density, PA Z Number of commercial activities, SAZ Buffer area coverage.

where Ml(i) is the mixedness index of the catchment area within 800 m radius; Lr and Lo refer to residential and nonresidential land uses, respectively. For each residential point of “j”, the proportion of non-residential is calculated. The mixedness value can range from 0 to 1; and the balanced land-use mixedness is 0.5, implying equal share between residential and non-residential land uses.

4.2.2. Land-use diversity Land-use diversity is a critical measure to compile the TOD index. Such diversity requires a balanced mix of different

4.2.4. Distance to transit 4.2.4.1. Pedestrian path. Pedestrian path is calculated on the basis of the length of accessible roads for pedestrians

CD Z NCOSA

ð4Þ

Please cite this article as: Teklemariam, E.A., Shen, Z., Determining transit nodes for potential transit-oriented development: Along the LRT corridor in Addis Ababa, Ethiopia, Frontiers of Architectural Research, https://doi.org/10.1016/j.foar.2020.03.005

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Fig. 3

Existing land-use around St. Michael station.

within the analysis area by using ArcGIS. The unit of measurement used is meters. All road networks are reclassified on the basis of slow traffic, which is comfortable for pedestrians. Fast traffic roads that are inconvenient for pedestrians are removed from the road network data. Schlossberg and Brown (2004) adopted the concept of approximating walkable/cyclable path on the basis of the reclassification of road networks. 4.2.4.2. Intersection density. Intersection density is used to measure the number of junctions of road networks within the analysis area. High densities of intersections may correspond to comfortable and walkable environments and easily reach destinations (Ewing and Cervero, 2010). Hence, intersection density is one aspect of walkability because it helps shorten routes. Literature identifies intersection frequency as a significant impact between walking and transportation. ArcGIS is used to compute the indicator. 4.2.5. Design The design dimension investigates the built environment related to the urban design and space utilization of the analysis area, such as amenities, usage of parking areas, and open/public spaces. This indicator influences the quality of the city and provides a pleasant design around transit nodes. Parking utilization indicates the efficient use of spaces. Open/public spaces and surface parking are investigated using GIS and aerial maps.

5. Result and discussion The TOD index results of all 22 stations are presented in Table 2. Stations with the highest and lowest TOD levels can be compared with each other using the TOD index results. This study is new for Ethiopia, thus the reference value may differ from the literature. Thus, TOD index values must be

compared with each other depending on the existing condition of neighborhoods for an improved TOD planning. Depending on these results, stations that accommodate transits to different transportation modes have high TOD index scores. These stations are Megenagna, Mexico, Stadium, Torhailoch, St. Ureal, and Gurdshola 1. Due to such developmental characteristics around the nodes, scores for criteria such as land-use diversity and density are high. Moreover, transit services for these stations are comparatively higher than those for other stations. Stations with the lowest scores along the LRT corridor are Management Institute, Meri, Ayat, and CMC stations. These nodes are mainly residential neighborhoods. All stations within the walking distance of transit nodes do not accommodate parking lots for motorized and nonmotorized users. Safety, amenities, and open spaces for green areas and other purposes are also deficient within each station. The final TOD index results are classified into four categories depending on the current characteristics of each transit station. The highest TOD index value ranges from 0.82 to 0.91, whereas the lowest ranges from 0.45 to 0.54. As noted, stations with high TOD index scores can reach high TOD levels in terms of the characteristics of a place. Table 2 shows the data used to support the definition of TOD planning in each individual station. This table gives a clear insight into the contribution of each criterion toward the final TOD index. The results indicate that transit nodes need improvements or should incorporate new TOD. Moreover, this information can provide an improved understanding of how stations have good potential for future growth. The TOD index of each station along the corridor of the E-W line is spatially predicted in Fig. 4. According to the results, the top five stations are presented on the web diagram below. Megenagna, Mexico, St. Estifanos, Stadium, and Gurshola 1 stations show high TOD

Please cite this article as: Teklemariam, E.A., Shen, Z., Determining transit nodes for potential transit-oriented development: Along the LRT corridor in Addis Ababa, Ethiopia, Frontiers of Architectural Research, https://doi.org/10.1016/j.foar.2020.03.005

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LRT corridor in Addis Ababa, Ethiopia Table 2

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Criteria and TOD index values for all 22 stations.

Station Name Criteria Density

Ayat Meri CMC St. Michael Civil Service Management Institute Gurd Shola 1 Gurd Shola 2 Megenagna Lem Hotel Hayahulet 1 Hayahulet 2 St. Urael Bambis St. Estifanos Stadium Lagehar Mexico Tegbared St. Lideta Coca-cola Tor Hayiloch

Diversity

Distance Accessibility

Distance to Transit

Design

Population density

Commercial Land-use density diversity

Mixedness

Pedestrian Intersection Parking Open path density space

Final index

Rank

0.98 0.96 0.59 0.96 0.92 0.95

0.33 0.17 0.07 0.20 0.16 0.17

0.49 0.40 0.33 0.55 0.75 0.72

0.06 0.16 0.07 0.17 0.82 0.80

0.27 0.28 0.27 0.21 0.28 0.27

0.86 0.91 0.95 0.93 0.96 0.78

0 0 0 0 0 0

0.47 0.51 0.45 0.61 0.48 0.47

0.48 0.50 0.45 0.59 0.56 0.54

21 20 22 15 18 19

0.94 0.96 0.95 0.83 0.94 0.94 0.75 0.57 0.63 0.60 0.87 0.85 0.90 0.94 0.39 0.29

0.18 0.07 0.48 0.50 0.38 0.08 0.29 0.27 0.16 0.31 0.33 0.35 0.32 0.21 0.31 0.22

0.72 0.68 0.31 0.58 0.92 0.58 0.64 0.74 0.77 0.78 0.78 0.78 0.79 0.73 0.61 0.51

0.76 0.86 0.81 0.75 0.75 0.78 0.45 0.74 0.37 0.67 0.59 0.55 0.65 0.78 0.79 0.80

0.29 0.26 0.27 0.52 0.21 0.23 0.23 0.23 0.43 0.52 0.41 0.42 0.31 0.27 0.27 0.41

0.35 0.57 0.62 0.73 0.74 0.87 0.84 0,87 0.48 0.36 0.38 0.56 0.70 0.74 0.92 0.86

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

0.82 0.65 0.86 0.72 0.34 0.42 0.76 0.59 0.94 0.92 0.84 0.87 0.82 0.78 0.87 0.61

0.82 0.71 0.91 0.74 0.56 0.58 0.70 0.63 0.85 0.82 0.79 0.89 0.79 0.78 0.78 0.69

5 11 1 10 17 16 12 14 3 4 6 2 7 8 9 13

levels. These stations are the core of the city, which means that they comparatively have maximum development among all the stations, but they still hold potential for improvements. Megenagna station has a relatively high score in population density and in the balance between residential and non-residential uses. The station is a major transport hub and transfer point of the city. Megenaga station is currently regarded as a significant urban development area in Addis Ababa. However, the diverse uses of activities and priorities to pedestrians need improvement around this station area. Mexico and Stadium stations have diverse uses of activities within the walking distance of the study area. Addis Ababa is a polycentric city, and the hierarchy of the development is along the network of the LRT. Thus, it helps neighborhoods to have active character zones, but improvements are still needed. Similarly, St. Estifanos and Gurdshola 1 stations have diverse uses of activities within walking distance from the station. However, more or less, these stations provide transit systems with intended hierarchies in terms of their current services and sizes. Further attention is given to vehicular access, which makes all stations not pedestrian user-friendly places. St. Estifanos station can become a vibrant and pedestrian-friendly area because of the public squares and public spaces found within walking distance of the station. Therefore, the TOD index can be used to make a TOD policy by comparing different stations and identifying specific problems of each station (see Fig. 5).

Fig. 6 presents a web diagram of the next seven stations, namely, Leghar, Tegbared, St . Lideta, Coca-cola, Lem Hotel, Gurd Shola 2, and St. Ureal. E-W LRT line intersects the main corridor of the city connecting the urban with the suburban areas with the transit system; thus, stations have high potentials for TOD. These stations relatively share similar patterns as they have high TOD index scores, which imply that all stations lack good pedestrian paths, diverse uses, and parking for motorized and non-motorized users. As such, the stations seem to have the potential for improvements and new developments. Thus, in TOD policy decisions, these stations should improve certain criteria or indicators by identifying specific problems. Except for Torhailoch station, all stations in Category 3 have high urban density scores, and these stations are Bambis, St. Michael, Hayahulet 2, Hayahulet 1, and Civil Service stations. The web diagram for these stations is presented in Fig. 7 and each station seems to have a high potential for improvement. These stations are sufficiently close to the high centers of growth, yet they have low TOD scores. Therefore, these stations can be prioritized for improving the TOD around them. For example, the TOD policy for Torhailoch station can enhance access to the station, accommodating diverse uses and user-friendly environments to enhance the area. The TOD policy within these stations should incorporate different commercial and other services. Torhailoch is currently a significant transportation hub and transfer point to the new expansion of

Please cite this article as: Teklemariam, E.A., Shen, Z., Determining transit nodes for potential transit-oriented development: Along the LRT corridor in Addis Ababa, Ethiopia, Frontiers of Architectural Research, https://doi.org/10.1016/j.foar.2020.03.005

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Fig. 4

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E.A. Teklemariam, Z. Shen

TOD index for the 22 stations of the E-W line.

A. Category 1: Top five stations

Fig. 5

Web diagram for the top five stations.

B. Category 2: Sixth and 12th ranks

Please cite this article as: Teklemariam, E.A., Shen, Z., Determining transit nodes for potential transit-oriented development: Along the LRT corridor in Addis Ababa, Ethiopia, Frontiers of Architectural Research, https://doi.org/10.1016/j.foar.2020.03.005

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LRT corridor in Addis Ababa, Ethiopia

Fig. 6

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Web diagram for Category 2 stations.

C. Category 3: 13th and 18th ranks the city where the LRT line ends and transfers to bus lines; therefore, an improved pedestrian path is recommended to get easy access to another transport mode. As noted, to improve the TOD quality in this significant corridor, all indicators should be incorporated within these stations. Priorities should be given to land-use diversity, mixedness, transit to interchange from one mode of transport to another, and user-friendly stations. The lowest TOD scores are recorded for Ayat, Management Institute, Meri, and CMC stations. The characteristics of these stations are similar to those of suburban areas, dominated by low-density residents in the outer district of the city. TOD index scores significantly drop due to the extreme importance of land-use diversity and density within walking distance from stations. These stations relatively share a similar pattern. Further effort should be made to improve the TOD around these stations by applying all the involved indicators. The TOD policy must improve land-use diversity; balance the relationship between residential land use and other land uses; and improve parking,

pedestrian-friendliness, and access to transport modes (see Fig. 8).

5.1. Architectural and urban design characteristics of nodes The architectural and urban characteristics of each station are analyzed, in addition to the initial results. Both factors are analyzed according to street type specification (i.e., vehicular lane widths, number of lanes, pedestrian accommodations, street trees, and light requirements), landuse mix (in relative percentages of commercial, civic, residential, and other uses), proximity to the urban core (increase attractiveness), and closeness to nature (public spaces, rivers, green areas). These scenarios are presented if each result solidifies the character of the place to support TOD. Thus, from each category, one station is selected for further illustrative maps and details, depending on the architectural and urban importance of each node.

Please cite this article as: Teklemariam, E.A., Shen, Z., Determining transit nodes for potential transit-oriented development: Along the LRT corridor in Addis Ababa, Ethiopia, Frontiers of Architectural Research, https://doi.org/10.1016/j.foar.2020.03.005

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Fig. 7

E.A. Teklemariam, Z. Shen

Web diagram for Category 3 stations.

D. Category 4: Bottom four stations

Fig. 8

Web diagram for Category 4 stations.

5.1.1. Category 1 stations St. Estifanos station is one of the five stations ranked in Category 1, located in the core of the city. This station is distinguished as an excellent location, with better access

and road infrastructure with proximity to entertainment and conventional facilities compared to other stations (see Table 3).

Please cite this article as: Teklemariam, E.A., Shen, Z., Determining transit nodes for potential transit-oriented development: Along the LRT corridor in Addis Ababa, Ethiopia, Frontiers of Architectural Research, https://doi.org/10.1016/j.foar.2020.03.005

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LRT corridor in Addis Ababa, Ethiopia Table 3

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Characteristics of Category 1 stations.

Rank

Node

Street Type Specification

Land-use Mix

Proximity to the Urban Core

Closeness to Nature

1

Megenagna Mexico St. Estifanos Stadium Gurdshola 1

Medium Medium Medium Medium Medium

High High High High High

High High High High Medium

High Medium High High Low

Fig. 9

Existing land use and vehicular access of St. Estifanos station (top right) and section of the main arterial street (bottom).

Fig. 10

Meskel Square (left), Meskel Square during religious festivities (right).

Please cite this article as: Teklemariam, E.A., Shen, Z., Determining transit nodes for potential transit-oriented development: Along the LRT corridor in Addis Ababa, Ethiopia, Frontiers of Architectural Research, https://doi.org/10.1016/j.foar.2020.03.005

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Table 4

Characteristics of Category 2 stations.

Rank

Node

Street Type Specification

Land-use Mix

Proximity to Urban Core

Closeness to Nature

2

Lagehar Tegbared St. Lideta Coca-cola Lemhotel Gurd Shola 2 St. Urael

Medium Medium Low Low Medium Low Low

High High High Medium Medium High High

High High Medium Medium Medium Medium High

High Low Medium Medium Low Low Medium

Fig. 11

Existing land use and vehicular access of Lagehar station.

Please cite this article as: Teklemariam, E.A., Shen, Z., Determining transit nodes for potential transit-oriented development: Along the LRT corridor in Addis Ababa, Ethiopia, Frontiers of Architectural Research, https://doi.org/10.1016/j.foar.2020.03.005

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LRT corridor in Addis Ababa, Ethiopia

Fig. 12

13

Existing land use and vehicular access of Torhailoch station and section of the main arterial street.

Table 5

Characteristics of Category 3 stations.

Rank

Node

Street Type Specification

Land-use Mix

Proximity to Urban Core

Closeness to Nature

3

Torhailoch Bambis St. Michael Hayhulet 2 Hayhulet 1 Civil Service

High Medium Medium Low Low High

Medium High Medium Medium High High

Medium Medium Medium High High Medium

Medium Low Low Low Low Low

This neighborhood includes public spaces, such as public squares (civic open spaces), green areas, civic spaces, and stadiums (see Fig. 9). The land use of the area is balanced and includes schools, shopping malls, hotels, and office towers within 800 m walking distance from the station. Existing buildings and uses to transition to high development intensity are intended for future TOD. The historical importance of the place, where the United Nations Economic Commission for Africa headquarters and city palaces are located within walking distance from the station, provides opportunities for development (see Fig. 10). 5.1.2. Category 2 stations Lagehar station is one of the earliest and historic cores of the city. This neighborhood includes the oldest railway station in the city, indicating that the area accommodates a relative percentage of commercial, civic, residential, and

other users with good access connectivity within a specific study area. Among the stations in Category 2, Leghar station tends to have the highest score in architectural and urban design. Development is ongoing, and the new development displays an integrated mixed-used development to foster a neighborhood employment center with significant regional retail and residential uses within the convenient walking distance from the train station. The existing condition of the location, building height, and different activities in the area indicate the potential of the place for improvement (see Table4). The historic railway station is built to connect Ethiopia to the capital of Djibouti. The station is the main core of the city. The architectural style of the buildings and neighborhoods is French, reflecting the nationality of the builders. The existing road section of the main arterial street accommodates the same in St. Estifanos station (see Fig. 11).

Please cite this article as: Teklemariam, E.A., Shen, Z., Determining transit nodes for potential transit-oriented development: Along the LRT corridor in Addis Ababa, Ethiopia, Frontiers of Architectural Research, https://doi.org/10.1016/j.foar.2020.03.005

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14

E.A. Teklemariam, Z. Shen

Fig. 13

Existing land use and vehicular access of Meri, Ayat, and CMC stations.

5.1.3. Category 3 stations Torhailoch station is a significant transportation hub and transfer point to the new expansion of the city where the LRT line ends. Torhailoch station is one of the most urban

development areas of Addis Ababa. The area has a high potential for housing because of the closeness to public transportation. Residential units with major governmental offices dominate the place. The street pattern prioritizes

Please cite this article as: Teklemariam, E.A., Shen, Z., Determining transit nodes for potential transit-oriented development: Along the LRT corridor in Addis Ababa, Ethiopia, Frontiers of Architectural Research, https://doi.org/10.1016/j.foar.2020.03.005

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LRT corridor in Addis Ababa, Ethiopia Table 6 Key design guidelines for TOD derived from indicators. Dimension/ Indicator

Recommended guideline

Density

-

-

-

-

-

-

-

-

-

-

-

Public space

-

-

-

-

Connection/Density intersection -

-

Pedestrian/Cyclist orientation

Table 6 (continued ) Dimension/ Indicator

Recommended guideline -

-

Diversity

15

-

-

Provide high densities to enhance transit investments Allow high-density development Allow taper densities with distance from stations “Wedding cake” density development Allow tall buildings, following the existing development of areas (set floor area ratios) Ensure comfortable walking distances between points (i.e., 800 m) Provide affordable housing options (housing typology) Intensify land uses (provide commercial uses, jobs, parks, civic centers within walking distance of the transit). Provide services within a radius of 800 m (at least six services) Avoid monotony in terms of use and appearance Avoid uniform planning regulations Create a sense of identity depending on the environment of the place Avoid long streets (break up with parks and other public spaces) Provide accessible and useable green spaces that comprise 20%e40% of neighborhoods and must be within 800 m. Include natural elements to design public spaces (rivers, fountains, green areas, trees) Make public spaces the focus of building orientation and pedestrian activity (i.e., cluster benches and sitting ledges, provide special public arts, accommodate outdoor activities, encourage water features, and discourage large setbacks) Provide large shade trees Create landmarks and gateways to development Provide small blocks to comply with the standard of walking (on an average block of 400e500 m) Provide pedestrian/cyclist-friendly streets that directly connect local destinations Avoid cul-de-sacs or dead ends Design wide sidewalks wherever possible Provide safe street crossing with long pedestrian signal timing on wide streets

-

-

-

Parking/Car movement

-

-

-

User-friendliness

-

-

-

-

Provide continuous sidewalk networks Give priority to pedestrians and cyclists when designing projects Limit cars on commercial streets Apply traffic calming devices (i.e., speed bumps, medians, low speeds, signal timing, and narrow roadways) Introduce shared bikes around transit stations Create segregated bus lanes Limit motorized traffic speed Eliminate minimum parking requirements Provide enclosed parking buildings if possible Create awareness on the need to prioritize people over motorized in the street design Ensure high-quality design of main transit stops Provide attractive, comfortable, informative, and sheltered transit stops Ensure their accessibility and safety to all users (handicapped, children, elders) Ensure modal integration (i.e., connections between buses and trains)

motor vehicles, giving discomfort to pedestrians. The major streets are dominated by government buildings, making the streets frontage inactive and not user-friendly. This node is considered to have a great potential for TOD because of its location and closeness to public transport (see Fig. 12 and Table 5). 5.1.4. Category 4 stations CMC, Meri, and Ayat stations are the modern suburbs in the eastern part of Addis Ababa. Management Institute station shares the same characteristic pattern with the three other stations, but this station includes certain services and governmental offices. When the city horizontally expands its development, new housing policies offer low-density residents to live in the outer district of the city. These neighborhoods accommodate blocks of residential units where shops, services, and institutions are located along the train line. The area is designed with a grid pattern of streets that is different from the other part of the city. The neighborhood includes a courtyard playground within the blocks designed and equipped for children’s recreation. These four stations have low TOD index values. Thus, this new expansion neighborhood needs new TOD policies and proposals. The main arterial street section of these stations is the same as that of Torhailoch station (see Fig.13).

Please cite this article as: Teklemariam, E.A., Shen, Z., Determining transit nodes for potential transit-oriented development: Along the LRT corridor in Addis Ababa, Ethiopia, Frontiers of Architectural Research, https://doi.org/10.1016/j.foar.2020.03.005

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16 Table 7

E.A. Teklemariam, Z. Shen Criteria holding the potentials for improvement of each station.

Number

Station name

Criterion with the most potential for improvement as inferred on the results

1.

Megenagna

2.

Mexico

3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14 15 16. 17. 18. 19. 20. 21. 22.

St. Estifanos Stadium Gurdshola 1 Lagehar Tegbared St. Lideta Coca-cola Lem Hotel Gurd Shola 2 St. Urael Torhailoch Bambis St. Michael Hayhulet 2 Hayhulet 1 Civil Service Management Institute Meri Ayat CMC

Density, diversity, pedestrian connectivity, connection, parking, and userfriendliness Density, diversity, pedestrian connectivity, connection, parking, and userfriendliness Density, pedestrian connectivity, transit, parking, and user-friendliness Density, pedestrian connectivity, connection, parking, and user-friendliness Density, pedestrian connectivity, connection, parking, user-friendliness Density, diversity, open space, pedestrian connectivity, parking, connection, and user-friendliness

Density, diversity, pedestrian connectivity, open spaces, parking, connection, and user-friendliness

New TOD policy starting from 400 m buffer

6. Recommendation After identifying the significant hotspot indicators, the design guidelines related to these indicators are made certain. Many discussions on TOD in academic literature to date are limited to planning and policy measurements, such as integration of land use and transit and implementation of development and control (Curtis et al., 2009). Thus, urban design issues related to TOD indicators are quite limited to date. Therefore, depending on the local nature of the environment and system of the local governance, specific principles and models of urban designs related to TOD are recommended in this article. The recommended guidelines of TOD designs are suitable for the Addis Ababa context. Moreover, depending on the dimensions identified in the TOD index and its results, design guidelines are recommended for improving specific criteria or indicators, namely, density, diversity, public space, pedestrian/cyclist orientation, car movement and parking, connection, and transit system (see Table 6). Based on the information in the web diagram and architectural and urban analysis of each station, design guidelines are recommended for improving specific indicators. For Megenagna and Mexico stations, TOD policy should improve urban density, diversity, walkability for pedestrians, parking, and the safety of transit stations. St. Estifanos station must improve commercial density, pedestrian connectivity, transit, parking, and userfriendliness of the neighborhood. TOD policy for Stadium and Gurdshola 1 stations should focus on improving urban

density, pedestrian connectivity, connection, parking, and user-friendliness of transit nodes. Gurdshola 1 should also improve the user-friendliness and access of the transit indicator. Almost all stations in Categories 2 and 3 must improve density, diversity, open space, parking, pedestrian and cyclist orientation, and user-friendliness. An improvement in the latter should mean an increase in TOD for an improved accessibility and functionality of the node. The last four stations should focus on developing new TOD areas starting within 400 m walking distance from the station. New TOD should be incorporated in these stations. Thus, a TOD index can be used to make TOD planning by comparing stations located in different parts of the city. Thus, planners and designers should focus on the detailed criteria and indicators before proposing TOD for a node (see Table 7).

7. Conclusion This article uses the approaches of quantifying TOD around existing stations of Addis Ababa through the TOD index to measure the TOD of transit stations. The 5D principles are employed to measure the development and related factors that influence ridership. The literature review provides the indicators related to the study area that are needed to measure the potential of TOD. The indicators selected for this research are density, diversity, destination accessibility, distance to transit, and design, all of which are the ideal and well-established indicators of TOD around transit stations. The result shows that only five out of 22 stations have high TOD index scores because of the existing

Please cite this article as: Teklemariam, E.A., Shen, Z., Determining transit nodes for potential transit-oriented development: Along the LRT corridor in Addis Ababa, Ethiopia, Frontiers of Architectural Research, https://doi.org/10.1016/j.foar.2020.03.005

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LRT corridor in Addis Ababa, Ethiopia characteristics of these stations. Consequently, four stations have low TOD index scores, as the existing built environment is mainly a residential neighborhood. Therefore, the E-W LRT line of Addis Ababa has a high potential for TOD because the development is along the LRT line. This article elaborates how the TOD index can be useful for planners and designers to plan TOD by comparing the existing characteristics around different transit stations. Each station should be treated according to its unique characteristics and problems to obtain the best TOD index results. The TOD index indicators cannot only improve transit nodes but also can be involved in improving Addis Ababa at large level. Therefore, the TOD index can improve development around transit stations and access to transit at various locations in the city. The index is also helpful in identifying which parts of the city have high or low scores for its development. For this significance, the methodology can make it easy for planners to inform planning, funding, and investment policies for TOD. By improving such kinds of developments around transit nodes, the TOD planning system can be further helpful in making each station more accessible, functional, and vibrant than before.

Conflict of interest The authors declare that there is no conflict of interest.

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Please cite this article as: Teklemariam, E.A., Shen, Z., Determining transit nodes for potential transit-oriented development: Along the LRT corridor in Addis Ababa, Ethiopia, Frontiers of Architectural Research, https://doi.org/10.1016/j.foar.2020.03.005