Wayfinding is part of everyday life, and most humans are quite proficient at it. However, wayfinding is a complex activity, usually divided into several tasks or actions. Simple wayfinding, i.e., without alternatives or constraints, still requires three stages: planning, route instructions, and moving [18]. Wayfinding is an individual ability to reach a destination by a cognitive process to make connections and organize information that has been received from the physical settings from the surrounding environment to generate a cognitive map in one’s mind [19, 20]. On the other hand, spatial orientation is an awareness of one’s location in space [18]. The interaction processes between a person and physical settings of the surrounding environment occasionally occur, but significantly, they are similar to the decision-making processes. The action of the person to the physical settings that is the result of the interaction must have the purpose of an action, seeking for an opportunity, readiness of the environment, discreet planning, execution of planning and evaluation of the action [14]. Human behavior is caused by the relationship between the inner influence of the individual and the external influences that the individual perceives [21]. Passengers’ behavior and route selection involve a wayfinding system that consists of; 1) environmental information, 2) decision, and 3) behavioral action. The most important part of the wayfinding system is the decision, which is imperative in making connections of the information in mind and leads to expression in behavior [14]. There are also personal experiences, race, religion, culture, ability to evaluate the surrounding environment, ability to comprehend signs and maps, local traffic congestion, underground retail space and the characteristics of the public transport environment development [8]. Thus, the individual perception and understanding of the surrounding environment are different.

Gestalt theory stated that human perception is caused by feeling, resulting from stimuli all around that affects and generates perception without analyzing the flow of information. Humans have a multitude of sensors which are a mechanism of the five senses, which are sight (vision), hearing (audition), taste (gustation), smell (olfaction), and touch (somatosensation), the five traditionally recognized senses that send information to the brain which is the perception of feeling. Therefore, each person who perceives the same stimulus may interpret the information differently by using their existing experiences and insight self-learning results in the concept of learning or problem solving, which occurs instantly in foreseeing the way to solve a problem and understanding the interconnection of the factors of the problem [22-25]. The principle of the theory of interconnection state that the studies of human perception in real environments are important to study the visual and understanding abilities that help people to improve their perception skill. Perception of the importance attached to words or pictures in signs is often communicated by the size, position, and proximity of the sign to the visuals [26]. The two main types of communication, which are verbal communication and visual communication, are both different in their mechanisms and potential [4]. Signs and pictorial symbols have the purpose of being used and being part of the wayfinding system. The signage system is a part of the environmental design which is a system that helps to guide people in large and complex areas [27] to reach their destination using the directional graphics system. The beneficial use of signage can divide into four types which are Directional, Identifying, Informational, and Restrictive or Prohibitive, which facilitate the travel of passengers to their destinations quickly and more efficiently [28]. There are additional factors that affect the perception and understanding of signage system which is individual personality culture, social, and experience [9, 28].

This research applies multi-stage sampling. Information is divided for classification purposes according to the types of electro-powered trains for mass passenger transport in Thailand [29] (Fig. 2). It can be classified according to the service in three types:

• The Bangkok Mass Transit System (BTS) is an overground train system with a total service line of 36.9 km; the entire line is overground, and there are 34 stations in total.
• The Metropolitan Rapid Transit, Chaloem Ratchamongkhon Line (MRT) is an underground train system with a total service line of 20 km; the entire line is underground, and there are 18 stations in total.
• The Airport Rail Link is an overground train system that provides a connection to Suvarnabhumi Airport with a total service line of 28 km; the entire line is overground, and there are eight stations in total.

Fig. (2). Route diagram of Metropolitan Rapid Transit Chaloem Ratchamongkhon Line (MRT) [30].

This is based on a comparative study between travelling on the ground train and subway systems, which are different in the elements of the environment [8, 9, 15], and affect the mental picture or map [14, 18] of the passengers in memorizing the environment. Consequently, it is crucial for passengers to rely on the directional or informational signs to confirm the routes and guide them to their destination throughout the journey. The Metropolitan Rapid Transit has been selected to be the study area, Chaloem Ratchamonkhon Line (MRT). It has 18 stations in total. The distance between stations is about 1 km. It starts at Hua Lamphong Station, ends at Bang Sue Station [30].

Sampling criteria for the stations in the sample group for data collection in this research include: 1) Selection based on characteristics of physical environment and form of entries-exits, and 2) Selection based on the importance of stations, in order from the highest statistics of passengers who used the Metropolitan Rapid Transit, Chaloem Ratchamongkhon Line (MRT) [30]. The stations can be divided into four forms as summarized in Table 1.

To summarize the selection of subway stations, they were divided by their location characteristics regarding the environment and by the form of entries-exits and ordered by importance according to the amount of usage by passengers. Four principal stations were thus taken as the sample group and locations for the research; they were Silom Station (2-way exits), Sukhumvit Station (3-way exits), Huai Khwang Station (4-way exits) and Phahon Yothin Station (5-way exits). Also, a data sample from a total of 445 questionnaires from passengers was collected.

The research tools have been used to collect data in this study were postal return questionnaires. The structure of the questionnaires and variables that were used in the study consisted of two parts. They include: part (1) personal attributes data about the passengers, which are the independent variables; they include gender, age, education, profession, objective of going, frequency of going and environment; and part (2) the levels of suitability of specifying location information on directional signs, which are the dependent variables; they include signs with 1-point location, signs with 2-point locations and signs with 3-point locations. The Likert scale was used for the questionnaire what the needs of location information to help the passengers’ decision to choose the way were. Reproductions of directional signs for exits corresponding to the characteristics of each station were made in four sets. The questionnaire was pilot tested with passengers and revisions were made accordingly before the actual data was collected. (Fig. 3).

Fig. (3). Reproduction of directional signs (four sets) for passengers at each station and a 5-level measure scale (Likert scale): (a) Silom Station (2-way exits); (b) Sukhumvit Station (3-way exits); (c) Huai Khwang Station (4-way exits); (d) Phahon Yothin Station (5-way exits).

Data of this research was collected from passengers who have used the subway train service of the Metropolitan Rapid Transit, Chaloem Ratchamongkhon Line (MRT). The timeframe in which the questionnaires were handed out was rush hour in the morning (6:00 to 9:00 AM) and the evening (4:30 to 7:30 PM). Those times are when a high number of passengers use the service. Field data were collected at four subway stations: Silom Station (2-way exits), Sukhumvit Station (3-way exits), Huai Khwang Station (4-way exits) and Phahon Yothin Station (5-way exits). The questionnaires were distributed in front of the exits and passengers were informed about the objective. They took the questionnaires with them to fill out and returned them via post as shown in Fig. (4).

Fig. (4). Data collection with questionnaires in front of the entries-exits of the subway stations.

Based on the data gained from the survey and analysis of data with statistic t-test and ANOVA measures, with post hoc LSD was used to a statistical significance of .05 was determined. All statistical analyses were performed using the software package SPSS 23.0 (IBM Corp, Armonk, NY, USA) for Windows.

There are 18 stations in total on the Metropolitan Rapid Transit, Chaloem Ratchamongkhon Line. They can be divided into three forms: 1) central platform, 2) side platform, 3) stack platform. This depends on the form of stations and the topographic conditions around them. Most stations have a central platform with rail tracks on two sides of the platforms. An exception is the stack platforms of some locations which have tracks on different levels. The stations can be divided into three types. They include structures with two levels, structures with three levels and structures with four levels and a platform screen door, lifts and escalators as shown in Fig. (5).

4.1.1. Analysis of the Physical Environment of Silom Station (2-way Exits)

Silom Station is a subway station at Phra Ram 4 Road in Bangkok at the Sala Daeng Intersection. Its location is in the city centre, in the business district of Silom Road. The subway station is 30 meters wide and 156 meters long from the ground. The platform type is a stacked platform because the building location is narrow and there are several restrictions, for example, because of the water canalization, foundation piles of pedestrian bridges and buildings. The station structure consists of 4 levels: level 1 (general passenger hall, passenger ticket selling and check facilities and display of train line maps), level 2 (platform number two; it is the level where trains stop to let passengers get on and off in the direction to Lumphini Station and towards the final destination of Bang Sue Station), level 3 (a storage room for different train system tools; this level is not open for passengers) and level 4 (platform number one; it is the level where trains stop to let passengers get on and off in the direction of Sam Yan Station and towards the final destination of Hua Lamphong Station) as shown in Fig. (6a).

Fig. (5). Structures and forms of subway stations: (a) Central platform; (b) Side platform; (c) Stack platform [30].

Fig. (6). Forms of entries-exits and the physical environment of the subway stations: (a) Silom Station (2-way exits); (b) Sukhumvit Station (3-way exits); (c) Huai Khwang Station (4-way exits); (d) Phahon Yothin Station (5-way exits) [30].

Based on the specific characteristics of the physical environment of the underground stations in the field study, and to survey the travelling behavior among passengers with relation to seeing signage for choosing a way at each parting for wayfinding in subway stations, four steps of the route as below can be classified as shown in Fig. (7).

Fig. (7). The diagram steps of travelling behavior and the relationships between signage [30].

• Step 1 Exit Sign: Passengers exit from the subway trains, see the exit signs and get on the escalators to the next floor. (Fig. 8).
• Step 2 Directional Sign: From the escalators, passengers see directional signs and decide to go on certain routes towards important locations to leave the subway stations. (Fig. 9).
• Step 3 Informational Sign: In case that passenger cannot decide to go through a certain exit and need further information about directions, the informational sign can once more help them decide to go through a certain exit. (Fig. 10).
• Step 4 Confirmational Sign: Passengers receive information about the way while they are going, which is shown on confirmational signs, and are guided to exits of the different sides of the subway stations. (Fig. 11).

Fig. (8). Step 1 Exit Sign.

Fig. (9). Step 2 Directional Sign.

Fig. (10). Step 3 Informational Sign.

In the analysis of the travelling behavior among passengers that is related to seeing signage in underground stations in four steps, the types of signage for information and directions can be defined. They can be classified according to two characteristics; 1) Information signs with one-direction which are step 1 exit sign and step 4 confirmational sign. This group includes directional signs with 1-point location or with the objective to merely provide travelling information. The passengers do not need to choose a route. 2) Information signs with the multi-directions which are step 2 directional sign and step 3 informational sign. This group includes directional and informational signs for various routes. The passengers always need to choose a way.

Fig. (11). Step 4 Confirmational Sign.

In addition, another factor that is relevant for passengers, are the decision points, which are very important and essential for the way that passengers take action and as for the analysis of the environmental graphic designs in this research, the first decision point is in step 2 the directional sign; the informational sign in step 3 is the second decision point (they are used in cases in which passengers are not sure about the way and need further information for selecting a way). Therefore, the possibility to provide further information on the directions and important locations to the passengers in step 2 directional sign refers to an increase in opportunity for better decision making for their routes. See Fig. (12).

Fig. (12). Signs with information for multi-directions at present; they are located at important decision points for passengers: (a) Silom Station (2-way exits); (b) Sukhumvit Station (3-way exits); (c) Huai Khwang Station (4-way exits); (d) Phahon Yothin Station (5-way exits).

The data from the questionnaires include 445 samples of which the data collection ratios are from the similar quantity of passengers. They can be divided into the group of passengers from Silom Station (2-way exits) with 121 samples, constituting 27.2%; the group of passengers from Sukhumvit Station (3-way exits) with 109 samples, constituting 24.5%; the group of passengers from Huai Khwang Station (4-way exits), with 112 samples, constituting 25.2%; and the group of passengers from Phahon Yothin Station (5-way exits) with 103 samples, constituting 23.1%. The data showed that most were female (306 people), constituting 68.8%, followed by the male (139 people), constituting 31.2%. The sample group was aged 13-79 years (M=35.64, SD=11.59). Their educational level starting with the most common included BA (302 people; constituting 67.9%), followed by MA (103 people; constituting 23.1%), below BA (43 people; constituting 7.6%) and the least common: Ph.D. (6 people; constituting 1.3%).

The occupation that they worked in starting with the most common included: government officials/private sector employees: 368 people, constituting 82.7%, followed by pupils/students: 44 people, constituting 9.9%, trade/personal business: 18 people, constituting 4.0%, people who do housekeeping/age retirees: 15 people, constituting 3.4%. The objectives for travelling starting with the most common included: going to work: 345 people, constituting 77.5%, going for travelling/recreation: 51 people, constituting 11.5%, going because of studies: 26 people, constituting 5.8%, and the least common: going for shopping: 23 people, constituting 5.2%.

Data on frequency of travelling and using the service starting with the most common included: usage of 5-6 times/week: 156 people, constituting 35.1%, followed by usage of more than 6 times/week: 136 people, constituting 30.6%, usage of fewer than 2 times/week: 80 people, constituting 18.0%, and the least common: usage 2-4 times/week: 73 people, constituting 16.4%. A summary is shown in Table 2.

From the data on the mean values among the passengers regarding their need for location information to assist their decision making of the passenger groups at Silom Station (2-way exits), Sukhumvit Station (3-way exits) and Phahon Yothin Station (5-way exits), the mean levels of need for information in order from the highest values are as follows: signs with 3-point locations, followed by signs with 2-point locations and signs with 1-point location respectively. Passengers at Huai Khwang Station (4-way exits) are the exception. The order is different from all other groups and is as follows, starting with the highest mean values: signs with 2-point locations, followed by signs with 3-point locations and signs with 1-point location respectively (Table 3).

According to the data analysis of the mean values of the need for location information among passengers, they are overall at a high level for the signs with 3-point locations and signs with 2-point locations respectively. It shows that the passenger groups demand more information on the locations, compared with the present when there are only signs with 1-point location. This is also the basic form for providing information at all stations.

The ANOVA data analysis found that the need for specifying location information to assist the passenger’s decision making is different according to 2 factors; 1) signs with 1-point location at the significance level of p<.05=.002 and 2) signs with 3-point locations at the significance level of p<.05=.000. Meanwhile, for signs with 2-point locations, the need for location information among the respondents at all stations did not differ (Table 4).

When a paired comparative data analysis of the signs with 1-point location, the signed form that is used at present, was conducted in pairs, it was found that the passenger groups at Huai Khwang Station (4-way exits) and Phahon Yothin Station (5-way exits) had the highest mean values for the need of further location information, and they were different from the passenger groups at Silom Station (2-way exits) and Sukhumvit Station (3-way exits). Based on the comparative analysis in pairs for signs with 3-point locations, it was found that the passenger groups at Silom Station (2-way exits) had the highest need for location information and was different from all other station groups. It can be explained as follows. For the stations with little complexity of the physical environment, such as Silom Station (2-way exits), the passenger group has a need for more location information for wayfinding than that at present where there are signs with 1-point location. Further information on the locations can be added with signs with 3-point locations. However, if the location’s physical environment is more complex and the passengers have a need for further location information, the directional sign design containing a lot of venue information requires caution with regards to environmental graphic design. This is because the information that exceeds the passengers’ limit will affect the need for less location information for wayfinding. This is another important factor (Table 5).

For better understanding of the data, the researcher analyzed the relationships between the variables of the passenger group’s specific characteristics referred to as independent variables; 1) gender, 2) age, 3) education, 4) occupation, 5) objective of travelling, and 6) frequency of travelling, with variables regarding the need for location information; 1) signs with 1-point location, 2) signs with 2-point locations, and 3) signs with 3-point locations, which are the dependent variables in this research as follows.