After conducting the interviews, we have agreed upon taking the following three design principles for our "CityWindow":

1. "Information about Transportation has the Highest Priority". From the people we have interviewed, we have found that people will first look for transportation information in such a system like “CityWindow”. This actually makes sense, because people go to underground station as they want to go different places and usually they would find transportation information most useful. The priority is done in a descending order for the following means of transportation: underground, bus and other types of transportation.

2. "The System should provide results in a very quick and efficient manner". There are two reasons for this principle. The first one is because people are usually in a hurry when they are in an Underground station. Only a few minutes delay can make the passenger wait for another one hour until the next train comes. If the user finds our system slow, and interacting with the system takes more time than the conventional system like "Train time tables", they will use the timetables instead.

One of our subjects asked, what would happen if more than one user tries to use the system at the same time. In our system, only one user can interact with the system in order to get information. By decreasing the response time of the system, we are increasing the service rate, and at the same time decreasing the waiting time for potential users.

3. "Do not put personal information on the big screen display; use as less personal data as possible". This is our last design principle. We found from our interviews, that users may not feel very comfortable if private information, such as the destination, or home address of a person is displayed on the screen. So we have decided to take this design principle. Personal information will not be shown on the display. If any personal information is required, it may be directly sent to the cell phone of the user. A big screen display placed in a public place like “CityWindow” should display information that is helpful to more than one person simultaneously. If we go too personal on a user, then the system is useful to one person only. So by not taking the system to a too personal use, we increase the chance of making it useful to many persons.

We have decided to change our design of the system in the following way:

1. At the beginning, we wanted to implement the possibility of the user to enter a specific address. The ”CityWindow” was then going to show maps of that specific location. Since this goes against our third design principle by putting personal information on screen, it will have to be modified.
2. Previously, we proposed a system of buying tickets by using a mobile phone. When the user chooses a specific destination and wants to buy a ticket, a barcode was supposed to be displayed on the big screen. The user was then going to take a picture of that barcode using his phone camera and send it to a specific phone number. As a response, the system was going to send a SMS containing a valid code, which was going to prove that the user has bought the ticket. The price of the ticket was supposed to be deducted from the cell phone account. Our interview subject pointed out that this might be too complex. Therefore we have decided to drop this option.
3. Previously, we planned to implement the game functionality in our system. Playing games usually take longer than other options and when a person is playing, he does not want to be bothered. Some other person may be waiting to use the system. So implementing games is going against our first design principle as transportation information is not getting the highest priority. Also it conflicts with the second design principle, that the system should provide results in a quick way. As a result, we have decided to drop games from our system.
4. One of the interview subject mentioned that it would be good to have a printed copy of the maps on screen. This will be especially useful for a newcomer in the city. He can make a map using different layers and than print a copy of it. We have decided to charge a high rate for printing maps. Only people who really need a copy will print it. If it was cheap, everyone might start printing a copy, and that can make another person wait longer for using the system.