Game Maker: Studio version 1.4 was utilized to program the roundabout simulation. The

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1 Jonathan Sigel January 5 th, 2016 Methodology Materials Game Maker: Studio version 1.4 was utilized to program the roundabout simulation. The professional version of the software is needed for this project, but the additional export modules are not required. After fourth version of the simulation was completed, the code was imported into the beta version of Game Maker Studio 2. Both development environments and their respective documentation are available on yoyogames.com. The project was coded on a Surface Pro 4 laptop, but any computer operating on Windows XP will suffice. Procedure To create a solid foundation for the simulation, the program s initial forms modeled a generic roundabout. This was done to make it simpler to add and adjust features, before using traffic data to recreate Newton Square. Each of the roundabout s five versions have added functionality to increase the veracity and usability of the program, as detailed below.

2 Version One The first version of the simulation was basic, and included a small number of features. The program was designed to model two roads that intersect into one street using a simple queue model. Later versions of the program would expand the logic behind this model in order to simulate an entire roundabout. ***Figure?: The first version of the roundabout simulation. Although the preliminary model was simplified and basic, it would later be adapted and expanded to model an entire roundabout.

3 Version Two The program s second rendition added four roads intersecting to form a roundabout. Version two had the ability to model traffic entering and exiting from numerous streets, making it far superior to its predecessor. Pedestrian crosswalks were added, but were limited in function. The code was rearranged and condensed to utilize arrays, which would make future versions far easier to modify. Version Three Version three of the simulation was aimed at making the program more user-friendly. Various hot keys were added that allowed the user to have more control over the program: the simulation could now be slowed down, sped up, or reset. Nodes were placed on each section of the road that displayed more data when the mouse cursor was hovered over them, allowing an individual to have a better understanding of the flow of traffic. Data for each node included the width, length, and capacity of the section it occupied. Additionally, pedestrian crosswalks were reprogrammed to be more accurate and versatile. Previously, crosswalks could only be placed at the end of roads. In version three of the program, pedestrian crosswalks could be placed anywhere in the roundabout.

4 Version Four The nodes used in the previous iteration of the software were programmed to change color based on how full their respective section of the roundabout was. Green signified that the section was nearly empty, while red signified that the section was full or nearly full. In addition to graphical upgrades, car crashes were implemented into the simulation. Each vehicle in the roundabout has a randomized variable called risk factor. A vehicle with a great risk factor value is much more likely to get into an accident. The flow of traffic was programmed to fluctuate based on the time of day. The simulation s ability to keep track of time directly tied in with its new data exportation feature. After every twenty four hours in the simulation, the program would reset and record summary statistics to a.ini file for future data analysis. Version Five: The Current Model A major feature added in version five of the roundabout was a visual mode. Small squares representing cars travel along the roundabout s streets based on their position in the roundabout. The straight roads were animated using a highly modular marker system; markers could be placed into the roundabout at the beginning and end of straight roads, plotting the course that cars would follow. However, the circular portion of the roundabout is not compatible with the marker system, making it more difficult to edit. Future iterations of the program will include a more flexible method of displaying cars on circular roads. Other features were added to increase the accuracy of the roundabout, such as more types of car collisions. In addition to accidents caused by vehicles hitting each other, accidents caused by vehicles hitting pedestrians

5 were implemented. To account for the expanded car collision system, the data export system was upgraded to include the time that each type of accident occurred. ***Figure??: The latest version of the roundabout simulation. The most notable feature is the visual mode, which depicts vehicles moving around in the roundabout. Cars are portrayed as green, yellow, or red depending on how congested that portion of the traffic is. Future Versions Version five of the roundabout simulation depicts a generic roundabout. After making some final refinements to the visual mode and data export system, the program will be modified to imitate the Newton Square roundabout. Once the Newton Square roundabout is being accurately simulated, multiple variants it will be created. Each variant will have a minor

6 adjustment or change, to see which modification has the greatest positive impact on the flow of traffic. Possible changes include altering road widths, adjusting the dimensions of the central median, and moving pedestrian crosswalks. The data exported by each model will then be compared to determine which model of the Newton square roundabout simulation is the most effective. Statistics Being Observed In order to decide which iteration of the simulation works best, various data points generated by the simulation will be compared. These data points will include some basic things, such as the number of cars through and the number of accidents. The time of the accidents will be recorded to see if they correspond with spillback statistics. Spillback is a phenomenon that occurs in roundabouts when a car tries to advance on the road, but is unable, due to the next section of the roundabout being full. This will eventually lead to congestion in the roundabout, as cars become unable to advance. The maximum number of cars spilled back, as well as the time that the maximum spillback occurs, will be exported by the simulation.