Continued development of GPS device mapping website features and visualizations

An existing GPS device tracking website written in RoR/Javascript/Coffeescript with a MySQL backend overlaid on Google Maps needs continued enhancement and development. The architecture uses phone apps to upload GPS information to the MySQL database which can then be viewed in near realtime or played back later via the web app. There are numerous improvements needed. Performance and efficiency are of key importance - the software must be written lean to allow hundreds of tracked objects to be displayed on the map. Experience with map overlays and visualization optimization is a big advantage. Bitbucket is used for tracking issues, enhancements and code repository. There will be many specific enhancement tasks; each sub-task will be quoted individually by the developer as sub-projects. We will agree on an hourly rate and then a number of hours to complete each sub-project, or fixed-bid each sub-project (same end result). Some weeks will have more hours than others - this is a long-term project but not usually full-time work. The main website can be viewed at: [login to view URL] The tracking application can be accessed from links on that page