The following cards define the specification for a simple taxi cab trip tracking application for a mobile phone platform. This is the sort of thing we could implement easily across multiple platforms (iPhone, Android, Blackberry, Symbian, and Palm WebOS) using custom code and tools like Rhomobile's Rhodes framework.

Look at these cards from two perspectives. First, what do you think of the idea? If a lot of people like it, we might make it. Second, consider that this is typical of the detail we need before we start working with a client to begin an engagement. We would take diagrams like these, break them into small, prioritized user stories and features, then start development that same afternoon.

This is the main screen for the application.

There was a step before this next one, but it got scrapped (horray!). The user jumps right into the taxi trip tracking process. By now the GPS will know where you are, but you can also get an idea if it is having trouble by seeing if the signal is weak (reposition the phone if it looks bad). Starting the trip records the start location. The GPS gets turned off to save batteries. Towards the end of the trip the user can (optionally) turn the GPS back on to get a good fix on the location as soon as the cab has stopped. Ending the trip will record the next reliable GPS location and the time.

During the taxi trip, the user can record the taxi cab company name and the cab number. This can be augmented by one or more photographs of the taxi license information, the meter, and even the driver. They form part of the trips audit/safety file.

At the conclusion of a trip, the use can enter the start and end location names/addresses. The GPS entries can be deleted if the distance looks unreasonable (GPS does not always work).  The trip distance can be populated by the GPS data, or the use can enter the value manually.

After a trip, a user might want to go to the Trip History from the home page. This appears below. It lets the user get a quick sense of how this trip compares to other similar trips. Or it can help with trip planning in terms of time and cost.

At any time, an expense report can be emailed to a user, or an accounting person, documenting all of the trips and their cost.

This shows a number of expected features, including the standard Facebook and Twitter status updates/integration, and SMS updates. These can be used to support record keeping, keep other staff aware of plans, keep the people you are visiting up to date on your schedule, or keep a record (including photographs) of your taxi trip as a safety precaution.

This next design is all scratched out. That is important. One of the best things you can do when designing an application, or working with us to refine it, is to discover you can live with less and still achieve your objective.