When you say you want to "quantify the number of crash accidents..." That implies you want to create data where none exists. Is that what you mean? If so, Tableau cannot do that. Do you have a data set for such accidents? If so, then Tableau is a great tool to help you visualize that data.
There are many ways Tableau can help visualize accident locations over time. If you can attach a packaged workbook (twbx), we can suggest some solutions.
However, before attempting a visualization, the biggest question that must be answered is, "What is your goal?" For example, are you wanting to show problem roadways? Maybe the best location to station ambulances? Or the response time to various accident locations? Without a goal, any visualization will be an exercise in futility.