Solarwinds if you have the $$$$ for it. Engineer's tool edition will work for a short while it is MSDE based ( limited records) Orion if you need true robustness and long term data.

Not sure how close to exact thou cause you would have to turn up the polling. You could easily cripple your information with intervals to close together. This will cause false positives, and erratic behavior. But it does a nice job of keeping fairly accurate traffic information.