CB3 wrote:
Take a look at the below link. You could easily ride from downtown over to the Katy Trail and take that out to white rock lake. Lake & trail are open and easy to ride at any speed. Definitely safest option I know of in the area. http://www.mapmyride.com/us/highland-park-tx/katy-trail-white-rock-lake-white-rock-la-route-103285253
As was already mentioned, just as a +1, this is terrible advice.
The Katy (probably the most popular running spot I know of in north TX) is full of recreational runners with their dogs and moms with their strollers, you want to know what doesn't belong on the same path? A biker over 15mph. The west side of the lake on the roads is great, on the east side you either have the same crowded path that nobody should be training on, or a bunch of roads not conducive to biking.