as the person against the park mentioned i do agree that traffic could become a concern. i do not believe that traffic or the park in general would become an issue at night as most people take the family dog during the day, usually during the weekend very rarely during the week if at all.
exercise beyond a daily walk is very important for certain types of dogs, some breed,s should only be exercised rarely if at all especially with older dogs.
walking an older dog for the same amount of time as a younger dog can be both unhealthy