Air Force graduation in San Antonio TX

[Southwest Dave]

Wanted to make sure you understand i was hoping for 63mph AVERAGE not the 75 mph AVERAGE you keep refering to in both posts.

Yes, I understood.

10 hours @75mph=750 miles but if i stop 4 times for 20 minutes each time thats still 640 miles in a 10 hour period (8.5 actual driving)

With the estimate above you are hoping to average 75mph with 'on the road time' the rest of the time you are taking a rest. I just don't see any leeway for further slow downs/delays. I know you say "if I stop" but you really should take a minimum of 2 hours for breaks in a 10 hour period with one of them being for an hour. [in my opinion of course].

It's not impossible, but I guess you are hoping for the best outcome, and we are preparing you for what is considered to be the 'average' outcome based on regular members experience who have travelled millions of miles between them.

Despite all that and not getting too carried away with averages, you should make the trip in just under 20 hours in my opinion, so lets split the difference. ;-)

Good luck.

[Midwest Michael]

Wanted to make sure you understand i was hoping for 63mph AVERAGE not the 75 mph AVERAGE you keep refering to in both posts.

We completely understand that you plan to have an average cruising speed of 75 mph, and you think that will allow you to have a total overall average of 63 mph.

We're simply telling you that based on millions of miles of experience, that's simply not likely. To have an average overall speed that high, you generally have to be cruising at closer to 85 mph, and have to be very dedicated to keeping your stops short.

We've explained a couple of times why your math is faulty, and you're basically making the same mistakes that a computer program uses. Specifically your calculations continue to assume you'll be able to travel at 75 mph for every minute you are on the highway, and going straight to zero for your stops. It ignores that there are many times where your actual travel speed will be lower, pushing your average down. For example, A 20 minute stop means at least 10 minutes where you'll be moving, but be doing significantly less than your cruising speed, as you prepare to exit, slow down for the off ramp, hit a traffic light or two, etc... (not to mention that a planned 20 minute stop is many times going to become 30 minutes when you've got a van full of people.) If things go exactly as you've planned, sure you might hit 63, but thing rarely go exactly as you plan.

In any case, your travel time will be what it will be. It looks like you're set with your plan, and we certainly wish you the best.

[glc]

I don't want to beat a dead horse here, but here are some numbers from an actual trip I took a few years ago. I drove from the east side of Dallas to Lordsburg NM in one day. It was 805 miles. I got through Dallas on the freeway just after the height of morning rush hour, so the delays were very minimal. I cruised at 5 over the speed limit (verified by GPS and cruise control) all the way and hit no traffic or construction. The speed limit was 80 mph for a substantial portion of the drive, and it was 75 for the majority of the rest of the drive. The ONLY stops I made were 2 quick gas and pee stops, one pee-only stop, and a 20 minute lunch stop. It took me 13.5 hours, which works out to 59.6 mph.

You aren't going to average 63, sorry. I believe the highest speed limit you are going to encounter on your trip is 70.