A black box in your car? Some see a source of tax revenue (road repair)

On 2013-11-05, T0m $herman > wrote:
> On 11/4/2013 12:07 PM, Brent wrote:
>> On 2013-11-03, T0m $herman > wrote:
>>> On 10/28/2013 1:18 AM, Brent wrote:
>>>> Actually anything under about 4-5000 lbs is pretty much irrelevant for
>>>> road wear. Heavy trucks, etc do practically all the vehicle based wear
>>>> and tear. Everyone else subisidizes them. But yes, fuel taxes are a
>>>> decent easy measure for user fees. The government doesn't like that they
>>>> are anonymous.
>>
>>> I ran the numbers under AASHTO PAS 1993, and one 72,000 pound garbage or
>>> dump truck is equal to 7,000 to 8,000 2-ton passenger vehicles (depends
>>> on how one distributes the axle loads) in pavement fatigue damage. For
>>> pretty much any roadway pavement design, one can ignore vehicles under 8
>>> tons, as their effect disappears when rounding (generally pavements are
>>> rounded to the nearest half-inch, and base courses to the nearest inch).
>>
>>> Heavy vehicles also do significantly more damage from loads parallel to
>>> the pavement (driving/acceleration and braking forces), although
>>> powerful cars can do the same - I had to take odd lines through Turns 1
>>> and 7 at Blackhawk Farms due to the damage done by cars.
>>>
>>> Turn 1:
>>> <https://maps.google.com/?ll=42.490477,-89.117179&spn=0.000534,0.001321&t=k&z=20>
>>> Turn 7:
>>> <https://maps.google.com/?ll=42.484565,-89.117424&spn=0.000534,0.001321&t=k&z=20>
>>
>> Is it so much the power or excessive number of cycles on the exact same
>> portion of pavement at high speeds? That is drivers at the track being
>> more precise than drivers on the roads and the forces largely resulting
>> from changing direction at speed.

> The cars of a similar class will end up close to the same line in the
> corners which does not help. But a near 3000 pound car with 600+ HP,
> high quality brakes, and sticky racing slicks will put enough force to
> deform asphaltic cement concrete if the mix design is not just right.
> Certainly more lateral stress than me on my 600 pound gross weight, 30
> HP motorcycle.

What I wasn't seeing was how the power level mattered, but I do now. The
power being applied on the exit of the turn.

>> Another factor to consider, is the track's pavement may not be designed
>> for heavy trucks the way a road's pavement is, thus, not being over
>> designed for light weight cars, the cars are capable of wearing it out
>> after some defined cycle life.

> Two different things entirely - most roads suffer more from fatigue
> cracking (from tensile stresses at the bottom of the pavement) than
> horizontal stresses, except for the braking zone right before an
> intersection.

I had also thought of that, there aren't many turns on roads that can be
taken like those at the track resulting in different loading as well.
Still not sure a track would make the investment to hold up to semi
truck use though.

On 11/5/2013 1:01 PM, Brent wrote:
> On 2013-11-05, T0m $herman > wrote:
>> On 11/4/2013 12:07 PM, Brent wrote:
>>> On 2013-11-03, T0m $herman > wrote:
>>>> On 10/28/2013 1:18 AM, Brent wrote:
>>>>> Actually anything under about 4-5000 lbs is pretty much irrelevant for
>>>>> road wear. Heavy trucks, etc do practically all the vehicle based wear
>>>>> and tear. Everyone else subisidizes them. But yes, fuel taxes are a
>>>>> decent easy measure for user fees. The government doesn't like that they
>>>>> are anonymous.
>>>
>>>> I ran the numbers under AASHTO PAS 1993, and one 72,000 pound garbage or
>>>> dump truck is equal to 7,000 to 8,000 2-ton passenger vehicles (depends
>>>> on how one distributes the axle loads) in pavement fatigue damage. For
>>>> pretty much any roadway pavement design, one can ignore vehicles under 8
>>>> tons, as their effect disappears when rounding (generally pavements are
>>>> rounded to the nearest half-inch, and base courses to the nearest inch).
>>>
>>>> Heavy vehicles also do significantly more damage from loads parallel to
>>>> the pavement (driving/acceleration and braking forces), although
>>>> powerful cars can do the same - I had to take odd lines through Turns 1
>>>> and 7 at Blackhawk Farms due to the damage done by cars.
>>>>
>>>> Turn 1:
>>>> <https://maps.google.com/?ll=42.490477,-89.117179&spn=0.000534,0.001321&t=k&z=20>
>>>> Turn 7:
>>>> <https://maps.google.com/?ll=42.484565,-89.117424&spn=0.000534,0.001321&t=k&z=20>
>>>
>>> Is it so much the power or excessive number of cycles on the exact same
>>> portion of pavement at high speeds? That is drivers at the track being
>>> more precise than drivers on the roads and the forces largely resulting
>>> from changing direction at speed.
>
>> The cars of a similar class will end up close to the same line in the
>> corners which does not help. But a near 3000 pound car with 600+ HP,
>> high quality brakes, and sticky racing slicks will put enough force to
>> deform asphaltic cement concrete if the mix design is not just right.
>> Certainly more lateral stress than me on my 600 pound gross weight, 30
>> HP motorcycle.
>
> What I wasn't seeing was how the power level mattered, but I do now. The
> power being applied on the exit of the turn.
>
>>> Another factor to consider, is the track's pavement may not be designed
>>> for heavy trucks the way a road's pavement is, thus, not being over
>>> designed for light weight cars, the cars are capable of wearing it out
>>> after some defined cycle life.
>
>> Two different things entirely - most roads suffer more from fatigue
>> cracking (from tensile stresses at the bottom of the pavement) than
>> horizontal stresses, except for the braking zone right before an
>> intersection.
>
> I had also thought of that, there aren't many turns on roads that can be
> taken like those at the track resulting in different loading as well.
> Still not sure a track would make the investment to hold up to semi
> truck use though.
>
What a track needs is a mix where the aggregate particles provide enough
interlocking to minimize deformation (since the asphalt binder is a
viscous material). Or they could use Portland cement concrete, but for
some reason that is not favored.

While a similar mix is beneficial for truck traffic to prevent rutting
(Illinois had to redo hundreds of miles of overlays on Interstates back
in the early 1980's a few years after they were put down due to
excessive rutting), the thickness of the pavement along with it's
elastic modulus is key in reducing fatigue. And you are correct, that
fatigue of that type is not a concern on a race track.

--
T0m $herm@n