The most heavily traveled rail lines are occupied by rolling rolling stock only 5% of the time.
For most interstate traffic, at least near most cities, it's at least twice - 3X as high.
This is particularly wasteful as the efficiencies of road vehicles are so much lower than those of rail.
Bret Cahill
What's the definition of "occupied" as applied to an interstate highway?
John
Safe following distance.
With 100% sedans packed in one lane, it comes out to 100 vehicles/ mile, each averaging 10 kW or 1 MW/mile.
Packed semi rigs would ave. 1.6 MW/mile.
A mile long train needs 24 MW and at 70 trains/day it's only 1.2 MW/ mile.
All three situations are in the same 1 - 1.6 MW ballpark as far as power/mile.
Compare grid v. grid-battery costs/mile for 100 sedans:
$100/hr to power one mile of road directly from the grid without using the battery.
$200/hr for batteries if grid-battery.
$300/hr total for grid-battery.
On a 24/7 basis that's $2.6 million/year-mile for grid-battery, 0.9 for the juice and 1.7 for the batteries.
In other words, powering vehicles directly from the road bed would save commuters $1.7 million/mile-year in battery costs.
This would be possible to finance if electrification of two lanes was less than $20 million/mile.
This doesn't necessarily mean batteries are eliminated -- something will always be necessary when off the electric road -- just that the savings from not having to constantly replace batteries justifies electrification.
Electrification of roads would certainly open up some interesting possibilities.
The real advantage of hybrid-air over hybrid electric is the _overall_ costs are much lower -- a cheap fiber wound pressure vessel can be cycled 13 gazillion times -- but there isn't any easy way to supply compressed air from the road to a moving vehicle. And the added complexity / reduced efficiency of first running grid energy through a compressor and then an expander may be an issue.
It may be better to start out with hybrid electric but no matter what happens, there must be an electric motor somewhere in the vehicle because we're just in the eye of the hurricane.
Obama seems serious about getting the economy going and when that happens fuel prices will resume spiraling.
With a vengance.
Bret Cahill
In other words, the roads are typically much more useful at trasferring people from A to B.
Graham
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