C152 pilot reports NMAC with opposite direction C172 west of SLC at 5500 FT.

Narrative

After practicing ground reference maneuvers in the practice area just North of Grantsville; I began following the I-80 east bound for SLC; and climbing to 5500 FT MSL. If I had been thinking ahead; I would have climbed to 6000 FT MSL; having learned from experience that this is where SLC ATC was most likely to put me. Another pilot; following the same freeway west; was at approximately the same altitude. My plane flew right under his; missing by only 50-100 FT. Neither of us took evasive action. I did not see him the very last moment; due in part to the fact that I was distracted; recording SLC ATIS on my kneeboard. The other aircraft probably never saw me; since I was under this nose. Thankfully; the altimeter in my plane reads a little high; or we might have been at exactly the same altitude. Because westbound aircraft exiting the SLC I-80 Transition are hesitant to cross over the lake; much of the East-West traffic is confined to the area over the freeway. This may be caused by a tendency to avoid the lateral boundaries of SLC airspace; insufficient altitude to cross the lake safely; or simply because it's convenient to follow the freeway. Pilots inbound from; say Wendover (ENV); are often directed to descend and begin following I-80; and other simply do that on their own; to avoid the airspace. As a result; the route from the northern extents of the two mountains that surround the Tooele Valley is also congested. I don't see this as a huge problem that necessarily requires a solution; but thought I'd share a heads up. The near miss did; however; motivate me to illuminate another problem that is somewhat related; and perhaps a bit more serious. The Tooele Valley (area around TVY) is a popular practice area for many flight schools; especially for schools based in SLC. When SLC ATC directs VFR traffic into the valley; they usually order pilots to follow the I-80 Transition west at 5500 FT MSL. Similarly; most VFR pilots entering the SLC airspace from the Tooele valley are instructed to follow the I-80 east at 6000 FT MSL. This creates a narrow 'funnel area' a few miles aouthwest of the Garfield Stack; bound by mountains on one side; the Class B airspace on the other; where the potential for collision is high. Last year; while flying with my CFI; I experienced two near misses at the funnel area. On both occasions; my CFI took evasive action while uttering profanities. I'll bet if you ask other instructors about this funnel area; they too will have several tales of near misses. I believe its just a matter of time before a collision occurs here; between Eastbound and Westbound aircraft that are just entering or leaving the I-80 transition. After a typical pilot enters Tooele Valley at 5500 FT MSL; just west of the Garfield Stack; he makes a beeline to TVY for pattern work. He will remain at the field for a while; do some touch-and-goes; and then when he is finished; fly straight back towards the Garfield Stack. This creates a condition where many aircraft are flying reciprocal; head-on courses; while in a climbing attitude. Combine this pattern with the funnel effect described above; and you have significant risk of collision. The risk is magnified by the fact that; during transition between the Garfield Stack and TVY; the pilot's workload is high. Pilots entering the valley from SLC first listen to TVY AWOS; and are not usually tuned to the CTAF yet. On the flip side; pilots exiting the valley for SLC are distracted; staining to hear SLC ATIS; which is often unintelligible before the aircraft reaches the lake (due to signal obstruction from the Oauirrh Mountains). Futhermore; the returning pilot might also be recording ATIS on his kneeboard. While all this is going on; everyone is in a nose-high attitude; heading right for each other; and crossing through each other's altitudes. Again; I think it's just a matter of time before something goes horribly wrong here. I don't know what the right answer is; but if arrangements can bemade to ensure that aircraft following these two well traveled routes; on reciprocal heading; aren't transitioning each other's altitudes unless they are under ATC control; that would probably solve the problem. One option might involve extending; to the west; The east-west portion of the I-80 transition for outbound traffic; and using the northeast-southwest leg only for inbound traffic. One might also consider dropping the floor of the Bravo airspace around the funnel area and maintaining radar coverage in that area.