But freeways-only charges could not save the three or four billion dollars of travel time projected in the three scenarios in the Appendix and Figure 2 with a systemwide congestion-charge component, thanks to the massive, self-defeating exemption of surface streets from charges in all WSA model runs. WSA was sophisticated enough to foresee diversion from charged, crowded freeways segments to uncharged, uncrowded freeway segments. They appropriately added "balancing" charges to the uncrowded freeway segments, thereby preventing harmful diversion and keeping them uncrowded. But they did not add balancing charges to prevent harmful diversion to surface streets, and, hence, cancelled out most of the time savings from charging freeways. There were two reasons for this: WSA's model was not coded for surface streets and could not model for surface-street charges even if asked to; and the Task Force's higher-ups expressly ruled surface streets out of the model. They argued that surface streets were outside of SCAG's jurisdiction and that congestion charges on surface streets were not only technically impossible to simulate with WSA models, but also politically unthinkable.
Congestion-charge advocates on the Task Force objected to this exclusion and asked for at least an educated guess as to what would happen if surface streets were also charged. They argued that congestion charges make sense only if they are not self-cancelling; that they are no more unthinkable for surface streets than for freeways, either politically or technically; that they have been successfully used in Singapore for 20 years; and that SCAG should not act as though the public's need for knowledge of smog and congestion impacts stopped at the edge of SCAG's political jurisdiction. WSA, however, declared it impossible to make an educated guess about systemwide charge impacts without destroying their professional reputation, leaving congestion-charge advocates with three options: rely on Deakin-Harvey's estimates; make estimates of their own; or forget the whole thing.
The congestion-charge advocates chose the first two options. Under the assumptions of the Appendix, Deakin-Harvey estimated that a 15 cents/peak-hour mile charge for all roads would control $138 million worth of smog per workyear (the same as WSA's 1-cent/mile emission charge), plus $3.3 billion worth of traffic delay. Our extrapolations of WSA estimates assumed that adding the same charges to surface streets as those that WSA modeled for freeways would produce roughly the same percentage of "good" diversions (to ridesharing, offpeak hours, or trips foregone) systemwide, but not the "bad" net diversion to surface streets.
Added systems costs would not be prohibitive, maybe five cents per average trip, rather than three. Such costs are negligible compared to the dollar or so worth of time per p.m. peak-hour trip which congestion charges could save. See notes to the Appendix, Sections 4 and 5. Under these assumptions, a systemwide 15/30-cents/peak-mile congestion charge would control $136 million worth of smog (again the same as WSA's 1-cent emission charge), plus $4 billion worth of traffic delay. The optimal combination from this perspective would be what appears in Figure 2 as WE (i.e., Ward Elliott) CP3+, EM1, a 15/30-cents congestion charge for all roads, combined with a 1-cent per average mile emissions charge proportional to each vehicle's actual emission rates. This would control $374 million worth of smog per workyear, plus $4.6 billion worth of traffic delay. The strategy, after deducting systems costs, would save the average household in the Basin $714 per workyear in health, property, time, and productivity costs (Appendix, column 14). It would yield $1,094 per household in net revenue, just enough to cover all of what they paid for gas taxes, vehicle registration fees, and transit fares at 1991 rates ($1,038 per household), or, alternatively, more than half of what they were paying for property or sales taxes ($1,700-1,900 per household, calculated from the Appendix).
These estimates could and should be further refined, but both the Elliott estimates and the Deakin-Harvey estimates strongly suggest that massive savings -- several billion dollars in time benefits, along with several hundred millions in smog benefits, plus billions of dollars of extra revenues -- could be realized by an all-roads congestion charge and a 1-cent emissions charge. The same combination with freeways-only congestion charges would yield two or three times lower smog benefits and negligible net time benefits. This was not just true of projections for the year 2010; it was also true of Deakin-Harvey's baseline modeling year, 1991. See D-H's 10¢/peak mile scenario, in the Appendix. If the models and assumptions are true, the average household was losing about $700 in preventable smog and congestion costs every work year, in 1991, and has continued to do so for almost a decade of dithering over pricing policy. We shall never get it back. If these estimates are half-right, or even a tenth-right, the costs of inaction on emission, and, especially, on congestion charges have already far outweighed the costs of action. The Task Force's recommendation to "develop a strategy to implement mid- and long-term, fair and equitable region-wide congestion and emission [fees]" was a prudent, minimal acknowledgement of these costs, and should have been a significant step toward reducing them.