There have been hundreds of thousands of articles, papers and reports in tens of languages about the effects of the major cordon charging schemes of Stockholm, Singapore and London (LCC and WEZ). Surprisingly, the subject remains unexhausted.
Reports about these systems generally claim an instantaneous 10% increase in speed, a 15% decrease in air pollution, a 20% decrease in congestion, and a critical shift in public acceptance from somewhat below 50% to somewhat above. Any variability that you note is due to the lack of a single audit standard and confounding factors or assumptions that change from report to report.
However encouraging the good news, there is also some bad news. Because these cordon-class systems are new, we have not yet deployed appropriate technology. We are over-reliant on a clutter of road-side infrastructure of fixed DSRC and cameras, and we have been limited in scope – so far, we deploy in 20sqkm areas for about 200-400,000 daily car-trips.
With Google as the lazy researcher’s crutch, I worked out some rough, unaudited figures. I neglected Singapore because I could not find all the data I needed to complete the requisite calculations. Accordingly, for each of LCC, WEZ and Stockholm, after-deployment daily trip counts of 130,000, 178,000 and 329,000 meant trip-count reductions of 60,000, 72,000, and 81,000, respectively. Using average cost reports of capital and operating costs combined to estimate an annual cost for the first five years ($239M, $255M, and $91M, respectively – all figures in rough 2007 US dollars), the annual cost of servicing a daily car trip (250 trips) into each of these three cordons was $1835, $1433 and $277, respectively. (Stockholm, a peninsular island, has only a few choke points.)
Far more interesting, however, the annual cost of removing a daily car trip (250 trips) – is $3975, $3542 and $1123, respectively. Of course this is double-dipping; if a city paid to service the trips that remain in the system, the trips that moved to car-pool, bus, bike or telework are the bonus. But the whole point of this exercise is to reduce peak-hour trips, isn’t it?
I looked also at the area-costs of servicing a cordon – roughly $11M, $20M and $4M /sqkm/per annum, respectively, over the first five years.
This contrarian’s back-of-the-envelop accounting method tells us something: relatively small, equipment-heavy cordons – as any city mimicking London would create – are disastrously expensive. We should learn how to reduce the road-side infrastructure by deploying privacy-assured GPS technology rather than continuing to punish our central business districts with high-maintenance crapscapes.