| What about SCOOT (Split Cycle Offset Optimization Technique)? Rob Ford wants to install this evyrwehere. That should certainly help if it's installed on Spadina.Steve: A fundamental premise of SCOOT is that there is enough capacity to go around, and SCOOT will figure out the optimal arrangement given current demand. So-called priority provided by extended green time in transit's direction of travel depends on there being spare capacity to reallocate for the transit movements. Much more fundamental to the discussion is a question of policy how an intersection should operate when it is under stress, to what degree transit moves should take precedence even if this reduces the quality of service for other traffic. This discussion has different outcomes where transit is in its own right-of-way and when it is in mixed traffic.Part of the debate on Spadina turns on locations such as Queen Street where a route running in mixed traffic crosses one running on its own right-of-way. In brief, the argument against improved Spadina priority is that this will only make conditions on Queen worse. Spadina cars would benefit at the expense of Queen cars.The infamous newspaper article about how travel on Spadina is slower than on Bathurst started this whole discussion, although it didn't allow for the different level of demand and stop service times on the two routes southbound in the AM peak (the time in question). The Spadina right-of-way, however, suffers because the general flow of traffic is managed on the cycle that suits cars. The streetcars stop for long enough that they fall out-of-cycle with the auto traffic are are more likely to be held by a high proportion of signals at cross streets. This wastes the benefit of farside stops by making the streetcars waste time waiting just to cross to their platform, with the added insult that they must let left turns go first.At locations such as Lake Shore, the east-west green time is very long in an attempt to clear traffic from connecting streets and to maintain flow in that direction. However, the transit service suffers especially when the cycle time for north-south transit moves produces delays on the order of one headway. Compounding this is the close presence of signals at Bremner, Lake Shore and Queen's Quay. The last of these is particularly tricky because most of the service turns one way or another, and this is harder to fit into a scheme where transit vehicles share green time with motorists. The intersection only works because traffic volumes are comparatively light.One reason that TTC staff is so strong in advocating the Bremner LRT alignment for the Waterfront West line (leaving aside whether it will ever be built) is that this eliminates the need to operate frequent service across the Lake Shore and Bathurst intersection, something that would require much more aggressive transit priority and allocation of green time than is now available. As long as traffic planning treats Lake Shore as a major arterial to be kept moving as fast as possible, transit will suffer.Harbourfront differs from Spadina in that streetcars can only proceed at signals on their own green time because left turns are not controlled separately as they are on Spadina. When Queen's Quay is reconfigured, this problem may disappear, although it could be offset by the increased number of signals planned for this street.That brings us to the problem that the signal scheme used in Toronto does not appear to be capable of creating green waves when a transit vehicle approaches a series of signals so that it can proceed to its next stop unhindered. Each signal is treated as a separate control system, and only when a streetcar is within a signal's local area is it detected and provided for in the priority scheme. The simplest example of this can be found westbound approaching York where a car leaving Queen's Quay station triggers a priority request for the signal at the top of the ramp, but the request for York is not initiated until after the streetcar crosses into the next block . A run straight through is rare, and usually happens when the transit phase has been triggered by an eastbound car that happens to be in just the right location.Finally, for streets that do not have transit lanes, the single biggest problem is that we use far too much space for parking, not to mention incursions for construction such as we see on King near Spadina. There is only so much capacity to go around, and we waste a lot of it. This argument is independent of whether transit is present or what technology is used.
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