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We investigate control of a non-linear process when communication and processing capabilities are limited. The sensor communicates with a controller node through an erasure channel which introduces i.i.d. packet dropouts. Processor availability for control is random and, at times, insufficient to calculate plant inputs. To make efficient use of communication and processing resources, the sensor only transmits when the plant state lies outside a bounded target set. Control calculations are triggered by the received data. If a plant state measurement is successfully received and while the processor is available for control, the algorithm recursively calculates a sequence of tentative plant inputs, which are stored in a buffer for potential future use. This safeguards for time-steps when the processor is unavailable for control. We derive sufficient conditions on system parameters for stochastic stability of the closed loop and illustrate performance gains through numerical studies.

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Many congested intersections have a heavy traffic volume on movements for which capacity is insufficient because of geometric limitations. An unconventional approach that increases the capacity of heavily congested intersections is presented: this approach opens up exit lanes for left-turn traffic dynamically with the help of an additional traffic light installed at the median opening (the presignal); this situation is referred to as exit lanes for left-turn (EFL) control. An optimization problem for EFL control was formulated as a mixed-integer nonlinear program, in which the geometric layout, main signal timing, and presignal timing were integrated. The mixed-integer nonlinear program was solved by transformation into a series of mixed-integer linear programs. The latter problem can be solved with the standard branch-and-bound technique. The results of extensive numerical analysis and VISSIM simulation showed that the EFL approach could increase intersection capacity and reduce traffic delay substantially, especially under high left-turn demand. Moreover, the EFL control can be applied to one or multiple legs simultaneously; thus the control is particularly useful for intersections with an unbalanced left demand and a degree of saturation in travel directions.

One problem in existing bus priority strategies is that while a decision is being made to grant priority at an intersection, the bus arrival time at the downstream intersections is not considered. Moreover, only strategies for late buses are discussed; the strategies for early buses are seldom studied. This research tests a different bus priority approach, coordinated and conditional bus priority (CCBP). Coordinated, signalized intersection groups are adopted as control objects. Buses are detected one or more cycles before their arrival at the first intersection of the control object. A CCBP, with two kinds of priority strategies (increasing and decreasing bus delay strategies), is proposed. A model was built to generate the optimal combination of priority strategies for intersection groups so that the real delay of buses would be close to the permitted delay defined by the bus operation system. In the field application, the CCBP approach is compared with other two options: no priority and unconditional priority. Significant reductions on bus delay deviation and bus headway deviation were achieved with the use of the CCBP approach. Application of the CCBP approach resulted in only minor increases in total average delay of motor vehicles. The results of the field application studies performed as part of this study suggested that the CCBP approach could be used to decrease bus delay deviation and enhance the reliability of bus service without significantly affecting the delay of other motor vehicles.

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