- The Basic Model Framework
- Traffic is considered at the level of individual vehicles;
- Individual vehicles' movements are simulated at every one second, according to:
- Car-following models, lane-changing models and gap-acceptance models;
- Vehicle follow fixed routes from their origins to destinations;
- 6 vehicle types are currently modelled: car, bus, guided-bus, taxi (HOV), LGV and HGV;
- Individual vehicle characteristics:
- vehicle type;
- vehicle length;
- driver's reaction time;
- minimum safety headway;
- normal and maximum acceleration;
- normal and maximum deceleration;
- desired speed as a factor of "standard" link speeds;
- acceptable gap
Public Transport Simulation
- Junctions : priority, signalised, roundabouts, signalised roundabouts, merge, and dummy;
- Links: two-way, one-way, guideway, rural two-lane roads without double-white lines (i.e. overtaking may take place on road space in the direction of opposing traffic);
- Lanes: turning restriction, access restriction (e.g. bus lane, HOV lane), lane closure partially or fully in space and time;
- Detectors: selective vehicle detector;
- Bus stops: ordinary bus stop or bus layby.
Selective Vehicle Detection and Responsive Signal Control
- PT service (bus, guided bus);
- Service routes and bus stops;
- Two types of bus stops: ordinary bus stops and bus laybys;
- Bus dwell time in response to passenger flow;
- Reserved bus lane with setbacks;
- Guideway for guided bus.
- Selective vehicle detection;
- Journey time prediction (from the detector to the stopline);
- Signal priority measures:
Automatic Speed Control
- extension of bus green signal;
- early termination of bus red signal;
- demand-dependent signal phase;
- plan selection;
- equi-saturation policy.
- "Electronic traffic calming" where only the speeds exceeding the speed limits are controlled;
- Externally-defined speed limits can vary from link to link, and even within a link to represent, say, different speed limit for a sharp bend on the road;
- Levels of driver compliance or system penetration.
Pollution and Energy Modelling
- "Congestion Metering" as proposed for Cambridge, where a charge is levied if the travel time over a certain distance (such as 0.5km) road exceeds a threshold time (such as 10 minutes);
- Variable charge levels according to the time exceeding the threshold;
- Time-based charging;
- Distance-based charging;
- (Cordon-based charging).
- Emissions from pollutant CO, NOx, and HC;
- Fuel consumption;
- Calculation takes into account of vehicles' acceleration, deceleration, idling and crusing.
- On-line animation of the traffic movements;
- Individual vehicles' space-time trajectories;
- Statistical measures of:
Link with assignment models
- queue length;
- flow and flow variation;
- delay and delay variation;
- speed and speed variation;
- pollution emission; and
- fuel consumption at regular output time interval, for each type of vehicles, each link, each route, and the whole network.
- Speed distribution (by road types in terms of speed control limits);
- Detector measures: flow, speed and speed variation.
- Link with the DRACULA day-to-day model of:
Link with SATURN: use SATURN networks and its equilibrium assignment.
- route choice;
- departure time choice; and
- drivers' network learning process from day-to-day.