It should be also noted that the research did not attempt to answer the question of how drivers change their acceptance characteristics and adapt themselves to accept shorter or large headways based on traffic levels of the circulating volume.
The midday six-minute headways are based on a combination of two Metrorail lines (Orange/Blue and Yellow/Green) as each route can run every 12 minutes; in the case of the Red Line, every other train bound for Glenmont terminates at Silver Spring instead.
We proposed a train headway adjustment model based on linear quadratic optimal control.
The follow-up headway was calculated based on various combinations of leader and follower vehicles among the vehicle types under consideration.
Several studies have documented that critical and follow-up headways might vary based on intersection geometry, vehicle type, approach grade, and traffic movements, so that more accurate estimates of these headways can be obtained based on specific conditions [18].
Open image in new window Fig. 3 Steps in longitudinal movement procedure Step 1 Value of randomisation parameter determines the probability of deceleration based on headway and speed of the subject vehicle and the brake light status of the leader.
Wu [38] also estimated the distribution function of critical headways at unsignalized intersections based on equilibrium of probabilities; thus, he presented a solution accounting for different predefined distribution functions of critical headways.
If the gap in front is less than the interaction headway, it would adjust itself based on the speed of the leader vehicle.
Since vehicles enter a roundabout using the gaps between circulating vehicles, the entry capacity is correlated to the driver gap acceptance and its estimation is based on the critical headway and the follow-up headway when the analytical (gap-acceptance) models are used to analyze roundabout operations and performances.
Open image in new window Fig. 1 Random-effect model: the forest plot showing the relative weights for critical headways at single-lane roundabouts based on Rodegerdts et al. [28]; Gazzarri et al. [36]; Zheng et al. [37]; Fortuijn [38].
The next step consists in simulating the threefold interaction between passengers and the train so as to estimate a new dwell time vector, that is ({boldsymbol{dwt}}^{{left( {i + 1} right)}}), based on the headways obtained by SeSM.
