Calculate travel time on road map with semaphores
- by Ivansek
I have a road map with intersections. At intersections there are semaphores. For each semaphore I generate a red light time and green light time which are represented with syntax [R:T1, G:T2], for example:
119 185 250
A ------- B: [R:6, G:4] ------ C: [R:5, G:5] ------ D
I want to calculate a car travel time from A - D. Now I do this with this pseudo code:
function get_travel_time(semaphores_configuration)
{
time = 0;
for( i=1; i<path.length;i++)
{
prev_node = path[i-1];
next_node = path[i]);
cost = cost_between(prev_node, next_node)
time += (cost/movement_speed) // movement_speed = 50px per second
light_times = get_light_times(path[i], semaphore_configurations)
lights_cycle = get_lights_cycle(light_times) // Eg: [R,R,R,G,G,G,G], where [R:3, G:4]
lights_sum = light_times.green_time+light_times.red_light; // Lights cycle time
light = lights_cycle[cost%lights_sum];
if( light == "R" )
{
time += light_times.red_light;
}
}
return time;
}
So for distance 119 between A and B travel time is, 119/50 = 2.38s ( exactly mesaured time is between 2.5s and 2.6s), then we add time if we came at a red light when at B. If we came at a red light is calculated with lines:
lights_cycle = get_lights_cycle(light_times) // Eg: [R,R,R,G,G,G,G], where [R:3, G:4]
lights_sum = light_times.green_time+light_times.red_light
light = lights_cycle[cost%lights_sum];
if( light == "R" )
{
time += light_times.red_light;
}
This pseudo code doesn't calculate exactly the same times as they are mesaured, but the calculations are very close to them.
Any idea how I would calculate this?
