begin
  # grassy borders
  rectangle grass 0 0 450 300 green green

  # horizontal road (dotted white line)
  rectangle roadH 0 112 450 75 gray gray  
  rectangle dot1 10 146 15 1 white white
  rectangle dot2 50 146 15 1 white white
  rectangle dot3 90 146 15 1 white white
  rectangle dot7 130 146 15 1 white white
  rectangle dot4 310 146 15 1 white white
  rectangle dot5 350 146 15 1 white white
  rectangle dot6 390 146 15 1 white white
  rectangle dot8 430 146 15 1 white white

  # vertical road (double yellow line)
  rectangle roadV 150 0 150 300 gray gray
  line yellowLine1 222 0 222 112 yellow
  line yellowLine2 228 0 228 112 yellow
  line yellowLine3 222 187 222 300 yellow
  line yellowLine4 228 187 228 300 yellow

  # light that controls horizontal road
  rectangle poleH 315 102 5 10 black black 
  rectangle lightH 308 65 20 37 black black
  circle redH 315 69 7 white white
  circle yellowH 315 80 7 white white
  circle greenH 315 92 7 white white

  # light the controls vertical road
  rectangle poleV 140 202 10 5 black black
  rectangle lightV 103 195 37 20 black black
  circle redV 108 201 7 white white
  circle yellowV 119 201 7 white white
  circle greenV 131 201 7 white white
end

# create some cars and let vertical traffic flow
begin
  changeParam greenV bkgrd green
  changeParam redH bkgrd red
  rectangle car1 250 250 25 37 blue blue
  rectangle car2 175 0 25 37 orange orange  
end

# create another car
begin
  rectangle car3 420 116 35 25 red red
  circle wheel31 425 138 8 black black
  circle wheel32 442 138 8 black black
  groupObject redcar 3 car3 wheel31 wheel32
end

# move the traffic
begin
  moveRelative car1 0 -61
  moveRelative car2 0 73
  moveRelative redcar -500 0
end

# change lights
changeParam greenV bkgrd white
changeParam yellowV bkgrd yellow
changeParam yellowV bkgrd white
changeParam redV bkgrd red
changeParam redH bkgrd white
changeParam greenH bkgrd green

# move the traffic again
begin
  moveRelative car1 0 -250
  moveRelative car2 0 250
end

# create more traffic
begin
  rectangle car4 460 116 35 25 cyan cyan
  circle wheel41 466 138 8 black black
  circle wheel42 483 138 8 black black
  groupObject cyancar 3 car4 wheel41 wheel42
  moveRelative cyancar -158 0
end

# change lights again
changeParam greenH bkgrd white
changeParam yellowH bkgrd yellow
changeParam yellowH bkgrd white
changeParam redH bkgrd red
changeParam redV bkgrd white
changeParam greenV bkgrd green

# create more traffic
begin 
  rectangle car5 250 250 25 37 pink pink
  moveRelative cyancar -35 0
  moveRelative car5 0 -130
end

# have accident
begin
  polygon crash5 4 245 120 268 133 268 155 245 155 pink pink
  moveRelative wheel41 -25 25
  moveRelative wheel41 -125 55
  moveRelative wheel42 10 -7
  moveRelative wheel42 10 -15
end

# create ambulance to come to the rescue
begin
  rectangle body 450 120 45 35 black white
  rectangle front 435 135 15 18 white white
  circle wheel1 456 152 10 black black
  circle wheel2 476 152 10 black black
  rectangle redline 450 140 43 2 red red
  rectangle light 455 115 8 5 white white
  groupObject ambulance 6 body front wheel1 wheel2 redline light
end

moveRelative ambulance -20 0
changeParam light bkgrd red
moveRelative ambulance -20 0
changeParam light bkgrd white
moveRelative ambulance -20 0
changeParam light bkgrd red
moveRelative ambulance -20 0
changeParam light bkgrd white
moveRelative ambulance -20 0
changeParam light bkgrd red
moveRelative ambulance -20 0
changeParam light bkgrd white
moveRelative ambulance -10 0
changeParam light bkgrd red
changeParam light bkgrd white
changeParam light bkgrd red