101 Worst Traffic Engineering Misteaks

Over the years, traffic engineering, the science of moving automobile traffic safely, has improved. But quite a few mistakes (or is it "misteaks" instead?) have been made. These are usually made by people without enough training. This includes politicians, who have no training at all in the subject, yet consider themselves experts solely because they were elected to office.

Note: MUTCD = US Department of Transportation Manual of Uniform Traffic Control Devices.

Here are the worst of these dillies, with the worst of the worst first:

  1. Yellow trap at traffic signals (click for more)
  2. The three-lane two-way highway with the shared center lane
  3. Using the vehicle extension interval to substitute for properly placing the detector farther from the stop line
  4. Weaving major movements across each other (Weaving is streams of traffic changing lanes across each other)
  5. Freeway entrances without acceleration lanes
  6. bike box mess Bike boxes politically please cyclists, but cause hazards when large vehicles are present (see image)
  7. Leaving a gap in a needed freeway, to please politicians or pressure groups (e.g. Breezewood PA, Trenton NJ)
  8. Multiple uses of the same lane (e.g. left turn, passing, and weaving)
  9. Traffic signal left turn arrows without any clearance periods or with hidden (invisible) clearance periods
  10. Violating the dilemma zone by allowing phases to stop timing at the first gap or to reach a short phase maximum
  11. Designing intersections that don't move traffic well (see image)
  12. Using green arrows for permissive turns
  13. Not checking approaches without left turn signals for yellow trap
  14. Green arrows turning across pedestrian crossings with walk or flashing don't walk signals
  15. Green arrows faces used for lane use control, instead of lane use signs and circular greens
  16. Carpool lanes (reduce overall capacity)
  17. Toll lanes to bypass traffic (reduce overall capacity, abet government greed)
  18. Railroad, drawbridge, or emergency vehicle preemptions that cause yellow trap
  19. Red light cameras (cause more accidents, wrongly intended to raise revenue, and remove the right to cross-examine)
  20. Movements not provided at traffic interchanges
  21. Interchange ramps too close together
  22. Traffic signal clearance interval too short
  23. Violating the dilemma zone with detectors placed too close to the stop line for the speed limit used
  24. Signs installed in the wrong place (e.g. post mounted signs intended for overhead use)
  25. Setting signal progression to favor drivers using government offices, rather than the major movements
  26. Lane drops in between other lanes going the same way
  27. Inadequate signing for which lane to use for which destination
  28. Intersections spaced too close
  29. Setting speed limits by legislation, rather than by solid engineering
  30. Setting a speed limit lower than the design speed of the road
  31. Driveways too close to intersections
  32. Bad geometry
  33. Inadequate sight distance
  34. Signs hidden behind trees, telephone poles, or other signs
  35. Insufficiently posted speed limits
  36. Substandard sign sizes
  37. Traffic control devices used wrong
  38. Restricting trucks to the same lanes that traffic must use to exit and enter the freeway
  39. Different speed limits for different kinds of vehicles on the same road
  40. Reserving a lane for passing
  41. Curves too close to intersections
  42. Using "3-WAY" supplemental plates on stop signs with one approach that does not stop
  43. Placing traffic signs to close to intersections
  44. Locating traffic signs where it is ambiguous which drivers they are meant for
  45. Using span wires to hold up limited visibility signals
  46. Allowing turns on red where left turn signals send traffic into all lanes
  47. Causing "second yellow trap" by ending a permissive turn while an opposing right turn has a green arrow or flashing yellow arrow
  48. Making intersections too small for trucks to be able to turn
  49. Refusal to use one-way streets to improve traffic flow and facilitate signal progression
  50. Using simultaneous signal synchronization with short block lengths
  51. Using yellow paint to designate a prohibition
  52. Sending unsuspecting motorists from highways onto side streets, to handle traffic leaving a concert or a sporting event
  53. Not clearly posting a detour
  54. Not posting what street a detour is for on the signs
  55. Wrongly choosing a detour route that trucks can not maneuver through
  56. No provision for directions back to a freeway for traffic sent off a freeway closed by an accident
  57. Unnecessary slowing high speed traffic by allowing schools to be built on major highways
  58. Insufficient school zone signs that do not notify drivers turning from side streets about the school zone
  59. Flashing lights on school zone signs placed where traffic on the main road can see them, but not side-road drivers
  60. Putting on-street parking on major thorofares
  61. Not providing enough shoulder to keep a disabled vehicle away from traffic lanes
  62. Making curbs too high, damaging vehicles that would otherwise be stopped without damage
  63. Requiring through traffic to change lanes to stay on the through route
  64. Making traffic lanes too narrow
  65. Not providing left turn lanes where they are needed
  66. Placing aesthetics above safety and function
  67. Not installing needed overhead signs, because government officials want to preserve a view
  68. Letting the capabilities of the detector signal cable limit the distance the detector is placed from the stop line
  69. Setting traffic controls at the request of government or nonprofit road users
  70. Protecting emergency vehicle drivers with designs that create hazards for other drivers (e.g. yellow trap)
  71. Making the traffic circulating on a traffic circle yield to entering traffic
  72. Unsafe installation of bicycle lanes and paths
  73. Mass transit systems that block other vehicles, wasting fuel
  74. Allowing mass transit vehicles to destroy signal progression by blocking vehicles or preempting signals
  75. Adjusting signal progression for mass transit, rather than for most vehicles
  76. Improper or absent preemption for railroad crossings and drawbridges near signalized intersections
  77. Failure to design to accommodate long vehicles, including double trailers
  78. Requiring highway traffic to stop for recreational trail users
  79. Requiring or allowing trees to be planted too close to the road
  80. Any ambiguous traffic sign, signal, marking, or other traffic control device
  81. Allowing utility lines to be run lengthwise under major thorofares, rather than alongside them
  82. Left turn phases on low volume approaches
  83. Giving a low-volume driveway its own exclusive signal phase
  84. Insufficient vertical and/or horizontal clearances for large vehicles
  85. Misplacing the word "only" (an adjective, not an adverb) in signs
  86. Allowing environmentalists to inject their religious beliefs (rather than facts) into traffic control
  87. Allowing citizen pressure groups or layman politicians to override MUTCD specifications or the decisions of trained engineers
  88. Concentrating on stopping traffic, rather than moving it
  89. Designing cities with additional diagonal streets
  90. Ignoring the use of evergreen trees as a sound blocking medium
  91. Expecting mass transit to handle more than 10 percent of the trips
  92. Overuse of left-turn phases, instead of considering alternatives (one-way streets or indirect turns)
  93. Parking lots marked with the wrong paint colors
  94. Traffic calming devices used to remove traffic from a politician's street
  95. Parking meters and parking time limits
  96. Speed bumps
  97. Misunderstanding the red arrow on a traffic signal, or refusing to allow its use
  98. Toll roads
  99. Signs advertising government facilities in areas with billboard bans
  100. Letting a layman traffic commission make decisions
  101. The full cloverleaf interchange, with the weaving of left turn movements