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Portland Bureau of Transportation

We keep Portland moving

Phone: 503-823-5185

Fax: 503-823-7576

1120 SW Fifth Ave, Suite 800, Portland, OR 97204

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Traffic Circles

Table 4: Typical Impacts of Traffic Circles on Emergency Vehicles

Bureau of Traffic Management
Portland Office of Transportation
City of Portland, Oregon
January 1996



Vehicle
Lowest Speed (mph) Desirable Speed
(mph)
Travel Time Delay
(seconds)
Impact Distance
(feet)
Engine 18 14 25 2.8 261
  14 30 4.3 489
  14 35 6.1 671
  14 40 8.5 814
Rescue 41 16 25 1.3 170
  16 30 2.3 301
  16 35 3.1 467
  16 40 5.1 612
Squad 1 17 25 1.2 172
  17 30 2.3 326
  17 35 3.7 501
  17 40 5.3 776
Truck 1 10 25 4.8 319
  10 30 6.4 524
  10 35 8.4 749
  10 40 10.7 1034
Truck 4 11 25 4.3 322
  11 30 6.2 549
  11 35 8.1 799
  11 40 10.3 1139
Truck 41 11 25 3.9 338
  11 30 5.2 555
  11 35 7.3 845
  11 40 9.2 1255
 
Lowest Speed: This is the lowest speed a vehicle travels when navigating around a traffic circle.
 
Desirable Speed: This is the speed a driver might wish to travel if there were no traffic circles.
 
Travel Time Delay: This is the additional time required to travel to a destination due to a traffic circle's influence.
 
Impact Distance: This is the length of street where a given vehicle cannot be driven at the desired speed because of the traffic circle's influence.