Capacities used by state highway departments

[Revive 755]

Curious to see what the values the various states use.

Arkansas
Considered congested above
* Rural two lane:  9,000 ADT
* Urban two lane:  13,000 ADT
* Four lane freeway:  50,000 VPD
* Six lane freeway:  80,000 VPD

Source:  http://www.arkansashighways.com/stip/2006_Needs_Study_Highway_Improvement_Plan.pdf (Page 19/73)

Iowa DOT
*  Seems to be capacity of two lane road:  6,000 VPD
* Two lanes plus Two Way Left Turn Lane:  15,000 to 17,500 ADT
http://www.iowadot.gov/design/dmanual/06c-06.pdf

Florida? (Not sure; see Page 50 of http://www.franklinmo.org/Highway_Department/Franklin_Co_long_range_transportationplan.pdf

Also see http://www.dot.state.fl.us/planning/systems/sm/los/pdfs/2009FDOTQLOS_Handbook.pdf

For Level of Service E:
* Two lane undivided signalized:  16,600 ADT
* Four lane undivided signalized:  33,350 ADT
* Four lane divided signalized:  35,100 ADT
* Six lane divided signalized:  52,350 ADT
* Eight lane divided signalized:  67,400

* Two lane uninterrupted undivided:  27,000
* Four lane uninterrupted divided:  75,550
* Six lane uninterrupted divided:  117,750
* Eight lane uninterrupted divided:  159,950
* Ten lane uninterrupted divided:  202,000
* Twelve lane uninterrupted divided:  244,150

[mapman]

The engineering company Kimley-Horn uses Table 8 from the 2009 FDOT QLOS Handbook to evaluate roadway capacities, even outside of Florida.

Example:  Appendix A of a traffic impact fee study in Monterey County, CA: 
http://www.tamcmonterey.org/programs/devimpfee/pdf/2008-0326_TAMC_Nexus_Study_Update.pdf

[J N Winkler]

The traditional Caltrans rule of thumb (cf. Newman's primer on highway capacity back in the 1960's) was LOS D in urban areas, and LOS B in rural areas.  Both were measured in relation to facility type, taking DHV as the volume corresponding to the thirtieth highest (most-trafficked) hour in the design year.