13.5.2.3 Throughput

To measure and compare field data and simulation throughputs, this guidance uses the Geoffrey E. Havers (GEH) formula. The GEH statistic is typically calculated for mainline segments and ramps. It is recommended that calibration of the model using the GEH formula is calculated to a value of 3 or lower:

where,

m = output traffic throughput volumes from the simulation model (veh/h/ln)

c = traffic throughput volumes based on field data (veh/h/ln)

Additional criteria for GEH statistics are shown in Table 13-4

and Table 13-5

.

Table 13-4: GEH Statistic Guidelines
GEH Statistics	Guidance
< 3.0	Acceptable Fit
3.0 to 5.0	Acceptable for Local Roadway Facilities
> 5.0	Unacceptable

Table 13-5: Throughput Traffic Volume (veh/h/ln) Calibration Criteria
Criteria	Acceptable Targets
GEH < 3.0	All State facility segments within the calibration area
GEH < 3.0	All points of entry and exit locations within the calibration area
GEH < 3.0	All entrance and exit ramps within the calibration area
GEH < 5.0	At least 85% of applicable local roadway segments
Sum of all segment flows within the calibration area	Within 5%

13.5.2 Acceptability Criteria