Articles

Free Web App

Download

Pocket Guide

State DOT recommendations for calibration against field observations, not universal validity limits. A dash means not specified; recommended values, defaults, and distributions are identified separately.

Guidance documents and publication years

Dates are from the document editions, not upload dates. Web guidance without a dated PDF is identified separately.

Driving behavior parameters - Wiedemann 74 (w74)

Parameter Name Default Range (VDOT 2020) Range (WisDOT 2021) Range (Oregon DOT 2011) Range (WSDOT 2014) Range (Maryland SHA 2017) Range (FDOT 2026)
AX: Average Standstill Distance 6.56 ft
2 m
3.28 - 6.56 3.28 - 9.84 N/A N/A 3.28 - 6.56 >3.28
BXadd: Additive part of safety distance 2 2.0 - 2.2 1 - 3.75 N/A N/A 2.0 - 2.2 1 - 3.5
BXmult: Multiplic. part of safety distance 3 2.8 - 3.3 2 - 4.75 N/A N/A 2.8 - 3.3 2 - 4.5

Additional state guidance - W74

ParameterDefaultIowa DOT 2017Michigan DOT 2020MoDOT web guideCDOT 2018KYTC 2021NDOT 2024
AX: Average standstill distance6.56 ft
2 m
>3.283.28 to 6.56-3.28 to 6.56Composite distributions4-
BXadd: Additive part of safety distance21 to 3.552.0 to 2.2-2.0 to 2.2--
BXmult: Multiplicative part of safety distance32 to 4.552.8 to 3.3-2.8 to 3.3--

Driving behavior parameters - Wiedemann 99 (w99)

Parameter Name Default Range (VDOT 2020) Range (WisDOT 2021) Range (Oregon DOT 2011) Range (WSDOT 2014) Range (Maryland SHA 2017) Range (FDOT 2026)
CC0: Standstill Distance 4.92 ft
1.5 m
Basic: 4.5 - 5.5
Weave/Merge/Diverge: >4.92
Basic: 4.0 - 5.5
Weave/Merge/Diverge: >4.92
Basic: 4.5 - 5.5
Weave/Merge/Diverge: >4.92
Basic: 4.5 - 5.5
Weave/Merge/Diverge: >4.92
Basic: 4.5 - 5.5
Weave/Merge/Diverge: >4.92
Basic: >4
Weave/Merge/Diverge: >4.92
CC1: Headway Time 0.9 s Basic: 0.85 - 1.05
Weave/Merge/Diverge: 0.9 - 1.5
Basic: 0.7 - 3.0
Weave/Merge/Diverge: 0.9 - 3.0
Basic: 0.85 - 1.05
Weave/Merge/Diverge: 0.9 - 1.5
Basic: 0.85 - 1.05
Weave/Merge/Diverge: 0.9 - 1.5
Basic: 0.85 - 1.05
Weave/Merge/Diverge: 0.8 - 1.5
Basic: 0.7 - 3
Weave/Merge/Diverge: 0.9 - 3
CC2: Following Variation 13.12 ft
4 m
Basic: 6.56 - 22.97
Weave/Merge/Diverge: 13.12 - 39.37
Basic: 6.56 - 22.97
Weave/Merge/Diverge: 13.12 - 39.37
Basic: 6.56 - 22.97
Weave/Merge/Diverge: 13.12 - 39.37
Basic: 6.56 - 22.97
Weave/Merge/Diverge: 13.12 - 39.37
Basic: 6.56 - 22.97
Weave/Merge/Diverge: 13.12 - 39.37*
Basic: 6.56 - 22.97
Weave/Merge/Diverge: 13.12 - 39.37
CC3: Threshold for Entering "Following" -8 Use default Use default Use default Use default Use default Use default
CC4: Negative "Following" Threshold -0.35 Use default Use default Use default Use default Use default Use default
CC5: Positive "Following" Threshold 0.35 Use default Use default Use default Use default Use default Use default
CC6: Speed Dependency of Oscillation 11.44 Use default Use default Use default Use default Use default Use default
CC7: Oscillation Acceleration 0.82 ft/s2
0.25 m/s2
Use default Use default Use default Use default Use default Use default
CC8: Standstill Acceleration 11.48 ft/s2
3.5 m/s2
Use default Use default Use default Use default Use default Use default
CC9: Acceleration at 80 km/h 4.92 ft/s2
1.5 m/s2
Use default Use default Use default Use default Use default Use default

* The Maryland guidance lists the CC2 upper value as 39.27 ft. Because the other referenced agencies list 39.37 ft, the Maryland value is most likely a typographical error; 39.37 ft is shown in the table.

Additional state guidance - W99

ParameterDefaultIowa DOT 2017Michigan DOT 2020MoDOT web guideCDOT 2018KYTC 2021NDOT 2024
CC0: Standstill distance4.92 ft
1.5 m
Basic: >4.00
Weave/merge/diverge: >4.92
Basic: 4.5 to 5.5
Merge/diverge: >4.92
Basic: 4.5 to 5.5
Weave/merge/diverge: >4.92
Basic: 4.5 to 5.5
Weave/merge/diverge: >4.92
--
CC1: Headway time0.9 sBasic: 0.7 to 3.0
Weave/merge/diverge: 0.9 to 3.0
Basic: 0.85 to 1.05
Merge/diverge: 0.90 to 1.50
Basic: 0.70 to 3.00
Weave/merge/diverge: 0.90 to 3.00
Basic: 0.85 to 1.05
Weave/merge/diverge: 0.90 to 1.50
0.7 to 1.6Overall: 0.75 to 1.30
Basic: 0.70 to 1.20
Merge/diverge: 0.75 to 1.30
Weave: 0.80 to 1.30
CC2: Following variation13.12 ft
4 m
Basic: 6.56 to 22.97
Weave/merge/diverge: 13.12 to 39.37
Basic: 6.56 to 22.97
Merge/diverge: 13.12 to 39.37
Basic: 6.56 to 22.97
Weave/merge/diverge: 13.12 to 39.37
Basic: 6.56 to 22.97
Weave/merge/diverge: 13.12 to 39.37
--
CC3 through CC7CC3: -8
CC4: -0.35
CC5: 0.35
CC6: 11.44
CC7: 0.82 ft/s2
Use defaultUse defaultUse defaultUse default--
CC8: Standstill acceleration11.48 ft/s2
3.5 m/s2
Use defaultUse defaultUse defaultUse default9.2 (recommended value)-
CC9: Acceleration at 50 mph4.92 ft/s2
1.5 m/s2
Use defaultUse defaultUse defaultUse default4.5 (recommended value)-

4 KYTC recommends three W74 standstill-distance distributions with weights 35%, 40%, and 25%: urban means 6, 9, and 11.5 ft; rural means 7, 10, and 13.5 ft. These are not a single AX min/max range. KYTC's CC8 and CC9 entries are recommended values, not ranges.

5 Iowa links the W74 parameters: BXmult = BXadd + 1.

Kentucky and Nevada caution against applying below-default CC1 values broadly. Nevada also provides a separate CC1 distribution spanning 0.50 to 2.00 s; its endpoints are not the scalar ranges above. Iowa and Nevada entries were checked against indexed PDF text; direct downloads were unavailable during review.

Utah DOT (web guidance, undated) recommends CC1 = 1.3 s as a starting value and normally retaining CC2 = 13.12 ft; these are not min/max ranges. Texas DOT (web guidance, undated) discusses CC0, CC1, CC2 and lane-change calibration without a numeric behavior-range table in the reviewed section.

Driving behavior parameters - Lane change

Recommended ranges and settings from the linked guides, for freeway and arterial lane changes. A dash means no tabulated recommended range or setting is provided for that parameter; it does not mean zero. “Field-based” means adjust to match field observations.

Parameter name Unit Range (VDOT 2020) Range (WisDOT 2021) Range (Oregon DOT 2011) Range (WSDOT 2014) Range (Maryland SHA 2017) Range (FDOT 2026)
General lane-change behavior - - Free lane selection or slow lane rule Free lane selection Free lane selection Free lane selection -
Maximum deceleration - own vehicle ft/s2 - -15 to -12 -15 to -12 -15 to -12 -15 to -12 -15 to -12
Maximum deceleration - trailing vehicle ft/s2 - -12 to -8 -12 to -8 -12 to -8 -15 to -8 -12 to -8
Deceleration-reduction distance - own vehicle ft - 100 to 250 150 to 250 150 to 250 100 to 250 m1 Freeway: >100
Arterial: >502
Deceleration-reduction distance - trailing vehicle ft - 50 to 250 150 to 250 150 to 250 100 to 250 m1
Accepted deceleration - own vehicle ft/s2 - -2.5 to -4 -2.5 to -4 -2.5 to -4 -12 to -2.5 -2.5 to -4
Accepted deceleration - trailing vehicle ft/s2 - -1.5 to -2.5 -1.5 to -2.5 -1.5 to -2.5 -12 to -1.5 -1.5 to -2.5
Waiting time before diffusion s - 99,999 60 200 200 Keep at least 60; increase only if supported by field observations
Minimum headway / clearance (front/rear) ft - 1.5 to 6 1.5 to 2 1.5 to 2 1.5 to 2 1.5 to 6
To slower lane if collision time is above s - 0 to 0.5 0 to 0.5 0 to 0.5 0 to 0.5 Use default
Safety distance reduction factor unitless - 0.1 to 1.0 0.25 to 1.00 0.25 to 1.00 0.10 to 1.0 0.1 to 0.9
Maximum deceleration for cooperative braking ft/s2 - -32.3 to -3 -8 to -15 -8 to -15 -8 to -20 -32.2 to -3
Overtake reduced speed areas - - Typically not modified Unchecked Unchecked Unchecked Field-based
Advanced merging - - Field-based - - - Checked
Vehicle routing decisions look ahead - - Typically not modified - - - -
Cooperative lane change - - Field-based - - - Checked, especially at freeway merge/diverge areas
Cooperative lane change - maximum speed difference mph - Typically not modified - - - 6.71 or field-based
Cooperative lane change - maximum collision time s - Typically not modified - - - 10.0 or field-based
Zipper merging3 - - - - - - Use default
Zipper merging - minimum speed mph - - - - - 12.43 or field-based
Zipper merging - overtaking time distribution s - - - - - 2 to 4 or field-based

Additional state guidance - Lane change

ParameterUnitIowa DOT 2017Michigan DOT 2020MoDOT web guideKYTC 2021
Maximum deceleration - own vehicleft/s2< -12-15 to -12-15 to -12-
Maximum deceleration - trailing vehicleft/s2< -8-12 to -8-12 to -8-
Deceleration-reduction distance - own vehicleftFreeway: >100
Urban: >50
150 to 250150 to 250-
Deceleration-reduction distance - trailing vehicleftFreeway: >100
Urban: >50
150 to 250150 to 250-
Accepted deceleration - own vehicleft/s2< -2.5-2.5 to -4-2.5 to -4.0-
Accepted deceleration - trailing vehicleft/s2< -0.5-1.5 to -2.5-1.5 to +2.5 (as printed)6-
Waiting time before diffusions-200 (recommended value)30 to 60-
Minimum clearance (front/rear)ft1.5 to 61.5 to 21.5 to 21.64 (use default)
To slower lane if collision time is aboves-0.0 to 0.50 to 0.5-
Safety distance reduction factorunitless0.1 to 0.90.25 to 1.000.25 to 1.00-
Maximum deceleration for cooperative brakingft/s2-32.2 to -3-8 to -15-8 to -15-
Overtake reduced speed areas-Field-basedUncheckedUnchecked-
Advanced merging---Can adjust-
Cooperative lane change-Field-based; checked in most freeway merge/diverge/weave areas-Can adjust-
Cooperative lane change - maximum speed differencemph<20---
Cooperative lane change - maximum collision times<15---
Rear correction of lateral position---Unchecked-

6 MoDOT prints a positive +2.5 ft/s2 endpoint for trailing accepted deceleration. This may be a missing minus sign; verify with MoDOT before using it.

No comparable numeric lane-change behavior range table was located in the reviewed Colorado or Nevada guides. KYTC separately recommends a connector lane-change-distance distribution; that is not deceleration-reduction distance. Iowa's one-sided limits are shown without inventing a second endpoint.

Additional sources: Iowa (October 18, 2017), Table 7-2; Michigan (August 14, 2020), Tables 1, 2, and 4; MoDOT live Engineering Policy Guide, tables 905.3.5.3.2.3.3.1 and 905.3.5.3.2.3.3.3; CDOT (July 2018), Tables 14-15; KYTC (November 2021), Tables 9-14; NDOT (December 2024), Appendix B, Table 9. CDOT's car-following ranges are adapted from Virginia guidance.

1 Deceleration-reduction distance is the distance over which maximum deceleration reduces toward accepted deceleration by 1 ft/s2. Maryland Table 3 explicitly lists 100 to 250 meters for both own and trailing vehicles; those units are preserved here.

2 FDOT Table 8-7 lists this distance by road type (freeway/arterial), without separate own/trailing-vehicle ranges. Its shared guidance is shown across both rows.

3 FDOT notes that zipper merging is available in VISSIM 2024 or later.

Sources: VDOT v2.0 (January 2020), section 5.3.3.2; WisDOT calibration settings (March 30, 2021), pages 2-3; Oregon DOT (June 2011), Table 4-3; WSDOT (September 2014), Table 3; MDOT SHA (August 2017), Table 3; FDOT (June 2026), Table 8-7. VDOT discusses lane-change calibration but does not publish a numeric lane-change range table. Negative ranges retain the order printed in each guide; values and settings require project-specific calibration.