Editing the driving behavior parameter Lane change behavior

Diffusion time

DiffusTm: The maximum amount of time a vehicle can wait at the emergency stop distance for a necessary change of lanes. When this time is reached the vehicle is removed the network, at the same time a warning is written to the *.err file and displayed in the Messages window.

Minimum clearance (front/rear)

( MinClear): The minimum distance between two vehicles that must be available after a lane change, so that the change can take place (default value 0.5 m). A lane change during normal traffic flow might require a greater minimum distance between vehicles in order to maintain the speed-dependent safety distance.

To slower lane if collision time is above

Free driving time (FreeDrivTm): only for Slow lane rule or Fast lane rule: defines the minimum distance to a vehicle in front, in seconds, which must be present on the slower lane, so that an overtaking vehicle switches to the slower lane.

Safety distance reduction factor:

The Safety distance reduction factor (lane change) (SafeDistRedFact) is taken into account for each lane change. It concerns the following parameters:

• The safety distance of the trailing vehicle on the new lane for determining whether a lane change will be carried out
• The safety distance of the lane changer itself
• The distance to the preceding, slower lane changer

During the lane change Vissim reduces the safety distance to the value that results from the following multiplication:

Original safety distance • safety distance reduction factor

The default value of 0.6 reduces the safety distance by 40%. Once a lane change is completed, the original safety distance is taken into account again.

Maximum deceleration for cooperative braking

Maximum cooperative deceleration (CoopDecel): Specifies to what extent the trailing vehicle A is braking cooperatively, so as to allow a preceding vehicle B to change lanes into its own lane, default value -3 m/s². Thereby the following applies:

• The actual deceleration required is usually much lower, because vehicle B would not impose such a high deceleration on vehicle A, but would instead comply with the driving behavior parameter MaxDecelTrail.
• When the trailing vehicle A detects that it would have to brake more heavily than what this value indicates if the preceding vehicle B is set for lane changing, the cooperative braking stops or is not initiated.
• The higher the attribute value, the stronger the braking and greater the probability of changing lanes.
• The attribute is effective even at very low speed, when vehicles are almost at a standstill, for example, when a queue forms.
• Trailing vehicle A preferentially allows preceding vehicle B to change lanes. If the next preceding vehicle C, downstream of vehicle B, also wants to change lanes, it changes lanes, but not vehicle B. This makes it possible to change lanes in alternation (zipper merge)
• While changing lanes, the preceding vehicle B considers the factor for the reduced safety distance and the parameters of the car-following model.

During cooperative braking, a vehicle decelerates with the following values:

• 0% to a maximum of 50 % of the desired deceleration, until the vehicle in front begins to change lanes (Defining functions for acceleration, deceleration and speed)
• Between 50% of the desired deceleration and the maximum deceleration (100 %) specified in the Maximum deceleration field. Typically, the deceleration during the lane change will be considerably less than the maximum deceleration, because the preceding vehicle, which changes lanes, does not expect such a high deceleration from the trailing vehicle.

Overtake reduced speed areas

OvtRedSpeedAreas: This option is not selected by default.

•  If this option is selected, vehicles immediately upstream of a reduced speed area may perform a free lane change (Applications and driving behavior parameters of lane changing). If there is also a reduced speed area on the lane the vehicle changes to, it is accounted for.
•  If the option is not selected, vehicles never start a free lane change directly upstream of a reduced speed area. They also completely ignore the reduced speed areas on the new lane.

Advanced merging

AdvMerg: This option is selected by default in the driving behavior parameter sets in newly created networks. The option is considered for any necessary lane change towards the next connector along the route.

•  If this option is selected, more vehicles can change lanes earlier. Thus, the capacity increases and the probability, that vehicles come to a stop to wait for a gap, is reduced.

If vehicle A has to change lanes and recognizes that the neighboring vehicle in front B on the target lane has approximately the same speed or is only slightly faster (-1.0 m/s < dv < 0.1 m/s), A slows down slightly (by 0.5 m/s²) to move into the gap behind B, if the option is selected.

•  If the option is not selected, the vehicle A slows down only when it approaches the emergency stop distance.

If the vehicle A with vehicle in front C detects that a neighboring vehicle in front B wants to change to the lane of A, this option can be used so that cooperative braking of A also take place when B is downstream from C.

 If this option is not selected, vehicle A leaves the cooperation to its preceding vehicle C. In this case, C might already be too close to B, so that C overtakes B, whereby A eventually gets too close to B for cooperative braking:

Let us assume vehicle B is a neighboring vehicle in front of vehicle A. A plans to let B merge, who is meanwhile driving downstream of C (in front of vehicle A), on its own lane. In this case, vehicle A forgets that B should have been permitted to merge. Thus, vehicle A can immediately permit other vehicles to change into its lane.

 If this option is not selected, then within the next 50 m vehicle A will not brake for any other neighboring vehicle in front, also if vehicle B is downstream of the vehicle in front, C (on vehicle A’s lane).

If vehicle A wanted to allow the vehicle ahead of it on the other lane, B, to merge, but B did not change lanes and A, in the meantime, has overtaken B, this option allows vehicle A to forget that it should have let B merge. Thus, vehicle A can immediately permit other vehicles to change into his lane.

 If this option is not selected, then within the next 50 m vehicle A will not brake for any other neighboring vehicle in front, also if A has meanwhile overtaken B.

Vehicle routing decisions look ahead

VehRoutDecLookAhead:  If this option is selected, vehicles leaving the route identify new routing decisions on the same link in advance and take them into account when choosing the lane.

Cooperative lane change

CoopLnChg: If vehicle A observes that a leading vehicle B on the adjacent lane wants to change to his lane A, then vehicle A will try to change lanes itself to the next lane in order to facilitate lane changing for vehicle B. For example, vehicle A would switch from the right to the left lane when vehicle B would like to switch to the left from a merging lane to the right lane.

Vehicle A behaves during this lane change as if it would have to change lanes due to a connector at a long distance. It accepts its own Maximum deceleration and the deceleration of the trailing vehicle C on the new lane, in accordance with the parameters for the necessary lane change.

Vehicle A does not make a cooperative lane change, when the following conditions are true:

• the new lane is less appropriate for continuing its route
• if vehicle B is faster than the maximum speed difference (in the example 10.80 km/h ( =3 m/s)
• if the collision time exceeded the maximum collision time (in the example 10 seconds), and the speed of vehicle A increased by the maximum speed difference (in the example 10.80 km/h).
•  When you select Cooperative lane change, the user-defined cooperative lane change rule is activated for the respective driving behavior parameter set. For Maximum speed difference and Maximum collision time the user-defined settings are used.

•  If this option is not selected, the user-defined cooperative lane changing behavior is not active for the particular driving behavior parameter set.

• Maximum speed difference: If option Cooperative lane change has been selected, the user-defined value for the maximum possible speed difference is taken into account.
• Maximum collision time: If option  Cooperative lane change has been selected, the user-defined value for the maximum collision time is taken into account.

Rear correction of lateral position

RearCorr: If a lane change takes place at a lower speed than specified in the Maximum speed box, the vehicle's rear end moves laterally. The rear correction compensates for this movement. This causes the vehicle to be aligned to the middle of the lane at the end of the lane change, instead of at angle in the original lane. The rear correction is performed completely, even when the vehicle comes to a standstill.

A rear correction affects the capacity.

Rear correction is only performed if for the driving behavior parameter Lateral behavior the option Observe adjacent lane(s) is selected (Editing the driving behavior parameter Lateral behavior).

• Maximum speed: Speed up to which the correction of the rear end position should take place. Default value 3 km/h. Lateral correction of the rear end position is not performed for faster vehicles.
• Active during time period from: Time after the start of the lane change at which the lateral movement of the rear end position should start, default value 1.0 s.
• until: Time after the start of the lane change at which the lateral movement of the rear end position should end. The value includes 3 s for the lane change of the front end, default value 10.0.

The attributes Active during time period from and to also determine the speed at which a rear correction is performed.