6.6 LaneChangingParameters

SimMobility ST has simple structures to save most of the parameters used in the previous models. However, these parameters are not input during runtime or simulation loading, but specified in the code.

1. General lane change parameters

For the minimum time in lane that controls high frequency of LC is set by:

<!-- H. LANE CHANGE MODEL PARAMETERS -->
<!-- H.1. Minimum time in lane -->                  
<param name="min_time_lane" value=" 3.0 #minimum time in lane (s)"/>

2. Look ahead distance parameters

The look ahead distance is used in the lane selection model and is drawn from a uniform distribution defined by (used in Section 6.2):

<!-- H.2. Look ahead distance parameters-->                                
<param name="look_ahead" value="
						400.0          #lower bound(m) 
						1500.0         #upper bound(m)
"/>

3. Lane utility model parameters

The next section of the XML configuration file defines the parameters of the lane utility model described in Section 6.4.

<!-- H.3 Lane utility Model
This model describes drivers’ choice of lane they would want to travel in. A driver chooses one of up to three alternatives: to stay in the current lane ( CL ) or to target changing either to the right lane ( RL ) or to the left lane ( LL ) -->
	<param name="lane_utility_model" value="
		 3.9443  # current lane constant
		-0.3213  # right lane constant
		-1.1683  # right most lane dummy
		 0.0     # currently unused
		 0.0633  # front vehicle speed (all lanes)
		-1.0     # bus following dummy
		 0.0058  # front vehicle spacing
		-0.2664  # heavy neighbor in lane
		-0.0088  # density in lane	
		-3.3754  # tailgate
	    	 10      # gap behind threshold for tailgate dummy (meters)
		 19      # density threshold for tailgate dummy	
		-2.3400  # one lane change required
		-4.5084  # two lane changes required
		-2.8257  # each additional lane change required
		-1.2597  # next exit, one lane change required
		-0.7239  # next exit, each additional lane changes required
		-0.3269  # distance to exit
	"/> 

4. Critical gap model parameters definition

Defines parameters of additional gap acceptance model in Section 6.5:

<!--  I. GAP MODEL PARAMETERS -->
<!--  I.1 CRITICAL GAP MODEL PARAMETERS
Once a driver has decided to change lanes, he/she will examine adjacent gaps and deem them acceptable or unacceptable for merging. Below are parameters to describe driver (critical) gap acceptance using Tomer model:
<param name="critical_gaps_param" value="
		 0.5 		# lead gap - constant
		 -0.231	# lead gap - negative speed difference
		 -2.700	# lead gap - positive speed difference
		 1.112		# lead gap - standard deviation
		 0.5 		# lag gap - constant
		 0.000  	# lag gap - negative speed difference
		 0.2 		# lag gap - positive speed difference
		 0.742		# lag gap - standard deviation
		 6.0		# max speed difference
"/>

5. Target gap model parameters

Defines the parameters values in the target gap utility model (chooseTargetGap) presented in Section 6.5:

<!--  I.2 GAP UTILITY MODEL PARAMETERS
					 const  dis2gap gap-size gap-vel	front-dummy-->
<param name="GAP_PARAM_0" value=	"-1.230,-0.482,0.224,-0.0179,2.10"/>   #back
<param name="GAP_PARAM_1" value=	" 0.000, 0.000,0.224,-0.0179,2.10"/>   #adj
<param name="GAP_PARAM_2" value=	"-0.772,-0.482,0.224,-0.0179,2.10"/>   #fwd

6. Nosing and yielding parameters

The main threshold parameters for the yielding and nosing states are defined in a specific section of the XML file (see Section 6.4):

<!--  J. NOSING AND YIELDING MODEL PARAMETERS -->
<!--  J.1. NOSING AND YIELDING THRESHOLDS -->
<param name="nosing_param" value="
		   1.0	# time horizon (second) for constant acc
		   0.5	# constant
		   0.6	# coef for number of lanes
		   0.1	# coef for time (in minutes) since tagged
		   0.2	# max prob one on ramp lane drop, incident, red LUS, etc
		   1.0  # max prob two in connection to next link
		 300.0	# max yielding time (seconds)
		 180.0	# max stuck time (seconds)
		 600.0  # max distance for nosing	
		  40.0  # min distance for nosing
"/>

The next section defines the parameters values for the nosing probability, and the reduction of reaction time during the nosing/yielding (see Section 6.4):

<!-- J.2. NOSING MODEL PARAMETERS -->
<param name="kazi_nosing_param" value="-3.159  0.313  -0.027  2.050  0.028  0.6"/>
<param name="CF_CRITICAL_TIMER_RATIO" value="0.5"/>

The next section defines the parameters values for the yielding probability (see Section 6.4):

<!-- J.2. YIELDING MODEL PARAMETERS 
<param name="LC_Yielding_Model" value="
		    0.13    # None
		    0.71    # Upto 1
		    0.13    # 2
		    0.03    # 3
"/>