GUIDANCE ASSIST VEHICLE MODULE

FIELD OF THE INVENTION

This invention was not made pursuant to any federally-sponsored research and/or development.

The present invention relates to a method and system for collection and processing of the real-time traffic data and using the data in assisting the drivers of vehicles, and the intelligent in-vehicle systems in partially or fully automated vehicles, to select a specific lane for vehicle travel on limited access highways, as well as a recommended vehicle speed.

BACKGROUND

The patent application Ser. No. 14/108,710 titled “Management Center Module for Advanced Lane Management Assist for Automated Vehicles and Conventionally Driven Vehicles” describes a process (ALMA) for improving the selection of the most appropriate freeway lane to select and a target speed for that lane. The use of data from a traffic management center TMC is a key source of information for that process. The prior patent application describes a functional architecture that includes the following modules:

- ALMAMC—ALMA Management Center Module
- SD—Static Database
- ODE—Operator Data Entry
- GAVM—Guidance Assist Vehicle Module

The prior patent application describes the overall ALMA functional architecture and provides the computational algorithms, procedures and requirements for the ALMAMC module. The prior patent application also describes the background leading to the need for ALMA and the benefits to be derived from it. Using the data output from the ALMAMC, ODE and SD, and the data structures described in the prior patent application, this patent application describes the computational algorithms, procedures and requirements for the GAVM module.

The GAVM module combines information from the ALMAMC together with information from the vehicle and the driver. It provides information on appropriate lane changes and speed commands to the vehicle. Physically it may be a separate computer based unit, or alternatively the software may be incorporated into the vehicle's Navigation and Control System. “Cloud” computation, external to the vehicle may also be employed. A typical computer-based unit may include a processor or processing system, data and information storage, an input-output system, and a user interaction system.

SUMMARY

It is an object of the present invention to achieve, provide, and facilitate:

- The collection and processing of real-time data from the ALMAMC, SD and ODE described above.
- The further processing of this data to provide the vehicle's control system or the driver with information on the most appropriate lane to select and the desired speed for that lane.

The vehicle control will be determined not only based on direct external parameters such as those provided by the vehicle sensors, but also the data collected and processed by the TMCs from its own vehicle detectors, cameras, incident reports, scheduled roadway closures and TMC operator input. Additionally, the vehicle's operator may put in some information about the vehicle's characteristics, passenger occupancy and willingness to take highways, pay tolls, and other driving preferences.

BRIEF DESCRIPTION OF THE DRAWINGS

These features, aspects and advantages of the novel Advanced Lane Management Assist for Automated Vehicles will become further understood with reference to the following description and accompanying drawings where

FIG. 1 is the block diagram representation of the ALMA Relationships;

FIG. 2 is the flowchart for the Zone and Sequence Identification Module;

FIG. 3 shows the percentage of vehicles operating at a speed which is below a speed represented by the speed limit plus the difference between the actual motorist speed and the speed limit.

DESCRIPTION

Introduction. The patent application titled “Management Center Module for Advanced Lane Management Assist for Automated Vehicles and Conventionally Driven Vehicles” describes a functional architecture for conventionally driven vehicles and for partially and fully automated vehicles to select the most appropriate freeway lane and the most appropriate speed for that lane. The architecture contains the functional module “Guidance Assist Vehicle Module”. This patent application provides the details for that module. The prior patent application also describes the emerging increased intensity in the use of traffic lane management controls by operating agencies and the need by motorists and automated vehicles for improved in-vehicle information on lane use.

Basic Functions. FIG. 1 (reproduced from the prior patent application with appropriate identification notation) provides a functional architecture and the basic data flow relationships for the entire process of transforming information developed by traffic management centers (TMCs) into information that drivers or automated vehicles may use to assist in lane selection and the development of a target speed for that lane. This patent application focuses on the details of the Guidance Assist Vehicle Module 205 (GAVM) in that figure. The basic function of the GAVM 205 is to obtain information from the ALMA Management Center 202, (ALMAMC) and combine it with information from the vehicle operator and from the vehicle itself to provide the lane guidance information. ALMA provides information to vehicles to enable them to respond to information from the freeway traffic management center in a way that is similar or superior to the way that a human driver would respond to the commands.

Inputs to the GAVM 205 from the ALMA Management Center 202 include the following:

- Lane speed and other lane based traffic parameters;
- Vehicle class. Lanes may be restricted for use by certain vehicle classes*;
- Vehicle overheight and overweight restrictions; Lane closure commands;
- Lane closure commands*;
- Permitted use of shoulders for travel*;
- Availability of required vehicle occupancy*; and
- Speed limits by lane*.

*This information may vary by time-of-day or by traffic conditions.

Information from the vehicle 101, 102 and the operator 204 includes:

- Vehicle location
- Driver aggressiveness preferences;
- Identification of desired freeway entry and exit locations
- Availability of toll tag;
- Willingness of vehicle operator to pay toll; and
- Number of passengers.

Vehicles using ALMA require a route development capability (navigation system). Using the information described above, the GAVM 205 provides information to select appropriate lanes and provide target speeds. If the GAVM 205 determines that restrictions on the freeway prevent the completion of the planned route, the GAVM 205 notifies the vehicle's navigation system that a different path is required.

Functional Architecture. FIG. 1, reproduced from patent application titled “Management Center Module for Advanced Lane Management Assist for Automated Vehicles and Conventionally Driven Vehicles” shows the principal data flow relationships among ALMA modules and the freeway traffic management center 201 and the vehicle navigation and control system 101, 102. The ALMA Vehicle Module 205 (ALMAVM) combines information from the ALMAMC 202 together with information from the vehicle navigation and control system 101, 102 and the driver 204. It provides information on appropriate lane changes and speed recommendations to the vehicle control system 102 or to the driver. Physically it may be a separate computer based unit, or alternatively the software may be incorporated into the vehicle's Navigation and Control System 101, 102. Cloud computing facilitates other physical arrangements. The prior patent application describes the relationship and function of the other modules.

The ALMA concept utilizes a data structure (physical division of the freeway into information related segments.) This data structure, consisting essentially of barrels and zones is described in detail in the prior patent application.

Data Inputs to the ALMAVM. Table 1 describes a number of the data inputs into the GAVM 205 from the functional modules in FIG. 1.

TABLE 1

ALMAVM 205 Data Inputs

DATA SOURCE

ODI
VNC

Operator
Vehicle

Data
Navigation

ALMAMC
Entry
and Control

Symbol
Parameter
202
204
101, 102

AVL
Average vehicle length
√

AVSPD
Average lane speed in
√

barrel

BARNORM
Barrel incident status
√

CURLANE
Lane vehicle is

√

currently in

Distset
Distance to begin

√

search for zone next

to exit location

EC
Exit open
√

EXZ
Zone vehicle exits

√

from path

H
Overheight restriction

√

INCZONE
Closed lane(s) in this
√

zone

LC
Lane commands
√

LFD
Lane flow direction
√

LSS
Lane control ATM

command from TMC

LVR
Lane vehicle
√

requirements

PO
Number of vehicle

√

occupants

SPPUSH
Incremental speed

√

SPTMC
Zone speed
√

TRA
Toll rate by lane
√

TTA
Set of types of toll tags

√

available to vehicle

TTU
Does driver want to

√

use toll tag for trip

VC
Vehicle class

√

VH
Vehicle height

√

VS
Vehicle speed

√

VW
Vehicle weight

√

ZC
Zone that vehicle is

√

currently in

ZE
Entry zone to path

√

ALMAVM Top Level Module and Processes. ALMA executes its processes through software modules. The in-vehicle processes are computed in the following order:

Module 1—Sequence Identification

Based on barrel and zone information from the vehicle, this module schedules the sequence of computations.

Module 2—Operator and Vehicle Constraints

The lane selection process is influenced and constrained by vehicle characteristics and vehicle operator preferences with regard to the payment of tolls. These constraints include:

- The availability of an appropriate toll tag and the operators desire to elect a toll facility
- Vehicle satisfaction of height restrictions
- Vehicle satisfaction of weight restrictions
- Vehicle satisfaction of lane use restrictions. These include adherence to the type of lane use (e.g. HOV) and satisfaction of passenger occupancy requirements

Module 3—Adjustment for Vehicle Exit

Modules 3 and 4 provide the vehicle with instructions to select the most appropriate lane. The modules identify a “target” or recommended lane to which the vehicle should move. In some cases, the vehicle will traverse the entire portion of the path from the vehicle entry point until the last zone in the barrel. In other cases, the vehicle will exit the path prior to the last zone in the barrel. Module 3 develops the guidance instructions to accommodate vehicles that will exit the freeway shortly. Module 4 develops the guidance instructions for other vehicles.

Module 4—Lane Guidance

Module 4 identifies the target lane. It first identifies allowable target lanes based on the presence of incidents, lane drops and vehicle exit requirements. Two alternative sets of lane selection rules are provided by Module 4.3.A and Module 4.3.B.

Module 4.3.A provides a simple set of rules for selecting the target lane. These rules do not consider operator speed preferences, weather and roadway alignment. Module 5 is used in conjunction with this module to select target speed.

Module 4.3.B considers vehicle operator speed preferences, weather and roadway alignment. It provides target lane and target speed. Other rule sets are possible.

Module 5—Speed Guidance for Module 4A

For the lane selected in Module 4A, a rule set for the target or recommended speed for the target lane is described. Other rule sets are possible. If the current zone lane speed for the targeted lane exceeds the speed limit for that lane, the module targets the vehicle speed as the speed limit. If the lane speed is lower than the speed limit, the targeted speed is set to the current speed plus an increment. The increment is intended to push the vehicles speed into a vehicle following condition to avoid unnecessary gaps being developed in the traffic stream.

ALMAVM Module Process Descriptions

Module 1—Sequence Identification

FIG. 2 shows the flow chart for this module. The data structures are described in the patent application titled Management Center Module For Advanced Lane Management Assist for Automated Vehicles and Conventionally Driven Vehicles.

Module 1.1 301 Inputs from Vehicle

The vehicle's mapping function must correlate the vehicle map links with the ALMA barrel and zone structure. Thus when the vehicle is in an entry zone for the ALMA controlled roadway, the vehicle must identify the entry zone and barrel to ALMA. The vehicle must continue to identify the barrel and zone to ALMA. When the calculation is performed for Zone Z (the zone that is subsequent to the zone the vehicle is currently in) the module awaits a new input from the vehicle in order to start the next computational sequence.

Module 1.2 302 Determine if Vehicle is on the Controlled Network or is in an Entry Zone for the Controlled Network

Module 1.3 303 Select the Zone for which the Guidance Computation is to be Performed

Guidance computations are to be performed for a zone (Z) that is downstream of the zone in which the vehicle is currently located (ZC). The downstream zone is identified from its position in the path set (identified as ZP in Section 4).

Module 1.4 304 Perform Calculations for Zone Z for Modules 2, 3, 4, and 5

This module transfers the sequence of computations to the modules that will develop the guidance information for Zone Z.

Module 1.5 305 Test to Determine Whether Zone Z is the Last Zone in the Barrel that the Vehicle's Path will Traverse

If the vehicle will traverse no additional zones in the barrel after Zone Z, no future computations need be performed for this barrel, and a search is instituted for an entry zone in the next barrel in the vehicle's projected route. The last zone that the vehicle will traverse in the barrel is identified as the last element in path set ZP. Note that Zone Z may also serve as an entry zone to the next barrel.

Module 1.6 306 Reset Barrel Index

If the vehicle will enter the last zone in barrel then reset the barrel index to indicate that vehicle will have left barrel after it has exited the zone (the next barrel must be re-identified by the inputs from the vehicle (Module 1.1).

Module 2 Operator and Vehicle Constraints

This module determines which lanes in a barrel may or may not be available based on the vehicles classification, characteristics, toll tag availability, and the operator's willingness to pay the toll. Barrels should be defined such that these characteristics are homogeneous throughout the barrel. Below is a representative listing of the pseudocode for these sub-modules.

Module 2 Pseudocode

‘Module 2.1 Toll Tag and Vehicle Occupancy Clearance for Lane

For L = LSTART(B) to LN

TTC(B,L) = 0

If TTL(B,L) = 0 ‘Chck for HOT lane

then if LTYPE = HOT ‘Indicates that lane is HOT

then if PO ≧ ON ‘Sufficient occupancy so toll not needed

then TTC(B,L) = 1

else ‘Check for other than HOT

If TTL = Y

and (A ε TTA) ‘A is the type of toll tag. It is tested for membership in the set

TTA

and (TTU = Y)

then TTC(B,L) =1

else if

TTL = N ‘No toll tag required

then TTC(B,L) = 1

Next L

‘Note:

TTA and TTU must be entered by vehicle operator

‘Module 2.2 Overheight Clearance for Barrel

OC(B) = 0

If VC = A then OC(B) = 1 ‘Passenger cars are exempt from check

else if VH ≦ VHL(B) then OC(B) = 1

‘Note:

VH must be entered by vehicle operator

‘Module 2.3 Overweight Clearance for Barrel

OWC(B) = 0

If VC = A then OWC(B) = 1 ‘Passenger cars are exempt from check

else if VW ≦ VWL(B) then OWC(B) = 1

‘Note:

VW must be entered by vehicle operator

‘Module 2.4 Vehicle Classification Test

For L = LSTART(B) to LN

LA(B,L) = 0

If VC = A then ‘passenger car guidance

If (LVR(L) ≠ B) and (LVR(L) ≠ C) and (LVR(L) ≠ E)

then LA(B,L) = 1

If VC = B then ‘bus guidance

If (LVR(L) ≠ A) and (LVR(L) ≠ C)

then LA(B,L) = 1

If VC = C then ‘bus guidance ‘truck guidance

If (LVR(L) ≠ A) and (LVR(L) ≠ B)

then LA(B,L) = 1

Next L

Module 2.5 Determine Allowable Lanes Based on Vehicle, Operator and Roadway Constraints

If ACT(B) =1 and Z = ZE(B) then ‘barrel is active

For L = LSTART(B) to LN

VOK(B,L) = 0

If (LOK(L) = 1) and (TTC(B,L) = 1) and (OC(B) = 1) and

(OWC(B) = 1) and (LA(B,L) =1) then VOK(B,L) = 1

Next L

Module 2.1 Toll Tag Clearance for Lane

The module checks to see that the vehicle has an appropriate toll tag if required by the lane and that the operator is willing to pay the toll.

Module 2.2 Overheight Clearance for Barrel

For vehicles other than passenger cars, the module compares vehicle height with barrel requirements.

Module 2.3 Overweight Clearance for Barrel

For vehicles other than passenger cars, the module compares vehicle weight with barrel requirements.

Module 2.4 Vehicle Classification Test

The module compares the vehicle's classification (passenger car, bus, truck) with lane restrictions that may apply.

Module 2.5 Determine Allowable Lanes Based on Vehicle, Operator and Roadway Constraints

The module combines the results of modules 2.1, 2.2, 2.3 and 2.4 to determine the lanes that may be used by the vehicle.

Module 3 Adjustment for Vehicle Exit

If the vehicle is to exit the barrel prior to the last link in the barrel, this module develops the appropriate instruction for lane guidance. Below is a representative listing of the pseudocode for this module.

Module 3 Pseudocode

Module 3 provides guidance for vehicles that exit the barrel prior to the last zone in the barrel. It activates when the vehicle is sufficiently close to the exit to require preparation to access the exit ramp.

Module 3.1 Check Exit Open

The planned exit EXZ is the zone that services the exit ramp. This zone is identified by the vehicle. Information on exits that are closed (EC(B,Z)=0) are communicated to the vehicle from the ALMAMC. They are identified as zones in the barrel that access the exit ramp.

- If EXZ not ε{EC(B)} then go to Module 3.2 ‘exit is open Else EXC=True ‘EXC is the ID for the zone servicing the exit ramp ‘Notification must be sent to the vehicle that the ramp serviced by zone EXZ is closed.

In that case, a new value for EXZ is expected from the vehicle.

Module 3.2 Check Exit Proximity

‘Check to see if vehicle is within Distset of zone servicing exit ramp. Distset is in earth arc

degrees, One degree is 0.0105 miles.

‘Compute distance between vehicle and zone serving planned exit (EXZ)

DTE = ((PELAT−VLAT)²+((PELON − VLON)*cos(VLAT))²)^0.5

If DTE > Distset then go to Module 3.3 else
‘Vehicle too far from exit to require

proximity guidance

If B = BEX then ‘Number of lanes do not change before exit

TARLANE = TAROFF(BEX,EXZ)
‘TAROFF is provided by static database. It

is the
lane in the zone that accesses the exit ramp

Else ‘ Exit is close

If TAROFF(BEX,EXZ) > 1
‘Right hand exit

then if LN(BEX) > LN(B)
Lane add before vehicle exit

then TARLANE = LN(B)
‘Vehicle will move to rightmost lane. If barrel

changes vehicle will move to rightmost lane again

else TARLANE = 1
‘Left hand exit

Module 3.3 Check Entry Zone Open

‘Module receives information on closed entry zones from ALMAMC. If the planned path uses this entry zone, it sends information to the vehicle navigation system requesting a path re-computation.

If ZE=ε{ZEX(B)} then EN=1 else EN=0

‘If EN=1 then planned entry zone is closed. Send signal to vehicle navigation module indicating that a route re-computation is required.

Module 3.1 Check Exit Open

Checks to see whether the exit ramp has been closed for any reason.

Module 3.2 Check Exit Proximity

Determines whether the vehicle is sufficiently close to the planned exit ramp to warrant guidance to access the ramp. If sufficiently close, guidance to reach the lane servicing the exit ramp is provided. The test distance (Distset) may be set by the operator.

Module 3.3 Check Entry Zone Open

Checks to see if entry zone is open

Module 4 Identify Allowable Target Lanes and Select Guidance Algorithm

Module 4 provides guidance for vehicles that are not located at a short distance from an exit which is before the end of the barrel. It provides guidance under various conditions that include the presence or absence of lane closure incidents, lane speed and whether or not speed limits are automatically enforced. Below is a representative listing of the pseudocode.

Module 4 Pseudocode

Module 4 provides guidance for vehicles that are not located at a short distance from and exit which is before the end of the barrel.

Module 4.1 Identify Allowable Target Lanes and Select Guidance Algorithm

‘Identify allowable target lanes based on no incident

For L = LSTART(B) to LN

For Z = ZE to ZU

If (VOK(B,L) =1) and(LSS(B,L,Z) = A

then LOTV(B,Z,L) =1

else LOTV(B,Z,L) = 0

Next Z

Next L

If the vehicle is in the last zone of the barrel and is not exiting here and the first zone of the

downstream barrel has a right lane drop and the vehicle is in the lane to be dropped the provide

guidance to move the vehicle.

If LN(B+1) = LN(B) −1 ‘Lane drop in next barrel

and ZC = LZ(B) ‘Vehicle is in the last zone

and ZC<> EXZ ‘Vehicle doesn‘t exit in this zone

and CURLANE = LN ‘Vehicle is in the right lane

then TARLANE(B+1,1) = LN(B+1) ‘Moves vehicle to right lane in first zone in next

barrel

‘Select guidance algorithm

‘BARNORM is barrel state (normal or incident) as obtained from ALMAMC. If any lane in a

barrel is not fully open (down arrow), BARNORM(B) = 1. This information is transmitted from

the ATMAMC to the vehicle.

If BARNORM(B) = 0 then go to Module 4.3 else go to Module 4.2

Module 4.2 Guidance Under Incident Conditions

‘If a lane in a barrel is not fully open and if the vehicle is upstream of the closure point the

strategy is to provide directions to the vehicle to comply with the lane control signals.

If LSS(B,Z,CURLANE) =E then LC(B,Z,CURLANE) = E ‘Vehicle must change lane at earliest

possible time

else if LSS(B,Z,CURLANE) =D then LC(B,Z,CURLANE) = D Vehicle must change

lane at
earliest possible time

else if LSS(B,ZCURLANE,) =A then LC(B,Z,CURLANE) = A ‘Vehicle may

continue in lane

else LC(B,Z,CURLANE) = H ‘vehicle must stop prior to entry into

Zone Z

‘In the absence of lane control indications by the traffic management center, the ATMAMC will

set LSS(B,Z,CURLANE) = A

Module 4.3A Normal Guidance (Speed Stays within Speed Limit)

‘Find average speed of lanes in anticipated vehicle route

For L = LSTART(B) to LN

For Z = ZE to EXZ

SUMSPD(Z,L) = 0

SUMSPD(Z,L) = SUMSPD(Z,L) + SPTMC(B,Z,L) + ‘SPTMC(B,Z,L) from

ATMAMC

Next Z

AVSPD(B,L) = SUMSPD(Z,L)/LN

Next L

‘Identify acceptable lanes above speed limit

{LNASL} = {} ‘{LNASL}is the set of lanes above the speed limit {}is an empty set

For L = LSTART to LN

LACC(B,L) = 0

If (LOK(B,L) =1) and (AVSPD(L)) > SL(B,L)) then LACC(B,L) = 1

{LNASL} = {LNASL} + L ‘L is an element added to {LNASL}

‘LACC(B,L) = 0 represents lanes with vehicles below speed limit - use Module 4.4

Next L

‘If there is no acceptable lane above the speed limit, go to Module 4.4

ACCTEST = 0

For L = LSTART to LN

If LACC(B,L) = 1 then ACCTEST = 1

Next L

If ACCTEST = 0 then go to Module 4.4 else do
‘TARLANE is the recommended lane.

Vehicle may move when convenient

If OPT = 2 then Go to Module 4.3R else continue

‘Find target lane as the allowable lane with the lowest difference between the lane speed and the

lane speed limit above speed limit

TARLANE = −1

For each element E in {NASL} do

Begin

SPDTEST = 100 ‘Seed value

SPDDIF = AVSPD(B,L) − SL(B, E ε NASL) ,

If SPDDIF < SPDTEST then

Begin

TARLANE(B) = E ε C NASL

SPDTEST = SPDDIF

End ‘If SPDDIF

End ‘For each

Module 4.3R Guidance with Driver Attitude Input

This module describes the functionality for achieving this when the vehicle may change only one lane at a time. The lateral control system should be provided with a request to change lanes when traffic flow is relatively unconstrained and when the following conditions are satisfied:

- 1. The vehicle is following another vehicle and the following vehicle's driver desires to achieve a faster target speed (Module 4.3R.1).
- 2. Adjust the vehicle's speed to a stable following condition (Module 4.3R.2)
- 3. Determine whether the change to another lane will probably result in the achievement of a speed that is closer to the target speed by a meaningful amount. Select the appropriate lane (Module 4.3R.3)
- 4. If condition 3 is true, determine whether the target lane is likely to have a gap that is acceptable for vehicle merge purposes. If so, request a lane change (module 4.3R.4).

Module 4.3R.1 Develop Target Speed

‘Switch to Module 4.5 if speed limits are automatically enforced

If AUTOENF(B)=1 then go to Module 4.3A

else ‘No automatic speed enforcement

Module 4.3R.1 develops a target speed (TARSPD) as follows:

TARSPD=TS1(AGR)*WE(B)*RWA*DN

Values for the variables may be developed as follows:

TS1(AGR) Baseline Speed Based on Driver Aggressiveness Factor

TS1 is the base desired speed (desired speed with fair weather, a favorable roadway alignment and daytime visibility conditions),

FIG. 3 plots data from Ahmed (Ahmed, K. I., Modeling Drivers' Acceleration and Lane Changing Behavior, Doctoral Thesis, MIT, February 1999) showing the fraction of drivers that drive above the speed limit as a function of the driving speed relative to the speed limit. This figure essentially provides the basis for identifying a target speed based on the aggressiveness of the driver. Table 4.3-1 shows representative values for TS1 and was constructed using this data.

TABLE 4.3-1

Driver Aggressiveness Level

Aggressiveness
Cumulative
TS1(AGR)

Aggressiveness
Level
probability
MPH above

Descriptor
(AGR)
Level
Speed Limit

Aggressive
1
90%
+7.5

Mildly Aggressive
2
75%
+5.0

Average
3
55%
+3.0

Mildly Conservative
4
25%
0

Conservative
5
10%
−3.0

WE(B) Weather Factor

This factor describes the fraction of fair weather speed that is usually achieved when inclement weather is encountered. An example of the factors that may be employed is provided in Table 4.3-2 (Chin, S. M., Franzese, O., Green, D. L., and H. L. Hwang, Temporary Loss of Highway Capacity and Impacts on Performance, Oak Ridge National Laboratory, November, 2004.)

TABLE 4.3-2

Reduction in Speed and Capacity

Highway type

Weather
Urban freeway
Rural freeway
Urban arterial
Rural arterial

condition
Capacity
Speed
Capacity
Speed
Capacity
Speed
Capacity
Speed

Liht rain
4%
10%
4%
10%
6%
10%
6%
10%

Heav rain
8%
16%
10%
25%
6%
10%
6%
10%

Light snow
7.5%
15%
7.5%
15%
11%
13%
11%
13%

Heavy snow
27.5%
38%
27.5%
38%
18%
25%
18%
25%

Fog
6%
13%
6%
13%
6%
13%
6%
13%

Ice
27.5%
38%
27.5%
38%
18%
25%
18%
25%

It is not recommended that this factor be applied to short roadway sections, but rather to reflect general conditions in a longer roadway section such as a barrel.

RWA(B) Roadway Alignment Factor

This factor provides an adjustment for target speed reduction when design characteristics for major sections of the roadway (such as a barrel) that feature characteristics that are below interstate standards. These characteristics may include lane width below 12 feet, lack of paved shoulders and tighter horizontal alignments. Estimates of the operating speed for roadway sections with substandard alignments are provided by Table 4.3-3 (University of Southern Queensland on line 07/02/13 http://www.usq.edu.au/course/material/SVY2301/CIV2701/Lectures/Lectures%207-%20CIV2701-%20Design%20Factors%20-%20Speed.pdf)

TABLE 4.3-3

Operating Speeds with Substandard Alignment

Range of

Section

Radii in
Single Curve
Operating

Section
Section Radius
Speed

(m)
(m)
(km/h)

45-65
55
50

50-70
60
52

55-75
65
54

60-85
70
56

70-90
80
58

75-100
85
60

80-105
95
62

85-115
100
64

90-125
110
66

100-140
120
68

105-150
130
71

110-170
140
73

120-190
160
75

130-215
175
77

145-240
190
79

160-260
210
82

180-285
235
84

200-310
260
86

225-335
280
89

245-360
305
91

270-390
330
93

295-415
355
96

320-445
385
98

350-475
410
100

370-500
440
103

400-530
465
105

425-560
490
106

450-585
520
107

480-610
545
108

500-640
570
109

530+
600
110

DN Nighttime Factor

This factor provides for the situation where roadways may experience speed reduction under darkness conditions.

Module 4.3R.2—Select Lane to Consider for Transfer

The average distance between freeway lane changes is approximately 2.8 miles (Lee, S. E, Olsen, E. C. B. and W. W. Wierwille, A Comprehensive Examination of Naturalistic lane Changes, USDOT Report No. DOT HS 809702), March 2004). The objective of the module is to identify lane changes that will lengthen this distance (saving fuel, reducing crashes and providing a smoother ride) while still maintaining the driver's preferences.

The module identifies candidate lanes in which to merge, compares the current speed with the speed ahead in the candidate lanes and recommends the lane to consider further. Sub-module descriptions are provided below.

Module 4.3R.2.1 Comparison of Vehicle Speed to Target Speed

If the current vehicle speed is within an acceptable threshold relative to the target speed no further action is required. Otherwise the Module 4.3R.2 module processes will continue.

Module 4.3R.2.2 Delay Action

Vehicle is traveling at an acceptable speed, take no further action for a period equal to T1, then return to Module 4.3R.1.

Module 4.3R.2.3 Test for Stable Following

Module 4.3R.2 is based on the assumption that the vehicle is following a preceding vehicle with a speed difference that does not vary by more than a preset threshold. Otherwise the gap relative to the preceding vehicle is changing and following is not stable. It is assumed that the vehicle's ACC will provide the difference in the vehicle's speed and the speed of the preceding vehicle (SPPRE). Two tests, at time differences of T2 seconds will be required. Each will be required to show a SPDIF within STTH5 before the remainder of the module is executed.

If SPPRE(T) and SPPRE(T+T2)<|STTH5| then SF=True else SF=False

If SF=True then go to Module 4.3R.2.5 else goto Module 4.3R.2.4

Module 4.3R.2.4 Delay Action

If following is not stable, the driver or ACC must take action to provide stable following before lane changing criteria can be further tested.

Module 4.3R.2.5 Number of Look-Ahead Zones

Zone lengths vary. To provide a basis for examining the region ahead of the vehicle a conversion between the desired look-ahead distance and the number of zones required to achieve this distance must be developed and rounded. This module computes the number of look-ahead zones required to approximately satisfy the desired look-ahead distance DLA.

‘Find last look ahead zone (ZLA) based on current zone (Z6). ZLA may temporarily exceed number of zones in barrel (will be corrected later)

ZLA=ZC+1

While LAD<DLA do

Begin

LAD=LAD+LEN(ZLA+1)

Next ZLA

End

End ‘While

‘Select last zone for look-ahead computation

If ZLA>ZL(B) then LASTZONE(B+1)=ZLA−ZL(B) else LASTZONE(B)=ZLA(B)

Module 4.3R.2.6 Look-Ahead Speed using Current Zone Speeds

A length weighed average of zone speeds is computed for the look-ahead distance according to the following expression:

$Look ahead speed for each lane = \frac{Σ_{Z + 1}^{Last zone} Zone speed * zone length}{Σ_{Z + 1}^{Last zone} Zone length}$

The algorithm is as follows:

SPLEN =0

LENSUM =0

For L = 1 to LN

For ZZ = Z + 1 to LASTZONE

SPLEN = SPTMC(B,ZZ,L) * ZLEN(B,ZZ)

LENSUM = ZLEN(B,ZZ)

Next ZZ

ZWAS(L) = SPLEN/LENSUM

Next L

Module 4.3R.2.7 Identify Speed for Adjacent Lanes

‘CURLANE obtained from vehicle

‘Algorithm is based on no use of shoulders as a travel lane. Must be altered if this is not the

case.

If CURLANE =1 then LAL = X else if CURLANE − 1 not an opposite flow lane then LAL =

CURLANE −1 else LAL = X
‘Identifies left look-ahead lane

If LAL ≠ X then SLAL = ZWAS(LAL)
‘ Speed for left look-ahead lane

If CURLANE = LN then RAL = X else if CURLANE − 1 not an opposite flow lane then RAL =

CURLANE + 1 else RAL = X
‘Identifies right look-ahead lane

If RAL ≠ X then SRAL = ZWAS(RAL)
‘ Speed for right look-ahead lane

Module 4.3R.2.10 Establish Criteria for Lane Change

To this point, it has been determined that the vehicle is not close to the desired speed, look-ahead zones have been established and look-ahead speeds have been developed for these zones. This module establishes the criteria for determining whether a lane change is worthwhile. This criteria could be the subject of future research, therefore this module has been established as a placeholder for the results of such research.

The current criterion is the establishment of a threshold STH4 defined as the speed improvement in look-ahead speeds required to justify the move to an adjacent lane.

Module 4.3R.2.11 Select Lane for Merge Consideration

The module tests look-ahead speeds in the current lane and lanes to the left and right of current lane relative to the desired speed. The module selects the highest speed lane that does not exceed the desired speed, provided the speed difference exceeds a threshold STH4.

If (SLAL − ZWAS(L)) > STH4 and SLAL < TARSPD then MLAR = OK else MLAL = NOK

‘tests left lane indifference to move and target speed compliance

If (SLAR − ZWAS(L)) > STH4 and SLAR < TARSPD then MLAL = OK else MLAR = NOK

‘tests right lane indifference to move and target speed compliance

If MLAL ≠ OK and MLAR ≠ OK then go to Module 4.3.1 ‘No lane change

Else if MLAL = OK and MLAR ≠ OK then MOVELEFT ‘consider left lane for gap

criteria

Else if MLAR = OK and MLAL ≠ OK then MOVERIGHT ‘consider right lane

for gap criteria

Else if MLAL = OK and MLAR = OK then ‘select faster lane

If SLAL > SLAR then MOVELEFFT else MOVERIGHT

Go to Module 4.3R.2.12

Module 4.3R.2.12 Request Move if Gap is Sufficient

The preceding sub-modules of Module 4.3 have quantified driver preferences and have constrained the adjacent lane change possibilities by various factors. Some of these constraints are oriented to retaining existing traffic flow conditions and motorists' driving habits as developed for conventional vehicles. This assumption was made for the following reasons:

- When market penetration is low, non-conformance with existing traffic patterns will result in modifications to these patterns. While strategies exist that may be acceptable to automated vehicles, they may be discomforting to drivers of conventional vehicles. Initial introductions of this technology should probably avoid these issues.
- Strategies that result in roadway capacity changes may have unintended traffic redistribution effects.

Module 4.4 Guidance when Lane Speed is Below the Speed Limit

Begin

‘Direct vehicle to fastest lane when no lanes above the speed limit are

available

DVAR2 = 0 ‘DVAR2 is temporary parameter

For L = 1 to LN

If VOK(B,L) = 1 and AVSPD(B,L) > DVAR2 then TARLANE = L

If AVSPD(B,L) > DVAR2 then DVAR2 = AVSPD(B,L)

Next L

End
‘Module 4.4

Module 4.1 Identify Allowable Target Lanes and Select Guidance Algorithm

Module 4.1 identifies lanes available based on vehicle characteristics, tolling and operator preferences. Based on closure information from the ALMAMC, if lane in the barrel is not fully open, module 4.2 is selected. Module 4.3 is selected in the event of no lane closures

Module 4.2 Guidance Under Incident Conditions

If all lanes in the barrel are not fully open (down arrow) the directions provided to the vehicle emulate the lane control signals.

Module 4.3A Normal Guidance if Speed Limits are not Automatically Enforced

The module switches to Module 5 if there is automatic speed enforcement. The module determines which lanes have speeds above the speed limit and directs the vehicle to the lane with the lowest speed above the speed limit. When the control speed is set to the speed limit in Module 5, this will result in the least disruption to traffic in the barrel.

Module 4.3R Guidance with Driver Attitudinal Input

This module provides guidance when driver attitude input is considered along with roadway alignment and weather factors.

Module 4.4 Guidance when Lane Speed is Below the Speed Limit

When all lanes are fully open but the speed in all lanes is below the speed limit, the vehicle is directed to the fastest lane.

Module 5 Lane Speed Guidance

Used in conjunction with Module 4A, this module sets a target speed for the target lane. The target speed is the speed limit or lower.

‘Compare current zone speed for target lane with current speed limit

If (SPTMC(B,Z,L) = −1 then TARSPD(B,Z,L) = −1 ‘Speed data not accurate, can't set target

speed

If SPTCM(B,Z,L) = −1 then Go to [A] ‘Eliminates next statement if speed is not accurate

If SPTMC(B,Z,L) > SL(B,Z,L) then TARSPD(B,Z,L) = SL(B,Z,L) ‘sets to speed limit

else TARSPD(B,Z,L) = SPTMC(B,Z,L) + SPPUSH ‘sets to current lane speed with

push to close gaps

[A]
‘branch to bypass previous statement when necessary

Module 5 Speed Guidance

For the target lane selected in Module 4, if the if the current zone lane speed for the targeted lane exceeds the speed limit for that lane, the module targets the vehicle speed as the speed limit. If the lane speed is lower than the speed limit, the targeted speed is set to the current speed plus an increment. The increment is intended to push the vehicles speed into a vehicle following condition to avoid unnecessary gaps being developed in the traffic stream.

Appendix A
Symbols and Abbreviations

Refer to process descriptions for index referencing

- A—Type of toll tag (e.g. EZ Pass)
- ACCTEST—Temporary parameter
- ACT—Currently relevant barrel activation limits
- AGR—Driver aggressiveness level
- AUTOENF—Automatic enforcement of speed limit in barrel
- AVL—Average vehicle length
- AVSPD—Average lane speed in barrel
- B—Barrel number—a barrel is a homogeneous section of roadway (number and static or time of day use of lanes remains constant). Barrels may be separated by physical or functional separation. Barrel number must include a reference direction (N or E). E.g. E4
- BARNORM—Barrel incident status (0 if normal, 1 if abnormal)
- BC—Downstream barrel when vehicle path continues past current barrel
- BEX—Barrel containing exit zone
- CURLANE—Lane in which vehicle is currently located
- DI—Test zone width
- Distset—Distance to begin search for exit location prior to end of barrel
- DLA—Look-ahead distance threshold
- DN—Nighttime factor
- DTE—distance to exit
- DVAR—Temporary parameter
- E—Element in NASL
- EC—Set of in barrel that access closed entry ramps
- EN—Indicated entry zone state
- EXC—Required exit closed (true, false)
- EXL—Lane to access exit ramp
- EXZ(BEX)—Zone vehicle exits from path (Last zone in path that vehicle traverses prior to exit from barrel)
- INCZONE—Set of closed lane(s) in this zone
- INTESTZONE—Vehicle in test zone
- ITS—Intelligent Transportation Systems
- L—Lane ID. Relative to reference direction for barrel even when major or complete flow is in opposite direction. Designate full left shoulder as L=0 (denote as X if shoulder doesn't exist, designate full right shoulder as RS if present. The leftmost normal travel lane is designated as L=1. With opposite flow lanes, add the designator R after the lane ID
- LA—Lanes available in entire barrel for vehicle
- LACC—Lane with speed above speed limit. L is the ID number of the lane with speed above the speed limit that is acceptable (LACC(B,L)=1) including the other vehicle constraints. LACC(B,L)=0 is below the speed limit
- LAD—Look-ahead distance
- LAL—Left look-ahead lane
- LASTZONE—Last zone for look-ahead averaging
- Lat—Latitude
- LC—Lane commands. Define as follows
  - A—Left or right merge or straight permitted
  - B—Prohibited merge to left
  - C—Prohibited merge to right
  - D—Required merge to left
  - E—Required merge to right
  - F—Required merge to left or right
  - G—Vehicle not qualified to use lane
  - H—Stop vehicle
  - J—Notify vehicle that lane guidance is terminated
  - K—Straight permitted
- LEN—Look-ahead distance
- LFD—Lane flow direction
- LN—Number of lanes in barrel
- LNASL—Set of lanes in barrel with speeds above speed limit
- LOK—Certain static lane closure requirements
- Long—Longitude
- LOTV—Lanes open to vehicle (0=No, 1=Yes)
- LSS—Lane control command from ALMAMC
  - A—Straight permitted
  - D—Move to left
  - E—Move to right
  - F—Lane closed
  - J—No guidance provided
- LSTART—Dynamic lane index (0 indicates open running shoulder, 1 indicates restricted use)
- LTEMP—Intermediate parameter
- LTYPE—Lane type (LTYPE=HOT for hot lanes else LTYPE=C)
- LVR—Lane vehicle requirements. May be dynamic. Define as follows:
  - A—Passenger cars only
  - B—Buses only
  - C—Trucks only
  - D—No trucks
  - E—Buses and trucks only
  - F—No restrictions
- LZ—Last zone in barrel
- MLAL—Identifies whether OK to move left
- MLAR—Identifies whether OK to move right
- MOVELEFT—Recommendation to vehicle controls to move left
- MOVERIGHT—Recommendation to vehicle controls to move right
- NEXTZONE—The subsequent zone in the path set
- OC—Overheight clearance
- ON—Number of vehicle occupants required for of HOV lane or toll free on HOT lane. This is provided in the static database as a function of time-of-day
- OPT—Driver selected option for selection of algorithm incorporating motorist preferences
  - OPT=1—No incorporation of motorist preferences
  - OPT=2—Incorporation of motorist preferences
- OWC—Overweight clearance
- P—Path in barrel
- PELAT—Latitude of planned exit
- PELON—Longitude of planned exit
- RAL—Right look-ahead lane
- RWA—Roadway alignment factor
- PO—Number of vehicle occupants (data from ODE)
- SF—Stable following condition
- SL—Speed limit
- SLAL—Speed for left look-ahead lane
- SLAR—Speed for right look-ahead lane
- SPDDIF—Difference between average lane speed and speed limit
- SPDTEST—Temporary parameter
- SPPRE—Difference in vehicle's speed and speed of preceding vehicle
- SPPUSH—Incremental speed
- SPTMC—Zone speed from ATMAMC
- STH4—Speed improvement in look-ahead speeds required to justify the move to an adjacent lane
- STTH5—Threshold for vehicle following test
- SUMSPD—Sum of zone speeds (intermediate computation)
- T2—Time difference for stable car following test
- TARLANE—Target lane
- TAROFF—Lane next to exit ramp or lane for connector ramp (static database)
- TARSPD—Target speed for lane in zone, −1 indicates that data is not available
- TRA—Toll rate by lane
- TS1—Miles per hour above speed limit
- TTA—Set of types of toll tags available to vehicle
  - A—E-ZPass
- TTC—Vehicle cleared for toll tag use
- TTL—Toll tag requirement for lane (Y/N)
- TTU—Does driver want to use toll tag for trip (Y/N)
- VC—Vehicle class
  - A—Passenger car
  - B—Bus
  - C—Truck
- VH—Vehicle height—Ft
- VHL—Vehicle height limit
- VLAT—Vehicle latitude (from GPS)
- VLON—Vehicle longitude (from GPS)
- VOK—Vehicle & toll characteristics OK for lane
- VS—Vehicle speed
- VW—Vehicle weight—Wt
- VWL—Vehicle weight limit
- WE—Weather factor
- Z—Zone ID in barrel for which computation is to be performed
- ZC—Zone that vehicle is currently in
- ZE—Entry zone to path
- ZEX—Set of closed entry zones in barrel
- ZL—Last zone in barrel
- ZLA—Last look-ahead zone
- ZLEN—Zone length
- ZP—Zone path (set)
- ZU—Number of zones in path
- ZWAS—Look ahead speed for each lane

Number	Date	Country
61911298	Dec 2013	US
61747331	Dec 2012	US
61750426	Jan 2013	US
61827067	May 2013	US

	Number	Date	Country
Parent	14108710	Dec 2013	US
Child	14558381		US

GUIDANCE ASSIST VEHICLE MODULE

Information

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CPC

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Abstract

Description

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CROSS REFERENCE OF RELATED APPLICATIONS

Provisional Applications (4)

Continuation in Parts (1)