PARAMICS Plugin - ramp metering
Contents
1. The following documents are required in order to correctly use this plugin 1 Ramp meter design map including the layout of detectors 2 Entrance ramp control plans obtained from the proper government agency 3 2 Adding demand detectors The demand detector should be added to the PARAMICS network which should be put just before the stop line based on the design map of the entrance ramp The number of demand loops installed in the real world and the layout of these loops will decide the length of the demand detector in PARAMICS The ramp metering API can work with or without detectors If with detectors the plugin requires a demand detector which should be specified by users in the ramp control file for the operation of orrramp signal If without detectors users need to specify the demand detector of the orrramp as N A 3 3 Adding on ramp signal through editing priorities file In order to let PARAMICS regard a node as a signalized node users must add or edit the priorities information of the node This can be realized through GUI or editing priorities file The priorities file a system file of PARAMICS defines movements of each phase of a signalized intersection We recommend the latter method There are two phases for each orrramp signal We define that phase 1 is the red signal to prohibit vehicles from entering the mainline freeway and phase 2 is the green signal to release the waiting vehicle into the freeway An exampl2. MICS Simulation Environment presented at TRB 2003 annual meeting 15
3. OD rate 1 metering off others metering rate Parameters rampnode is the name of an orrramp signal node 12 PATH ATMS Center Ramp Metering Control Plugin 4 2 How to use interface functions in other plugins These interface functions can be called in other plugins The following setting is required 1 In the workspace of your plugin that wants to use these interface functions specify the library file ramp_controller lib of the actuated signal plugin as an input object library module The path of ramp_controller lib should be specified as well 2 Specify the prototype of the interface function at the beginning of your plugin as follows _declspec dllimport void uci_ramp_set_parameters RAMP ramp Bool parameter _declspec dllimport RAMP uci ramp get parameters char rampnode declspec dllimport float uci ramp get tod rate char rampnode 13 PATH ATMS Center Ramp Metering Control Plugin 5 Technical Supports 5 1 Limitations of this plugin The controllers in the real world have more capabilities than this plugin For example SATMS one of Caltrans ramp metering algorithm contains local mainline responsive control i e demand capacity control and time of day control i e pre timed control However this plugin only emulates pre timed control In version 3 of PARAMICS sometimes the presence detector does not work correctly i e sometimes a vehicle cannot be detected though it is present on the
4. PATH ATMS Center Ramp Metering Control Plugin PARAMI CS Plugin Document Ramp metering control Lianyu Chu Henry X Liu Will Recker PATH ATMS Center University of California Irvine Plugin Compatibility V3 V4 Release date 3 20 2003 522 Social Science Tower Irvine CA 92697 3600 URL http www its uci edu NIA H CALIF Sey 08 mr Ppl ul University 6f California irvine P PATH ATMS Center Ramp Metering Control Plugin Table of Contents A A O O EM 2 Introduce ced o a ea deae ated E 3 2 Plugin implementation eiii did ni EE A E R A 4 2 1 Reak world ramp metering SUS ile 4 2 2 Modeling vehicle detec iii ies 4 23 Control LOGIC eaa a E E E ER A REE AER S 5 2A Pseudo codeine tite eei dis te etd iaaa ina ae ESEAS aaae d 6 3 Step by step user Mal cion iran dia nE a E E iden 8 3 1 Data preparation ardid indicada dps 8 9 2 Adding demand detect 4e dae eatem nsi eq sdu ga iem ad i 8 3 3 Adding orrramp signal through editing priorities file sesssse 8 3 4 Preparation of ramp control eerte te antennes ntt indian ie ese ea eate vods 9 OA DISTR oos ded eaa do Een a tuo E m C MR 10 3 6 Error checking ett ecran ON DR Ran E ARR 10 4 PROGRAMMER capabilities 000 cca tapete eh oou a eats 12 4 1 o a A E Poen N coi 12 4 2 How to use interface functions in other plugins see 13 2 Technical SUuppoltsco osos enn e 14 5 1 Limitations of this PU A a dt Gee aes 14 52 FA
5. Q inaa aao 14 5 5 Contact HifOEmallOl s odo ice a o a dae ate R eae 15 EM Se LT 15 PATH ATMS Center Ramp Metering Control Plugin 1 Introduction There have been a number of strategies to release vehicles into the mainline freeway traffic each with different demands on sophistication of control and detectorization Caltrans currently has three ramp metering systems SATMS SDRMS and SJRMS All of them use the 170 type controllers as hardware SATMS SDRMS and SJRMS are names of their software algorithms installed in the 170 controller This plugin is designed to model pre timed ramp metering control on ncars per green basis with n 1 in PARAMICS It also supports multiple timing plans and the use of ramp detectors for metering control The data input of this plugin is a time of day ramp control plan and the detector information of each meter In addition this plugin is designed to support the development of advanced ramp metering algorithms and integrated control strategies ramp metering plus arterial signal control A number of interface functions are provided by this plugin for external plugin modules to acquire the current metering rate and set a new metering rate to a specific ramp meter PATH ATMS Center Ramp Metering Control Plugin 2 Plugin implementation 2 1 Real world ramp metering system The easiest ramp meter is based on fixed time control Some latest ramp metering design has included the check in and chec
6. before the stop lane waiting for the green signal The detector for sensing the presence of a vehicle allows the signal to rest in red avoiding potential confusion to a driver approaching the signal due to the short greens The following three principles are used for metering signal control 1 If the length of red signal is longer than red and the demand detector has detected the presence of a vehicle waiting the green signal will be given with the length of green 2 If the length of red signal is shorter than red green signal will not be given even there are waiting vehicles 3 If the length of red signal is longer than red and no vehicle is waiting the metering signal keeps showing the red signal This plugin allows multiple metering plans A metering rate is fixed within a specific time window For another time window another timing plan can apply As an illustration suppose the ramp signal cycle length is 10 seconds from 4pm to 6pm This is one vehicle every 10 seconds so that a setting of a 2 sec of green followed by 8 sec of red could be used The metering rate in this case is 360 vph 2 4 Pseudo code The control logic is given in the following pseudo codes 1 Plugin initialization Read in all ramp information Allocate memories for all pointers to be used Store all necessary ramp information to global data structures Check the existence of ramp nodes and correspondent detectors Initialize
7. detector This case is very rare however this may cause severe problems in the simulation since all the following vehicles are blocked and the signal may remain red all the time To solve this problem a green signal is given as long as the time of red signal is over RAMP CYCLE The maximum number of timing plans is 256 for each entrance ramp signal The length of green time for single entry metering is 2 0 seconds and for platoon metering is 4 0 seconds which are pre set by the plugin No queuing control is involved in this plugin If a queue control is required please use queue control plugin together with this API 5 2 FAQ Grammar of input files Unlike the parser system of PARAMICS which allow flexible grammars and comments i e Hf the format of the input file of this plugin is rigid and thus any problem in the file may cause the plugin not work well Our recommendation for users is that the input file of the example network of this plugin is a good starting point to make your own input file in order to avoid editing problems 2 PARAMICS can model ramp metering Why do you develop this plugin PARAMICS can model fixed time ramp metering with multiple timing plans However a ramp metering controller developed in PARAMICS API is required for the support of development of adaptive ramp metering algorithms which have more complicated control logics The ramp metering controller should provide interface functions that can be
8. e of the priorities information fro an on ramp signal is as follows actions 92 phase offset 0 00 sec phase 1 0 00 max 30 00 PATH ATMS Center Ramp Metering Control Plugin red phase 0 00 fill all barred except phase 2 0 00 max 30 00 red phase 0 00 fill all barred except from 91 to 93 major Where fill means no yellow will be shown The initial phase lengths for both phases are set to 0 This plugin has set the maximum cycle of an orrramp signal to 24 seconds Currently in the above example max 30 00 means the maximum length of each phase is 30 seconds This value should be larger than 24 seconds in order to make ramp meters controlled by this plugin 3 4 Preparation of ramp control The ramp control file includes the ramp control information which is the input of this plugin It should be located at the same directory as any other network files An example of ramp control is shown below total number of controlled entrance ramps is 7 control cycle of ramp metering 30 on ramp signal 33 name 405N amp ICD 1 0 93 demand detector 405n0 93orb number of control plans 2 from 6 0 to 9 0 METER ON with 1 veh per 6 sec from 15 0 to 19 0 METER ON with 1 veh per 6 sec on ramp signal 36 name 405 N amp ICD 2 Q 1 11 demand detector 405nl 11orb number of control plans 2 from 6 0 to 9 0 METER_ON with veh per 12 sec from 15 0 to 19 0 METER_ON with 1 veh per 7 sec The first line defines the number of en
9. e to only use one PATH ATMS Center Ramp Metering Control Plugin check in detector or demand detector The simplified layout of ramp metering system 1s shown in Figure 2 gt Mainline Traffic Figure 2 A typical ramp metering layout The length of the demand detector is based on the real world design of ramp meter Based on the design manual of Caltrans District 11 typically uses 4 demand loops Districts 3 4 6 8 typically use 3 demand loops Districts 7 12 typically use 2 demand loops As a result the length of the demand detector is equal to the length that a demand detector can cover 2 3 Control logic The ramp signal generally provides two indications green and red Based on the time of day metering rate the metering cycle can be calculated as cycle 3600 rate If one car per green is applied we assume the green time a vehicle needs to pass the metering signal is 2 seconds If two car per green is applied we assume the green time for two vehicles to pass the metering signal is 4 seconds Then the length of red signal is red cycle green If there is no demand detector or check in detector metering signal will show red and green based on the above red and green time This guarantees that vehicles are released from ramp to the mainline freeway at a fixed ramp metering rate PATH ATMS Center Ramp Metering Control Plugin If there is a demand detector or check in detector every vehicle has to stop
10. g rate An advanced ramp metering algorithm API can be developed based on them Their prototypes are shown below RAMP uci ramp get parameters char rampnode Function Querying the current metering plan of a specific ramp meter Return Value The current metering control plan of an orrramp signal Parameters rampnode is the name of an orrramp signal node RAMP is the structure of ramp control data whose definition is typedef struct Ramp data RAMP struct Ramp data on ramp signal node name and its location char node char name ramp control types and parameters int type int cycle le Where controlType is the status or type of the ramp metering control which can be 0 if RAMP_CLOSURE 1 if RAMP ON with single entry metering 2 if RAMP ON with platoon metering and 9 if RAMP OFF void uci ramp set parameters RAMP ramp Bool parameter Function Setting a new metering rate to a specific ramp meter Return Value None Parameters ramp stores the new metering control data of a specific orrramp status is a Boolean value parameter TRUE means to set a new metering rate based on an external algorithm parameter FALSE means to restore the default time of day timing plans float uci ramp get tod rate char rampnode Function Querying the current time of day metering plan of a specific ramp meter Return Value The current time of day metering plan of an on ramp signal TOD rate 0 ramp off T
11. ingle entry metering BB 1 or platoon metering BB 2 CC is the cycle of metering control If the status is METER ON BB and CC should be specified If there is no timing plan for a certain time period it is regarded as METER OFF 3 5 Loading plugin After the completion of the ramp control file and the update the priorities file you can load the simulation network together with this plugin The names of this plugin files are ramp controller dll Modeller Plugin ramp controller p dll Processor Plugin Run simulation and then you will see that this plugin is used to emulate the ramp metering control at specified ramps via GUI 3 6 Error checking 10 PATH ATMS Center Ramp Metering Control Plugin This plugin can work if ramp_control and priorities are prepared correctly If any mistakes happened in the ramp control file the plugin will be disabled The report window of PARAMICS will show whether this plugin is working If the metering control is not working or is not working as you expected you may need to check if there is any error in the ramp control file This plugin generates a file named Log ramp txt under the network directory which can be used for this purpose 11 PATH ATMS Center Ramp Metering Control Plugin 4 PROGRAMMER capabilities 4 Interface functions There are three interface functions used for querying current and time of day metering rate and setting a new meterin
12. k out detector for a better control and the consideration of safety Caltrans has the following basic design of ramp metering system Five types detectors can be possibly installed for a ramp meter including orrramp detector demand detector passage detector queue detector and ramp HOV detector The orrramp detector is used for counting total number of vehicles entering freeway from entrance ramps The demand and passage detectors 1 e corresponding to the check in and check out detectors are used for the operation of oncramp signals The demand detector employs to initiate green and the passage detector employs to return the signal to red The queue detector is located at the upstream end of the entrance ramp used for detecting the excessive queue length in order to avoid interference with the arterial traffic The ramp HOV detector is used for counting the number of carpool vehicles entering freeway from entrance ramps Mainline Station Queue Figure 1 Typical ramp metering configuration 2 2 Modeling vehicle detection This plugin is designed to implement the easiest ramp metering control i e pre timed control Only the time of day metering plan is the necessary information required by the plugin The plugin can also work with the use of detectors The check in and check out logic of the reat world ramp metering system needs accurate detection of passing vehicles However simulation suffers the problem of missing vehicles We decid
13. the ramp signals based on the initial simulation time 2 Main program Get simulation time For controlled ramp 1 n Check the current running phase Get green left time of the current running phase Find the correct ramp control plan according to the simulation time If ramp cycle length changed due to entering another time period Notify the operator Recalculate the green times for the 2 phases 15 If controltype is always ON set next green time for always ON PATH ATMS Center Ramp Metering Control Plugin Else if controltype is always OFF set next green time for always OFF Else If the running phase is 2 amp amp green left time lt time step Set the next green time for phase 1 Else if the running phase is 1 If no vehicle presence If the running time is less than RAMP_CYCLE continue to increment green time for phase 1 Else the running time is equal to RAMP_CYCLE set the next green time for phase 2 else Set the next green time for phase 2 PATH ATMS Center Ramp Metering Control Plugin 3 Step by step user manual In order to use this ramp metering plugin two files need to be prepared 1 priorities file is a system file of PARAMICS provided with the action and phase definition of a ramp signal 2 ramp control file is the input of actuated ramp API including the ramp control information such as ramp name control type cycle effective time etc 3 Data preparation
14. trance ramps to be controlled by this plugin The second line defines the control cycle of the ramp metering control PATH ATMS Center Ramp Metering Control Plugin The following is the necessary input information of each entrance ramp which always begins from a blank line 1 on ramp signal is the global node number of the omramp signal in the PARAMICS network 2 name is the description of the entrance ramp such as its location 3 demand detector is the name of the demand detector of the entrance ramp If there is no demand detector or the demand detector is not used for orrramp signal operation please specify as N A If the specified detector can not be found in the detectors file a warning message will be given and the entrance ramp will be operated without demand detector 4 number of control plans is the number of orrramp signal control plans The number will decide how many timing plans followed 5 The following are time of day timing plans The possible format might be one of the following from TIMEI to TIME2 METER ON with BB veh per CC sec from TIMEI to TIME2 METER OFF from TIME1 to TIME2 RAMP CLOSURE where TIME1 is the starting time of a timing period and TIME 2 is the end time of a timing period The format of TIMEI and TIME2 is HH MM only hour and minute is specified The timing periods of any two timing plans should not overlap BB is the type of metering operation s
15. used for querying the old metering rate and setting a new metering rate based on the adaptive ramp metering algorithms When the adaptive ramp metering algorithm is not activated the fixed time metering will be the default control 3 In priorities file the two phases of ramp signal node has the input of max 18 00 will this setting affect meters controlled by this plugin 14 PATH ATMS Center Ramp Metering Control Plugin Yes These meters will not work correctly The reason is described in Section 3 3 Our recommended value is max 30 00 4 About advanced ramp metering algorithm This plugin is the ramp metering controller of any advanced ramp metering algorithm such as ALINEA or BOTTLENECK used for providing current metering rate and setting a new metering rate based on the request of the advanced algorithm If an advanced algorithm is associated with an entrance ramp more detectors such as the queue detector HOV detector orrramp detector might be required 5 3 Contact information Any comments and suggestions are welcome Please contact us at the email address Ichu translab its uci edu 5 4 References 1 Liu X Chu L and Recker W 2001 Paramics API Design Document for Actuated Signal Signal Coordination and Ramp Control California PATH Working Paper UCB ITS PWP 2001 11 University of California at Berkeley 2 Chu L Liu X and Recker W 2003 Development of the Capability Enhanced PARA
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