Integration of emme/2 and corsim

EMSIM Features

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  There is an existing CORSIM graphical editor (ITRAF) but it does not provide any link to travel demand models; also many users in many cases develop their input data in ASCII format (“Record Type Files” in CORSIM lingo). EMSIM provides users with a graphical editor, in which each node or link has its own associated fields for different "Record Types" and user can spatially relate data within the geographical area;
  

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  EMSIM automatically calculates many link or node attributes needed as input for different record types, thus eliminating time consuming data entry typically done by the user;
  

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  EMSIM can import a DXF file and user could start developing the network based on the imported file;
  

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  In many cases there is a regional model available in EMME/2 format and EMSIM can use the model to build CORSIM Record Type Files;
  

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  In cases where the regional model encompasses a bigger area than a CORSIM project requires, EMSIM lets the user pick an area to keep and automatically deletes the rest of the network. This eliminates the requirement for the user to manually delete all the unnecessary links and nodes;
  

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  If the original model is in TRANPLAN, a program can be run to quickly convert the TRANPLAN roadway network ASCII file into EMME/2 format and then run EMSIM;
  

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  To prevent the user from having to manually input data, the following fields of data can be automatically calculated and created by EMSIM:
  

Entry 1 - Link's upstream node number

Entry 2 - Link's downstream node number

Entry 3 - Link Length (feet)

Entry 18 - Downstream node k that receives left turning traffic.

Entry 19 - Downstream node m that receives through traffic.

Entry 20 - Downstream node n that receives right turning traffic.

Entry 21 - Downstream node -d (left) or +d (right) that receives diagonal traffic.

Entry 1 - Upstream node number i of subject link (i,j)

Entry 2 - Downstream node number j of subject link (i,j)

Entry 3 - Downstream node number k of link (j,k), which receives through-movement traffic from subject link (i,j)

Node coordinates are automatically developed

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  EMSIM can also take all turning movements from a regional model and automatically fill the following fields, preventing the user from having to both enter the data and calculate the percentage of turning volumes on each approach:
  

Entry 3 - Percentage of traffic (or vph) turning left to node k

Entry 4 - Percentage of traffic (or vph) going through to node m

Entry 5 - Percentage of traffic (or vph) turning right to node n

Entry 6 - Percentage of traffic (or vph) turning diagonally to node -d (left) or node +d (right)

Entries 7 through 10 relating to turn prohibition.

Entry 3 - Downstream node number k of link (j,k), which receives through traffic from subject link (i,j)

Entry 4 - Percentage of vehicles or the total number of vehicles that have a through movement to link (j,k)

Entry 5 - Downstream node number l of an off-ramp that receives traffic exiting from subject link (i,j)

Entry 6 - Percentage of vehicles or the total number of vehicles that exit at the off-ramp link (j,l)

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  If a regional model is not available, any number of observed turning movement data could be taken, and based on those, the rest of the turning movements at intersections in the entire network could be estimated automatically. This procedure links to the macro built by Heinz Speiss called demadj22.mac (3). Then based on the generated numbers, Record Types 21 and 25 can quickly be built. This procedure uses an algorithm in which a trip table can be estimated based on turn movements and/or link traffic volumes. As a result of this process a demand matrix is also built and the user can perform “what if” analyses and run CORSIM accordingly;
  

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  Entering link volumes for Record Type 50 can easily be built using the program;
  

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  Using future variables, EMSIM can take advantage of the assigned future trip table and build the corresponding Record Types accordingly;
  

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  Finally, since EMSIM is being developed in the EMME/2 environment, CORSIM user can also take advantage of extensive EMME/2 features for their analysis and in presenting the analysis result. Some of the advantages include plotting volumes of the study area network, or any other node or link attributes, as well as features regarding turning movements. This integration (EMME/2 + CORSIM = EMSIM) will enable users to do alternative analysis and generate reports for different alternatives (comparing volume, values associated with speed, VMT, VHT, etc.);
  

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  Numerous error detection messages are built into EMSIM to communicate with the user; and,
  

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  When the analysis is done, the EMSIM menu allows the user to export data in CORSIM format, with all data for different CORSIM Record Type Files in their appropriate columns.
  

EMSIM Screen

When EMSIM is activated, the following screen appears:

This screen will assure the user that the correct scenario is being activated. The user has the option to change the scenario number at this level by answering yes to the question. The next screen will include the main menu.

Main Menu

While on the above screen, the user can see the name of the project and scenario automatically, that is already defined in EMME/2’s data bank.

Create Subnetwork

The following shows the entire Rochester, Minnesota network.

The above network covers an area coded in a regional model which is much larger than required for the CORSIM model. It also includes many centroid connectors that should not be coded in CORSIM. The user has the option to automatically delete centroid connectors and part of the network and keep just the CORSIM study area. By choosing first option in EMSIM’s main menu, the user will be prompted to the next screen as follows.

Based on answers provided by the user, part of the network will be kept, using node number 1 as the center with a radius of 5 miles.

EMSIM generates the new subnetwork in a different scenario (scenario 91 in the above example).

When study area network is defined the user is ready to select option 2 in the main, menu, which is creating CORSIM files.

By pressing option 2 of the main menu user will be prompted to the next screen.

The above screen will enable the user to quickly create attributes needed for various CORSIM Record Types.

The user will be prompted to a sub menu for various Record Types to choose options to calculate some of the attributes automatically, eliminating the need to manually enter the data. For instance by choosing option 2 the next screen will be displayed as follows.

After activating the above options the next screen will be displayed for data entry. As shown in the following network from Downtown Austin in Texas, length and downstream node numbers for through, right, left and diagonal nodes are entered in their link attributes automatically. Also as the user modifies the network each link turns red, making it easy for the user to trace the modifications. If the user chooses to stop and returns to the program later, all links that are already modified will still be shown in red.

When the user selects to input turn volumes, if the model already has those volume then the option for transferring the turn attribute to link attribute can be selected, to have all the values moved in link fields while converted to percentages. Otherwise the user will be prompted to the following screen to manually enter the turn volume. In the following example all turn volumes are entered in up2 field belonging to node 479.

Since CORSIM requires turn volumes in percentages and entered on links, EMSIM lets the user automatically transfer all the turning volumes in their link attributes as node 479 in the above example is transferred into it’s associated links in percentages. In this example turning volume was transferred from model, then EMSIM converted the result to percentages in links. Below displays link 512 to 479, showing 85% going through, 6%turning left and 9% turning right.

After all attributes are inputted either manually or automatically, the user is ready to export all data in CORSIM format.

In the main menu, the option for exporting data will lead the user to the following screen. This will batchout different link or node attributes and using an external AWK program developed for this purpose, the EMME/2 output will be converted to CORSIM format input files.

Conclusion

As a consequence of development of an EMME/2 macro called EMSIM, integration of EMME/2 with CORSIM has now become possible, A user with minimal training on EMSIM can run the program to develop CORSIM input files. EMSIM is being developed by applying the advance EMME/2 macro language features in a user friendly, menu driven context. Many error detection messages are also created in the macro to make the program communicate with the end user. Since many of the fields are also generated through an automation process, error made by users are minimised. Using EMSIM also reduces the time spent for many hard and time consuming tasks. EMSIM allows users to take advantage of features already built in EMME/2 software. An area to consider for further research is using functions to estimate signal configurations in EMME/2 which could be exported into CORSIM and looped back into EMME/2 again through an iterative process until convergence is reached (4).

References

1. 
   EMME/2 User’s Manual, Software Release 9.2. INRO, Montreal, Quebec, Canada, Ninth printing, 1998.
   

2. 
   CORSIM, TSIS, and TRAFVU, Users Guide – CORSIM Version 1.03. Kaman Sciences Corporation, Colorado Springs, CO, 1997.
   

3. 
   Spiess H. (1990b). A gradient approach for the O-D Matrix Adjustment Problem. Publication 693, Centre de recherche sur les transports, Université de Montréal.
   

4. 
   Aashtiani H. and Iravani H. Use Of Intersection Delay Functions To Improve Reliability Of Traffic Assignment Model. Tehran, Iran, 1998.
   

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