Development of Fosim 5.1

The development of the new version 5.1 of Fosim is approaching completion. Currently, final tests are being performed and the documentation is updated. The list below gives an overview of the changes implemented in the new version (in comparison to Fosim 5.0 build 2).

If there are any questions or remarks, please e-mail us at Fosim wishes.

New functionalities:

• Fosim 5.1 enables simulation of lanes that are temporarily open to traffic. These types of lanes are increasingly used in the Netherlands (referred to as plus or peak lanes).
  Current status: completed
  

Changes in the user interface:

• The new Fosim version can display time in the hours:minutes:seconds format (where previous Fosim versions always used seconds only).
  Current status: completed
• The detector graphs always used fixed axes. In the new version, the axes scale with flow rates and densities.
  Current status: completed
• When a batch of simulations is carried out to determine capacities, it is from now on possible to select a number of lanes for which the capacity is presented (while before always all lanes were considered).
  Current status: completed
• The flow rates generated by the sources are specified in a table in which flow rates are entered for specific moments in time. The new version includes an extended option to easily insert a larger series of moments in time (i.e., columns) for which the flow rates can be specified.
  Current status: completed
• When in a simulation the vehicle colours are used to indicate their destinations, in the new Fosim version the destination locations themselves on the roadway are indicated with the corresponding colours.
  Current status: completed
• The object list in the new version also includes the lane change areas.
  Current status: completed
• The type of license is indicated in the about window.
  Current status: completed
• Through the about window it is possible to view detailed information on the versions of the different modules of which Fosim consists.
  Current status: completed
• The scroll bar (to scroll to the different parts of the roadway) now adapts on the basis of the current zoom level.
  Current status: completed
• When an error (e.g., an accident in the simulation) occurs while running simulations with 'batch', the simulations now no longer stop until the user undertakes action. Instead, the error message is saved and Fosim continues with the next simulation.
  Current status: completed

Fosim 5.1 includes solutions to several problems found in earlier versions:

• An issue could occur with respect to correctly linking the specified flow rate data to the origins.
  Current status: completed
• Sometimes vehicles chose to decelerate in a way for vehicles that intended to make lane changes that did not fit in with the new system of lane changing areas introduced in Fosim 5.0.
  Current status: completed
• Fosim occasionally crashed when the most downstream section or all sections were selected.
  Current status: completed
• Fosim generated incorrect lane change areas when route choice situations occurred for roadway divisions that were one or more lanes wide.
  Current status: completed
• When lane change areas were updated (using the button ‘update lane change areas’ in the menu Road design → Generate lane change behaviour), areas that concerned route choice decisions were inadvertently changed to normal lane change areas (thus, without route choice).
  Current status: completed
• Fosim could crash as a result of an internal conflict in references to the origins and destinations.
  Current status: completed
• When an input file was read, a speed limit of 120 km/h was always assigned to all sections, also when the input file specified different speed limits.
  Current status: completed
• A small problem in setting the simulation speed could occur.
  Current status: completed
• When detector graphs (showing speed, flow rate, etcetera) were opened, sometimes the graphs did not refer to the selected detectors.
  Current status: completed
• The detector graphs did not assign unique colours to lanes 9 up to 12.
  Current status: completed
• At very high flow rates Fosim could issue a warning that a queue had reached the origin, while, in fact, this was not the case. The criteria that determine queues reaching origins have been changed to alleviate this problem.
  Current status: completed
• Fosim sometimes allowed the combination of speed suppression and speed limits lower than 120 km/h.
  Current status: completed

Apart from a number of changes because of problems that were found, the underlying simulation kernel was changed as follows:

• When lane changes to the right were considered (in cases where this was not required because of the road geometry) sometimes it was decided not to change lanes, while there was sufficient opportunity. The condition involved in this decision was slightly adapted to counter this problem.
  Current status: completed
• It was sometimes possible (depending on the road geometry) that vehicles were generated with speeds that lead to collisions with the object directly downstream. The module that determines the speed and location of vehicles when they are generated has been improved.
  Current status: completed
• The values for the anticipation time are now specified through two parameters (only available in the source code), instead of through the direct values specified at several places in the program.
  Current status: completed
• Previously two variables were used that indicated when a vehicle was decelerating for queues in neighbouring lanes. The code was changed in such a way that the same was done with only a single variable.
  Current status: completed

Further, the following (small) changes have been carried out:

• Where necessary, the format of the input files has been changed. However, backward compatibility (to Fosim 5.0) has been achieved in cases where new functions from Fosim 5.1 are not used.
  Current status: completed
• The minimum value for the parameter ‘preferred_v (70)‘, that is, the desired speed when the speed limit is 70 km/h, is now 70 km/h. This allows setting the preferred speed to exactly the speed limit over the whole range of possible speed limits, by changing the parameter values accordingly.
  Current status: completed
• The maximum value for the parameter ‘length‘ now is 26 m.
  Current status: completed
• Fosim 5.1 allows shorter lengths for tapered lanes, with a minimum of 100 m (instead of 250 m). However, such short lengths should be applied carefully, if possible with lower speed limits.
  Current status: completed

Apart from the changes described above, which have been actually implemented, also research was carried out for the longer term. An important aspect in this research is currently fixed sequence in which Fosim considers each vehicle (from downstream into the upstream direction). The current method complicates the introduction of more complex networks, and, thus, new approaches are considered. However, these can have important consequences for the model results. Further research is required before changes in the distributed version of Fosim are feasible.