Exchanges between partners in 2013

During the second year of the project we had the following research visit exchanges:

1. Alexandre Bayen, UC Berkeley Professor, visited Inria from March 20 to 22, 2013.
2. Maria Laura Delle Monache, Inria Phd Student, visited UC Berkeley from April 29 to May 23, 2013.

Advances of the work program

During this second year we focused on the development and the solution of the ramp-metering junction problem by the adjoint method. In particular, we considered a network of junctions each consisting in a mainline, an on-ramp and an off-ramp and we applied the coupled PDE-ODE model, developed during the first year of the collaboration. The model has been discretized and the corresponding optimization problem has been solved using the adjoint method. Moreover, we showed how the complexity of the gradient computation in nonlinear optimal control problems can be greatly decreased by using the discrete adjoint method and exploiting the decoupled nature of the problem’s network structure, leading to efficient gradient computation methods. We demonstrated the efficiency of this method by running a coordinated ramp metering strategy on a 19 mile freeway stretch in California faster than real-time, and with better traffic performance than the state of the art practitioners tools.
Go to Demos for some examples of our results.

Joint papers resulting from the collaboration

During this year we submitted the paper

J. Reilly, S. Samaranayake, M.L. Delle Monache, W. Krichene, P. Goatin and A. Bayen, Adjoint-based optimization on a network of discretized scalar conservation law PDEs with applications to coordinated ramp metering,

and the paper

M.L. Delle Monache, J. Reilly, S. Samaranayake, W. Krichene, P. Goatin and A. Bayen, A PDE-ODE model for a junction with ramp buffer,

has been been accepted for publication on Siam Journal of Applied Mathematics.

In addition to this, we organized the workshop
TRAM2 - Traffic Modeling and Management: Trends and Perspectives
in Sophia Antipolis from March 20 to 22, 2013.

Future work

The next goal is the production-scale implementation of the discretized model for ramp-metering on an actual traffic management system. The code will be migrated in Java within the larger UC Berkeley Connected-Corridors traffic system. We will further pursue extensions of the continuous model for the case of multi-commodity flow.