MOLA (MCONTRM On-Line Assistant)-development of a real time network model As part of the Highways Agency’s plans to make the best use of existing roads, it is increasingly common for key intersections of the UK strategic road network to be provided with variable message signs (VMS). In the event of an incident affecting part of the network, the VMS can be used to warn drivers of the problem, and possibly to divert them onto alternative routes. Warning messages or diversions are usually selected from a library of plans, prepared in advance, to cater for a range of incidents. It can be difficult for system operators to determine which of the library of plans is most appropriate for a given incident, under the prevailing traffic conditions. To assist operators in making this decision the Highways Agency has developed MOLA (MCONTRM On-Line Assistant), a computer system able to model traffic conditions on a road network in real time and, when an incident occurs, to predict the effectiveness of alternative strategies and recommend to the operator which he should implement.