Five rules for a different vision of the urban motorway
When a region has been expecting to hit a traffic saturation point for several decades, and signs of urban “thrombosis” build up, the entire economic ecosystem and life balance of the area in question are endangered. In this context, relaunching an earlier project for a connecting motorway axis to link two existing highways in the very heart of the city, requires the approach of an urban planning expert, as well as a resident-centric view, in addition to building expertise. What are the rules for putting a road at the heart of a civic project?
First rule: identify the function of the road
Its purpose is not to connect point A and point B, but to reduce the travel time from A to B from 45 minutes to 10 minutes. Its second function is to reduce accidents and therefore their economic and social cost. The third, and this is not the least “paradoxical”, is to reduce the carbon footprint of the area and the pollution caused to people living near the existing roads. Finally, it means reclaiming space by creating new areas for urban facilities on the covered parts of the highway.
Second rule: collect measurable data for each function.
Socio-economic studies have been conducted to assess the impact of infrastructure on a region’s economy (economic cost of traffic jams, benefits of easier access to business centres), the reduction in accidents (motorways are less accident-prone than secondary roads for the same amount of traffic), and to identify the environmental gains linked to the reduction in the volume of emissions for a constant amount of traffic (in this case, 100,000 vehicles per day travelling for 10 minutes instead of 45 minutes) or to the treatment of runoff water on the road concerned. Lastly, the reduction of noise pollution requires covered trenches to be built, for example to cover more than 50% of the highway, as in Marseille with the L2. These coverings make it possible to firstly maximise the flow of traffic by adding traffic axes above the covered road, and secondly to use these coverings for new urban developments to benefit the inhabitants: gardens, sports facilities, etc.
Third rule: management
A motorway cannot just be left alone to run itself. It needs to be monitored and its traffic supervised to ensure the safety of users in case of accidents or traffic jams. Management is carried out by a set of technical systems allowing the command and control of traffic data collection, video surveillance, incident detection and dynamic signalling equipment. Other systems ensure the safety of goods and people in tunnels, such as ventilation and closure equipment or air quality sensors. To ensure the optimal operation of the infrastructure, all these technical systems are themselves controlled by a hypervision system that meets the specific needs of the operator and the functions of the road.
Today’s road is therefore an information system equipped with tools for collecting and reporting data, as well as tools for processing and presenting this data. We then need tools to support decision-making, intervention and to remotely control equipment, enabling traffic management, fluidity and diversion to alternative routes.
The unsuspected role of your car’s Bluetooth…
Vehicle speed measurement equipment performs poorly when measuring low speeds of around 10km/h. Bluetooth technology is useful for measuring slow speeds. How? By installing Bluetooth signal collection beacons at the entrance and exit of a tunnel. These beacons will detect cars or mobile equipment that have their Bluetooth signal activated. The signals from each device are captured on the way in and on the way out, allowing the time to be calculated very precisely
between the two beacons, and thereby calculate the speed. As such, in the event of a fire, it is the speed of the vehicles that directs the response plan indicating the safest ventilation and smoke extraction scenario for the drivers.
Fourth rule: foresight
Securing the functions is based on foresight, i.e. defining and implementing standardised operating processes. In the event of an accident, the operator is notified, either by video or by message on a warning screen. These alarms automatically activate proposed action plans executed by all the other systems after the operator’s decision: dynamic speed signalling, switching on traffic lights and lane assignment signals, displaying messages on illuminated display panels, broadcasting radio messages, closing access barriers, smoke extraction, and more.
Fifth rule: technological and urban integration
A highway is a component of a larger network. The road communicates with and on the roads that feed it. For example: the detection of oversized vehicles is accomplished by a laser and camera system positioned on the upstream roadways. As soon as the size is detected and the number plate is read, the services are alerted and a message is displayed on the variable message panel, with the number plate, asking the vehicle to leave. If it continues on its way, a second detector will display a second message requiring the mandatory exit and will direct the vehicle to a dedicated stopping area. An identical protocol is applied to vehicles carrying hazardous goods. The urban motorway provides frequent links to the city’s road network. Intermediate entries and exits are provided and lead to traffic light junctions which are themselves controlled by the control centre. An urban motorway is reserved for vehicles and motorised two-wheelers, but not for soft transport. Nevertheless, as soon as there are covered trenches, many opportunities arise to build cycle paths and wide pavements for pedestrians. Re-engineering all the traffic light junctions at the associated interchanges enables operators to give priority to public transport such as trams and buses.
Centralised technical management of the Marseille L2 bypass
The Rocade L2 is the A507 motorway which links the A7 to the A50. It is part of the trans-European road network. It is composed of 8 tunnels which form 52% of its length.
As leader of the EFE consortium (Bouygues E&S / Aximum / Egis Projects), Bouygues Energies & Services was responsible for the design, construction and commissioning of the traffic management and safety systems for France’s best-equipped urban motorway: 400 cameras mainly dedicated to automatic incident detection, 500 dynamic traffic signs, 200 vehicle counting stations, 180 emergency call stations, 80 km of fibre optic network… on 10 km of motorway.
The supervision system interfaces with all of the operator’s existing equipment (DIR Méditerranée) and provides decision support in the event of an incident.
It also makes it possible to measure low traffic levels in tunnels by Bluetooth detection, to control tunnel ventilation according to vehicle speed, to detect oversize lorries and lorries carrying hazardous materials by automatically reading their number plates and more.
