According to current plans, there will be roughly 850 children in the Maternelle and Primary Circle of the Mamer school from autumn 2012 onwards. If half of this children will be taken to school by private car, about 425 cars will arrive there each morning plus 50-100 cars for staff and another 125 cars for the secondary circle sums up to 600 or more cars each morning. This is a continuous line of 3,6 km (600 cars x 6 m) to and from the school, roughly the distance from the school to the exit of the motorway, in both directions. Probably 400 cars, navettes and buses would want to arrive (and leave) within a 20-minute time slot between opening of the school gates and in good time before the start of classes. If the school will grow to up to 3 500 children (as currently foreseen) the number of cars will increase accordingly.
The roundabout to the school has a capacity of roughly 1 500 vehicles per hour or 500 vehicles in 20 minutes. Considering the above mentioned number of about 800 cars which have to pass this roundabout (400 to and 400 from the school) during 20 minutes, and the incoming and outgoing traffic is crossing each other in the roundabout making it likely that the streams of cars will block each other, resulting in traffic queuing.
In essence, there appears to be a serious risk that during the morning peak, the roundabout and car park capacity are insufficient to cope with demand, potentially leading to a gridlock situation with congestion spilling over onto the N6 Mamer-Strassen. As buses and navettes do not have priviledged access to the school, both cars and public transport users will be affected.
Some observations of the design of transport infrastructure, based on the “Basic Plan” found on the school website (Plan_général_Ecole_Euroéenne_Lux_2_et_CPE_2011_09_29)
- access to the school is provided via the Luxembourg-Strassen-Mamer road (N6). A flyover is currently under construction, to give access (single lane) to the school from direction Luxembourg. Access from direction Mamer is provided by another road (one lane per direction), which also serves as the only exit road from the school, serving as well the Lycée Josy Barthel Mamer.
- access and access roads meet at a roundabout. From there, the parking for the CPE, maternelle, some kiss and go spaces are reached via a singe lane bi-directional road. Beyond the parking spaces, the bus station is located. Teachers parking is “at the end of the chain”. There is no roadspace provided that would allow for buses/navettes, or school staff cars, passing the other vehicles in case of congestion on the single-lane access/exit roads.
- all traffic coming from Luxembourg direction is conflicting with traffic already on the roundabout on its way to the exit road. In addition, all traffic attempting to leave the primary school parking is conflicting with all traffic arriving to all parkings and the bus station.
- for comparison: Lux I parkings are reachable via 6 lanes per direction (On Bd Adenauer 2 each from each east and west, 2 on Rue Coudenhove linking from Bd Kennedy)
There are now several issues arising from the selected configuration of the transport infrastructure, which should merit a thourough analysis within the mobility concept:
- The new Mamer school has a design capacity of some 3000 pupils: 360 in the maternelle cycle, 1050 in the primaire and 1600 in the secondaire. As rough estimate, it may be assumed that 90% of maternelle pupils, 50% of pupils in primary cycle and 10% of pupils in secondary cycle are taken to school by car. Taking into account siblings and carsharing, this would mean some 800 parents cars to be accomodated in the morning peak, plus buses/navettes, plus teacher’s and staff cars (for whom 190 parking spaces are provided).
- a more conservative assumption, based on a lower number of pupils at the school in starting years, still would see some 600 parents and staff cars plus buses/navettes wishing to arrive at the school in the morming, of which 400 within a 20-minute time slot between opening of the school gates and in good time before the start of classes.
- a rule-of-thumb for the technical hourly capacity of a roundabout as built yields about 1500 vehicles per hour (i.e. 500 vehicles per 20 minutes). This assumes cars can freely leave the roundabout, otherwise there is a large reduction up to a gridlock situation.
- 400 vehicles entering, assuming a working kiss-and-ride-concept, means 400 vehicles would want to leave some minutes later (assuming staff would arrive before or after the peak period). Unfortunately, the given layout means that vehicles wishing to leave the premises have to twice mix with traffic entering via the roundabout (see above). 400 vehicles (trying to enter) + 400 vehicles (trying to leave) > 500 vehicles (roundabout capacity) which means traffic will tail back i.e. create a traffic jam during the peak. There is some 300 m “queuing space” equivalent to 50-60 cars when coming from direction Luxembourg before the queue spills over into the national road, and some 500 m coming from Mamer.
- the parking/kiss and go facilities at primaire and maternelle provide some 200 spaces, that would fill up within 10 minutes according to above assumptions. As cars leaving the car park after kissing the children goodbye (requiring a good training of the maternelle children to make sure they find the classroom, hang their coats, untie their boots, find their slippers & register into the garderie lists themselves….) face the same capacity problem at the roundaout as traffic approaching the school, a gridlock situation may occur: You cannot get into the car park because I cannot get out of the car park.
- the given road configuration does not encourage use of the school bus or navette, no separate acess route for these are provided hence it is not possible to “beat the jam” by using public transport
The above text is necessarily a bit technical. In essence, there appears to be a serious risk that during the morning peak, the roundabout and car park capacity are insufficient to cope with demand, potentially leading to a gridlock situation with congestion spilling over onto the N6 Mamer-Strassen. As buses and navettes do not have priviledged access to the school, both cars and public transport users will be affected.