Opinion please - Chaos on the street

London is preparing for the Christmas shopping rush. Since the beginning of this month one of the city’s busiest junctions, Oxford Circus, has a diagonal pedestrian crossing, the BBC reports.

The lights at the crossing stop all vehicular traffic and allow pedestrians to cross the intersection in all directions simultaneously. A video on the BBC website shows that soon after the lights have turned green, pedestrians swarm across the street and the centre of the crossing transforms into what looks like an anthill.

The mayor of London, Boris Johnson, believes that once people get the hang of it, the crossing will be able to handle double the number of pedestrians. But people do need to become more skilful when passing each other in the centre of the crossing. When, after 30 seconds, time is up and the light changes, many people have to run to the traffic islands to avoid being run over by buses.

“Such a crossing is a good idea if you have to deal with huge amounts of pedestrians,” says traffic expert, Theo Muller (faculty Civil Engineering & Geosciences). “I’ve also seen an enormous diagonal crossing in front of a train station in Tokyo, where every cycle up to 3,000 pedestrians cross the street. It was quite an experience to witness. I think about ten times more people cross there each time than at Oxford Circus.”

Generally speaking, Muller says that ‘X’ crossings are advantageous for pedestrians and unfavourable for motorists: “When there are relatively many pedestrians, the average waiting time for people will decrease. In the end it’s a political choice to favour pedestrians.”
Muller has also seen an ‘X’ crossing in Vlaardingen (the only one of its kind in the Netherlands) that “serves no purpose”. “Only a handful of people cross during each cycle,” he says, adding that in such cases it’s not worth deviating from the optimal traffic cycle for motorists.

Muller investigates various ways in which traffic can be orchestrated at junctions using traffic lights: “Slightly complicated intersections, such as the one next to TU Delft’s Botanical Garden, where traffic from seven directions meet, can be organized in roughly a thousand different ways.” Which one is most efficient depends, among other factors, on the amount of time the traffic needs after each consecutive green light to clear the crossing. 
The BBC video clearly shows pedestrians having difficulties in clearing the intersection when their crossing time is up. “It’s interesting to see how chaos arises in the centre,” says Dr Winnie Daamen, of the transport and planning section (faculty of Civil Engineering & Geosciences). “How do people decide what lane to follow and how to pass one another? I’d find it interesting to study this,” concludes the researcher who specialises in the dynamics of pedestrians at bottlenecks, such as revolving doors or train station entrances.