Cyclists clog the streets

Returning to simulations this is a look at the impact of cyclists mixing with traffic on major roads, simulated here by a divided road with 2 narrow 3m (10 foot) lanes in each direction, a speed limit of 80km/h (50mph), and 3 different rates of cycling.

car throughput when mixed with bicycles

Adding just a minor number of cyclists with the orange example averaging a cyclist every 2 minutes, already throughput of cars is substantially affected. By the time there is a cyclist every 12 seconds the cars are effectively blocked from using the left most lane and are flowing as if the road had only a single lane. Without any alternative cyclists will continue to reduce road throughput, has a better argument for cycling infrastructure ever existed?

With a bill currently under debate in the Victorian parliament to mandate a minimum 1m (3 foot) gap between vehicles passing a cyclist within the same lane, on many of the roads that currently support lane splitting for cyclists it will be no longer legal. It may spur on the rapid introduction of more cycle lanes to these areas as passing a bicycle in a different lane will remain uncontrolled, and given the distressingly narrow lanes which are being rolled out across Melbourne (here here and here) safety for cyclists remains notional at best.

For comparison the same 3m wide lane if dedicated to cyclists is shown in green, based on cycling behaviour of typical commuters and utility cyclists of this country. Although organised pelotons can ride both faster and more densely, and populations accustomed to cycling achieve higher throughput, a large gap appears in the throughput as measured in vehicles per hour. Reliable data from multiple sources suggests the vast majority of commuting cars are single occupancy, to compete with bicycles for efficiency of space on non congested streets cars would need to average 3 occupants, once the congestion sets in bicycles are competing with busses for passenger efficiency as the average car lacks the 6 seats required.

While foreign readers may be shocked to read of cyclists sharing lanes in 80km/h traffic this is entirely normal for the commuting or sporting cyclists in Melbourne due to a complete lack of connectivity between shared paths, cycle lanes, and through routes on quiet streets. Positive examples of change include the Nepean Highway which has seen speed limits progressively dropped *or* bike lanes added, while other major arterials which don’t see the same level of sporting use such as Springvale road remain entirely hostile. This remains one of the most significant barriers to wider uptake of cycling as few people feel safe riding in such conditions, and in the usual chicken and egg situation cycling numbers are unlikely to increase to the volumes that would require dedicated infrastructure, because without the infrastructure it is so unpleasant. To make use of bicycles where they are best suited (the densely developed and congested city) they need safe routes to get there.

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