Isochrons and Potential Modal Shift

This one is going to get very technical, but stay with me. I think the way we have been deciding where to build cycle infrastructure is fundamentally flawed. My day job is as a software engineer with a smattering of data science. I also play around at hackathons and winning a few.

At the weekend I won one in Bristol with this analysis

Screen Shot 2017-10-14 at 18.22.41.png Given a ward, how many people living in the ward drive to work in the ward? How many people living 5km or less away drive to work in the ward and from what direction?

So what does this tell us?

Screen Shot 2017-10-19 at 23.11.15

A good segregated cycle route from Headley Park and Hengrove to Brislington would have a huge impact.

Screen Shot 2017-10-19 at 23.11.26 Avonmouth probably could do with some really good infrastructure.

Huh? But nobody wants that?

BaNES once asked Sustrans to identify a series of routes in various areas. They asked people. I mean why? What do you gain by asking people? You get people that already cycle affirming certain routes. Anybody already in a car doesn’t really care anyway.

So what should Councils be doing?

Isochrons are the measurement of something as a unit of time. In terms of cycling, 5km is about 20 minutes of cycling and we really don’t care about people already cycling. Yes the infrastructure could all be vastly improved, but let’s ask a simpler question.

Time is money, and congestion costs time

Given that congestion is estimated to cost Bristol £43.7 million a year can we use 20 minutes of travel time to determine the maximum Potential Modal Shift (PMS) for road networks and choose to develop infrastructure to maximise reduction in congestion?

Yes we can!

The work at MSOA level (ward) that I have done indicates that an LSOA (smaller than a ward) commuter flow exclusively using travel to work by car and limiting it to 20 minutes travel by bike applied using route finding, should enable identification of key routes with high PMS. This analysis should define the investment we need to do.

Implication

This method unfortunately absolutely shafts rural investment. Neither does it take into account the school run. However neither does it preclude using school travel plans to add the data into the mix.

Focusing on the problem

Let’s be honest, we could keep on spending money on cycle infra for the next 50 years and still not catch up with the Netherlands, however if we actually want to maximise the shift away from cars to bikes, then let’s identify the maximum PMS by focusing on the actual problem. The private car and the cost of congestion.

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s