Thursday, 3 March 2016

Sustainable Safety: A thorough look into each of the 5 principles. Part 1: Functionality

In my detailed look at Sustainable Safety, it's 5 core principles, I am going to go over what is ideal for the Dutch according to each of their principles (if it can have a realistic ideal, I mean it would be nice if every driver, cyclists and all pedestrians were 100% aware, but that doesn't hold up to human nature), some of the details and trying to give a more detailed explanation than most blogs tend to go into.

But first, some research. When researching this topic, I started out with the Aviewfromthecyclepath and BicycleDutch blogs, and also looked towards the SWOV, which is an acronym from Dutch meaning, and I kid you not, Stichting Wetenschappelijk Onderzoek Verkeersveiligheid. Translating roughly to Foundation for Research into Road Safety. They published a few (relatively short) papers on this, and a more lengthy paper on this is a paid for document, so I don't have a copy of that. Links here:, and

The first is functionality. Roads are one of three kinds of roads. A through road, an access road or a distributor road. Through roads focus as close to 100% as possible, flow on ordinary stretches of road but also at intersections (usually interchanges). Distributor roads focus as much as possible on flow on ordinary stretches of road, but also exchange at intersections. The roundabout is perfect for this job. Access roads focus on exchange not only at intersections but also along the road itself, like going into a driveway for example. These functions must not be mixed as close to 100% as much as possible, ideally 100% dedicated to their task.

This means that distributor roads also don't have driveways. They may have frontage roads, but along the road itself, driveways or private accesses and as few access road junctions as possible should be minimized. This also applies to businesses. This is crucial in an area like,-113.5173391,3a,69y,271.98h,84.39t/data=!3m6!1e1!3m4!1sHk3vpUdpUtp4bAYlXJCstA!2e0!7i13312!8i6656?hl=en, where there are lots of businesses that A have distracting signs and B, interrupt the flow of traffic just to have people go to their business. That traffic light up ahead actually only connects some parking lots to Ellerslie Road.

So what are the ideal roads under the Dutch vision? A 130 km/h freeway is the ideal through road, urban and rural (speed limits may be reduced here if required). Looking like this: Dutch motorway, with a crash barrier in the middle of the road, a very sturdy one I might add, paved shoulders, ideally at least 3 metres wide, wide lanes, at least 2 of them per direction, the Dutch specify 3.5 metres, Canada and the US usually specify 12 foot (3.7 metre) wide lanes. And full grade separation with long ramps and full control of access, meaning no local access except via service roads (and interchange ramps to get to gas stations), and no slow or non motorized traffic.

The next option is what the Dutch call an autoweg. The best translation is expressway, but usually that comes with a picture of a freeway in many people's eyes. It literally translated to a road for motor traffic. It comes with the control of access in the same way a freeway does, a 100 km/h default speed limit, subject to being decreased, it means it's a higher quality road that doesn't quite meet motorway standards. Often it is either a dual carriageway, or divided highway, that perhaps doesn't quite have all the interchanges or a full shoulder, or it means a 2 lane highway with a green stripe in the middle with some interchanges, possibly some roundabouts or traffic lights or drawbridges.

An ideal autoweg looks like this:,3.5775217,3a,41.2y,129.83h,84.92t/data=!3m6!1e1!3m4!1swIHUKxqWZgyEsoA1D5iiRQ!2e0!7i13312!8i6656. There is a divide between the two directions, a sturdy double sided metal crash barrier and some space, there are wide lanes, a  paved shoulder on each side of the road, grade separation (though a bit further down the road there are some roundabouts). no local access, a pair of 60 km/h service roads do that, and controlled access. A 100 km/h speed limit applies here. Neither an autoweg or motorway may have an at grade railway crossing.

Distributor roads take a number of flavours. The ideal urban distributor road has a 50 km/h speed limit, 1 lane per direction, a median, no local access, intersections controlled by roundabouts only, no at grade railway crossings either, and only being used to get at medium speeds to other districts of the city. Looking like this:,3.8356605,3a,49.2y,333.13h,82.35t/data=!3m6!1e1!3m4!1s1jaFHC8RxgCUXvl8AOcJnw!2e0!7i13312!8i6656?hl=en.

Some distributors in the urban area have 70 km/h speed limits. I thought these were through roads before, but they are actually distributor roads. They are through roads in the sense that you could use them to get from district to district in a fast way, but not the kind that Sustainable Safety classified them as.

In the rural areas, the ideal distributor road is an 70 km/h 2 lane highway (1 lane per direction), no local access, no slow traffic, and bypasses built up areas. Intersections should be roundabouts if possible. Example here:,5.354184,3a,21.4y,123.17h,89.89t/data=!3m6!1e1!3m4!1sSUwW5LqTjUdEQ0LH-zesgA!2e0!7i13312!8i6656?hl=en.

In the urban area, the ideal access road has no through traffic function whatsoever, a speed limit and measured speeds of 30 km/h, brick paving, raised intersections with no assigned right of way, mixed cycling, and narrow roads. The Aviewfromthecyclepath blog has the perfect picture:

Rural access roads tend to come in 2 flavours. With cycle paths and without cycle paths. The former is usually a higher volume access road. Still for local traffic, but it takes the role of main route from a pair of villages for example. This kind has a cycle path. The other kind tend to be narrow back lanes which on which only residents drive on occasion. Because of the low volume, there is no cycle path. A 60 km/h speed limit applies to both kinds of access roads in the rural area. On the kind without a cycle path there are generally no markings. On the kind with cycle path, there are optical narrowing lines on both edges but no centre line.

So these are all the features of a road that is true to it's function. Not all roads can be 100% correct to it's function, but the Dutch strive to make it as close as it can be, or reclassify and redesign the road. Closing minor side streets to motor traffic helps in this regard, creating more grade separated interchanges and simple flyovers and creating bypasses all help here. The next phase is homogenity of masses, speeds and directions. Stay tuned for that blog post!

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