Wednesday, 20 January 2016

Our roads are too big

You might be interested to know that single lane roads generally have the ability to handle 19000 vehicles per day on a regular stretch of roadway. And they can handle up to about 24000 per day given other upgrades like roundabouts. Given that cycle paths, 30 km/h roads, a dense grid of cycle routes that provides a fast, safe, direct, mostly non stop and easy to follow routes that connect ever home, destination, or other place you might be to every other destination you might want to go. Successful road diets have been around this number.

A single lane roundabout has a surprisingly high capacity, even without right turn and sometimes T roundabout bypasses. With at grade bicycle crossings they can have up to 1500 motor vehicles per hour, for a total of 36 thousand per day. Without at grade bicycle crossings, this can happen either with grade separation or a lack of any need to put a bike crossing near the roundabout, or at least not on a crossing, it can go up to 1750 per day, for a total of 42 thousand. For a single lane roundabout, I'm cool with that.

So what? Don't our roads have too much volume for that?

Actually no for the most part. Yes there are some roads where it would be ill advised to narrow it to a single lane or use a single lane roundabout, but a large number of roads can be narrowed successfully.

Some intersections do not have the space for a single lane roundabout without obtaining private property. So how to deal with that? Well, in many cases, a mini roundabout with similarly shaped bicycle paths around it as with normal single lane (non annular), but with the circle in the middle traversable, low and small and the roundabout being much smaller often works. It has the expectation that you can go over it if you are a truck, bus, pulling a trailer or for some reason need the central island to go anywhere, but most traffic is comprised of private cars or smaller vans. And in many cases, the buses can be re routed away from mini roundabout locations, not all, but some, and trucks can be regulated, perhaps no longer than 10 metres and no heavier than 7.5 tonnes (7500 kg), and school buses would be mostly a thing of the past because all the kids are on their bicycles, walking or taking the city bus, maybe creating exceptions for winter, and smaller minibuses 9 metres long perhaps for those with disabilities where it would be a challenge to use other means.

Parking on these roads, especially collector ones, is often not needed, especially given that on the arterials where there are destinations directly off the roads without a parking lot for it's own use tend to be in areas of the city where it's on the grid system, and in areas where there is even more potential for cycling, walking and transit than usual. Collector roads might have some parking left if there are homes and businesses without parking lots directly next to them, but can only be considered after cycling and walking both have safe and efficient places to be.

But this post is about how our roads are too big. How do we solve that? On collector roads, the ones we have now, can mostly have 1.75 metre (round up to 1.8 metres generally) to 2+ metre wide cycle lanes or 2-2.5 metre wide one way cycle tracks, sometimes 3.2-4 metre wide cycle tracks, we can widen the sidewalks, narrow the car lanes, the parking lanes, widen boulevards and planting boundaries, and make it more pleasant for all.

There are a couple other things needed to make them work right. They need bus stop inlets when you can, especially on the arterial roads that will be downgraded to 2 lane roads. Most arteries have more than enough width for this. Some routes even would benefit from completely separated lanes, but that is not always going to be the case. They still need separate bicycle paths away from cars. There is still considerable volume here, and there is still more than 30 km/h speeds. Speaking of speeds, the ideal speed limit for a distributor road in an urban area is 50 km/h. Pedestrian crossings will be made much easier, and bicycle crossings. The crossings can be set back at sideroad intersections, the speeds at the main road will be lower, and there will be median refuges, more zebra striped crossings, fewer traffic signals and less guessing what cars will do, and less guessing which lane a car is in, as there will often be only 1. The lanes will need to be narrower, as many roads are still too wide even with a single lane. There will sometimes be a median for most of the length, but not always.

Here is a nearby collector to my home: https://www.google.ca/maps/@53.4210446,-113.515195,84m/data=!3m1!1e3?hl=en. It is a little skewed because it's right near a school, but we can account for that. Especially the desire to cross as few roads as possible, provide good links to the park and route the path directly to the bicycle parking, and bypass all of the hullabaloo near the school parking lot. And the tidal waves of bicycles. The parking near the school is not needed, there are no real destinations and there will be a parking lot at the school. There are no homes within hundreds of metres directly affronting the road, and it creates a risk to children, cyclists and creates a sightline hazard. The width as I measured at the bus stop is 21 metres wide. Lets create a cross section to fairly account for it.

Here it is:

It has a 4 metre wide cycle path on the south side, near the school, a 5.6 metre wide roadway, 2.8 metre wide lanes per direction, a 2.6 metre wide bus bay inlet, a 2.9 metre wide bus stop waiting area, a .5 metre wide row of plants, maybe with a chain link fence between cycle path and sidewalk, a 2 metre wide sidewalk on the south side and a 1.9 metre wide sidewalk on the north side, plus a 1.5 metre wide tree boulevard on the north side. It creates a design with bus stops that doesn't obstruct any kind of traffic, cycle or motor vehicle, it has room for safe crossings of the road and cycle path, when it is not a bus stop, the cross section can look more like this: 

Here is another example on collector roads. It has 19.9 metres of width, sidewalk to sidewalk, link to it here: https://www.google.ca/maps/@53.4133445,-113.5315215,100m/data=!3m1!1e3?hl=en. It's not near any major destination, and the intersections on either side are numerous, so one way cycleways are more preferable, and there aren't really tidal flows. There are houses directly next to the road, so I will keep some for the residents. It's less busy, but still has a respectable amount of traffic, about 6 thousand per day. It can be redesigned like this: 

Those are just some collector roads. Let's look at arterial roads now. 

This is Rabbit Hill Road. https://www.google.ca/maps/@53.4565601,-113.5656929,3a,75y,355.54h,80.57t/data=!3m6!1e1!3m4!1sq433H2lRFbdU1uE-jJ8SaQ!2e0!7i13312!8i6656?hl=en. It is a 60 km/h divided 4 lane arterial road with about 16 thousand cars per day, the peak hourly volume has about 1300 cars per hour, both directions. That volume means that there is no need for a second lane. Add some roundabouts, they can't be put everywhere due to the volume on the intersecting street, 23 Ave comes to mind unless we build a turbo roundabout somehow, Terwillegar Drive should be a freeway as it was intended to be, and is designed for that, but in the meantime, traffic lights will be needed. For the interchange ramps, which would probably be diamonds, the two remaining intersections could be roundabouts, probably single lane. I checked the public road intersections and all of them would fit a single lane roundabout. The rest would be a simple right of way crossing with a yield sign. 

Its cross section could look like this: 

It has a 4 metre wide bidirectional cycle path on the west side, with a 2 metre wide sidewalk and a 1 metre wide planting bed between the path and sidewalk, 3 metre wide travel lanes, a 3.1 metre wide median between the two directions, which will be ordinarily along this road, a 2.9 metre wide bus inlet at the stop, the platform is 3.5 metres wide, a 1.8 metre wide access sidewalk to the stop, a 2 metre wide tree boulevard between the sidewalk and stop platform, and 3 metre wide tree boulevards on the outskirts of the road. The 5(5.5 on east side) metre wide divides on either side of the road between motor vehicle lanes and paths/sidewalk keeps people subjectively safe near the 50 km/h (reduced speed limit, for it's own good, and is a safer speed here. Plus it makes it very clear that it is not a through road, but a distributor road linking neighbourhoods to neighbourhoods and neighbourhoods to main arteries like 91 St and freeways), and provides enough room that the cycling path does not need to bend out at intersections, or maybe slightly, by about 1-2 metres, but much less than normal, so that you turn 90 degrees or very close to it, go over a raised table and yield to the cycle path/sidewalk.

Many other roads can get this treatment too. The collection of 101 Ave, 106 Ave, 71 St and 84 St, even 50 St north of 101 Ave all work well for narrowing to a single lane per direction and most work for roundabouts. Some will have to be mini roundabouts due to space constraints, but given the volume it should be OK. I used to go to that area a lot. 106 Ave will have a traffic signal at a couple locations but a number can be removed in favour of roundabout control. 

40 Ave and 106 St both have way less traffic than the 19000 per day, 24000 with other improvements, cut off point for single lane roads and have low enough volumes where they cross paths, and also when 106 St crosses 29 Ave, plus when 40 Ave crosses 119 St, to have roundabouts. 119 St is busier, but still low enough in volume to have reductions and roundabouts. At 34 Ave it will work for a roundabout but cyclists won't be able to cross at grade without a signal due to the volumes, so either a traffic light assisted crossing or an underpass is needed unless the extra volume can be contained on right turn bypass lanes for at least one arm, preferably not the ones cyclists may need to cross.

Having single lanes as much as possible simplifies intersections. It makes it harder to misjudge which vehicle is in which lane, which while that's easier to do during daytime, when there is a lot of traffic at once, traffic switching lanes, traffic turning right that quickly wants to turn left and vice versa, it can be really difficult. It's a challenge when I make a right on red at Ellerslie Rd sometimes from a collector road at night. There is simply more snow to remove and ice to de salt too. Collisions can happen via sideswipes and side crashes along straight stretches of road more easily. And when human brains are given the capability of making mistakes, they will inevitably make mistakes at some point. It also takes up many more resources, asphalt uses tar remember, than just planting grass. 

We can do even better with roundabouts being the common way to connect larger and busier roads as much as possible. The safety is better, a low angle Y collision at something like 25-30 km/h is likely to only cause minor property damage and no injuries, even to babies, than a T bone crash or head on at something like 50-60 km/h. As Minutephysics said, an average car at 60 km/h has the energy of a stegosaurus being dropped from a 3 story building. And it saves on the fuel and environment due to the reduced need of stopping and idling, plus the use of less asphalt. We even use less electricity to power it, we only need nighttime lighting with roundabouts, you need nighttime and traffic signal control electricity. 

And many roads can have their volumes reduced by modal shift onto cycling, walking, and transit use. Many roads already have the low enough volumes. How about we make them only as they need to be and not be wasteful, and maybe let the traffic lights pick on volume closer to their size? 

No comments:

Post a Comment

Thanks for commenting