Examples of Structures built and construction techniques used on the North Shore, North Vancouver, British Columbia, Canada.
Most well constructed trails in the North Shore have a lot of ladder bridges and rock work. If you can do good bridge and good rock work you have the basics of a really sweet trail. For example, good rock work makes for a nice bombproof transition from a big gap jump; or a rollout from a steep drop. Good transitions are important to prevent huge ruts forming where everyone hits the landing.
This next part of the article shows examples of good ladder bridges and good rock work.
GOOD LADDER BRIDGES
This picture shows a good cedar bridge that will be here for a long time. The bridge crosses a swampy area. The rungs are close together and big. The ends are cut evenly. You can't even fit a little pekinese through the holes in the rungs! It is a nice looking bridge that looks like its been made with some pride.
The next picture below shows that the bridge itself is suspended out of the muck and is pretty easy to ride. Even the skinny at the end is easy to get on; the corner flows into the skinny. After all, the goal is to let people ride the bridge out of the mud bog without dumping them into a puddle - so long as they are concentrating.
The picture below shows that the cedar bridge has been built high above the boggy area. Notice the supports; they were overbuilt so that rot wouldn't be a problem for a long time..
The next two pictures are examples of a cedar ladder bridge that is built to last. It is two seasons old in this picture and gets a ton of traffic. It's as good as new! Notice that it is built quite a bit above the mud. Notice also the additional support tacked on to the middle truss of the bridge so that the bridge does not sway..
GOOD ROCK WORK
Another VERY important technique is Rock Work. Most rock work is found at crucial entry or exit points onto stunts - for example, a beginning of a ladder or a skinny or more likely; a transistion landing from an air drop or a roll-out from a steep section. Rocks take care of places where people are more likely to put tire pressure or skid.
What this requires is the builder searching in the surroundings for the biggest rocks he can carry, placing them in the path of the rider and making sure the rocks don't move. It is very important that the rocks DON'T MOVE when they are laid down. Any movement will be amplified as riders ride over them and the rocks will be dislodged. The best builders must have played with a lot of LEGO when they were kids.
This picture shows a moderately steep section where the organic soil has been excavated then the builder has found huge rocks and buried them in the ground. Then a layer of sandy "gold" coloured soil is added between the rocks. With some skill, luck and time; the soil turns into a very hard almost-cement consistency and anchors in the rock. Unfortunately, you can see on the inside of the rocks a trench is forming indicating that people are avoiding them. RIDE THE ROCKS.
This picture below is another example of rock work.
After this drop, rocks have been placed for the rider to ride down. It is possible to roll right off this line and make the drop. However, when it is muddy, a huge mud hole forms swallowing up the front wheel and pitchforking a rider headfirst into the puddle.
Unfortunately putting rocks there dumbs down the drop. Without the rock, the roll-over from the root was bigger and more challenging but it got really eroded. At the expense of dumbing down this drop, the rocks prevent a mud hole from forming after your front wheel lands below the drop.
Note the alternate log line rollover drop to the left of the picture. That line doesn't flow as well since the rider has to turn on to it. However it is doable and is preserved..
If you build a ladder ramp, placing rocks in the landings will also prevent a hole from forming. Unfortunately, the picture below shows that riders are avoiding the rocks that were placed in the landing. Part of the reason for this is the logical flowing line off this ladder and on to the next section of trail actually makes faster riders cheat to the right of the ladder ramp and therefor, to the right of the rocks. A gouge will form here that will puddle in the winter. One way to correct this might be to make the ladder bridge narrower and force the riders on to the rocks or to move the rocks.
You cannot control rider habits but you can certainly play with their minds.
This next picture below shows a section of trail that was an otter chute not two years ago. It was loose, steep and not very fun to ride down. The builder placed rocks on the trail, and then placed drainages cribbed by wood built in his trademark drainage channels. One person did this work! Kudo's to Dean.
This picture is in the 'steeper than it looks' category.
This next picture below shows a really steep section going down, with a ladder at the bottom that keeps you above a river that flows down the trail when it rains. It is way steeper than it looks. You can see where Dean has raised the left section of trail at least 3 inches then banked it a little so it drains off on to the right channel. You can also see where he has placed in branches to anchor the rocks he has bedded into the trail surface on the left. Now this is quality!
This picture belows shows the view looking back up this section of trail
This next picture below shows steps built out of cedar placed in the trail to help anchor the soil. The steps themselves are anchored by the rock. While this section might look a little like overkill it is important to note that this trail has an extraordinary amount of traffic. Moreover most of this traffic are beginner riders who are much more likely to skid and mess up perfectly good trails.
The picture below is a closeup of the rocks cribbed with wood.
This picture below is is Dean's signature drainage. He digs out a hole bracketing the trail, borders the sides with cedar, then nails cedar rungs above the drainage.
Unfortunately, you can see riders avoiding riding over the drainage. If people continue to do this a rut will form here causing water to erode this section. I can not understand why anyone would be scared to ride over the drains! There is no accounting for rider incompetence! Maybe some punji sticks are in order.
The next picture shows the starting process of armoring a section of trail. You dig a big hole to get rid of all the organic black soil that becomes gooey mud, then you pile lots of rocks in the hole. Start with big rocks and end with smaller rocks.
Walk the trail when it rains so where you know where puddles will develop.
If one end of the rock bed is close to a dropoff then ideally you want to crib the rocks within wooden supports, then layer mineral dirt over top of the rock to cement them in. This is what the picture below shows. If the rock bed is in the middle of the trail then just fill in the rocks with "gold" sandy dirt.
The next two pictures below are classic example of a rock bed cribbed in by logs and branches on either side.
