My factories are demanding more workers. I currently have 5,500 citizens. Only 500 more and I will unlock high rise building, which will solve the problem nicely. Unfortunately, I have no more room for new residentials, which is what got me into this pickle in the first place.

Across the river! That's where I want to... Oh wait, no bridges. Would Cims mind swimming to work?
I have a few options. My city is currently built on top of a plateau and there is still some room in the valley by the river. If I do that, citizens who live in the valley need to drive through the industrial district to reach the highway. That seems less than ideal since the area isn't exactly light on traffic as it is.
Expanding to the area at the bottom is also not an option. I can't build an overpass, so I have no way to cross the rails and I'm also not allowed to make a second connection to the highway.
The easiest solution seems to expand into the area to the right. It's a bit farther from the central road than all the other neighbourhoods, but we'll just cross our fingers in the hope it'll turn out fine.
Now that's what I call living on the edge.
That one little expansion is enough for 500 extra citizens, so now I unlock high rise buildings. The rules of the challenge dictate that I build no new zones until I have converted all my existing ones to high rises. I learned in a previous town that replacing all low rise residentials with high rise residentials at once is a Really Bad Idea, so I start out with only a couple of zones.
Don't get used to the peace and quiet. It won't last long.
After a while the new buildings are done...
If the cargo trains start passing by, I'm going to have to build some really high sound barriers.
...which solve the labour problem...
It's dull, it's dirty, and it's dreary, but at least a lot of people work there now.
...but leads to some extra traffic.
Well, that was predictable.
Also, shit happens.
I want to wake up in a city that always reeks.
I built a cargo station at the edge of my industrial area, so that my city can now transport cargo by rail. This should get rid of the traffic jams at the entrance of the city. In fact, it does, but I'm not entirely sure my traffic problems are actually solved.
If only we could export traffic jams; we'd be rich!
Oh well, I'll leave it for now. In the meantime, I still have some rubbish complaints.
How many days of piled-up garbage would it take to fill one high rise building?
Nothing an extra incinerator can't fix. I have heaps of cash by now, so I can solve these pesky little service problems by just throughing more money at the problem. Works like a charm!
Soon, I will have to upgrade my factories to office buildings, which requires well educated citizens. I build a couple more schools and a university.
Can someone do research on how to pave roads?
Next up is a metro system. The tunnels have to take a bit of a detour at one point, because the slope is too steep. Apparently, my unadventurous citizens don't like a rollercoaster ride to work.
If the rails aren't laid on gravel, is building a metro system cheating?
It would kinda suck if you take the metro to work and still have to walk a mile to get to your place of employ, so I create a bus line in the industrial area. The road layout in that area is a bit loopy, so I can't cover it all with one bus line, but as soon as I connect some of the factories to the public transport system, the others start feeling left behind.
Yeah, I didn't no what that icon meant either until I clicked on the building.
A few extra bus lines later, everyone is happy.
Traffic at the entrance of the city is increasing again. I also notice that a lot of citizens are walking to work, but they have to cross the road to get there. Of course, they pick the most inconvenient, jam-inducing spot for that. Those Cims are nothing if not predictable.
I bet my law-abiding citizens are all called Murphy.
I can't build elevated walkways, because bridges are not allowed in this challenge. I'll just ignore the pedestrians for now. Instead, I'm going to try to create some better roads for the car.
What if I split the traffic early? As soon as the cars come into the city, the have to pick the road that takes them to the place they need to be: one entrance road for every neighbourhood.
This traffic pattern is called: the hand that feeds.
Going into the city is neat and tidy now, but the problem is leaving the city. I can't build one-way streets so traffic that leaves the city uses the same roads which leads to problems. I don't know if it's worth trying to fix this. I'll just remove this stuff and try something else.
What if I build one long bypass around the city and connect each neighbourhood to the bypass separately? Since the highway connections are one-way, the bypass will effectively be one-way. I ban heavy traffic from the residential areas, so traffic to the factories has to take the long way round. Citizens can drive to work using the central service roads, but if they want to leave the city, they need to use the bypass again.
She'll be coming round the mountain when she comes. She doesn't have a lot of choice, really.
Interestingly enough, I now have a road that leads directly from the highway to the valley, so I guess I could have build houses there after all. Also, while building the bypass, I discover that you can cross the railway at ground level: no overpass required. So yeah, that area at the bottom was also an option. I based my decision on nothing but faulty information. Still, it seems to work out fine.
In fact, this works better than I expected! Services improve and traffic improves, until I discover that donut cars and box trucks are still driving through the residential neighbourhood, even though their destinations are factories. I guess they don't count as heavy traffic.
Can someone explain to these people the difference between the shortest route and the fastest route?
The traffic in the neighbourhood itself isn't even that busy, but the road to the industrial area is completely jammed. I build a second road out of the neighbourhood and now traffic that wants to go north splits early from traffic that wants to go south and that mostly fixes the problem.
There's still a little bit of congestion at the entrance of the industrial area, but I can fix that in the same way: an extra road and the traffic splits early according to where in the area they want to go. All problems are solved now.
Yeah, baby! This gravel thing is easy!
Well, unless you don't like noise.
Sorry, can't hear your complaints over all this noise.