Canarsie Pol: RHW-2 and Traffic Management on an Island City

My earlier post, Compact RHW-2 suburban interchanges on an island city, describes my three RHW interchanges on this island city, with closeup screenshots.  My very first interchanges using RHW!  

Traffic on this island city is a tad weird, because the only way on and off the island is by passenger ferry, and because it has a decentralised structure, with three commercial areas clustered around those ferry terminals.

1. Traffic should be lightest toward the centre of the island, with commuters in each part of the island heading toward their nearest ferry.
2. Inbound inter-city commuters are mostly contained within the ferry terminal commercial zones, two OWR-4 ferry loops, and one Fly-swat ferry loop.

I decided to use RHW-2 as my main highway in this island city, because it better fits the character of a bedroom community and little tourist island.  Dual carriageway would look out of place.  However, with RHW-2 having half the traffic capacity of 2 tile highway RHW-4, and 50% less capacity than the MHW, I may be pushing the limits of RHW-2 for this island, which is mainly zoned for medium density residential, with some areas planned to grow to high density residential later in the game.

This post is about the arterial roads and overall traffic management strategy for Carnarsie Pol, East New York.  See the following screenshot of my initial zoning, with my main highway RHW-2 highlighted orange, and all pieces of my arterial RHW-2 highlighted yellow.  I've discovered that RHW-2 is a surprisingly versatile road network, with many of the flexible features of the much lower capacity Maxis vanilla roads (RD-2).  Though RHW-2 and RD-2 are almost identical in many respects, the highway grade RHW-2 has 2½ times the traffic capacity of the RD-2, making it an ideal candidate for little arterial roads.

The weakest link in my main highway is a 3x3 OWR-2 central roundabout, circled red.

So versatile is the RHW-2, in fact, that I have to hold myself back from using it too much!  

Given the only drawbacks of the RHW-2 are no roundabouts, and no RCI access, it would be incredibly easy to put it in unrealistic places.  With much effort, I've restrained myself to only using RHW-2 as an arterial road in strategic spots, as follows:

1. Three "North-south" underpass/overpass roads, crossing my main RHW-2 highway.  Two of them full blown compact RHW-2 suburban interchanges.
    
2. The "south-bound" approach to the tiny 3x3 roundabout in the centre of my island (circled red), so that I could link in a MIS slip road to divert some of the traffic off that central little 3x3 roundabout.  That little roundabout is the weakest link in my main RHW-2 highway.
    
3. An odd-little curvy piece of RHW-2 highway, running "west" and "south" through my high density residential district, leading to the "western" diamond interchange.
    
4. Additional tiny pieces of "south-bound" and "east-bound" RHW-2 highway, immediately to the "east" of that weak 3x3 roundabout.

From a traffic capacity management perspective, these little pieces of RHW-2 are immensely attractive to sim commuters, because they allow 3 TIMES the speed limit of the regular suburban roads and avenues.  In cases 2, 3 & 4 above, the little pieces of RHW-2 encourage commuters to drive toward my higher capacity diamond interchanges, the "western" diamond next to the hospital, and the "eastern" diamond next to the police station, thus keeping them far away from the central dumbbell-ish interchange, and the weak 3x3 roundabout.

The suburban roads "north" of the weak 3x3 roundabout, are likewise shaped to encourage "east-west" traffic flow, away from that weak spot.

The suburban roads "south" of the weak 3x3 roundabout, are designed to allow backroad access to the "southern" ferry, again to pull traffic away from the weak spot.

The only two-tile networks on the island are my ferry loops, designed for maximum flow of inter-city commuter traffic, and high capacity handling of incoming tourist traffic.  The two OWR-4 ferry loops are carefully terraformed to allow expansion to three passenger ferries, or two car ferries ... an experiment I'm keen to try as my region grows.  

Surprises ... after 20 years in the simulator

Mostly, the traffic is looking really good.  Those OWR-4 ferry loops are worth their weight in gold, driving commercial growth.  No inbound commuters from the ferries, because the other cities don't know about little Canarsie Pol as yet.  I'll need to run each ferry-based city tile for a year so that they start coming in.  The Fly-swat ferry loop, on other other hand, didn't get much use at all.  I'm guessing that's because the Fly-swat ferry loop is AVE-4 based, with a speed limit of 50km/h, whereas the OWR-4 has a speed limit of 75km/h.  

That weak 3x3 roundabout is seeing lots more traffic than I was hoping.  The RHW-2 arterials I used to try to protect it made a little difference, but not much.  The backroad access to the "southern" OWR-4 ferry loop was much more useful, diverting 40% of the traffic that would have gone through the weak 3x3 roundabout ... except that most of that traffic would have gone down the MIS slip road, so not such a big win after all.   The only thing that saved my bacon was the NAM higher capacities for OWR-2!

One of the slip roads for the weak 3x3 roundabout was exceedingly useful, the other one scarcely useful at all!      I might get rid of it.

The main highway overpass was only marginally useful, with 65 cars and 34 bus passengers, but I'm keeping that one!  

These traffic levels will grow as Canarsie Pol grows, with more densely populated medium and high density residential.

The curvy piece of RHW-2 highway turned out to be quite the favoured route for freight, preferred over more direct roads, which bodes well for growing high density residential traffic in that area.

Finally, in Air Pollution view, what I call "liquid gold" (with the Clean Air Act ordinance turned off).  This screenshot points out the richest roads for C$$ and C$$$ commercial development.  This confirms the value of the OWR-4 ferry loops, even before there's any incoming ferry passengers.

The traffic along the main highway is also making me think that I might put LOTS MORE small commercial lots along the main highway (with RCI access from off-highway urban roads).