Largest area with the nicest surface streets

[tradephoric]

Here's a better visual of why 1/2 mile spaced signals that stop both directions of travel along a 45 MPH+ arterial just don't work very well.  Here's the time distance for a 70 second cycle length for two signals spaced 2640 feet apart (1/2 mile):


A 70 second cycle would be the perfect cycle length to achieve dual coordination between these 1/2 mile spaced signals (when driving 50 MPH).  However, a 70 second cycle length is too short during rush hours as too much of the pie is waisted having to run the yellow and all red times.

Another problem is the 6-lane wide roads with double left turn lanes often have pedestrian crossing distances of over 130 feet.  With this length of crossing it requires at least 40 seconds of ped times for each thru phase... add to that the left turn phases and you get a required cycle length of 120 second just to be able to fit the peds and run the turn phases.

Anything over a 70 second cycle length, and you will start to achieve bad coordination for at least one direction.  Here's the time distance for a 140 second cycle:


A 50 MPH arterial with traffic signals stopping both directions of travel every 1/2 mile is simply a poorly designed arterial for moving traffic efficiently... and there's nothing a traffic signals engineer can do to achieve dual coordination on such a road.

[roadfro]

^ Some notes for those unfamiliar with the diagram above.

It's called a time-space diagram, and is often produced in commercial signal timing software (such as Synchro).

For this particular drawing, the horizontal axis is distance between signals and the vertical axis represents time. The lines between the two signal timings represent traffic traveling at a certain speed between intersections.

The goal of signal coordination is to try and get the band of traffic through one signal, allow them to travel a certain speed (usually assumed to be the speed limit), and time the next signal to allow as much of that original band to pass through as possible. If you've got simple signals with no turn phases, you can find a balance such that adjusting the offset of the next signal allows the bands in both directions to remain wide, allowing good two-way progression. If signals are too closely spaced and speeds are the same, traffic going one way or the other will hit the next signal at red and be forced to stop for some time.

It's kinda tough to follow with a simple diagram, but makes a bit more sense when you see a time-space diagram for a system of signals along a corridor and how the timing and progression bands interact.

[JREwing78]

How many states can boast counties turning primary county highways back to gravel? That's right. They couldn't afford to rebuild their decrepit paved roads; it was cheaper to turn then back to gravel than to patch them up.

lots of places do this.  bypassed old alignments come to mind.  US-10 in North Dakota was once completely paved, and now is gravel in many sections, because it is used primarily for ranch access, while through traffic uses I-94.

nothing wrong with not overmaintaining a road.

Except in Michigan's case, it was primary county roads that had the traffic to justify being paved (and then some). These weren't remote cowpaths in the middle of nowhere. Many of these directly connected towns and cities to each other. Traffic hadn't decreased, the area hadn't shrank in population, but the road budget dwindled.