How are workers supposed to dig into the roads to install cables, lay need sewer lines/etc?
It's a different basic idea. I'm not sure how wise the idea is, but I can definitively tell you that they have thought about your concerns.
Here's how a solar roadway install would go:
First, dig up the old road, and install a mounting frame for the modular panels. Along one side of the road is a special underground service tunnel, and bundles of heavy cables run along that; this is the electrical bus, which lets multiple solar panels aggregate their output. Also in the special tunnel is the designed drainage, so that when it rains there is some place for the rain to go, and it is possible to install electric pumps to make sure the rain goes where it needs to go. The web site calls this the "Cable Corridor". One of the claimed benefits is this lets electrical transmission wires be conveniently underground by the roadway, instead of up on poles where winds can bring them down.
If one of the solar road modules is damaged, or just stops working correctly, that one module is removed and replaced with another off-the-shelf module. The initial install will cost more than an ordinary road, and the modules cost more than an equivalent volume of asphalt or concrete, but the labor of swapping a single module is going to be massively less than repaving a pothole. I reckon that to fix one panel you would just need one or two people and a pickup truck; for fixing a pothole in a normal roadway you would need a digging machine, asphalt machine, steamroller machine, and people to drive all the machines.
The surface of the modules is textured glass: textured to make it less slippery. One of my questions is whether the texture will be ground down and polished away after a few years of heavy use, leaving a horribly slick and dangerous glass surface. Another of my questions is how often the mounting frame under the road will need repair or replacement... it's simple to swap out modules, but not so simple to pull all the modules, dig up the frame, and lay a new one.
If the solar modules last longer than asphalt, this may turn out to be a much better way to go, but that seems like an incredibly big if.
It's also not clear to me why the solar modules should be the road, rather than a roof mounted high over the road, with sloped sides to keep rain and snow from accumulating on the roof. Why melt snow off the road when you can keep it off with a roof?
After I read up on their web site, I did some math, and I determined that according to their numbers, each solar module will make something like $2 worth of electricity per month. I don't imagine the lifetime of the modules will ever be long enough that they would pay for themselves. So this is a good idea only if the reduced labor costs of swapping modules (vs. repaving a conventional road) work out to a net savings. Best to treat the free electricity as a small bonus, rather than gushing about how if 100% of all roadways were replaced with this technology, it could power the entire USA for free. And the part on their web page where they actually propose rewiring everyone's homes to run on DC power makes me wonder if these guys have practical engineering experience or are just pure ivory-tower types in love with a pretty theory.
I guess if massive mass production occurs of these modules, the cost could come down a bit. If the mass-produced panels are cheap enough, if they last long enough, and if the cost of the initial install isn't too horrible, these might be economic. If, if, if.