One of the most common recurring gripes I hear about road construction is that it seems like there's never any work being done on projects.  However, this is generally not the case.  Oftentimes, there is work being done that you simply don't see, typically underground or off-site drainage or other preparatory work.  That said, there are times when work sites are dormant as the result of a number of legitimate circumstances:

• Inclement weather or its after-effects
• Work cannot continue until concrete or pavement has cured
• The contractor is waiting on a utility adjustment or material delivery
• The workers worked the previous night and, by law, must be given time off to rest
• Something was discovered underground that wasn't in the plans and the contractor has to wait for a change order to be prepared and/or perform additional work to remedy it (this one happens quite often)

Why aren't projects worked-on 24 hours a day?
Construction on some mega-projects does continue round-the-clock (for instance, the 410/281 interchange).  However, most projects don't.  Doing so would require three shifts of workers, which would increase the labor cost of the project by at least three-fold (likely more since workers who work at night often are entitled to shift differential pay.)  This would drive-up the overall cost of construction not just on those projects, but also citywide since hiring that many workers would create a labor shortage, especially in the already-tight San Antonio construction labor market.  Given the existing highway funding shortfall and the reluctance of the public (that's you) to accept higher taxes and/or tolls, how can you want to increase the cost of construction projects any more?

Why not finish one project before starting another?
If highway construction were done one project at a time, it would take even longer to get things done.  First of all, what would be the boundaries of the "one-project-at-a-time" zone?  A specific freeway, a section of the city, the whole city, the county, the metro area...?  OK, let's say it's Bexar County.  Do you know how many projects there are in Bexar County?  Even working non-stop, the 281/410 interchange took three years to build.  Can you image how long it would take to build the half-dozen or so large projects typically underway in Bexar County at any given time if we had to wait three to five years for each one to be done before we could start the next, not to mention the plethora of smaller projects?  Besides being impractical, that's just plain nonsensical.  Projects don't take a long time because there are just a few workers that cycle around to the various job sites; if that were the case, then the one-project-at-a-time idea might make sense.  Rather, large construction projects simply take time to build.  They are complex, require an enormous amount of work, and all the while, traffic still has to be able to move through the area.  It's like trying to re-carpet your house while still using the furniture-- it substantially increases the time it takes to get the job done.  That's just reality.  On top of all that, construction costs typically increase every year, so waiting years to build projects just increases the cost to build them.

Why doesn't the state fine contractors who take too long to finish a project?
Actually, they do.  Nearly every construction contract let by TxDOT includes a timeline to finish the project and a provision for TxDOT to assess "liquidated damages" (i.e. a monetary penalty) if that timeline is not met.  Many projects also contain a bonus for early completion.