I'm looking for opinions on what a guy should be looking for in a double drum roller... be mostly looking at large parking lots, city streets and maybe some larger jobs. Thanks in advance.
It depends on how much (and what kind) of experience your operator has. Larger static (5 - 7 ton) rollers with split front drums are easier to operate and harder to mess up the mat with as opposed to articulating (vibratory) rollers which can "scar" the mat more easily and can break down the aggregate in the asphalt. It would also depend on the type of mix you usually work with (does it have a high crush content?, what is the bit content? what size aggregate is in the mix?, is it a superpave or marshall mix?). I've personally found that the most diverse roller we have right now (we use it on parking lots, and on streets as a finish roller) is a mid size caterpillar vibratory roller - CB32. If you find your self doing more roads then parking lots then I'd suggest something larger like a hypac C766ish 10 ton roller with a 3-5 or 5-7 static roller (that can also work on parking lots). My personal two favorite rollers we have in the fleet right now are the 2 CB32s and 2 dresser 708s (yeah they're old but it's a rock, we've had it for about 16 years now and never had a single problem with them).
If you're looking for an asphalt roller that is suitable for bigger jobs,A Bomag BW284AD might be a suitable size for it.If you're even looking for a vibratory asphalt roller that has oscillating vibrators in it,Hamm would be the only brand makes the vibratory rollers with the oscillation units in it.The oscillating vibrators reduces the already compacted mat from getting damaged while rolling on the newly uncompacted mat.
It obviously has to do the type of work you're into but as fast as paving specs change (around here, at least) be sure to plan ahead. Some of the best mats we've laid were with an Ingersoll DD110 but that machine is old and tired now, going to auction next week but not sure how much can be got for it. We're running Dynapacs now but we got into a situation where the spec/plans called for a 3" mat with some stiff mix and we simply had hell getting in place density and had to get a bigger roller (from a CC522V to a CC722) We don't pave all that much, just enough to keep one crew busy. We have a good relationship with several contractors who specialize in it. The Dynapacs do the job, especially the big one and we very seldom have problems with them but they are special use machines that get extra attention. Reliability is a must....having a key unit go down and losing mix is a really bad day. The other Dynapacs we have, are a mixed bag....the newer single drums are very good but the older, low hour 3 wheel finishers are awful, hard to get parts for and no one wants them if they can get an old school Ingram 3 wheel.
If you want a roller with high frequency/low amplitude and high amplitude/low frequency option,CAT actually has an optional feature on the 10 to 15 ton asphalt rollers called the Versa Vibe.That option allows roller operators to set the vibration settings on a high frequency/low amplitude or high amplitude/low frequency mode all in one roller.