Road Construction: What to Expect?
Road HazardsRoad closures often take place during construction not only to protect our workers, but also the motoring public. There are many hazards to be aware of when traveling on a closed road. Some of these might be: Stock piles of material (gravel, blacktop millings, culverts, soil, ect), raised manholes/catch basins, workers, open trenches, fresh blacktop/concrete, parked equipment, trucks backing up long distances ect. Trucks and equipment frequently back up and if you don’t see their mirrors, the driver doesn’t necessarily see you. If you happen to be behind these vehicles, you should stay back a minimum of 200 ft and traverse cautiously. Please use caution when navigating through the closed road as hazards may change not only day to day, but hour to hour.
Typically, Cross Culverts (pipes that allow water to flow from one side of the road to the other) are replaced the year before the road is reconstructed/paved. This is done to allow for backfill to settle over the winter before paving to minimize settling over the pipe. This settling causes a dip in the road which affects the ride quality of the new pavement. Often times one lane of travel is left open for traffic. A flagger will direct traffic through the open lane. Keep in mind that the excavator does swing out and can cross over the center line. Thus, making eye contact with the operator is good practice as they will generally direct you around the equipment when it’s safe to do so. This eliminates the possibility of the machine accidentally hitting your vehicle when it rotates. Similar to any ditching we may do.
Pulverizing is similar to milling, in that a large machine drives along the roadway, ripping up existing asphalt. Unlike milling, pulverization is the first stage in reusing asphalt as base to re-pave the same area.Pulverization leaves several inches of ground-up asphalt where old asphalt paving used to be. This makes it possible to then reform that asphalt into a solid surface. After the pulverizer has crushed the old pavement, a grader comes through to shape grindings. Many times, proper crown of the road is re-established to allow for better drainage and curves are super-elevated (banked) to counteract the lateral acceleration produced by tracking the curve. While the grader is shaping the road a water truck will be keeping the millings moist while multiple rollers compact the millings. These series of rollers (“Sheepsfoot” Roller, rubber tire roller, smooth drum roller) back up often so it’s important to give them space as you are traveling through the closed road. It is good procedure to make eye contact with the operator so they know that you are there and to receive any directions on where to travel on the road. Typically, about a mile of pavement can be pulverized and relayed by a grader per day.
After the existing blacktop has been pulverized or milled, it is then ready for new pavement to be layed. This is typically done in a two-step process called paving.
1. The first layer of asphalt called the “binder” is a coarser grade of blacktop containing a higher percentage of larger stones. These larger stones, when added to the asphalt mix, increases in stability. Typically, the entire binder is paved before the second phase (Top Mat) can be installed. After the road has been paved with the
2. The second layer of asphalt is called the “Top Mat” or finish mat. Top asphalt contains fine stone which makes it less porous than binder. This gives the asphalt a smooth finish. After the road has been paved with the top mat, intersections and driveways will be finished as well. Typically, a mile of pavement (one layer) can be paved/layed in one day.
How the Asphalt is Installed: Trucks haul asphalt from a “Hot Plant” where a combination of aggregates, sand, and oil are mixed and heated to a temperature of around 300F. The material is then loaded onto County trucks, tarped, and hauled to the paver at a temperature of around 280F. The paver then lays the blacktop at a uniform depth and width. After the paver lays the material a series of rollers compact the asphalt. The “hot roller” follows directly behind the paver and is the first roller to compact the asphalt. The “cold roller”, or finish roller, compacts the asphalt for the final time once it has cooled. Between the “hot roller” and “cold roller” will be a rubber tire roller. As in all phases of construction, make eye contact with the operator so he’s aware that you are there and keep a safe distance as equipment backs up/turns frequently.
• Avoid driving on hot asphalt as you may cause ruts in the fresh asphalt
• Go slow. There are numerous workers and machinery/backing trucks near the paver.
• Avoid sharp turns on hot asphalt. Turning sharp will tear the surface of the asphalt.
• Use caution when coming onto or off of the asphalt as often times there are lips/edges that are abrupt. These edges will sometimes “catch” your wheels if you aren’t paying attention.
After the road has been paved the shoulders (gravel at the edge of the pavement) must be brought to the height of the newly paved road. This is done with county trucks hauling gravel (3/4”) to the shoulder machine. After the shoulder machine has placed the gravel a roller compacts the gravel. This sometimes happens multiple times, or in lifts, to achieve desired compaction.
After the road has been shouldered the road will be line striped. The centerline will be painted first followed by the two edge lines (white lines). This is done at approximately 11 mph by the Paint Truck/Linestriper.
• There will be a truck with a message board behind the paint truck informing drivers what paint is wet
• Do NOT pass the line striping machine when it is painting the yellow centerline. This paint will track across the new road as well as cause permanent damage to your vehicle. The line striping truck will pull over to allow vehicles to pass at multiple points on the road.
• Do not pass the paint striper on shoulder while it is painting the centerline. Often times the shoulder that was just installed may have soft spots causing your vehicle to lose control.
• Paint will typically dry in about 10 minutes (depending on weather conditions). If you must cross the white or yellow line to access your driveway, do so slowly and carefully so that paint doesn’t get tracked onto your vehicle.
The process of installing signs can happen during any or all phases of the construction of the road. Signs are typically updated (reflectivity of signs tested) and replaced as needed. Updating of the signs includes: upgraded 4”x6” post to allow for proper height and distance off edge or roadway as well as spacing of the signs.
Project Completion/Road Opening
After all steps have been completed the road will re-open to traffic. All barricades and detours will be removed and traffic may resume its normal course.
Route and Seal (Crackfilling/Rubbering)Crackfilling is an essential part in maintaining our system of roads. After a road is paved it is subject to many different dynamics. It is caused by shear and tensile stresses in the asphalt layer brought about by traffic loads, change in temperature, expansive sub-grade soils, moisture changes, and existing crack and joint movements in the underlying pavement. Once the crack is open, moisture is able to reach the pavement’s subsurface and soften it, or freeze and expand it. Crackfilling will seal these cracks with a flexible rubber and not allow moisture/water to penetrate to the subsurface. By filling these cracks, it will increase the longevity of the road.
1. Signage/Traffic Control: Crews will set up signs (Road Work Ahead, One Lane Road Ahead, Flagger Sign) to alert traffic of the workers ahead. Typically, these work zones are 2 miles long so keep in mind that just because you don’t see any work happening immediately after the signs, doesn’t mean they aren’t further down the road
Rubbering operations will be typically done as a flagging operation which keeps one lane of travel open. The flagger will let you know whether to stop or continue through the work zone with a Stop/Slow paddle. They will also designate a lane to travel in. Stay in the lane in which the flagger designated until you see the last flagger. Please use caution when traveling past crews as they sometimes work very close to the centerline. It is important to stay in the designated lane to avoid driving over fresh rubber.
2. Routering: Cracks are typically routered (¾” wide x ¾” deep), or ground out, with a machine to remove deteriorated asphalt and remove debris that is wedged within the crack. This provides a clean, intact asphalt face for the sealant/rubber to adhere to. This also allows for the sealant (rubber) level to remain below the surface of the pavement protecting it from traffic and snow plow contact.
3. Dust/Debris Removal: After the router has come through to grind out the cracks there will be dust/grindings left on the road. Before a sealant/rubber can be applied this needs to be blown off the surface of the road.
4. Sealant/Rubber Application: After the crack has been routered and blown out, it is then ready to for a sealant/rubber to be applied. A machine heats the rubber to a temperature of 400F and is applied over the crack with a narrow band on each side of the crack. It is important to remember that the sealant/rubber
takes time to cool down and that driving on it before it is cool will cause it to lift up and possibly stick to your tires and/or track onto your vehicle.
• Stay in the lane that the flagger designated to avoid driving over sealant/rubber that hasn’t fully cured/hardened. Once you pass the second flagger you may follow his direction as to what lane to travel in and resume normal travel.
• Stay alert when traveling through the work zone as workers may be working close to the centerline/and or crossing the centerline with equipment. Remember, Cones = No Phones.• Often times at intersections, toilet paper is applied over the hot sealant/rubber to allow for traffic to cross. If you see crews applying toilet paper to an intersection, please be patient before crossing to avoid damaging the sealant/rubber or vehicle.
Sealcoating/Chip Sealing is a process in which a layer oil/liquid asphalt is applied to the road using a special spray truck. Immediately after spraying this asphalt, a layer of crushed gravel is applied by a spreader. The gravel is then compacted and
embedded into the asphalt by rubber-tired rollers. However, even with the high pressure rolling, some gravel will not become embedded in the asphalt. The new chip-seal surface can require up to two days to cure properly. After the curing, the loose gravel is swept off the surface. This may take several sweepings.
Tips:• During the application process
• Stay off the fresh liquid asphalt/oil. There may be a small gap between the tanker applying the liquid asphalt and the machine applying the chips (small stones).