Section 3: Pre-installation Inspections
Anchor: #i1003353Introduction
Pre-installation inspection includes the inspection of the roadway and weather conditions, striping equipment, and marking layout immediately prior to installation of the pavement markings. Pre-installation inspection is important to ensure proper bonding between the marking and the roadway surface.
Anchor: #i1003365Surface Moisture
The presence of moisture on the pavement surface prior to marking placement will likely have a negative effect on the bond formed between the pavement marking and the pavement surface. The presence of moisture on the pavement should be checked whenever conditions are questionable. Presence of pavement surface moisture can be determined using either of the following two methods in accordance with TxDOT Specification Item 666.4.2:
- Asphalt or Concrete Surfaces — Place a 12×12 inch square piece of plastic wrap on the pavement surface using duct tape to affix the edges. Let stand approximately 15 minutes and check for moisture bubbles on the inside surface of the plastic. If moisture bubbles on the plastic are larger than a pencil eraser, then the pavement contains too much excess water. Notify the contractor of this condition and postpone all marking operation until the pavement is dry enough to prevent the large moisture bubbles from forming on the plastic.
- Thermoplastic Applications on Asphalt Only — Using roofing felt paper, place a 12×12 inch square of felt on the asphalt and install the thermoplastic material directly onto the felt paper. Let it cool for approximately 10 seconds, then lift the paper to check for moisture on the back side. If moisture bubbles larger than a pencil eraser are present on the backside of the roofing paper, then the pavement contains too much excess water. Notify the contractor of this condition and postpone all marking operations until the pavement is dry enough to prevent the large moisture bubbles from forming on the back of the felt paper.
Dirt and Debris
Debonding of pavement marking materials is most often caused by an unclean pavement surface. The pavement surface must be free of dirt, debris, curing compound (new concrete only), grease, oil, mud, dust, grass, loose gravel, and other deleterious material that could affect the bonding capabilities of the material to the pavement. In addition, if the material is being placed as restripe over old markings, glass beads and loose or flaking marking materials should be removed from the existing markings. A number of approved methods exist for cleaning of the roadway surface. These methods include: brushing, washing, compressed air, and high-pressure water. Pavement surface preparation should be performed in accordance with TxDOT Specification Item 678.
Anchor: #i1003402Air and Pavement Temperature
Under questionable temperature or weather conditions, the temperature of the pavement surface and ambient air temperature must be checked to ensure that the temperatures are in accordance with manufacturers’ specifications. Pavement temperature should be measured in accordance with Test Method Tex-829-B. Pavement temperature is often measured with an infrared thermometer. Different materials require different surface and air temperatures to achieve proper bonding or curing. Wind chills should always be considered when determining ambient air temperature. Wind speed also affects the accuracy of the drop-on bead application. Markings using drop-on beads should not be placed on days with excessively high winds.
Table 3-1 presents general guidelines taken from manufacturer or research recommendations. Note that these are general suggestions. Always refer to specific manufacturer’s temperature requirements if discrepancies arise.
|
Material |
Minimum Air and Pavement Temperature |
|---|---|
|
Water-Based Paint |
40°F |
|
Thermoplastic |
55°F |
|
Preformed Tapes |
Varies with manufacturer and adhesive |
|
Epoxy |
35°F |
|
Polyurea |
32°F |
|
Methyl Methacrylate |
35°F |
Anchor: #i1003418
Material Temperature
Many pavement marking materials are applied at elevated temperatures and have strict temperature requirements for proper application. Application temperatures vary among materials. Most thermoplastic materials must be heated in the kettles to approximately 410–430°F, although optimum material temperatures vary based on formulation. Material temperature should be verified with the striping contractor shortly before striping. Thermoplastic will scorch if kettle temperatures are too high. It may be less durable or may not retain beads if kettle temperatures a re too low.
Anchor: #i1003428Lateral Placement Guides for New Pavement Surfaces
Guides to mark the lateral location of pavement markings on pavement surfaces with no existing marking should be established according to TxDOT Specification Item 666.4.1:. Establishment of lateral guides is usually the responsibility of the contractor and should be performed in accordance with the plans or as directed by the Engineer. The location of the guides must be inspected for accuracy prior to striping. Markings must be placed in proper alignment with the guides according to the tolerances established in TxDOT Specification Item 666.4.1.
Anchor: #i1003440Striping Equipment
Striping operations usually occur as part of a moving or mobile work zone and as such, safety of the workers and the motoring public should be of utmost importance. The equipment associated with the striping operation must therefore be inspected prior to striping to ensure that the materials can be placed on the roadway in a safe and efficient manner. When inspecting striping equipment, inspect both safety items and production items as follows.
Safety Items. Inspect the following safety items:
|
Item |
Make Sure... |
|---|---|
|
Lighting on equipment (strobe lights on vehicles, flashing arrow panels, etc.) |
they are proper and working. |
|
Truck-mounted attenuators (TMAs) |
they are undamaged. |
|
Conspicuity sheeting on TMA |
it meets specification. |
|
Two-way radios |
they are working properly. |
Production Items. Inspect the following production items:
|
Item |
Make Sure... |
|---|---|
|
Spray nozzles on striping truck |
truck has 3 spray nozzles for the yellow material and 2 spray nozzles for white material. |
|
Vehicles |
they are not leaking fluids and appear to be in generally good working condition. |
|
Vehicles |
they have valid licensing and inspections. |
|
Work-zone signs |
they are in good condition and meet specifications. |
|
Gauges on striping truck (oil, kettle, thermometer, etc.) |
they are operational. |
|
Bead gun |
it is working properly |
|
Hoses |
they have proper insulation and are free of abnormalities. |
|
Agitator on kettle or melter (thermoplastic only) |
it is functional. |
|
Melting kettles |
they are thoroughly cleaned prior to changing colors. |
|
Drip-pan |
contractor has one on-site to collect material when flushing out the guns. |
In addition to the preceding equipment inspection items, TxDOT Specification Item 666.3: describes minimum production capabilities for striping equipment, which also must be a part of the inspection process.
Anchor: #i1003466Traffic Control
One of the most important safety aspects to a pavement marking operation is the level of traffic control that is provided at the job site. Consult the contract for the level of traffic control required at a given job site. Appendix B lists and provides a link to the traffic control standard sheets. The traffic control equipment, devices, and operation should be inspected before and during application to ensure functionality and safety.