John Hoang P.E. ADOT Traffic Engineering Group Phoenix Design Section 1
Saw-cut groove in conjunction with (removable) temporary tape application Why should we saw-cut & use temp. tape? Would it be cost effective? 2
Major Reasons Minimize the damage of the pavement surface. Reduce the confusion for motorists. Cost saving compared to resurface the entire roadway. 3
Issue: Many scarred areas after HOV lane was built. Solution: Resurface the entire roadway. 4
Experimentation 3 temporary tape manufacturers: (3M, Advance Traffic Markings & Brite-line) 2 different types of tests performed Longitudinal (parallel to direction of travel) 5
Transverse (accelerated test that is perpendicular to the direction of travel). (Purpose: Testing temp. tape at the extreme condition to find out if it s able to withstand the heavy traffic and still easy to be removed). Testing periods: 6 months & 12 months 6
Removal In the summer after about 6 months All 3 different tapes come off relatively easy. Time to remove each 10 skip is between 15-45 sec. In the winter after about 12 months All 3 different tapes are much harder to remove. Time to remove each 10 skip is increased to between 45-115 sec. (Tape manufacturers recommended not to have temporary tape down >12 months). It would take about 10 minutes to remove a 300 long segment of temporary tape with some breakage involved. Note: All temporary tape removals are done by hand. The best hand we had out there.? 7
Leading by example 8
Implementation Saw-cut groove method in conjunction with the temporary tape application were implemented on the 101L and 202L HOV Design Builds. 9
Where to use continuous temporary tape and paint When temporarily shifting striping during construction Temporary tape shallbe used if installed on future travel lane pavement. Paint can be used in the gore and shoulder areas. 10
Solid temporary tape on future travel lane & paint in shoulder area. 11
After TCB s are installed with saw-cut groove and temporary tape are in placed Before Construction During Construction 12
During construction The temporary condition lasts between 9-18 months depending on the project. Speed Limit is lowered to 55 MPH throughout the construction area. Solid temporary tape is required for the transitional areas of both entrance and exit. 13
Transitional Areas using temporary tapes On Entrance On Exit 14
Obliteration Obliteration Equipment Types: Saw-cut Hydro-blast (water-blast) Per ADOT specification, all obliteration equipment shall have built-in vacuum recovery system. Operator& Inspector are the keys to asuccessful obliteration process. Operator: Adjust speed, nozzle size, water pressure Inspector: Make sure no excessive damage to pavement surface per ADOT specification. 15
A few different types of saw-cutting equipment were used Goal: To smoothly saw-cut permanent pavement markings. Note: Saw-cut equipment must have diamond blades. (see ADOT specifications for more details). 16
Saw-cut Groove Dimensions: Depth of saw-cut Depth is between 80 mils 120 mils (thickness of a nickel). 17
Width of saw-cut Width is about 7 +/-.25 and 13 +/-.25 for skip line and gore stripe respectively. 18
Length of saw-cut Approximately the length of a skip line (10 ). 19
There are 2 hydro-blasting machines that are most often used in Arizona. Stripe Hog Water Blasting Technologies 20
Star Jet -NLB Corp 21
Stripe Hog and Star Jet are at work together 22
Obliteration Time & Cost Comparison: It takes between 30 sec to 60 sec to saw-cuta 10 skip. It takes between 15 sec to 30 sec to hydro-blasta 10 skip. It costs about $.05 more per lineal foot ($.50 per 10 skip) to saw-cut compared to hydro-blast. (Saw-cut groove has much, much smoother surface for future permanent tape installation compared to H2O-blast). It costs about 3 times more to use the temporary tapes compared to temporary paint. (Temporary tape is much more reflective compared to temporary paint so added safety may be increased using tape). It costs about 10 times more to resurface the entire roadway compared to using saw-cut/temporary tape. 23
After Construction After the completion of the HOV lane construction, all lanes are shifted back to the original locations, 3M-380 Stamark permanent tape will be installed within the saw-cut grooves. 24
HOV lane is built and opened. Permanent tapes are installed in the saw-cut areas. No scarring is visible. 25
Completed Projects Comparison Withoutsaw-cut grooves and temporary tape Withsaw-cut grooves and temporary tape 26
Lessons learned Temporary tapes come off following immediate rainfall and/or too much water on the pavement. Option: P-50 adhesive may be an used if delaying tape installation is not choice. (Temporary tape manufacturers recommend a 24 hour window of moisture free before & after installation of tape). 27
Lessons learned cont Black paint over existing pavement markings. (ADOT specification states that painting over existing striping does not constitute pavement marking obliteration). 28
Lessons learned cont Excessive obliteration by ceramic blades instead of diamond blades. (Creating hazardous condition for motorcyclists). 29
Lessons learned cont Pavement was not free of debris when temporary tapes were installed. (ADOT Specification states that the pavement surface must be free from debris before any pavement marking installation). 30
Lessons learned cont Continuous auxiliary lane obliteration. (should only obliterate the 3 stripe and not touch/damage the 12 gap). 31
Questions? John Hoang ADOT Traffic Engineering Group 602-712-6694 jhoang@azdot.gov 32
More pictures Diamond Blades Not much water was collected in the saw-cut groove 33
Star Jet Obliterating Head Stripe Hog Obliterating Heads 34
Preferred aux. lane removal Not preferred aux. lane removal 35
Close up saw-cut shot Close up water-blast shot 36
Pavement Marking Removal Video Clip 37