17050 Bushard Street, Suite 200
Fountain Valley, CA 92708
(714) 848-8897
Technical MEMORANDUM
WIDE TRANSVERSE CRACK REHABILATION STRATERGY
EVALUATION
Cathedral City, CA
January 25, 2024
Prepared for:
Cathedral City
Engineering Department
68700 Avenida Lalo Guerrero
Cathedral City, CA 92234
Prepared by:
NCE
17050 Bushard St., Suite 200
Fountain Valley, CA 92708
(714) 848-8897
NCE Project No. 1261.30.2303
WIDE TRANSVERSE CRACK REHABILITATION STRATEGY EVALUATION
CATHEDRAL CITY, CA
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Introduction and Scope of Work
Nichols Consulting Engineers, Chtd. (NCE) was retained
by Cathedral City (City) to evaluate the rehabilitation strategies used by the City to address the wide cracks
observed by City staff in asphalt concrete pavement
within the Cove Neighborhood.
NCE’s scope included a site visit, gathering information regarding the rehabilitation methods used by the City
staff to address these wide transverse cracks, discussion with the City staff on the performance of their
rehabilitation techniques and providing recommendations on which strategy should be used going forward based on performance.
Please note that no material or field testing (except a site visit) was included in NCE’s scope of work. Furthermore, NCE’s evaluation of the rehabilitation techniques used by the City was based solely on visual observations in the field. The performance of the rehabilitation techniques to implement wide crack repairs was based on feedback
from the City staff and engineering judgement. Lastly, NCE’s scope of work was limited to the evaluation of these rehabilitation techniques of these wide transverse cracks in the Cove Neighborhood.
Field Observations
NCE staff conducted a field visit on December 1, 2023. The primary objective of the field visit was to observe these cracks and the performance of the repair strategies (if applicable) in the field. Images from NCE’s site visit are shown in Figure 2.
The main takeaways from the NCE’s field visit can be summarized as follows:
• The transverse cracks typically extended the entire pavement width. • The width of the cracks ranged from ~1.25-4 inches.
• The spacing between consecutive transverse cracks varied from 10-160 feet.
Figure 1. Cathedral City
Neighborhood District Map
WIDE TRANSVERSE CRACK REHABILITATION STRATEGY EVALUATION
CATHEDRAL CITY, CA
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Figure 2. Four Locations from the Site Visit on December 1, 2023
WIDE TRANSVERSE CRACK REHABILITATION STRATEGY EVALUATION
CATHEDRAL CITY, CA
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Information Obtained from the City
Pavement Structure: The City staff informed NCE that the existing pavement within the Cove Neighborhood where these wide cracks were observed typically consisted of 4.5 inches of asphalt concrete (AC) pavement over native subgrade.
Rehabilitation Strategies: To address the wide transverse cracks the City has used the following two strategies (detailed in Figure 3). The details provided below are based on the information provided to NCE by the City.
Strategy 1: Remove top 2 inches of AC (typically 1 feet on either side of the crack, 2 feet total) across the entire pavement width, clean and fill the crack with 0.5-inch gradation AC (PG 70-10), place a paving fabric, and place 2 inches of 0.5-inch gradation AC (PG 70-10).
Strategy 2: Remove top 2 inches of AC for 2 feet on either side of the crack (4 feet total); Sawcut the entire pavement depth (~4.5 inches) at a distance of 1 foot on either side of the crack and remove material, apply tack coat on all the exposed surfaces, place a 2.5-inch lift of 0.5-inch gradation AC (PG 70-10) over subgrade; place paving fabric, apply tack coat, and place 2 inches of 0.5-inch gradation AC (PG 70-10).
Figure 3. Rehabilitation Strategies
WIDE TRANSVERSE CRACK REHABILITATION STRATEGY EVALUATION
CATHEDRAL CITY, CA
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Comparison of Rehabilitation Strategies
As noted earlier, Strategy 1 involves replacing only the top 2 inches of pavement and leaving the bottom 2.5 inches of cracked (if crack exists to the bottom of the asphalt concrete) pavement in-place. This approach is more economical, however there is a possibility of the crack reflecting through the new overlay and fabric which was observed (see Figure 4) by NCE staff in the field.
Strategy 2 is a more intensive treatment as compared to Strategy 1. In essence it is a T-Cut and patch which ensures that the entire depth of cracked (if crack exists to the bottom of the asphalt concrete) pavement is removed. Additionally, a T-Cut ensures that the pavement has a joint to release the stress that will be built up in the pavement structure due to thermal expansion and contraction of the AC. Based on verbal communication with City staff, no cracking or pavement uplift was observed in locations where Strategy 2 was used in one year of service.
Figure 4. Reflection Cracking observed in Strategy 1 Patches Conclusion
Based on the field observation and discussion with City staff, NCE recommends the following:
• Use Method 2 (T-Cut and Patch) to repair wide cracks as observed in the Cove Neighborhood. Based on the discussion noted above, it is a better treatment than Strategy 1.
• Going forward, City staff should monitor these patches for failures. Reflection cracking at the pavement cut edges are also a concern and should be monitored.
WIDE TRANSVERSE CRACK REHABILITATION STRATEGY EVALUATION
CATHEDRAL CITY, CA
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• The existing pavement between two successive patches should also be monitored as there is a possibility of new transverse cracking occurring between the two patches. • City should monitor patch construction to ensure that adequate compaction effort is made on the AC repair.