Final Acceptance of a New Span-Wire Intersection
Final field inspection of a newly constructed four-leg span-wire intersection. The major street is posted 45 mph with two through lanes in each direction; the minor street is posted 30 mph. The contractor installed 8-inch vehicle signal heads on both major-street approaches and 12-inch heads on the minor-street approaches. The pedestrian crossing across the major street is 64 feet curb to curb and has countdown pedestrian signals; the flashing DON'T WALK interval is timed at 14 seconds and the WALK at 7 seconds. One overhead major-street signal head is mounted with its bottom 16 feet above the pavement; the adjacent head is at 14.5 feet. The accessible pedestrian pushbutton on the northeast corner is mounted 40 inches above the sidewalk, but its audible tone does not operate. The contractor's test report states that all vehicle and pedestrian calls were verified, and the contractor is requesting final acceptance and release of retainage today because lane-rental charges begin tomorrow.
1. Which observed conditions are standard violations and which are acceptable? Explain the basis for each conclusion.
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Treat each item separately and tie it to the governing standard rather than to the contractor's test report.
- 8-inch heads on the 45 mph major street - violation. MUTCD requires 12-inch vehicle signal indications on approaches where the posted speed exceeds 40 mph. The minor street at 30 mph may use 8-inch heads, so the 12-inch heads there are acceptable (larger than required is not a defect).
- 16-foot mounting height - acceptable. Vehicle signal housings over the roadway must have the bottom of the housing at least 15 feet above the pavement. Sixteen feet is within the normal range.
- 14.5-foot mounting height - violation. The bottom of that housing is below the 15-foot minimum over the roadway.
- 40-inch pushbutton - acceptable. Accessible pedestrian pushbuttons are normally required between 15 and 48 inches above the sidewalk.
- Inoperative audible tone - violation. The accessible pedestrian signal is not providing the required audible indication, so the corner is not fully functional.
- 14-second pedestrian clearance - violation. The clearance interval does not match the crossing distance at the required walking speed, as calculated below.
The contractor's call-test report does not cure dimensional or equipment deficiencies; inspection is not a paperwork review.
2. Calculate the required pedestrian clearance interval for the major-street crossing and state the corrected timing. What else must be verified about the countdown signal?
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Use the standard walking speed of 3.5 feet per second for the pedestrian change interval:
- 64 ft ÷ 3.5 ft/s = 18.3 s, rounded up to 19 seconds of flashing DON'T WALK.
- The 7-second WALK interval is separately acceptable; it does not count toward the clearance distance.
- Total pedestrian phase would therefore be 7 s WALK + 19 s flashing DON'T WALK = 26 s, followed by the steady DON'T WALK during the vehicle clearance interval.
The existing 14 seconds is about 5 seconds short of the required 19 seconds, so a pedestrian entering at the end of WALK could still be in the roadway when the conflicting green begins.
For the countdown signal, verify that the countdown begins at the start of the flashing DON'T WALK and reaches zero at the start of the steady DON'T WALK. Confirm that the controller is not truncating the pedestrian change interval because of a vehicle call or coordination force-off, and that the countdown numbers are visible from the far side of the crossing. Also verify that the pedestrian signal is coordinated with the accessible pushbutton and that the audible tone operates for the full WALK interval.
3. What is your acceptance recommendation, and what documentation and next steps are required before the contractor is paid?
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Do not recommend final acceptance or release of retainage. The intersection has at least four deficiencies that affect safety and standards compliance: the 8-inch heads on the 45 mph approach, the 14.5-foot mounting height, the short pedestrian clearance interval, and the inoperative audible tone. Lane-rental charges are a contract-administration issue; they are not a reason to accept noncompliant work.
Issue a written punch list with each deficiency, the governing requirement, and a required correction date. Require the contractor to submit revised signal timing for the pedestrian interval and to re-test the accessible pedestrian signal. Re-inspect the corrected mounting height and the replaced 12-inch heads after installation. Require an updated test report that includes the measured pedestrian clearance time and the audible-tone test, and require the as-built drawings and controller timing sheets to reflect the final settings. Withhold final acceptance until the punch list is closed and a follow-up inspection is passed; document all findings, photos, and correspondence in the project record.