Taken in 1968, this photograph shows a vehicle used to measure road smoothness.
Smooth roads are a top ADOT priority and they have been for some time, even back in 1968 when these photos were taken…
Not sure what you’re looking at?
The vehicle in the photograph at right houses a “bumpmeter,” more officially known as a Mays Ride Meter. It was used by the Arizona Highway Department (that’s what ADOT was known as, prior to 1973) to measure the smoothness of its roads.
According to the third edition of ADOT’s Materials Preliminary Engineering and Design Manual, the Mays Ride Meter measured the roughness of the pavement surface by recording the movement between the rear axle and the body of the car.
As you can see in the photos, the device was mounted in the trunk and actually gave a printout that correlated to the road’s bumpiness. The device was mounted in the trunk of the vehicle pictured at top (click photo for a larger view).
The manual, which was written after 1968 and may be referring to slightly newer technology from what is pictured here, explains that, “the roadway roughness is measured in one-tenth-of-an-inch increments (counts) by a transmitter that is rigidly mounted in the trunk directly above the axle. As the rear axle moves up and down relative to the car body, the transmitter rotates and provides the counts.”
ADOT still measures all the state highways for smoothness, however, the technology is somewhat more advanced than it was in the late 60s. Currently, ADOT’s Pavement Management Section operates a van equipped with a profilometer, a sophisticated instrument that works with an onboard computer system to measure smoothness.
The profilometer looks a little more high-tech than what we’ve featured today (it even has lasers!) and is definitely worth a blog post of its own … so stay tuned for more. It’s safe to say things have changed since 1912 when the Arizona Highway Department was first established. But you don’t just have to take our word … we’ve got plenty of pictures to prove it. We combed through our archives and decided to periodically post these photos from the past in a blog series we’re calling, “From the ADOT Archives.”