Kicking the can down the road: balancing standards versus cost with city streets
May 16, 2018 10:39AM
By Cassie Goff
Asphalt rejuvenation is a fairly inexpensive method for maintaining the quality of roads. (Matt Shipp/Cottonwood Heights)
By Cassie Goff | [email protected]
Less than ideal roads and infrastructure were inherited by Cottonwood Heights from Salt Lake County when the city incorporated in 2005. Conversations, evaluations and attempts to maintain these roads have been ongoing ever since. As the city must prepare a final budget for the next fiscal year by June 19, pavement management has been a lengthy conversation.
A Resident Roadway Committee was formed to discuss strategies to address the growing concern of road maintenance within the city. They worked with consultants GeoStrata and Gilson Engineering, along with Public Works Director Matt Shipp and various members of his team.
“We went around the city and looked at the condition of each road,” City Engineer Brad Gilson said. Altogether, Cottonwood Heights has 114.9 centerline miles (a measure representing the total length of a given road from its starting point to its end point) and 252 lane miles (centerline mileage multiplied by the total number of lanes along the road).
The pavement management index (PCI) was used to evaluate these conditions. This index allows each road to acquire a rating between 0 and 100. A PCI rating of 100 would be a new or reconstructed road, while a PCI rating of 40 or below is considered a structurally failing road.
Only about 20 percent of roads within the city have a PCI rating over 75. Those are fairly new roads, such as Bengal Boulevard, and other residential roads within the city. Roads with a PCI rating around 85 are considered “good roads in good condition. They do not cost a lot to maintain and do not warrant expensive treatment,” Gilson said.
The majority of roads within the city have a PCI rating somewhere between 55 and 75. “These roads get a lot of cracking, especially on the seams. The cracks propagate from the cold joint,” Gilson said.
Such cracking can be found at the intersections of Fort Union Boulevard and Park Center Drive, which has a PCI rating of 70, and Fort Union Boulevard and 1300 East, which has a PCI rating of 65. In fact, most of Fort Union Boulevard is within this range, mostly with an average PCI rating of 55.
The remaining 20 percent of roads have a PCI rating under 50. Many have stretches with PCI ratings below 40. A stretch on Creek Road, before the intersection with Danish Road, in front of three different churches, received a PCI rating below 40. Another example of these roads is Alta Hills (approximately 3200 East and 8700 South). These roads are structurally failing with “many potholes, deep cracking, and they are very hard to drive on,” said Gilson.
Gilson explained that roads are made from a combination of first and second acidaffins, saturated hydrocarbons, asphaltenes and polar compounds, also known as asphalt.
Even though concrete can be used to create roads, most of the roads are asphalt. “We don’t use concrete because we have a lot of utilities under the road,” Gilson said. It’s much harder to cut into and repair concrete than asphalt is.
When designing roads, a few critical elements are taken into consideration, some of which are physical, including traffic and the related weight the road must withstand. If many heavy trucks are traveling along a road, it has to be designed to accommodate the truck traffic. Unfortunately, truck traffic has a detrimental effect.
“Europe has long-lasting roads because they don’t allow trucks to drive on local roads,” Gilson said.
Environmental elements are also taken into consideration, like snow and rainfall. These elements can quickly impact the lifespan of a road. Furthermore, when asphalt is exposed to sun, it oxidizes.
“Asphalt deteriorates by oxidation,” Gilson explained. Desiccation and hairline cracking follows oxidation. After asphalt has been exposed to the sun during the summer months, water from rain and snowfall trickles into the hairline cracks. The water freezes and thaws with the weather, creating much larger cracks and other deterioration.
Pavement maintenance is required when asphalt deteriorates. The most cost-effective ways to maintain roads are fog, slurry and mastic, and asphalt rejuvenation. More expensive maintenance includes crack sealing, microsurfacing and chip sealing, which are all methods to fill in cracks to keep water out. The most expensive road maintenance is an overlay.
“Over time, it is much less expensive to maintain a good road than it is to wait until an overlay, or worse, is required,” Gilson said.
The question the city council has to face is to what PCI standard all 252 lane miles should be held to, with the least amount of cost. They asked the Resident Roadway Committee to provide the council with a preferred methodology for approaching roadway maintenance and a repair program citywide.
“If we don’t do anything to a road in 30 years, it has to be completely redone,” Gilson said. “The best approach for addressing all roads is to treat each road at the critical stage before it drops to the most expensive category. A critical time for treating roads is when they are six or seven years old.”
The committee has considered many community values within their discussions, including efficient use of tax dollars; benefiting the majority; good roads in certain areas; public health and safety for all users; education for residents; public perception; supporting commerce; maintaining excellent quality of life and high property values through good roadway maintenance.
“Delaying work on road construction projects has a cost impact that is mindboggling. In five years, we can go from a cost-maintaining a road from 35 cents to $1 per square foot, to a cost that exceeds $4 per square foot. We can’t responsibly kick the can down the road on roads,” said Councilmember Mike Shelton.
The Resident Roadway Committee has asked consultants to re-evaluate some estimates brought forward. Once that is complete, the committee will make a recommendation to the city council. The council has asked for that recommendation no later than the end of May so they can accurately accommodate for pavement maintenance within next year’s budget.