Missouri DOT testing solar-powered roadways

Sun blocks. Topped by tempered glass, the 4.4-sq-ft, 70-lb hexagonal panels are embedded with solar cells and LED lights. — **Sun blocks.** Topped by tempered glass, the 4.4-sq-ft, 70-lb hexagonal panels are embedded with solar cells and LED lights.

by JOHN GREGERSON | July 20, 2016

Follow the solar-paved road...

Soon, Missouri motorists may have that chance. Under the auspices of its year-old Road to Tomorrow (R2T) initiative to seek out innovation, the Missouri Dept. of Transportation (MoDOT) says it will install solar panels along historic Route 66 at the visitors center rest area in Conway, MO, some 40 miles northeast of Springfield MO.

Before using the actual highway, however, MoDOT first will install the glass-covered pavers on sidewalks at the Welcome Center, providing a test run before the agency potentially proceeds with more ambitious plans. The eventual goal is to embed the panels in roadways across the state, a game-changing concept that “hopefully will create new revenue streams,” said R2T team leader Tom Blair, MoDOT Assistant District Engineer for the St. Louis Area. (At bottom, watch his June address to state officials.)

Thick glass allows traffic to pass atop panels. — **Thick glass** allows traffic to pass atop panels.

In fact, Blair says that if the technology fulfills its promise, roadways one day could pay for themselves. That would be welcome news for cash-strapped states like Missouri, which started R2T in part to contend with diminishing resources for transportation funding.

"The goal is two-fold: to seek out new innovations, and new revenue streams to fund transportation,” said Blair. Solar road panels fill both bills, he added, noting that the Conway project will be the nation's first to install solar pavers, a concept long-discussed by industry members.

In Conway, expectations already are high that the panels will generate energy sufficient to power the rest of area. Also, according to MoDOT, the panels will be equipped with a heating component to promote snow removal in the winter, while light-emitting diodes (LED) will replace the painted stripes on the road lanes in order to maximize the area available year-round for solar harvesting. MoDOT will be capable of reprogramming the lights in the event of lane closures, road work or other disruptions.

Idaho's bright idea

The 4.4-sq-ft, 70-lb hexagonal block panels, made of tempered glass and embedded with solar cells and lights, are the brainchild of Sandpoint, ID-based Solar Roadways (SR). Started in 2007 by a husband-wife team (Scott & Julie Brusaw), the manufacturer aims to replace asphalt surfaces with structurally-engineered solar panels capable of withstanding vehicular traffic while providing required traction. Solar cells within each panel will be capable of generating up to 44 watts of current, SR claims.

As planned, panels will be fabricated in two textures: “semi-smooth” surfaces intended for light surfaces; and a “rougher surface" for highways. SR has indicated the tempered glass is specially formulated to withstand the weight of semi-trucks and that its tractioned surface matches that of asphalt. Blair said the glass is bullet-proof. Targeted load capacity is 250,000 lbs.

However, Blair also noted that the technology is not quite ready to detour from sidewalk to roadways. “Both Solar Roadways and the Federal Highway Administration agreed we should test it on sidewalks first in order to ensure the panels generate sufficient energy to offset their cost," he said, "and that melting and lighting components are functioning as intended."

Below, Solar Roadways explains its product in a rather unorthodox, entertaining fashion.

Above, National Geographic filed this report in March on ongoing similar efforts in Europe.

As plans proceed, MoDOT and other stakeholders have yet to calculate premium or payback for the pavers, which presumably would profit from solar energy sold to the grid. “As far as first costs go, we're not there yet in terms of cost per mile,” Blair said. “We're more interested in determining that all components are in place and operating as intended. Once we're there, we'll work our way back to the point of making it feasible from a cost perspective."

The financial feasibility of solar roads has been an issue fiercely debated on the internet in recent years. Even so, SR has has managed to persuade more than a few investors, including the U.S. Dept. of Transportation (USDOT), which has provided monetary support since 200. That year, the agency awarded a $100,000 Small Business Innovation Grant (SBIR), followed by a $750,000 SBIR grant in 2011. Last year, USDOT also awarded Solar Roadways a phase 11B SBIR contract, allocating yet another $750,000 grant over a two-year period to support tests ranging from freeze/thaw cycling and moisture conditioning, to shear testing and advanced loading.

Should the federal investment pay off in Missouri, officials in the "Show Me" state should soon expect to be entertaining curious transportation officials from all over the world.