It differs in a number of key ways from the idea dreamed up by Hodgetts and Walker, who envisioned a much larger vehicle that normal buses could enter. Still, the TEB is similar in that it, too, straddles traffic.

Moving along specialized tracks—making it more like a train than a bus, actually—the TEB features an elevated midsection that glides over two lanes. Receiving electricity through the tracks, the vehicle travels at 40 km to 60 km (25 miles to 37 miles) per hour. It could be powered partly by solar energy. According to the company’s website (link in Chinese), the final version will have four sections, with a total length of 58 m to 62 m (190 ft to 203 ft).

The idea is to reduce air pollution and traffic jams in China’s most congested cities. Fifteen of the world’s 50 most congested cities are in China, according to the Dutch navigation company TomTom. Four of them—Tianjin, Nanyang, Shenyang, and Zhoukou—plan to run pilot projects of the road-straddling bus, along with Qinhuangdao, according to TEB Technology Development. Various nations have also expressed an interest in the system, among them France, Brazil, India, and Indonesia.

But not everyone is on board with the idea. Many worry about safety, especially in terms of how the TEB and regular traffic will interact. Others question the practicality of introducing it in cities that already have well-established transportation infrastructure.

Quartz shared some articles on the TEB with Hodgetts, now an architecture professor at the University of California in Los Angeles. He said it appeared be an “immature project” with some ”fundamental problems.”

Questions about the project’s readiness also linger in China, where the concept behind the TEB was received with a flurry of publicity when it was first unveiled in 2010. Yin Zhi, an urban planning professor at Beijing’s Tsinghua University, recently told the Global Times: ”The idea of the road-straddling bus was shot down six years ago by a panel for its impracticality. Yet it was brought back to the public again.”

Concerns about the TEB’s impact on regular traffic include:

• Too low. The space underneath the TEB is just 2.1 m (6.9 ft) high. That means trucks could, as Wired notes, get stuck between the road and the underbelly of the TEB. And let’s face it: People load all kinds of things atop their vehicles, in all manner of ill-advised ways.
• Too tight. The TEB-1 tightly confines two lanes of traffic. But sometimes while driving it becomes necessary to swerve, even if just slightly—perhaps to avoid a loose object. If you’re under the TEB when the need arises, good luck doing so safely, especially if the other lane is occupied. The tight space could also have a psychological effect on drivers, Hodgetts noted, making them nervous and more prone to braking.
• Visibility. Drivers under the TEB will have difficulty seeing signs and traffic lights, as noted by Wang Zhaoyang, a Qinhuangdao local and self-claimed Beijing Jiaotong University graduate, on Zhihu, China’s answer to Quora (link in Chinese).
• Signaling. How will drivers know when the TEB is approaching from behind? What if traffic is stuck and they choose the wrong moment to open a car door for whatever reason? What if they’re driving but just about to turn, swerve, or change lanes, Wang asked.
• Turning. How will the TEB affect the ability of regular vehicles to turn? Its sides could prevent turns, as noted (link in Chinese) by another Zhihu user (“hat600”), self-described as a Tsinghua University architect graduate.

There are other questions about the vehicle’s practicality:

• Too high. The vehicle’s height is 4.5 m (14.8 ft). That’s tall enough to be an issue with some overpasses in China, Sun Zhang, a rail expert at Shanghai Tongji University, noted to the Global Times.
• Exposed electric tracks. “It takes at least 1,500 volts—high-voltage electricity—to power the whole bus,” Wang Lin, a former railway engineer with 16 years experience, wrote to Quartz. “An exposed electric railway with 1,500 volts looks like a time bomb to me. To lay an electronic railway on the road is a very outdated technology that was used in the 1890s, when electricity just came into use.”
• Too heavy. The bus in its final form will have four 15-ton sections (link in Chinese), each capable of holding 300 passengers. That means the entire vehicle would weigh over 150 tons at maximum capacity, assuming an average passenger weight of 70 kg (154 lbs). Over time, noted engineer Wang, such a load would, at the very least, shorten road life.
• Maneuverability. Considering its length, the vehicle would have difficulty making turns, especially without affecting other traffic, as engineer Wang observed in a June editorial (link in Chinese) in the Beijing Daily. Not every city has long stretches of straight road in the places that most need public transportation.
• Cost. With each TEB costing about $4.5 million (paywall), the economics of it come into question. Adapting infrastructure (such as raising some overpasses) would also require city spending. Might zero-emission buses be a simpler solution? Hodgetts believes it would make more sense to deploy the TEB in a city “where the traffic system is not so established yet,” such as Urumqi, the capital of Xinjiang.

TEB Technology Development declined to respond to repeated requests for a comment about the project and the concerns it raises.