TuSimple, a San-Diego autonomous truck startup launched in 2015, which runs operations in China and Arizona, has just raised an additional $120m in Series D funding.

The funding round was led by Sina, the operator of China’s biggest microblogging site, Weibo. It takes the total raise to $215m as the company seeks to expand long haul routes in the south of the US.

TuSimple aims to bring the first self-driving truck to market — and therefore “increase safety, decrease transportation costs, and reduce carbon emissions.”  It makes use of the industry’s first 1,000-metre perception system, which is designed to work even in adverse weather conditions.

Techcrunch reports that the company hit unicorn status in February with a post-money valuation of $1.095bn. The new funding follows a formal partnership with package delivery company UPS, forged after the companies began testing the trucks in Arizona to assess how self-driving tractor-trailers carry freight and whether service and efficiency can be improved.

The site adds that TuSimple is working on a so-called “full stack solution”: developing all the technological pieces for entirely autonomous driving. This has been tested on a 120-mile highway between Tucson and Phoenix in Arizona, and another segment in Shanghai.

TuSimple CFO Cheng Lu told Techcrunch that the company has more than 50 trucks and 18 contracted customers.