If you drive in one of the HOV/toll express lanes on I-25 during rush hour without a second passenger, prepare to pay more to use the toll side of the lanes as of January 1. And you can blame higher bus fares. The High Performance Transportation Enterprise will raise the toll from $3.50 to $4 during peak hours (7:15 to 8:15 a.m. and 4:30 to 6 p.m. weekdays), according to Fox 31. "As RTD [the Regional Transportation District] recently announced that it was increasing its bus fares, the peak hour toll will now be increased to match RTD's express bus fare," Colorado Department of Transportation spokeswoman Stacey Stegman says in a statement. 

The HPTE explains that it had to raise the rate to honor a contract with RTD, because peak toll costs cannot be any less than the express bus fare for that route, writes 9News. Stegman tells the Denver Daily News RTD required the agreement so as to not discourage people from using bus transportation. HOV/toll express lanes are popular with lone drivers looking to skip heavier traffic; a toll is billed via transponder or through license-plate toll readers.