The consequences of missing your traffic court date will vary depending on the severity of your charge, and how long it takes for you to discover that you missed the court date (presuming it wasn't intentional of course).
If you have been charged with a traffic infraction, such as speeding in violation of § 46.2-870, missing a court date will very likely result in your being found guilty. If you choose to pre-pay your ticket in lieu of coming to court you are admitting guilt.
Trial in Absence
Generally, if you miss court without pre-paying the judge will have the trial in your absence. He will typically ask the officer what happened, if there were any unusual circumstances, and if you were cooperative. If the judge finds there was sufficient evidence of your guilt he will find you guilty in your absence. The clerk will then mail the fine and any court costs to the address listed on your summons.
How to Determine Whether You Must Come to Court
If you have been charged with a crime that is punishable as a class 1 or 2 misdemeanor, generally you do need to appear in court, but it is always a good idea to speak with a traffic lawyer in the area in which you received the ticket. The local judge's rules will play a large role in whether or not you need to appear. A local traffic lawyer will be able to address this issue for you. In some reckless driving cases (a class 1 misdemeanor) a traffic lawyer can appear on your behalf
Generally, you can tell whether or not you need to appear based on whether the box towards the middle of your summons with instructions stating that you do not need to appear if that box is checked, is actually checked. If it is not checked or the instructions are crossed out, you should appear in court. Failure to attend court will result in either the judge trying you in your absence, which will very likely result in the judge finding you guilty in your absence, issuance of a show cause, and/or a capias being issued.
A capias is a warrant for your arrest. This will involve the local police or sheriff's deputies being sent to find you and bring you before the court to tell the judge why you did not appear. Depending on the type of charge, you risk having your license suspended, jail time, a permanent criminal record, and a substantial fine.
License Suspension For Not Paying Court Costs
If you fail to come to court, and are found guilty in your absence it is important to pay your court costs and fines before 30 days has elapsed from the date of conviction. The court will suspend your privilege to drive in Virginia if you fail to do so. The court will mail the fines and costs to the address listed on your summons. Therefore, it is important to make sure to look at your summons to see whether the address listed on your summons is accurate. If it is not, call the court to ask them to send the bill to the correct address.
Appeal if You Missed Court Accidentally
If you missed your court date accidentally you may still be able to contest your case. This will mainly depend on how much time has passed since the date the court found you guilty. If only ten days have passed since you were found guilty, you can file an appeal with the general district court to the circuit court. You have a right to an appeal within 10 days, which means the judge in the general district court does not need to approve the appeal. In Virginia these appeals result in a "trial de novo", which essentially means you have will have a whole new trial in the circuit court as if the first trial never occurred. You can file and receive an appeal even if you plead guilty or pre-paid your offense.
If more than ten days have passed since your conviction date, your ability to contest your case will be more difficult. You can file a motion to reopen your case within sixty days from the offense date. However, you will need to show the judge "good cause" for reopening the case.