Of course, coming from a defense attorney, I would always request a contested hearing. Whether it is the right decision for you is another matter. It would depend on the facts of your case and how much your time is worth. The speeding statute talks about traveling at a reduced speed when necessary to avoid a collision and at a speed that is consistant with using due care. I would encourage you to consult with an attorney in the Kennewick/Tri-Cities area, who practices in the traffic infraction/criminal traffic field. He/she should be able to properly advise you regarding requesting a contested or other options.
There are many ways for a defense attorney to prevail on traffic matters. The attorneys I know prevail at the traffic hearings mainly by knowing the many procedural issues. People choose to contest traffic tickets for many reasons, ranging from- they flat out did not do it, insurance concerns, employment, family reasons to name a few. You can find a good traffic attorney by looking at the WA State Bar Association website at www.wsba.org and find a local chapter in your area, checking www.avvo.com & www.martindale.com. Good luck!
I always have my clients contest traffic tickets. This preserves your rights. With a too fast for conditions ticket the question becomes what speed was reasonable given due care. There are also numerous proceedural requirements that an experienced attorney can look into for you.