The trial judge should not necessarily deny the motion to dismiss. The decision would depend on the interpretation of the "impact rule" in Texas law. If the law strictly requires a physical impact with the defendant's car itself, then Alan's claim of water splashing on his leg may not be sufficient to satisfy the rule. However, if the law allows for a broader interpretation of "impact", then Alan's claim could potentially be valid. The judge's decision would depend on the specific interpretation of the "impact rule" in Texas law