<prompt> Translate the following text to EnglishGharama za kitengo kuonyeshwa katika sekunde na normalized kama ilivyoelezwa ni makadirio na muundo wa uhandisi ili kuruhusu simulations juu ya tofauti ya trafiki.  <response>: The unit costs expressed in seconds and normalized as explained are estimated by an engineering model19 to allow for simulations over variations of traffic. 