“…Based on the assumption that travel time is susceptible to variation, travel time budget is expressed as a combination of expected travel time and additional travel time reservation to hedge against travel time variability so that travelers can arrive at their destinations within a given on-time arrival probability, termed as travel time reliability in the literature (Chen et al, 2012). In considering travel time budget, most studies assume correlation independence among links (Lo et al, 2006), however, travel times are often spatially correlated across road links in reality (Chan et al, 2009;Ramezani and Geroliminis, 2012). For example, a traffic accident on downstream link may cause travel delay of the upstream links.…”