Headways. The Project’s land use plan and development pattern is centered on transit, and prioritizes walking and cycling on Treasure Island. To be effective, transit service must be reliable and frequent. Weekday service will be offered at least every 30 minutes throughout the service day. As ridership increases, TIMMA will fund increased service frequency with peak period service offered as often as every 10 minutes during weekday peak periods based on demand and available revenues to support service. AC Transit, in conjunction with TIMMA, will review service provision annually as described in Section 7.4, concurrent with the drafting of each Operating Agreement and calculation of each Operating Subsidy and adjust headways as necessary to accommodate demand and budgetary constraints. On Saturdays and Sundays, buses are expected to leave the island every 30 minutes throughout the service day.
Headways. The analysis shows that the headways calculated are too short. See fig 13. On a single track line headways for consecutive trains in the same direction must be given larger margins, in relation to the present structure of the signalling and interlocking system. This must be corrected in the input parameters. Different trains also have different properties, e.g. weight, acceleration etc., and need different headways.
Headways. The West Valley Connector Project will require 18 vehicles (15 in service with 3 spares) to serve the 10- minute peak headway and have sufficient spare vehicles.
Headways. Headways can be manipulated using the stops attributes window under different scenarios in the TBEST user interface (Figure 10). The stops attributes window allows modification of several attributes including description, number of arrivals, headways, in-vehicle travel time between two adjacent stops (IVTT), and types of amenities available at the stop location. Figure 10 Modification of stop attributes in TBEST. 2528 1659 1292 935 1060 Headways are systematically changed by 5-minute intervals to evaluate the impact of headway changes on ridership attraction. It should be noticed that TBEST preserves a fixed time span for service hours. In other words, by reducing/increasing the headways, the software automatically and proportionally adjusts the number of arrivals to fully cover the whole service hour period. Results for headway changes are illustrated in Figure 11. As expected, there is a negative association between headway intervals and ridership, however, the magnitudes of ridership elasticities are somewhat different in the two directions. Accordingly, increasing the headway by 5 and 10 minutes decreases ridership by 18% and 28%, respectively. On the other hand, decreasing the headway by 10 minutes will result in a drastic increase of approximately 96% in the ridership. This might indicate that there is a latent potential for using the express service route along I-95; however, the realization of this potential is highly dependent on improvements in the level of service offered by the express service. Ridership for different headway values 3000 2500 2000 1500 1000 500 0 HW increase HW increase Base HW decrease HW decrease by 10 mins by 5 mins by 5 mins by 10 mins Figure 11 Ridership estimate for different headway values.
