The Miasma Beach Transportation Model

1. Include All Costs:
   1. All improvements must be symmetrical (2-way), so cost estimates must reflect this.
   2. Upgrade costs are cumulative: major to primary is $200k per lane-mile, and primary to freeway is $600k per lane-mile, so major to freeway is $800k per lane-mile. Upgrades include any capacity and/or speed change for the new facility type.
   3. Intersection costs must be included in all improvements (whether new, added lane, or upgrade facility type). An improvement to a link requires the improvement to at least the two intersections that define the link. Use the higher cost when the facility types differ (e.g., primary and collector).
   4. This example is provided to help ensure that all cost elements are incorporated.

      

2. Bus Transit:
   1. Demand: Vehicle Trip Reduction

      Although the base figure provided was a 10% reduction in OD volume, you should adjust this figure based on the OD pair in question. Trips from TAZ 1 to TAZ 2 might reach 10% by transit, but from TAZ 5 to TAZ 6 the figure might be closer to 1 percent. Justify transit share for each OD pair where transit is to be added. Reasonable reductions would be in the 1-20 percent range, depending on the OD pair.

      For example, if you had 650 AM-peak vehicle-trips from TAZ 1 to TAZ 2, and you justify a 18% reduction due to transit, then 117 vehicle-trips would be removed from this OD pair (the OD table would be adjusted and fewer vehicle-trips would be assigned to the network).

   2. Demand: Estimate Transit Ridership

      Convert the reduction in the period-specific vehicle-trip matrix (the trip table that you load in traffic assignment) to person-trips by transit. Depending on your split of trip types for the time of day analyzed, you get a weighted vehicle occupancy. It's about 1.1 persons per vehicle for HBW trips but 1.3 for NHB trips, and the proportion of trips by trip type varies over time-of-day (see Task 4.3). For example, if you had 50% HBW, 30% HBO, and 20% NHB, the weighted average would be 0.5(1.1) + 0.3(1.2) + 0.2(1.3) = 1.17 persons per vehicle. So 117 vehicle-trips (see above) would be equivalent to 117(1.17) = 137 person-trips in the AM-peak. You must report both resulting trip tables.

   3. Cost: Compute Cost for Estimated Ridership

      The base cost is $2k per person-mile for each OD pair. In the example above, this produced 137 person-trips on transit for an OD pair, for example, 4 miles apart, yielding (137 person-trips)x(4 miles) = 548 person-miles. At $2k per person-mile, the total cost would be $1,096,000 for transit from the O to the D (cost in opposite direction, as well as for other OD pairs, would be separately estimated based on corresponding data). Assume that this cost estimate is the total cost to the city for bus service over the effective service life, reflecting a nominal fare, and with other costs borne by state and federal transit subsidies.

   4. Benefits:

      Benefits include the reduction in congestion due to a reduction in total vehicle-trips (this can translate into a speed improvement or a delay reduction), that you must estimate with the model, as well as environmental improvements and possible mobility improvements for residents without car access.

3. Sensitive Areas:

   Apply the penalties to the total cost estimated for infrastructure in or adjacent to the wetlands (20%) or the beach (10%). For example, the addition of a link of Miasma Blvd through the wetlands would incur a cost penalty for the entire 1 mile section in the wetlands area, which would include the intersection improvements with 3rd and 4th Streets. Similarly, improving 1st Street would only incur the 10% penalty for the necessary intersection improvements for the Coast Hwy & 1st Street intersection.

4. Truck Diversion:

   As a state road, Coast Highway is operated and maintained by the State DOT. The State can divert truck thru-traffic from Coast Highway. Check with the City Director of Public Works.

5. Demand Management:

   Be innovative. Ridesharing, parking restrictions, walking and biking programs, non-resident tolls on Coast Hwy, etc. These might be great spot improvements to consider. You need to estimate impact and cost.