The Pragmatic Transportation Choice

The following post is the follow up to the previous post critiquing the PSRC Transportation Plan with a response to Seattle Times editorial request for a pragmatic approach.    

The Pragmatic Transportation Choice 

A pragmatic approach to transportation is based on the recognition that reducing congestion requires adding transportation capacity by either increasing capacity with added transportation “lanes” or increasing the capacity of existing lanes.  The Sound Transit decision to use ST3 funds to extend the Central Link “spine” to Lynnwood and beyond to Everett, and to Federal Way and beyond to Tacoma, adds another transportation “lane” along I-5.  

“Lane” capacity is defined by the number of vehicles per hour times the capacity of each vehicle.  The decision to route the “spine” through the Downtown Seattle Transit Tunnel (DSTT limits the number of vehicles per hour. The PSRC 2004 Technical Workbook,  “Central Puget Sound Region High Capacity Transit Corridor Assessment” concluded the DSTT station lengths limit trains to four cars and that safe operation requires a minimum of 4 minutes between trains, or 60 light rail cars per hour.   

The PSRC Technical Workbook also concluded the capacity of the 74-seat light rail cars was limited to 148 riders for a total capacity of 8880 riders per hour (rph).   The DSTT capacity will presumably be split between the extensions to Federal Way and across I-90 Bridge, or 4440 rph each.  A pragmatist recognizes spending billions extending light rail along the I-5 corridor does nothing to increase the DSTT capacity.  At least during peak commute, riders attracted by the extensions will reduce access for those currently using Central Link. 

The I-90 Bridge East Link extension utilizes the two center roadway lanes rather than add another “lane”.  A pragmatist recognizes the billions spent implementing light rail on the center roadway for East Link’s limited capacity reduces cross-lake transit capacity rather than increases it.  

The capacity increase from an added freeway “lane” varies with vehicle velocity.   At 45mph a freeway lane can accommodate 2000 vehicles per hour (vph).   Achieving higher velocities requires reducing the number of vehicles and adding more vehicles tends to dramatically reduce speed, increasing congestion.   Thus a pragmatic approach recognizes adding a new lane increases roadway capacity by up to 2000 vehicles per hour. 

A 70-ft articulated bus can accommodate 119 sitting and standing riders.  If 120 of the 2000 vph were 70-ft articulated buses the lane capacity would increase by more than 14,000 rph, equivalent to 7 freeway lanes, and more could be added. (900 buses per hour are routed into Manhattan on a single lane.)  A pragmatic approach to transportation would increase bus routes to what’s needed to meet capacity and limit the number of non-transit vehicles to maintain the 2000 vph.  One way to do so is implement HOT on the bus lane and adjust fees to limit non-transit vehicles. 

Reducing congestion requires attracting sufficient numbers of commuters to the added bus service.  Thousands of additional parking stalls are required since all the existing parking with access to transit is essentially full.  Allowing commuters to pay to park and ride free at the new P&Rs gives them the opportunity to assure access to a parking stall whenever they wish.  Those paying for parking would have priority access to their bus route. 

The parking fees could provide the funds needed to cover the 35% of operating costs Sound Transit normally requires, leaving capacity for others to ride free.  (The 12/03/17 post detailed how the parking fees from 3 Pay-to-Park lots near Lynnwood ($10) and 2 near Everett ($15) would allow 20,000 more commuters to use public transit each day.)  Thousands of commuters would likely welcome the chance to ride free.  Commuters could share a stall taking turns to use the priority.  Even non-commuters could provide local routes to and from Pay-to-Park lots.  The Pay-to-Park lots would make living within walking distance more attractive, increasing density and reducing sprawl. 

Sound Transit could make the added bus service from pay-to-park lots even more attractive with Wi-Fi access on all the buses.  Allow riders to use transit time to conduct business or personal items during the commute.  Those running their own business or employers would likely welcome the opportunity to pay for parking that assures access to Wi-Fi during commute.

Sound Transit plans to spend billions implementing a light rail spine limited by DSTT capacity fails any pragmatic cost/benefit analysis.  Even worse, the added operating costs for extensions without increasing capacity will either require a huge increase in fares or a financial “black hole” from the fare box revenue/ operating cost short fall. 

The bottom line is Sound Transit could begin adding thirty-to-forty, 1000-stall pay-to-park lots throughout the area over the next five years. The funds required would probably be less than what they would spend on their light rail spine during that time.  At the end of the five years the pay-to-park lots could be dramatically reducing congestion on all the major roadways.   Compare that with what the money spent on the spine during that period would provide.  Additional pay-to-park lots can be added as needed to increase capacity while funds spent on the spine will never increase DSTT capacity. 

Pay-to-park is surely the pragmatic choice.