THE TRANSPORTATION THE TRANSPORTATION IMPLICATIONS OF A TERRORIST IMPLICATIONS OF A TERRORIST

ATTACK ON SEATTLE’S HIGHWAY ATTACK ON SEATTLE’S HIGHWAY NETWORKNETWORK

Chang-Hee Christine Bae (University of Washington)Chang-Hee Christine Bae (University of Washington)

Larry Blain (Puget Sound Regional Council) and Larry Blain (Puget Sound Regional Council) and

Alon Bassok (University of Washington)Alon Bassok (University of Washington)

INTRODUCTIONINTRODUCTION

► Primary aim is to model the impacts on Primary aim is to model the impacts on travel of a feasible terrorist attack on travel of a feasible terrorist attack on Seattle’s transportation networkSeattle’s transportation network

► The unique topography of the Puget Sound The unique topography of the Puget Sound Region implies that a few pinpointed attacks Region implies that a few pinpointed attacks can have major consequencescan have major consequences

► We explore taking down the 2 bridges (I-90 We explore taking down the 2 bridges (I-90 and SR520; Scenario 1) and adding an and SR520; Scenario 1) and adding an attack on I-5 under the Convention Center attack on I-5 under the Convention Center (Scenario 2)(Scenario 2)

CHARACTERISTICSCHARACTERISTICS

►Employment structure dominated by Employment structure dominated by Downtown Seattle and Eastside Downtown Seattle and Eastside subcenters (Bellevue and Redmond) subcenters (Bellevue and Redmond) separated by Lake Washingtonseparated by Lake Washington

►Other than circuitous trips around the Other than circuitous trips around the lake, there are only the two bridge linkslake, there are only the two bridge links

► I-5, running through downtown Seattle, I-5, running through downtown Seattle, links Canada with San Diegolinks Canada with San Diego

SeattleCBD Bellevue

Redmond

Scenario 1

Scenario 2

http://www.wsdot.wa.gov/PugetSoundTraffic/

5 Time Periods5 Time Periods

AM Peak

PM PeakMidday

EveningNighttime

Puget Sound Trends, 1997 <http://www.psrc.org/datapubs/pubs/trends/t6trend.htm>

http://www.wsdot.wa.gov/PugetSoundTraffic/

SeattleCBD Bellevue

Redmond

SeattleCBD Bellevue

Redmond

Travel Demand ModelingTravel Demand Modeling

GENERATIONGENERATION

DISTRIBUTIONDISTRIBUTION

MODE CHOICEMODE CHOICE

ASSIGNMENTASSIGNMENTAssign trip Assign trip tables to tables to networksnetworks

PRIMARY TASKSPRIMARY TASKS

►Estimate travel time losses (and related Estimate travel time losses (and related $ costs) associated with Scenario 1 and $ costs) associated with Scenario 1 and 2, essentially route diversion costs2, essentially route diversion costs

►Examining how modal shifts might Examining how modal shifts might mitigate the additional congestion of mitigate the additional congestion of Scenarios 1 and 2 (in progress)Scenarios 1 and 2 (in progress)

►Estimating the freight delay Estimating the freight delay contribution to business interruptioncontribution to business interruption

SECONDARY TASKSSECONDARY TASKS

►Results Outside the ModelResults Outside the Model Trip Diversion by TimeTrip Diversion by Time Trip DeterrenceTrip Deterrence Bridge Restoration Costs and PeriodBridge Restoration Costs and Period Traffic Mitigation MeasuresTraffic Mitigation Measures

TRIP DIVERSION AND COSTSTRIP DIVERSION AND COSTS

►With the 2 bridges down, tripmakers With the 2 bridges down, tripmakers have to go around Lake Washington have to go around Lake Washington either by the northern or the southern either by the northern or the southern routesroutes

► In Scenario 2, vehicles can either In Scenario 2, vehicles can either download from I-5 to surface streets download from I-5 to surface streets downtown or (if through Puget Sound downtown or (if through Puget Sound traffic) divert to the alternative traffic) divert to the alternative freeway (I-405)freeway (I-405)

Tab. 1: Tab. 1: Aggregate Daily Travel Times by Mode, Time of Day, and Aggregate Daily Travel Times by Mode, Time of Day, and Scenario (Hours)Scenario (Hours)

  SOV CP2 CP3+ Van L Truck M Truck H TruckTotal TT/Day

Night 112,478 15,458 4,258

- 8,080 2,149 1,197 143,619

Night 1 121,020 16,609 4,555

- 8,407 2,270 1,283 154,145

Night 2 122,470 16,803 4,603

- 8,526 2,308 1,305 156,014

AM 268,987 39,120 13,593 378 22,322 10,453 6,122 360,975

AM 1 295,756 42,343 14,382 417 24,441 11,754 7,018 396,111

AM 2 349,768 52,572 18,582 417 26,699 11,711 7,051 466,799

Midday 394,250 112,194 34,984

- 42,490 24,557 14,588 623,063

Midday 1 433,382 122,595 37,808

- 45,855 27,072 16,403 683,116

Midday 2 438,954 124,179 38,281

- 46,578 27,563 16,711 692,265

PM 504,966 119,423 40,696 485 32,922 14,150 8,155 720,798

PM 1 578,418 135,131 45,401 549 37,336 16,455 9,685 822,976

PM 2 592,389 138,149 46,329 563 38,485 16,989 10,012 842,916

Evening 176,266 58,491 20,478

- 13,325 3,090 1,397 273,046

Evening 1 188,470 62,354 21,756

- 14,138 3,340 1,535 291,593

Evening 2 190,329 62,951 21,954

- 14,332 3,395 1,564 294,524

Comments on Table 1Comments on Table 1► Baseline total travel time = 2.122 m. hoursBaseline total travel time = 2.122 m. hours► Increase in total travel time by 226,200 hours (10.7%) Increase in total travel time by 226,200 hours (10.7%)

in Scenario 1in Scenario 1► Increase by 330,800 (15.6%) in Scenario 2Increase by 330,800 (15.6%) in Scenario 2► Implication: Bringing the bridges down increases Implication: Bringing the bridges down increases

congestion and travel times more than the I-5 congestion and travel times more than the I-5 blockageblockage

► Much denser flows in PM than AM peak, but the event Much denser flows in PM than AM peak, but the event raises travel times by proportionately more AM than raises travel times by proportionately more AM than PMPM

► SOVs (as expected) dominate traffic flows (about SOVs (as expected) dominate traffic flows (about 4/5ths of total travel time)4/5ths of total travel time)

► ““Midday” (9 a.m.-3 p.m.) traffic flows quite high, Midday” (9 a.m.-3 p.m.) traffic flows quite high, possibly the result of “peak lengthening” of the possibly the result of “peak lengthening” of the morning peak towards 10 a.m.morning peak towards 10 a.m.

Tab. 2: Tab. 2: SOV Regionwide Average Travel Times by Time of Day and SOV Regionwide Average Travel Times by Time of Day and ScenarioScenario(mins)(mins)

  Night AM Peak Midday PM Peak Evening

Baseline 21.75 15.73 13.35 19.91 13.61

Scenario 1 23.4 17.3 14.67 22.81 14.55

Scenario 2 23.68 20.46 14.86 23.36 14.7

Comments on Table 2Comments on Table 2

► Increase in Increase in regional averageregional average travel times travel times consistently higher in the PM than the AM consistently higher in the PM than the AM peak (27% in the Baseline)peak (27% in the Baseline)

►Offpeak changes milder than peak Offpeak changes milder than peak changes, as expectedchanges, as expected

►Nighttime trips longer (longer trip Nighttime trips longer (longer trip lengths?)lengths?)

►Travel times shorter than some other Travel times shorter than some other sources (but Census deals only with the sources (but Census deals only with the generally longer worktrips)generally longer worktrips)

TRAVEL TIME VALUESTRAVEL TIME VALUES

► Important component of economic costs Important component of economic costs of this type of terrorist attackof this type of terrorist attack

►Research on value of travel time varies Research on value of travel time varies widely (20-50% of wage rate). The % widely (20-50% of wage rate). The % also varies with income and type of tripalso varies with income and type of trip

►Two personal values ($6.50 and $13.00 Two personal values ($6.50 and $13.00 per hour and commercial value of $35 per hour and commercial value of $35 per PCE-hour per PCE-hour [[the same as in the LA the same as in the LA ports studyports study])])

Tab. 3: Tab. 3: Value of Daily Travel Time for All Modes (Lower Range: $ Value of Daily Travel Time for All Modes (Lower Range: $ ))

  Night AM Peak Midday PM Peak Evening Daily Sum

Baseline 1,365,845 4,148,310 8,450,149 7,863,957 2,811,226 24,639,488

Scen. 1 1,462,836 4,588,000 9,299,245 9,009,926 3,006,635 27,366,641

Scen. 2 1,481,739 5,173,198 9,440,468 9,242,520 3,039,178 28,377,104

Tab. Tab. 4: 4: Value of Daily Travel Time for All Modes (Upper Range: Value of Daily Travel Time for All Modes (Upper Range: $ )$ )

  Night AM Peak Midday PM Peak Evening Daily Sum

Baseline 2,438,989

6,833,121

13,475,143

13,759,204

5,229,894

41,736,351

Scen. 1 2,614,772

7,518,877

14,794,433

15,713,385

5,586,721

46,228,188

Scen. 2 2,647,391

8,690,167

15,006,993

16,102,786

5,644,471

48,091,808

Tab. 5: Tab. 5: Comparison between Lower and Higher Values of Comparison between Lower and Higher Values of Travel TimeTravel Time

  Lower Value ($ ) Higher Value ($ )

  Daily Sum Reconstruction Period Daily Sum

Reconstruction Period

Baseline 24,639,488

4,435,107,753

41,736,351 7,512,543,142

Scenario 1 27,366,641

4,925,995,338

46,228,188 8,321,073,824

Scenario 2 28,377,104

5,107,878,781

48,091,808 8,656,525,359

TRAVEL TIME LOSSESTRAVEL TIME LOSSES

►Daily losses in Sc. 1 = $2.73m.,Sc. 2 = Daily losses in Sc. 1 = $2.73m.,Sc. 2 = $3.74m. lower end ($4.49m., $6.36m. $3.74m. lower end ($4.49m., $6.36m. Upper end). Increase over Baseline = Upper end). Increase over Baseline = 11% (Sc. 1) and 15% (Sc. 2)11% (Sc. 1) and 15% (Sc. 2)

►Total losses (180-day assumption): Total losses (180-day assumption): Lower end, $490.9m (Sc. 1) and Lower end, $490.9m (Sc. 1) and $672.8 m. (Sc. 2); Upper end, $672.8 m. (Sc. 2); Upper end, $808.5m. (Sc. 1) and $1.144.0m. (Sc. $808.5m. (Sc. 1) and $1.144.0m. (Sc. 2)2)

Tab. 6: Changes in Commute Times on Selected Disrupted Tab. 6: Changes in Commute Times on Selected Disrupted Routes (mins)Routes (mins)

  AM PM

Baseline Scen. 1 Scen. 2 Baseline Scen. 1 Scen. 2

Bellevue-Downtown 22.4 54.3 54.4 30.3 87.2 89.9

Downtown-Bellevue 22.1 51.0 51.2 31.6 86.5 90.6

Redmond-Downtown 30.6 58.0 60.4 39.8 90.3 94.5

Downtown-Redmond 29.9 57.7 59.8 39.9 90.3 94.5

Renton- Downtown 22.7 27.2 27.1 32.4 39.9 39.8

Downtown-Renton 21.3 22.8 32.6 33.7 47.3 49.0

UW-SeaTac Airport 26.4 27.6 34.2 41.6 47.6 56.7

SeaTac Airport-UW 27.5 29.9 33.5 48.8 53.0 63.7

SeattleCBD Bellevue

Redmond

+

+8

SeaTac

UW

Renton

+11

+29

+30

AM Peak Commute Time Differences

Baseline vs. Scenario 2

SeattleCBD Bellevue

RedmondUW

SeaTacRenton

+7

+59.6

+54.7

+14.9

PM Peak Commute Time Differences

Baseline vs. Scenario 2

Travel Times on Individual Travel Times on Individual RoutesRoutes

►Most extreme case: O/Ds near the Most extreme case: O/Ds near the SR520 Bridge (e.g. Downtowns SR520 Bridge (e.g. Downtowns Bellevue and Seattle) Bellevue and Seattle)

AM: 54 mins. vs. 22 mins.AM: 54 mins. vs. 22 mins.

PM: 90 mins. vs. 30 mins.PM: 90 mins. vs. 30 mins.

Travel Times From Microsoft HQ, Baseline (PM Peak)Travel Times From Microsoft HQ, Baseline (PM Peak)

Times From Microsoft HQ, Scenario 1 (PM Times From Microsoft HQ, Scenario 1 (PM

Peak)Peak)

Travel Times From Microsoft HQ, Scenario 2 Travel Times From Microsoft HQ, Scenario 2 (PM)(PM)

MAP COMPARISONSMAP COMPARISONS

► Compares Scenarios 2 and 1 with Baseline Compares Scenarios 2 and 1 with Baseline using Microsoft HQ as a base pointusing Microsoft HQ as a base point

► Trips , <10 mins. in Redmond, 10-20 mins. Trips , <10 mins. in Redmond, 10-20 mins. in to other Eastside cities, 20-30 mins. reach in to other Eastside cities, 20-30 mins. reach other Eastside cities, 30-40 mins. reach City other Eastside cities, 30-40 mins. reach City of Seattle, 40-60 mins. to other West of lake of Seattle, 40-60 mins. to other West of lake locationslocations

► In Scenarios 1 and 2, little difference on the In Scenarios 1 and 2, little difference on the Eastside, but travel times to Seattle and Eastside, but travel times to Seattle and other west of lake locations increase to 80-other west of lake locations increase to 80-90 or 90+ mins.90 or 90+ mins.

MODAL SHIFTSMODAL SHIFTS

►2.5% of trips are by transit. Total 2.5% of trips are by transit. Total equivalent to current tripmakers across the equivalent to current tripmakers across the bridges.bridges.

►With certain assumptions, we can estimate With certain assumptions, we can estimate shifts to buses (work in progress)shifts to buses (work in progress)

►Carpool shares (19% in AM peak and 25% Carpool shares (19% in AM peak and 25% in PM peak) already high. How far they can in PM peak) already high. How far they can be increased (even in a short-run situation) be increased (even in a short-run situation) is questionableis questionable

FREIGHT DELAYS AND BUSINESS FREIGHT DELAYS AND BUSINESS INTERRUPTIONINTERRUPTION

► Not so severe because most freight trips are Not so severe because most freight trips are North-South rather than cross-lake. Also, North-South rather than cross-lake. Also, trips originating outside the region can take trips originating outside the region can take I-405 even if I-5 is blocked. Hence, freight I-405 even if I-5 is blocked. Hence, freight delays increase by 12.6% in Scenario 1 over delays increase by 12.6% in Scenario 1 over the Baseline but only by another 2.1% in the Baseline but only by another 2.1% in Scenario 2Scenario 2

► Our model estimates of business interruption Our model estimates of business interruption because of freight delays are $201m.because of freight delays are $201m.

► Additional commuting costs will fall on labor Additional commuting costs will fall on labor rather than businessrather than business

TRIP DIVERSION BY TIMETRIP DIVERSION BY TIME

►Many non-worktrips (77% of total trips) Many non-worktrips (77% of total trips) take place in the peakstake place in the peaks

►Can these be diverted to off-peak? Can these be diverted to off-peak? Problem is 9 a.m.-3 p.m. already has Problem is 9 a.m.-3 p.m. already has heavy trafficheavy traffic

►Scope for diversion greatest in the Scope for diversion greatest in the evening and nighttime. Can freight evening and nighttime. Can freight traffic be diverted?traffic be diverted?

TRIP DETERRENCETRIP DETERRENCE

► 228,000 trips daily across the two bridges228,000 trips daily across the two bridges► Little evidence to suggest how many could Little evidence to suggest how many could

be deterredbe deterred► Most non-work trips could either be deterred Most non-work trips could either be deterred

or diverted to destinations on the origin side or diverted to destinations on the origin side of the lakeof the lake

► However, non-work cross-bridge share much However, non-work cross-bridge share much lower than regional averagelower than regional average

► Even if 5% of cross-bridge travel could be Even if 5% of cross-bridge travel could be diverted, it could make a difference to diverted, it could make a difference to congestion in Scenarios 1 and 2congestion in Scenarios 1 and 2

RESTORATION PERIOD AND RESTORATION PERIOD AND COSTSCOSTS

►This discussion is speculative because This discussion is speculative because much depends on the extent of the much depends on the extent of the damagedamage

►We assume a restoration period of 180 We assume a restoration period of 180 days, based on experience elsewhere days, based on experience elsewhere and the record of political and and the record of political and institutional delays in Washingtoninstitutional delays in Washington

►Bridge reconstruction and I-5 clearance Bridge reconstruction and I-5 clearance costs are speculative. Our best guess is costs are speculative. Our best guess is $200 million $200 million

TRAFFIC MITIGATION MEASURESTRAFFIC MITIGATION MEASURES

► $ costs of a plan very small relative to $ costs of a plan very small relative to economic costs of additional travel timeeconomic costs of additional travel time

► Introduce traffic flow improvements on the Introduce traffic flow improvements on the around the lake routesaround the lake routes

► Promote more carpool use via public Promote more carpool use via public education, incentives and/or mandateseducation, incentives and/or mandates

► Induce a modal shift to buses via new Induce a modal shift to buses via new routes, increasing service frequency and routes, increasing service frequency and perhaps free faresperhaps free fares

► Facilitate trip diversion by time, e.g. Facilitate trip diversion by time, e.g. flextime, compressed work weeks flextime, compressed work weeks

Next StepsNext Steps

Travel Demand ModelingTravel Demand Modeling

GENERATIONGENERATION

Productions Productions and Attractions and Attractions from population from population

and and employmentemployment

DISTRIBUTIONDISTRIBUTIONConnect Connect

Productions to Productions to AttractionsAttractions

MODE CHOICEMODE CHOICE Split into ModesSplit into Modes

ASSIGNMENTASSIGNMENTAssign trip Assign trip tables to tables to networksnetworks

TIMETIME

(1,000 hours)(1,000 hours)

VMTVMT

(1,000 (1,000 miles)miles)

2000 Base2000 Base 2,4682,468 77,71077,710

No bridgesNo bridges 2,7142,714 80,71280,712

NoNo B + No I-5B + No I-5 2,7562,756 80,69680,696

No bridgesNo bridges

(full run)(full run)2,4502,450 76,50176,501

No B + No I-5No B + No I-5

(full run)(full run)2,4592,459 76,07876,078

Summary StatisticsSummary Statistics

Map of Sub-areas

Sub-area ExampleSub-area Example

Home-Based Work TripsHome-Based Work Trips Entire RegionEntire Region Bellevue to Seattle Bellevue to Seattle CBDCBD

TripsTrips % % TransitTransit

TripsTrips % % TransitTransit

Assignment OnlyAssignment Only 2,377,7362,377,736 7.5%7.5% 8,5778,577 33.0%33.0%

Scenario 1 with Scenario 1 with feedbackfeedback

2,377,7362,377,736 7.6%7.6% 2,0232,023 57.5%57.5%

Scenario 2 with Scenario 2 with feedbackfeedback

2,377,7362,377,736 7.6%7.6% 2,1332,133 57.5%57.5%

CONCLUSIONSCONCLUSIONS

►We evaluated the transportation We evaluated the transportation implications of bombing two bridges implications of bombing two bridges on I-90 and SR520 (Scenario 1), thon I-90 and SR520 (Scenario 1), theen n added blocking I-5 under the added blocking I-5 under the downtown Convention Centerdowntown Convention Center

►Travel times increased by 10.7% in Travel times increased by 10.7% in scenario 1 and 15.6% in Scenario 2scenario 1 and 15.6% in Scenario 2

CONCLUSIONS (cont.)CONCLUSIONS (cont.)

►As expected, travel times increase As expected, travel times increase more in the peaks, especially the AM more in the peaks, especially the AM peak (although volumes are larger in peak (although volumes are larger in the PM peak)the PM peak)

►The upper end value of extra travel The upper end value of extra travel costs are $809m. in Scenario 1 and costs are $809m. in Scenario 1 and $1,144m. in Scenario 2. This helps to $1,144m. in Scenario 2. This helps to evaluate the resources to be devoted evaluate the resources to be devoted to prevention and mitigation to prevention and mitigation

CONCLUSIONS (cont.)CONCLUSIONS (cont.)

► Individual tripmakers close to the bridges Individual tripmakers close to the bridges incur a high cost, up to 2.3x more in the incur a high cost, up to 2.3x more in the AM peak and 3x more in the PM peakAM peak and 3x more in the PM peak

►Freight delays add $201m.Freight delays add $201m.►Estimate of infrastructure reconstruction: Estimate of infrastructure reconstruction:

$200m.$200m.►Traffic mitigation plans could be helpful, Traffic mitigation plans could be helpful,

but would need to be prepared well in but would need to be prepared well in advanceadvance