Tito F. Hermoso / Brent Co, Martin Tee Ten | August 06, 2015 01:32
Suggestions for a safer Skyway
The first "fly over"
One intensely rainy afternoon in 2006, an Isuzu driven by an inattentive driver drove up the elevated Skyway Magallanes ramp to avoid a traffic jam caused by construction of the NAIA Skyway piers at the Skyway at-grade section. Picking up speed upon mounting the elevated, he watched, probably with amusement, a hydroplaning Fortuner pirouetting up front, failing to notice that he was fast approaching the parapets. By the time he realized it, it was too late to hit brakes. His Isuzu mounted the curb, launched airborne, ploughed through the barrier and dove down on the halted traffic below, smashing into a PUJ and causing fatalities in the process.
Armor, smashing through
Several months later, one afternoon, a speeding bank armored car took the Skyway Amorsolo off ramp too fast, hit the railing and fell down the Arnaiz railroad crossing crushing a car as it was mounting the railroad level crossing. Besides the unfortunate car's driver, the were also fatalities in the armored car. Within the span of 10 years, these “fly over” mishaps were to cause several more fatalities as buses, SUVs and pick-ups, careening on soaked pavement, were to hit headlines and social media as fast and as hard as they smashed through the elevated Skyway barriers.
Driver error, always
Without a doubt, and considering the millions of vehicle kms. that Skyway elevated Stage 1 has carried since inauguration in October 1999, all of the shunts and “fly by/over” accidents were due to driver error. Mitigating circumstances were always excess speed, bald tires, swerving to spin out of control due to hydroplaning and sleep-deprived driving. Curiously, these fly by accidents only started occurring ten years ago, majority of which occurred in the bumpy “S” curve bend of the Skyway between Bicutan and TESDA.
Remedies, panaceas and prevention; going anal
During all these mishaps, SOMCo, the Skyway O & M company, was never remiss in actions remedial and preventive. Major repaving of surfaces has been done to diminish hydroplaning. CCTV camera networks were installed to monitor unsafe driving. Intensive anti speeding campaigns were launched to remind motorists to keep to posted speed limits. Curiously, right after the worst bus accident [Don Mariano] so far, the speed monitoring teams at the former Nichols A & B toll plazas went a bit overboard when they went anal enforcing strictly 100 for Class 01 vehicles, eschewing the margin of error allowed by their LTO trainers; i.e. warning only for 20km/h over the limit, ticketing for speeding in excess of 20km/h over the limit. On sections where the pavement hasn't been upgraded to asphaltic concrete with reduced hydroplaning properties, SOMCo has resorted to automatic 80km/h speed limit during heavy rains, similar to German practice on its older unreformatted Autobahns.
EuroDisney's porous asphalt
To fight hydroplaning and also reduce visibility impairing road spray generated by the huge tires of trucks, the EU road authorities developed special kinds of paving some 20 years ago. We got a taste of this while driving to the access Autoroutes of EuroDisney, Paris in 1992. This asphalt allowed some measure of drain-through drainage, like a porous sponge. This kind of asphalt prevents hydroplaning and eliminates road spray thereby negating the need to require trucks to fit spray preventive mud flaps with inward facing hedge hog needles [like Astroturf]. This asphalt is noticeably quieter than the standard smooth pavement. During heavy rain, the road barely glistens and splashing puddles never accumulates as rainwater disappears under the paving surface. At night, roads paved with this kind of asphalt do not reflect headlights and overhead road illumination, thereby reducing glare. Imagine this on a wet Skyway and all those road reflections from those pesky billboards vanish. The downside of this kind of twin layer “porous” asphalt is that it needs restoration every 3 years instead of 5 years for asphaltic concrete.
Social media's constructive criticism
What SOMCo hasn't done yet is what many eagle eyed motorists pointed out in social media videos and photos that have gone viral – raising the barriers. In truth, the Skyway parapets, railings, guard rail and crash barriers do meet international standards. But these international standards have been enhanced since the early 90s because of the need to prevent 22 wheeler juggernauts and buses/coaches from smashing through the guard rails and falling down on traffic below.
Stage by stage upgrades
Inspired by crash barrier improvements in F1 racing circuits, both temporary -like Monaco and Singapore - and permanent [who says racing doesn't improve the breed?] double height crash barriers are meant to prevent cars from launching airborne into either the crowd of fans or the scenery. These have been introduced in stages on the world's expressways. The first priority applications are usually bridges over rivers, gorges and valleys. Next are ravines and S-curve bends. When finished, expect all highway crash barriers, where present, to become double height. Now these barriers can be in the form of concrete, double height ARMCO, higher posts with more steel cables, F-1 style catch fencing [not just cyclone wire mesh], metal barriers that also serve as sound mufflers and even wood.
Skyway Stage 3 to be upgraded now
Because of the spate of flyby and flyover accidents on Stage 1, San Miguel Infra and Citra Metro Manila Skyway, announced that Skyway Stage 3 will already incorporate greatly improved parapets along the entire length of their newest elevated highway. A retrofit of Stage 1 and 2 is already in the planning stage.
That pesky launch curb
But what is most instructive is again courtesy of eagle eyed motorists posting on social media. Skyway Stage 1 and 2 have black and yellow curb side concrete embankments beside the parapets. If a bus or a car were to hit the railing with a side-swipe glancing blow, the concrete embankments function by bouncing the car or bus back to the carriageway. But if the car or bus comes from an uncontrollable spin and eventually aims dead straight at the embankment, it will serve as a launching ramp, sending the vehicle up – like in the “hanging” Strada with the shredded tire – or worse over the barrier and onto the road below - just like the flying “stani” Montero Sport and the Don Mariano bus of fairly recent memory.
Ideas from the old North Diversion Road
Ironically, our country has a much older elevated 5.0km expressway which, being arrow straight and if not radar monitored, can allow very high speeds, never had any flyover accidents in the nearly 40 years of its existence. It was built with ADB financing during the resource and dollar scarce years of the late 70s. In fact, because of PBM's [Phil. Blooming Mills] steel shortage that time caused by Mdme Imelda Marcos's “Gran Projets” [Experimental Cinema, Makiling Nat'l Arts center, FAT, etc.] imported ARMCO or tubular guard rails were substituted with concrete Freysinet guard rails on the earth filled expressway sections. This was the Candaba Viaduct.
Lessons from the Candaba Viaduct
Because of the said steel shortages then, NORCONSULT, a Norwegian company hired by PNCC suggested that all the NDR bridge parapets be made of concrete but shaped in such a way that a ledge molded top side to prevent launching a crashing vehicle airborne. The square section tubular steel railings on top of the parapets of the Viaduct were added much later in the Viaduct's life, long after it survived the shaking and bouncing of the 1991 Earthquake. To this, day, there haven't been any flyover accidents.
A taste of Norway
The old North Diversion Road [NDR] extension from Balagtas, as it was known then, had a lot of novel features like the road gradient that tilted the pavement to right not only to allow drainage to the shoulder but to “guide” steering feel away from the central divider and prevent a dozing driver from crashing head on to opposing traffic across the median. True to NORCONSULT's Scandinavian roots, the initial reflectorized warning signs of the '78 NDR, made by GJB, had yellow-orange backgrounds with red roundels as opposed to the usual white backgrounds. The yellow-orange, similar to road works signage color and vehicle hazard blinking lights, provided a high traffic visibility contrast to fog bound and snow covered backgrounds in Scandinavia. Which works just as well here against a background of monsoon downpours.
Ideas from the past- oldies but goodies
Destination signs then followed a road map format instead of today's less elegant signs that list destinations without showing directions and distances. Expressway info signs had white characters on blue backgrounds while National highways that intersected with the NDR had signs with yellow backgrounds and black characters. These have all disappeared, replaced, albeit inconsistently, by green backgrounds eliminating the distinction between expressway and national highway. Instead of small arrows, destinations had large chevrons and the signs themselves were shaped to trace the chevron's arrowhead.
Mixing the old with the new
Improving safety, rainy weather visibility and preventing spectacular flyover accidents on the Skyway won't need all new technology and draconian anti-speeding enforcement. Indeed, the porous asphalt might help, but some old ideas, borrowed from the North Diversion's NORCONSULT origins – like the bridge parapet shape and size- could be a simple remedy for Stage 3. In the meantime, demolishing those “launch curbs” on Stage 1 and 2 may cause too much traffic disruption. Retrofitting double height ARMCO barriers, like what the US federal authorities and EU road authorities are doing, will be just as effective and quicker to install, making the Skyway to finally be a “No Fly” zone.