The San Fellipe-Mexicali Highway

San Felipe, Baja, Mexico

The Highway from Mexicali to San Felipe - October 23, 2007

Highway 5 from Mexicali to San Felipe has always been a cosmetologist's nightmare. The road surface is in a perpetual state necrotizing fasciitis, a kind of bituminous apshalt-eating disease. Due to the increased traffic resulting from the local real estate and development activity -higher numbers of heavy freight trucks, mobile homes and RVs -the road surface has incurred an accelerated course of stress and fatigue.

The New Meets the OldThe road repair crews have made an effort to stay on top of it. But until recently, their solution was to mix up a pot of asphalt and dump it into a pothole, leaving it proud so the tires of passing cars could flatten it level with the road.

Earlier this year Mexicali committed several scrapers, rollers and pavers to applying new asphalt coats to several areas of the highway.

Entering Mexico through the old border crossing, the traffic moves efficiently because of the overpasses built in the last few years. New large and readable road signs indicate the direction to San Felipe are a welcome addition to Mexicali's ongoing makeover. But these signs revert to their tired predecessors at the last circle intersection and it requires some intuition to realize you need to be in the right or center lane to make the angled exit that crosses the railroad tracks. There is a stop sign just before the tracks, which no one observes. It's a good idea to stop here, if only briefly, to avoid a traffic ticket from any lurking police who use the traffic flow as a lure.

Road surfaces in Mexicali vary, but on the route to San Felipe they are pebbly and at places offer a selection of drained varicose veins. The traffic is always frenetic when passing through the city. Cars, trucks and buses commit to rapid lane changes without the virtue of signaling. Horns are sounded and lights are flashed to motivate any hesitant pilgrim.

At the southern outskirts of Mexicali, near the shoulder sign indicating 190 kms to San Felipe, the 4 lane road surface smoothes out into new blacktop, in places baptized by the blood of the ubiquitous dead canine.

At kilometer 17 the new blacktop reverts to old asphalt for 4 kilometers then magically smoothes to new surface again. At kilometer 35 the highway is old again, made drivable by numerous patches.

Just past the Algadones turnoff, the highway funnels into two lanes (north/south) and immediately offers up a recently applied layer of asphalt. As the foothills approach and the highway begins its twists and mountain turns, an extraordinary sight greets the windshield on a particularly curvaceous trajectory. A shiny new guardrail. This is a nod toward traffic safety that for generations has been conspicuously absent between Mexicali and San Felipe. The gift is largely symbolic, however. The majority of highway switchbacks and twisting shoulders remain unpromoted by the steel epaulets and offer only a brief panoramic delight before sending a driver with attention deficit disorder sailing toward his or her crucifix at the bottom of an arroyo or ravine. It would appear it will be some time yet before sufficient guardrails are erected to separate the living from the collections of crosses beyond them.

Past Cucapa Mayor the road surface is so new the lanes have yet to be painted. But the fresh asphalt is short-lived and the road returns to old surface. The 'causeway', that long stretch crossing the dry southern remnant of Laguna la Salada at around km 91, has a short swath of old road top at both ends and is most new asphalt in between.

The highway does a leapfrog presentation of new and old road surface for most of its remaining run to San Felipe. There are areas that sport a new coat of asphalt for three or four kilometers only to fall back on stretches of disrepair. In a few places, particularly south of km 158, potholes yawn with the boredom of the neglected.

Pot Luck HwyOnce past the drugs and arms inspection campment near kilometer 44, the area shows signs of exploitation and profit-mining. Billboards announce future and fledgling developments. Hyperbole and exaltation are their sales idioms and they share the same DNA as any billboard that has graced an arid, desolate landscape prior to its occupation by confidence people.

Roadbed preparations for another two lanes make an appearance around km 169, south of which spread an array of real estate billboards all the way to San Felipe. El Dorado heralds a short stretch of usable 4 lane but the true division of north and south traffic appears near km 181. The final six miles into San Felipe reflect meridians and boulevards, yet to be landscaped. Major or future influential intersections bristle with lamp standards and turn offs. It would seem the north campos are to have the black carpet treatment.

Entry into town remains two lane but is channeled to the Malecón through an endless series of stop signs. Prior to that the lane markings are confused, old lines from prior single lane careers showing through the newer paint. It's best to judge your lane by the shoulders and hazard sign locations rather than follow a streak of pigment into a concrete boulevard buttress.

Since San Felipe has been targeted by F.O.N.A.T.U.R - National Trust Fund for Tourism Development - to be one of Baja's great resort destinations, one would think tourist attractions would be linked to the their targets by healthy roads. Apparently this isn't the case. Or perhaps the machinery required to develop an area is inimicable to asphalt to the extent the roads are not worth repairing until the final deed is done, much as laying carpet in a newly built home is the last stage of construction.

So why is the old highway wearing out?

Asphalt, a brownish-black goo of hydrocarbons left over from oil refining, acts as the glue that holds together a mix of rocks and sand to form paving material. When asphalt, or indeed any material, experiences stress, the bonds between adjacent atoms or molecules break apart, forming microscopic cracks. If the stress continues, these tiny cracks grow and coalesce into big cracks. Vibration measurements show that highways lose their structural integrity long before you can see cracks on the surface. This emphasizes the need for the early maintenance of roads to prevent their deterioration.

6 miles north of San FelipeThe average life span of an asphalt highway is 20 years. In the United States, research is underway to develop tests that will yield specifications that'll allow a highway's longevity to be predicted with a greater degree of accuracy. Modified binder research will help to develop an adhesion for the aggregates that will last beyond the current life span. Binders function as an inexpensive, waterproof, thermoplastic adhesive. In other words, they act as the glue that holds the road together. Scientists are now introducing polymers into the binder mix to develop a self-healing brand of asphalt

Subgrade preparation, base selection, drainage design, thickness design, joint design, and shoulder characterization are obviously of immense importance as well. A road will deteriorate quickly without the necessary support.

Texas has come up with the Superpave binder specification. It classifies binders into performance grades, based on a range of climates and pavement temperatures. The physical properties required for the binder are the same for all grades, but the temperature at which those properties must be attained is determined by the specific climatic conditions at the paving location. The specification applies to all unmodified binders and many modified binders.

The tests mimic actual environmental and traffic conditions at the project site. The results of the dynamic shear test indicate the binder's ability to withstand permanent deformation (which is often evidenced as rutting in the pavement) and fatigue cracking. The bending beam test results are used to predict low-temperature cracking problems. The results of the direct tension test provide additional information on how the hinder will perform at low temperatures.

The Superpave system includes mix analysis procedures that predict how well a mix will perform in the field. These procedures are intended to provide additional information on asphalt mixes that will be placed in pavements with very high traffic volumes and loads. Two new, sophisticated pieces of laboratory equipment -the Superpave shear tester and the indirect tensile tester -are used to measure specific engineering properties of the laboratory-compacted asphalt mix. The test results are then entered into software models that predict how many equivalent single-axle loads the pavement will carry, or how much time will elapse, before a certain level of rutting, fatigue cracking, or low-temperature cracking develops.

Superpave binders are designated with a "PG" (performance grade) rating. The first number in the rating indicates the high-temperature grade; the second indicates the low-temperature grade. For example, a binder classified PG58-28 would meet the required physical properties at pavement temperatures as high as 58 degrees C and as low as -28 degrees C. The mix designer selects a Superpave binder based on the climate in which the pavement will serve and the traffic it will bear.

Before the existing highway is mollified by a thin sheet of asphalt ironed onto its existing defects, maybe the Mexican government will become more interested in the science of avant asphalt technologies and gift to our area an avenue of transportation that will gracefully grow old with the town of San Felipe. Hey, we can always hope, can't we?