(Figure 1) In 2001 I presented to this association the directions of traffic that could be determined archaeologically in Pompeii’s sixth region. It was demonstrated that several broad streets such as Via Consolare, Via delle Terme, Via di Mercurio, and Via della Fortuna carried, unsurprisingly, two-way traffic. (Figure 2) More importantly, however, the Vico di Mercurio, which transects the region from Via del Vesuvio to Via Consolare, was shown to be a one-way street flowing westbound. Every field season since has added more information about the movement of vehicles in the ancient city and has bolstered the methodology with new forms of evidence. Not all of this evidence, however, has been complimentary to the previous interpretation. The current paper is a re-examination of the Vico di Mercurio in light of these new methods and the new complexity they have brought to the data. It is also a discussion on the possible motivations for what the new evidence demonstrates. To phrase this as question: why did the direction of ancient cart traffic on the Vico di Mercurio switch from eastbound to westbound? Two hypotheses were presented and considered during the 2004 field season. These were 1) the repaving of the area surrounding the Casa del Fauno and 2) the construction of the Central Baths.

(Figure 3) Let us begin at the corner of Vico di Mercurio and Via Consolare. On the north curb is a stone with a parabola-shaped wearing pattern that is diagnostic of the direction of traffic. (Figure 4) Here’s how it works: as carts repeatedly made right turns, they brought their wheels into contact with the curbstone and, while moving forward, the iron rims of these wheels ground out a necessary and identifiable pattern. From this pattern we can recognize westbound carts on Vico di Mercurio turning north onto Via Consolare.

Marks made by carts overriding the same location were also diagnostic of direction. (Figure 5) Stepping-stones were the street feature most commonly overridden, but (Figure 6) curbstones and narrowing stones also preserve this form of evidence. In region VI, the evidence demonstrates a systematic use of Vico di Mercurio to carry traffic west between Via del Vesuvio and Via Consolare. (Figure 7) The previous argument used strong rutting to connect the directional evidence found at the intersections, such as the diagnostically worn curbstones at Via di Mercurio and at Vico dei Vettii in order to show this organization. However, since the reading of that paper, new and seemingly contradictory evidence has continued to appear on Vico di Mercurio. (Figure 8) Beginning in the west, we can see wearing on the south face of the northwest corner curbstone at Vico di Modesto that suggests eastbound traffic. (Figure 9) Likewise, the northeast corner curbstone is worn on its west face, with complementary wear on the stepping-stone, which could be from south-to-east turning carts. (Figure 10) However, the south face of the same curbstone is also worn which makes west-to-north turns equally likely.

(Figure 11) Farther east, where the Vico meets the Via di Mercurio the evidence is anything but equivocal. (Figure 12) There is an unmistakable overriding mark on the stepping-stone caused by eastbound traffic. (Figure 13) This is corroborated by strong wear on the north face of the southwest corner curbstone. (Figure 14) At the southeast corner of the same intersection, there is some suggestion that north-to-east turns occurred from the wear on the west face, but as we will soon see, the majority of the evidence here is from westbound carts.

(Figure 15) The paving on Vico del Fauno where it meets Mercurio was left unfinished at the time of the eruption and much of the evidence for traffic is also missing. The wearing on the northeast corner curbstone is discernable, but not definitive proof of a turn in either direction. Such is the situation with the corner curbstones at Vico del Labirinto, where two of the four show evidence that they are not in situ while another is missing altogether. (Figure 16) Only the northeast corner has reliable evidence and it shows both south-to-east and west-to-north turns.

The easternmost intersections of Vico di Mercurio also provide evidence for eastbound traffic. (Figure 17) At Vico dei Vettii there is an overriding mark on the stepping-stone east of the intersection that demonstrates the eastward movement of vehicles. (Figure 18) Finally, Vico di Mercurio ends at Via del Vesuvio where the southwest corner is angled dramatically to accommodate an east-to-south turn. (Figure 19) This turn is further supported by the strong if non-directional wear on the north face of the corner curbstone. (Figure 20) Likewise, the wearing curves around the northwest corner curbstone baring out an east to north turn [1] (Figure 21) Finally, the southeast corner curbstone is worn around both the north and west faces, evidencing in all probability both a north-to-east turn as well as a west-to-south turn.

(Figure 22) Individually, only a few of these wear marks are proof of eastbound traffic, but together with the circumstantial evidence they make a very strong case for an easterly direction on Vico di Mercurio. There are three ways to interpret these data in relation to the earlier arguments for westbound traffic: 1) that those earlier arguments are wrong and Vico di Mercurio carried only eastbound traffic; 2) that earlier arguments were incomplete and Vico di Mercurio carried an alternating flow of both east and westbound traffic; or, 3) that one pattern is older than the other and the Vico di Mercurio reversed its direction. As we now track back west towards Via Consolare the evidence for westbound traffic will be examined with particular focus on that evidence which supports the last interpretation: namely, that this street switched from carrying eastbound to carrying westbound traffic. 

(Figure 23) We actually begin farther east at the southwest corner of Via delle Nozze d’Argento and the street V.1 / V.2, where the curbstone preserves wearing marks including an overriding mark diagnostic of a north to west turn. (Figure 24) Back at the intersection with Via del Vesuvio, the westerly direction is again demonstrated by a small overriding mark on the northeast corner of the southern stepping-stone. (Figure 25) The overriding mark is of particular interest because it was developing over the top of the wearing from east-to-south turns on the stepping-stone. Here is the first direct evidence [2] for the reversal of direction on Vico di Mercurio, as one pattern of traffic is seen stratigraphically overlaying another.

(Figure 26) Moving west again to where Vico di Mercurio meets the Vico dei Vettii, we see strong evidence on the northeast corner curbstone. Wearing on the south face cuts into the stone and ends at the west face, again showing the western direction of cart travel. (Figure 27) The same kind of wearing is found at the northwest corner, showing a south to west turn. (Figure 28) At the intersection with Vico del Labirinto there is the second direct piece of evidence for the reversal. Here, the northeast corner curbstone worn in much the same way as the northeast corner curbstone at Vico dei Vettii [3] , which we have just discussed. (Figure 29) However, in this instance the diagnostic wearing on the south face ‘lips’ around onto the west face which already has wearing on it. Although not definitively directional, the overlapping of the west face wear shows a definite change in pattern. Moreover, since this stone is in situ, it is hard to explain how wearing in this location could have occurred if the supposition of earlier south-to-east turns is not accepted.

(Figure 30) Reaching Via di Mercurio, the evidence for westbound traffic is the strongest west of Via Consolare. The northeast corner curbstone preserves a diagnostic wearing pattern. [4] (Figure 31) In addition, the north face of the southeast curbstone is worn diagnostically from west-to-south turns. (Figure 32) Finally, the east side of the stepping-stone has an overriding mark from carts moving west on Vico di Mercurio. The southeastern curbstone is also important, like the curbstone at Vico del Labirinto, because its wear pattern cuts another pattern on the west face of the same stone. In this case, however, the wear is very suggestive of a previous north-to-east turn, an idea that is further bolstered by the overriding mark on the western stepping-stone ensuring that a flow of eastbound carts at one time passed through (or at least into) this intersection. And again, it is difficult to imagine how this pattern of wear could occur on the west face without north-to-east turning carts.

(Figure 33) Most important, however, is the wearing on the narrowing-stone situated at the northwest corner of the intersection. This small stone is set against the east face of the northwest corner curbstone and is blocking the wear on the south face of the same stone. (Figure 34) The narrowing-stone itself has wear on its east face that is carried around to the south face indicating a south-to-west turn. This evidence is a direct contradiction to the eastbound wearing marks on the stepping-stone and southwestern curbstone at this intersection. Moreover, the narrowing-stone is positioned such that it would block the wear found on the south face of the northwest corner curbstone and prevent it from continuing to accrue there. If the northwest corner curbstone is in situ (and it is possible that it is not) then we have our third piece of direct evidence for reversal of Vico di Mercurio.

(Figure 35) Vico del Fullonica is the next intersection to the west, but it is largely disturbed and the curbstones are missing on the south side. (Figure 36) Vico di Modesto, however, does preserve evidence for westbound traffic, despite the absence of its southwest corner curbstone. We have already discussed the wear on the south face of the northwest corner curbstone as being suggestive of east-to-north turns. The east face of the same stone is also worn, possibly from a south-to-west turn. (Figure 37) Crossing the intersection diagonally, the southeast corner curbstone is also worn on both its west and north faces. In this case, the diagnostic pattern on the north face begins to wrap around to the west face and cuts into another, likely earlier pattern of wear on the west face. (Figure 38) The westbound evidence is further supported by an overriding mark on the southeast corner of the stepping-stone. These two corner curbstones are the fourth and fifth pieces of direct evidence for the reversal of the Vico di Mercurio.

(Figure 39) In tracing the evidence for the reversal, it becomes possible to see traffic in Pompeii not only as a system, but as a living system, evolving and adapting to the city’s needs. But what caused this reversal? What caused it, of course, was the decision of the person or body in charge of regulating traffic. This is borne out in the evidence. However, the motivations for this decision may also be visible archaeologically. Two main hypotheses were considered and tested on the ground.

(Figure 40) The first motor for change considered was the repaving of the area surrounding the Casa del Fauno. As was mentioned earlier, the Vico del Fauno was in the process of being repaved at the time of the eruption. (Figure 41) The southern half of the street is set with unrutted metaling, while the northern section is unfinished. Vico del Labirinto borders the Casa del Fauno on it east side and is also completely free of ruts. (Figure 42) This is certainly due to the large upright stone which blocked access to this street from the Via della Fortuna. (Figure 43) At the intersection of Vico del Labirinto and Vico di Mercurio a fountain constricts the street to a narrow channel just barely wide enough for the smallest carts to pass. [5] Vico di Mercurio itself was repaved along the north of the Casa del Fauno. (Figure 44) The strong lines of the paving junctures are not visible as they are at the intersections of Vico del Labirinto and Vico del Fauno at Via della Fortuna. (Figure 45) Still, the repave can be noted in the depth of rutting on either side of this area and the relative absence of rutting within this area. Thus, we can see that the streets on three sides of the Casa del Fauno were repaved or in the process of being repaved. Moreover, carts were almost completely barred from Vico del Labirinto.

Whatever the cause of this repaving project, the interruption of traffic on Vico di Mercurio during the reconstruction was certainly an effect. The interruption would have required that a series of detours be used and perhaps served as the motivation for the reversal of direction on the Vico di Mercurio. However, after further consideration this seems unlikely. First, because the time that it would have taken to replace the paving stones in such a small section of Vico di Mercurio would have been relatively short, it seems temporary detours would have sufficed. Moreover, it is not at all clear how reversing the direction of traffic would have helped the situation. Finally, there is only weak circumstantial evidence to connect the reversal to the repave. That is to say, while the event had a direct effect on the movement and order of traffic on this street, that effect was temporary and does not seem sufficient to alter the flow of vehicles permanently across the entire northwest of the city.

(Figure 46) The second hypothesis is that the construction of the Central Baths caused the reversal. While the Central Baths may seem to be at some distance from Vico di Mercurio, the construction of this building has had direct effects on the movement of vehicles in the ancient city. (Figure 47) This is demonstrated most dramatically in the suppression of two streets surrounding the baths; the Vico di Tesmo in the west and the street IX.4 / IX.3 in the south. Although the latter street was a relatively minor route in the overall system of traffic, when the footprint of the Central baths overtook a portion of this street’s space, it became unusable. (Figure 48) In fact, where IX.3 / IX.4 intersects Via Stabiana the opening for the street has been filled in with curbstones. Wearing from both pre- and post construction periods is evident here as well. (Figure 49) On those stones that were originally corner curbstones before the blockage there is evidence that this street carried an alternating flow of east and westbound traffic. The south face of the former northern corner curbstone is worn from west-to-north turning carts. Likewise, the west face of the former southern corner is worn from north-to-east turns.

(Figure 50) The effects of this street’s suppression are minor and local. The closure of the northern section of Vico di Tesmo, however, had ripple effects across the city’s traffic system. Looking at the map, we can see that  this street connected two of the most important thoroughfares in the ancient city,  Via di Nola and Via dell’Abbondanza. It also intersects the Via Mediana which connects all the way to the Porta Marina. Most importantly, it paralleled the Via Stabiana, and offered an alternate route to that main artery of traffic, especially at major intersections.

(Figure 51) On the ground, even a cursory glance at the intersection of Via di Nola and Vico di Tesmo illuminates the importance this street once had in the flow of traffic. Deep ruts curve into the intersection and strong wearing is present on both the corner curbstones and stepping-stones. In fact, the southwest corner is dramatically angled to facilitate east-to-south turning traffic and the corner curbstone is strongly worn on from its north around to its east face. (Figure 52) The northwest corner of the western stepping-stone is very strongly worn from west-to-south turning carts, including an overriding mark diagnostic of southbound traffic.

(Figure 53) The southbound direction on Vico di Tesmo is further evidenced by the diagnostic wear on the northeast and northwest corner curbstones at the intersection with Via Mediana. (Figure 54) The strong wear on the east face of the southwest corner curbstone is the product of southbound carts which did not adjust fully for the jog in the street. Corroboration is found in following the ruts as they pass the diagnostic evidence in the north before crossing the intersection and sliding along the southwest curbstone, which also has some indication of east-to-south turns on the north face. (Figure 55) Furthermore, the stepping-stone in the south has overriding marks on its north face.

(Figure 56) One block south, at Vico di Balbo, the southwest corner is rounded to be hardly a corner at all, but still offers evidence of east-to-south turning carts again associated with rutting. (Figure 57) Finally, the evidence for southbound traffic on Vico di Tesmo culminates at the intersection with Via dell’Abbondanza. Although both corners angle to the east and west to facilitate turns, there is only weak evidence on the northwest corner curbstone to actually demonstrate such turns.

On the other hand, there is very strong evidence for northbound vehicles at this intersection. (Figure 58) For example, the south face of the northeast corner curbstone is worn diagnostically from west-to-north turns and (Figure 59) there is an overriding mark on the southwest side of the stepping-stone. (Figure 60) Back at Balbo there is wear at the southwest corner, actually on the opposite side of the very same stone that has the southbound evidence, which shows the north-to-west turning carts. (Figure 61) In addition, there is diagnostic evidence for west-to-north turning traffic at the west end of Vico di Balbo where it empties into Via Stabiana. (Figure 62) The most important feature, however, is the large upright stone cut into the pavement that stands between the ruts made by previous southbound carts. [6]

So the reversal of Vico di Tesmo is also now visible archaeologically and its cause is undoubtedly the construction of the Central Baths. (Figure 63) Once the baths blocked southbound carts at their most important source, the Via di Nola, those same carts were forced onto the Via Stabiana. (Figure 63a) Where once carts could exit for eastern parts of the city by a left turn onto Via dell’Abbondanza, now they had to maneuver though the busiest intersection in the entire city; Via dell’Abbondanza and Via Stabiana. (Figure 63b) The solution to the inevitable congestion was to detour northbound carts up Vico di Tesmo and onto Via Stabiana by way of Vico di Balbo in order to take the pressure off the Abbondanza / Stabiana intersection.

Now that we know that the construction of the Central baths caused the direction of traffic on one street to be reversed, it is more likely that the same cause reversed the Vico di Mercurio. (Figure 64) The case is made even stronger by being able to tie Vico di Mercurio to the Central Baths physically in the object of the Vico V.1 / V.2. Connecting the Via delle nozze D’Argento, where we have already discussed evidence of north-to-west turning carts, to Via di Nola, this street is effectively the northern extension of Vico di Tesmo.

Thus, it would not be surprising to learn that there is evidence indicating this street also saw a reversal of its direction. (Figure 65) The northeast corner curbstone at Via di Nola has wear on its west face that cuts around to the south face suggesting a south-to-east turn. (Figure 66) Wear from the wheel on the outside of the turn is seen on the southeast corner of the stepping-stone, supporting the curbstone evidence. The same location would have received wear from the proposed west-to-north turns, evidence of which can be found back at the northeast corner curbstone’s south face. (Figure 67) It is also no coincidence that the detour up Vico V.1 / V.2 and away from the congested intersection of Stabiana / Nola mirrors the southern detour already discussed up Vico di Tesmo and away from the Abbondanza  / Stabiana intersection. [7]

The Central Baths is both situated within and is a vital component of these smaller, subset systems of detour.  Although its design called for only a mere meter more than the insula had to offer, the effects of the Central Baths’s construction reverberated across the city. Indeed, the fix for the suppression of the Vico di Tesmo at Via di Nola was found four blocks to the south at the Via dell’Abbondanza. But for the magistrate in charge of managing this effect on the system of traffic, the interconnectedness of the streets forced him to also flip the direction of the southern extension of Tesmo, just has he had to do for the northern extension in Region V. (Figure 68) Finally, if Vico di Mercurio and Via delle nozze d’Argento remains eastbound, no congestion relief can occur at the Stabiana / Nola intersection, and the Vico V.1 / V.2 becomes an functionless appendix in the body of Pompeii.

In conclusion, I would like to say a few things about the big picture. What the preceding tour of curbstones and wear marks adds ups is a discernable pattern of traffic within the ancient city. The consistency of the information is also of note. In the first place, this coherence among the data shows unequivocally that the Romans drove on the right. In addition, the presence of one-way streets and pressure relieving detours demonstrates that an effective organization was in place to maintain the free flow of vehicles. The reversal of Vico di Mercurio and well as several other streets directly of indirectly affected by the construction of the central baths, however, shows that large scale changes could and did reorder that organization. The inescapable implication is that the traffic system was carefully managed by a central, executive individual or group at the municipal level. Finally, this research identified two distinct motors for such changes. The first, possibly a private endeavor, affected the physical structure of the streets, while the second was a massive public undertaking with effects rippling across Pompeii.